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899 results on '"Capitani G."'

1. Azimuthal single- and double-spin asymmetries in semi-inclusive deep-inelastic lepton scattering by transversely polarized protons

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Bacchetta, A., Belostotski, S., Bryzgalov, V., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Gavrilov, G., Gharibyan, V., Holler, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Kinney, E., Kisselev, A., Kozlov, V., Kravchenko, P., Lagamba, L., Lapikás, L., Lenisa, P., Lorenzon, W., Manaenkov, S. I., Marianski, B., Marukyan, H., Miyachi, Y., Movsisyan, A., Muccifora, V., Naryshkin, Y., Nass, A., Nazaryan, G., Nowak, W. -D., Pappalardo, L. L., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Statera, M., Terkulov, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vilardi, I., Yaschenko, S., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology, Nuclear Experiment
Abstract

A comprehensive set of azimuthal single-spin and double-spin asymmetries in semi-inclusive leptoproduction of pions, charged kaons, protons, and antiprotons from transversely polarized protons is presented. These asymmetries include the previously published HERMES results on Collins and Sivers asymmetries, the analysis of which has been extended to include protons and antiprotons and also to an extraction in a three-dimensional kinematic binning and enlarged phase space. They are complemented by corresponding results for the remaining four single-spin and four double-spin asymmetries allowed in the one-photon-exchange approximation of the semi-inclusive deep-inelastic scattering process for target-polarization orientation perpendicular to the direction of the incoming lepton beam. Among those results, significant non-vanishing $\cos{\phi-\phi_S}$ modulations provide evidence for a sizable worm-gear (II) distribution, $g_{1T}$. Most of the other modulations are found to be consistent with zero with the notable exception of large $\sin{\phi_S}$ modulations for charged pions and positive kaons.

Published
2020

2. Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Belostotski, S., Blok, H. P., Bryzgalov, V., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Deconinck, W., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Gapienko, G., Garibaldi, F., Gavrilov, G., Gharibyan, V., Hillenbrand, A., Holler, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Manaenkov, S. I., Marianski, B., Marukyan, H., Movsisyan, A., Muccifora, V., Nass, A., Nazaryan, G., Nowak, W. -D., Pappalardo, L. L., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Ryckbosch, D., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Statera, M., Terkulov, A., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vilardi, I., Vogel, C., Yaschenko, S., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

A measurement of beam-helicity asymmetries for single-hadron production in deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV electrons and positrons off gaseous hydrogen and deuterium targets were collected by the HERMES experiment. The asymmetries are presented separately as a function of the Bjorken scaling variable, the hadron transverse momentum, and the fractional energy for charged pions and kaons as well as for protons and anti-protons. These asymmetries are also presented as a function of the three aforementioned kinematic variables simultaneously.

Published
2019
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3. Recycling thermally deactivated asbestos cement in mortar: A possible route towards a rapid conclusion of the “asbestos problem”

Author

Capitani, G, Dalpiaz, M, Vergani, F, Campanale, F, Conconi, R, Odorizzi, S, Capitani G., Dalpiaz M., Vergani F., Campanale F., Conconi R., Odorizzi S., Capitani, G, Dalpiaz, M, Vergani, F, Campanale, F, Conconi, R, Odorizzi, S, Capitani G., Dalpiaz M., Vergani F., Campanale F., Conconi R., and Odorizzi S.

Abstract

The "asbestos problem" arises from the fact that asbestos is still abundant in many buildings and represents a hazard for human health. Current strategies adopted by law aiming at mitigating this hazard are far from being ideal. A smarter solution would be an energy sustainable detoxification treatment followed by recycling. If adopted, it would preserve the environment from pollution, natural resources from depletion and human health from hazard. Asbestos -cement slates were thermally deactivated through a sustainable process and reused in mortar for plaster applications. We found that the addition up to 7 wt% of the deactivated product does not affect significantly the water demand; does not affect thixotropy, stickiness and spreadability of the plastic mixture; slightly increases the strength of the mortar; does not compromise mechanical properties after aging. Considering the huge amount of traditional mortar employed worldwide, a rapid end of the "asbestos problem" is envisaged.

Published
2024

4. The use of honey bees (Apis mellifera L.) to monitor airborne particulate matter and assess health effects on pollinators

Author

Papa, G, Pellecchia, M, Capitani, G, Negri, I, Papa G., Pellecchia M., Capitani G., Negri I., Papa, G, Pellecchia, M, Capitani, G, Negri, I, Papa G., Pellecchia M., Capitani G., and Negri I.

Abstract

The honey bee Apis mellifera has long been recognized as an ideal bioindicator for environmental pollution. These insects are exposed to pollutants during their foraging activities, making them effective samplers of environmental contaminants, including heavy metals, pesticides, radionuclides, and volatile organic compounds. Recently, it has been demonstrated that honey bees can be a valuable tool for monitoring and studying airborne PM pollution, a complex mixture of particles suspended in the air, known to have detrimental effects on human health. Airborne particles attached to the bees can be characterised for their morphology, size, and chemical composition using a scanning electron microscopy coupled with X-ray spectroscopy, thus providing key information on the emission sources of the particles, their environmental fate, and the potential to elicit inflammatory injury, oxidative damage, and other health effects in living organisms. Here, we present a comprehensive summary of the studies involving the use of honey bees to monitor airborne PM, including the limits of this approach and possible perspectives. The use of honey bees as a model organism for ecotoxicological studies involving pollutant PM is also presented and discussed, further highlighting the role of the bees as a cornerstone of human, animal, and environmental health, according to the principles of the “One Health” approach.

Published
2024

5. Boosting of the water-mediated mineral carbonation by microwave chemistry

Author

D’Alessio, D, Corti, M, Campione, M, Capitani, G, Lucotti, A, Yivlialin, R, Tommasini, M, Bussetti, G, Malaspina, N, D’Alessio D, Corti M, Campione M, Capitani G., Lucotti A, Yivlialin R, Tommasini M, Bussetti G, Malaspina N, D’Alessio, D, Corti, M, Campione, M, Capitani, G, Lucotti, A, Yivlialin, R, Tommasini, M, Bussetti, G, Malaspina, N, D’Alessio D, Corti M, Campione M, Capitani G., Lucotti A, Yivlialin R, Tommasini M, Bussetti G, and Malaspina N

Published
2024

6. Longitudinal double-spin asymmetries in semi-inclusive deep-inelastic scattering of electrons and positrons by protons and deuterons

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Belostotski, S., Blok, H. P., Borissov, A., Bryzgalov, V., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Frullani, S., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Hasch, D., Holler, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lorenzon, W., Ma, B. -Q., Mahon, D., Manaenkov, S. I., Mao, Y., Marianski, B., Marukyan, H., Miyachi, Y., Movsisyan, A., Muccifora, V., Mussgiller, A., Naryshkin, Y., Nass, A., Nazaryan, G., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schnell, G., Seitz, B., Shibata, T. -A., Statera, M., Steffens, E., Steijger, J. J. M., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., van der Nat, P. B., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

A comprehensive collection of results on longitudinal double-spin asymmetries is presented for charged pions and kaons produced in semi-inclusive deep-inelastic scattering of electrons and positrons on the proton and deuteron, based on the full HERMES data set. The dependence of the asymmetries on hadron transverse momentum and azimuthal angle extends the sensitivity to the flavor structure of the nucleon beyond the distribution functions accessible in the collinear framework. No strong dependence on those variables is observed. In addition, the hadron charge-difference asymmetry is presented, which under certain model assumptions provides access to the helicity distributions of valence quarks.

Published
2018
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7. Ratios of helicity amplitudes for exclusive $\rho^0$ electroproduction on transversely polarized protons

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Belostotski, S., Blok, H. P., Borissov, A., Bryzgalov, V., Capitani, G. P., Ciullo, G., Contalbrigo, M., Deconinck, W., De Leo, R., De Sanctis, E., Düren, M., Elbakian, G., Ellinghaus, F., Felawka, L., Frullani, S., Garibaldi, F., Gavrilov, G., Gharibyan, V., Goloskokov, S. V., Holler, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Kroll, P., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Manaenkov, S. I., Marianski, B., Marukyan, H., Miyachi, Y., Movsisyan, A., Muccifora, V., Nass, A., Nowak, W. -D., Pappalardo, L. L., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Ryckbosch, D., Salomatin, Y., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Statera, M., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Yaschenko, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Exclusive $\rho^0$-meson electroproduction is studied by the HERMES experiment, using the 27.6 GeV longitudinally polarized electron/positron beam of HERA and a transversely polarized hydrogen target, in the kinematic region 1.0 GeV$^2$

Published
2017
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9. Recycling thermally detoxified asbestos-cement in stone-wool: An end-less-life material!

Author

Capitani, G, Vergani, F, Conconi, R, Mrvar, P, Bombač, D, Perše, L, Oseli, A, Bizjan, B, Perše, L. S, Capitani, G, Vergani, F, Conconi, R, Mrvar, P, Bombač, D, Perše, L, Oseli, A, Bizjan, B, and Perše, L. S

Abstract

Deactivated (detoxified) asbestos-cement (DAC), i.e. asbestos-cement slates thermally treated at 1100 °C in order to convert the harmful asbestos fibers into non harmful mineral phases, has been successfully mixed with 74.6 wt% quartz sand and up to 63.2 wt% basalt sand, to produce stone wool with mechanical properties and composition competitive with commercial stone wool. The sample with 50 % DAC and 50 % basalt provided the best comparison with commercial stone wool in terms of liquidus temperature (lower than for the other mixtures) and Young's modulus (higher). Through further composition optimization and utilization of multiple components, we estimate that future batches could utilize 70–75 % of DAC. These promising results and expectations highlight a feasible reuse of DAC as secondary raw material for stone wool production and a possible route to the elimination of a toxic waste from the environment and the preservation of primary raw materials.

Published
2024

10. Polyethylene glycol-assisted hydro-solvothermal growth of anisotropic magnetic iron oxides: The role of mixed environment conditions

Author

Bona, G, Bragaggia, G, Cantoni, M, Di Credico, B, Mostoni, S, Capitani, G, Scotti, R, Gross, S, Nistico', R, Bona, G, Bragaggia, G, Cantoni, M, Di Credico, B, Mostoni, S, Capitani, G, Scotti, R, Gross, S, and Nistico', R

Abstract

In this study, an alternative mixed hydro-solvothermal route has been investigated for the synthesis of magnetic iron oxide nanoparticles with anisotropic shape. The synthesis was performed at mild conditions (150 °C) in a water/2-propanol environment, using poly(ethylene glycol) (PEG400) as structure directing agent, sodium thiosulfate as reducing agent, and NaOH as precipitating agent. The resulting systems were characterized by combining morphological, structural, and magnetic techniques. Experimental results clearly demonstrate that magnetite/maghemite nanorods are preferentially obtained in water/PEG400 environment, whereas 2-propanol/PEG400 environment promotes the growth of magnetite/maghemite polyhedral systems. Interestingly, synthesis performed in a mixed hydro-solvothermal (i.e., water/2-propanol) environment favors the preferential growth of hematite phase.

Published
2024

12. The in vacuo release of Ar and rare gases from minerals: 3. The degassing of He, Ne, Ar, Kr and Xe from irradiated apatite

Author

Villa, I, Ando', S, Capitani, G, Clemenza, M, Conconi, R, Galimberti, L, Oddone, M, Villa, IM, Villa, I, Ando', S, Capitani, G, Clemenza, M, Conconi, R, Galimberti, L, Oddone, M, and Villa, IM

Abstract

The mechanisms of in vacuo release of Ar are investigated by bringing them into context with nine other rare gas isotopes and by studying the mineralogical modifications that occur in their host mineral. A 200 mg shard of Durango fluorapatite was step-heated after neutron irradiation. It contained radiogenic 4He from natural U decay and artificially produced major rare gas isotopes: 20Ne from F, 37Ar from Ca, 38Ar from Cl, 80Kr and 82Kr from Br, 128Xe from I, 131Xe from Ba and 134Xe from U. The 4He release rate was compared with that from an unirradiated aliquot. Helium was expected, and observed, to degas at the lowest furnace temperatures, with nearly complete exhaustion by 1300 °C. Neon followed a bimodal degassing pattern, with a peak of the release rate at 1178 °C and a higher one at 1406 °C. Argon degassing showed a similar bimodality. Krypton and xenon were both mostly released in a single, concentrated burst between 1362 and 1460 °C. The two Xe isotopes 128 and 131, produced from I and Ba, respectively, followed exactly the same degassing pattern. The crystallographic site of the target element had no control on the movement of the irradiation-produced rare gas atom. The He release from the irradiated and unirradiated aliquots gave two overlapping alignments in the Arrhenius diagram at temperatures between 450 and 1300 °C. The two slopes are indistinguishable at the 1 sigma level and yield an average activation energy of 62 ± 5 kJ/mol. In the 450–1300 °C temperature interval, all five rare gases showed parallel trends with an activation energy around 62 kJ/mol and release rate constants decreasing from He to Xe by about 4 orders of magnitude. Arrhenian trajectories for the Kr and Xe degassing rate merge and sharply steepen in the 1362 °C step, with a degassing rate in the 1406 °C step about 400 times higher than at lower temperatures and an activation energy of 1.28 MJ/mol. The high-T modes of the bimodal Ar and Ne release also merge on the same steep Arrhen

Published
2024

13. Microwave-driven carbonation of brucite

Author

Campione, M, Corti, M, D'Alessio, D, Capitani, G, Lucotti, A, Yivlialin, R, Tommasini, M, Bussetti, G, Malaspina, N, Campione, M, Corti, M, D'Alessio, D, Capitani, G, Lucotti, A, Yivlialin, R, Tommasini, M, Bussetti, G, and Malaspina, N

Abstract

The water-mediated mineral carbonation represents a promising solution for the capture and the storage of atmospheric CO2. Even though this reaction might be spontaneous for a number of Mg- and Ca-rich mineral phases, it is characterized by considerable activation barriers. In order to make it effective, associated energy costs related to the achievement of adequate reaction conditions must be minimized. Microwave chemistry is known to provide for substantial increments of the reaction rate for several systems. We applied here microwave chemistry to the process of carbonation of aqueous slurries of brucite, a model system of Mg-rich mineral, subjected to partial pressures of CO2 as low as 6 bar and to no other additive. The temperature of the reactor was finely varied while the radiation power and the reactor pressure were monitored in real-time. The radiation power was used to estimate the radiation energy budget needed to complete the carbonation process, whereas the reactor pressure was used as a proxy of reaction progression. We show a detailed evolution of the carbonate products obtained in terms of mineral phases, morphological properties, and degree of crystallinity, both as precipitate and as solid residue in the exsiccated supernatant reaction liquid.

Published
2024

14. Transverse-target-spin asymmetry in exclusive $\omega$-meson electroproduction

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avetissian, A., Belostotski, S., Blok, H. P., Borissov, A., Bryzgalov, V., Capitani, G. P., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Gharibyan, V., Giordano, F., Gliske, S., Hasch, D., Hoek, M., Holler, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Ma, B. -Q., Manaenkov, S. I., Mao, Y., Marianski, B., Marukyan, H., Miyachi, Y., Movsisyan, A., Muccifora, V., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schnell, G., Seitz, B., Shibata, T. -A., Statera, M., Steffens, E., Steijger, J. J. M., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Yen, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Hard exclusive electroproduction of $\omega$ mesons is studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. The amplitudes of five azimuthal modulations of the single-spin asymmetry of the cross section with respect to the transverse proton polarization are measured. They are determined in the entire kinematic region as well as for two bins in photon virtuality and momentum transfer to the nucleon. Also, a separation of asymmetry amplitudes into longitudinal and transverse components is done. These results are compared to a phenomenological model that includes the pion pole contribution. Within this model, the data favor a positive $\pi\omega$ transition form factor., Comment: DESY Report 15-149

Published
2015

15. Bose-Einstein correlations in hadron-pairs from lepto-production on nuclei ranging from hydrogen to xenon

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Etzelmüller, E., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gapienko, G., Gapienko, V., García, J. Garay, Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Hartig, M., Hasch, D., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Lu, X. -G., Ma, B. -Q., Mahon, D., Makins, N. C. R., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miyachi, Y., Movsisyan, A., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Stahl, M., Stancari, M., Statera, M., Steijger, J. J. M., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

Bose-Einstein correlations of like-sign charged hadrons produced in deep-inelastic electron and positron scattering are studied in the HERMES experiment using nuclear targets of $^1$H, $^2$H, $^3$He, $^4$He, N, Ne, Kr, and Xe. A Gaussian approach is used to parametrize a two-particle correlation function determined from events with at least two charged hadrons of the same sign charge. This correlation function is compared to two different empirical distributions that do not include the Bose-Einstein correlations. One distribution is derived from unlike-sign hadron pairs, and the second is derived from mixing like-sign pairs from different events. The extraction procedure used simulations incorporating the experimental setup in order to correct the results for spectrometer acceptance effects, and was tested using the distribution of unlike-sign hadron pairs. Clear signals of Bose-Einstein correlations for all target nuclei without a significant variation with the nuclear target mass are found. Also, no evidence for a dependence on the invariant mass W of the photon-nucleon system is found when the results are compared to those of previous experiments.

Published
2015

16. Pentaquark $\Theta^+$ search at HERMES

Author

The HERMES Collaboration, Akopov, N., Akopov, Z., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Di Nezza, P., Elbakian, G., Etzelmüller, E., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., García, J. Garay, Garibaldi, F., Gavrilov, G., Giordano, F., Gliske, S., Hartig, M., Hasch, D., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Ruiz, A. López, Lorenzon, W., Lu, X., Ma, B. -Q., Mahon, D., Manaenkov, S. I., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Nappi, E., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Stancari, M., Steijger, J. J. M., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, H., Ye, Z., Yen, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

The earlier search at HERMES for narrow baryon states excited in quasi-real photoproduction, decaying through the channel $pK_S^0\rightarrow p\pi^+\pi^-$, has been extended with improved decay-particle reconstruction, more advanced particle identification, and increased event samples. The structure observed earlier at an invariant mass of 1528 MeV shifts to 1522 MeV and the statistical significance drops to about 2$\sigma$ for data taken with a deuterium target. The number of events above background is $68_{-31}^{+98}\text{(stat)}\pm13\text{(sys)}$. No such structure is observed in the hydrogen data set.

Published
2014
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17. Spin density matrix elements in exclusive $\omega$ electroproduction on $^1$H and $^2$H targets at 27.5 GeV beam energy

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Augustyniak, W., Avetissian, A., Blok, H. P., Borissov, A., Bryzgalov, V., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Etzelmüller, E., Fabbri, R., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Hartig, M., Hasch, D., Holler, Y., Hristova, I., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Ma, B. -Q., Mahon, D., Manaenkov, S. I., Mao, Y., Marianski, B., Marukyan, H., Movsisyan, A., Murray, M., Naryshkin, Y., Nass, A., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rostomyan, A., Ryckbosch, D., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Stahl, M., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Yen, S., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Exclusive electroproduction of $\omega$ mesons on unpolarized hydrogen and deuterium targets is studied in the kinematic region of Q$^2$>1.0 GeV$^2$, 3.0 GeV < W < 6.3 GeV, and -t'< 0.2 GeV$^2$. Results on the angular distribution of the $\omega$ meson, including its decay products, are presented. The data were accumulated with the HERMES forward spectrometer during the 1996-2007 running period using the 27.6 GeV longitudinally polarized electron or positron beam of HERA. The determination of the virtual-photon longitudinal-to-transverse cross-section ratio reveals that a considerable part of the cross section arises from transversely polarized photons. Spin density matrix elements are presented in projections of Q$^2$ or -t'. Violation of s-channel helicity conservation is observed for some of these elements. A sizable contribution from unnatural-parity-exchange amplitudes is found and the phase shift between those amplitudes that describe transverse $\omega$ production by longitudinal and transverse virtual photons, $\gamma^{*}_{L} \to \omega_{T}$ and $\gamma^{*}_{T} \to \omega_{T}$, is determined for the first time. A hierarchy of helicity amplitudes is established, which mainly means that the unnatural-parity-exchange amplitude describing the $\gamma^*_T \to \omega_T$ transition dominates over the two natural-parity-exchange amplitudes describing the $\gamma^*_L \to \omega_L$ and $\gamma^*_T \to \omega_T$ transitions, with the latter two being of similar magnitude. Good agreement is found between the HERMES proton data and results of a pQCD-inspired phenomenological model that includes pion-pole contributions, which are of unnatural parity., Comment: "Erratum version", e.g., includes the corrected version of Figure 6, to be published in "Erratum to: Spin density matrix elements in exclusive omega electroproduction on 1H and 2H targets at 27.5 GeV beam energy". Three SDMEs were mislabeled in the figure of the previously published version [EPJC74(2014)3110]. The labels have been fixed, while none of the results or conclusions changed

Published
2014

18. Transverse polarization of $\Lambda$ hyperons from quasireal photoproduction on nuclei

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Lu, X. -G., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The transverse polarization of $\Lambda$ hyperons was measured in inclusive quasireal photoproduction for various target nuclei ranging from hydrogen to xenon. The data were obtained by the HERMES experiment at HERA using the 27.6 GeV lepton beam and nuclear gas targets internal to the lepton storage ring. The polarization observed is positive for light target nuclei and is compatible with zero for krypton and xenon., Comment: final version to be published in Phys. Rev. D (in press)

Published
2014
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19. Biological mechanism of cell oxidative stress and death during short-term exposure to nano CuO

Author

Moschini, E, Colombo, G, Chirico, G, Capitani, G, Dalle-Donne, I, Mantecca, P, Moschini E., Colombo G., Chirico G., Capitani G., Dalle-Donne I., Mantecca P., Moschini, E, Colombo, G, Chirico, G, Capitani, G, Dalle-Donne, I, Mantecca, P, Moschini E., Colombo G., Chirico G., Capitani G., Dalle-Donne I., and Mantecca P.

Abstract

It is well known that copper oxide nanoparticles (CuO NPs) are heavily toxic on in vitro systems. In human alveolar epithelial cells, the mechanism of toxicity is mostly related to oxidative insults, coming from intracellularly dissolved copper ions, finally leading to apoptotic or autophagic cell death. Our hypothesis is based on possible early oxidative events coming from specific NP surface reactivity able to undermine the cell integrity and to drive cell to death, independently from Lysosomal-Enhanced Trojan Horse mechanism. Two types of CuO NPs, with different oxidative potential, were selected and tested on A549 cells for 1 h and 3 h at 10, 25, 50 and 100 µg/ml. Cells were then analyzed for viability and oxidative change of the proteome. Oxidative by-products were localized by immunocytochemistry and cell-NP interactions characterized by confocal and electron microscopy techniques. The results show that CuO NPs induced oxidative changes soon after 1 h exposure as revealed by the increase in protein carbonylation and reduced-protein-thiol oxidation. In parallel, cell viability significantly decreased, as shown by MTT assay. Such effects were higher for CuO NPs with more crystalline defects and with higher ROS production than for fully crystalline NPs. At these exposure times, although NPs efficiently interacted with cell surface and were taken up by small endocytic vesicles, no ion dissolution was visible inside the lysosomal compartment and no effects were produced by extracellularly dissolved copper ions. In conclusion, a specific NP surface-dependent oxidative cell injury was demonstrated. More detailed studies are required to understand which targets precociously react with CuO NPs, but these results introduce new paradigms for the toxicity of the metal-based NPs, beyond the Lysosomal-Enhanced Trojan horse-related mechanism, and open-up new opportunities to investigate the interactions and effects at the bio-interface for designing safer as well as more eff

Published
2023

20. Effects of oral exposure to brake wear particulate matter on the springtail Orthonychiurus folsomi

Author

Papa, G, Power, K, Forestieri, B, Capitani, G, Maiolino, P, Negri, I, Papa G., Power K., Forestieri B., Capitani G., Maiolino P., Negri I., Papa, G, Power, K, Forestieri, B, Capitani, G, Maiolino, P, Negri, I, Papa G., Power K., Forestieri B., Capitani G., Maiolino P., and Negri I.

Abstract

Most of the heavy metals in urban environments derives from road traffic, particularly from tyres and brake wear (non-exhaust emission sources). These pollutants contaminate the soil, where several organisms have a primary ecosystem role (e.g., springtails, ants, earthworms). Springtails (Collembola) are soil-dwelling animals regulating soil fertility, flow of energy through above- and below-ground food webs, and they contribute to soil microbial community dispersion and biodiversity maintenance. In this study we investigated the ecotoxicological effects of oral exposure to particles emitted from brake pads and cast-iron brake discs in the euedaphic collembola species Orthonychiurus folsomi under laboratory conditions. Our results showed that chronic exposure to brake wear particles can have sub-lethal effects both at low and high concentrations and it can cause histological alterations. Here, SEM-EDX was applied to observe the particulate and we found its chemical markers in the gut and faeces of collembola, while histological analysis detected alterations of the digestive and reproductive systems and of the abdominal fat body at high concentrations.

Published
2023

21. From high-volume industrial waste to new ceramic material: The case of red gypsum muds in the TiO2 industry

Author

Marian, N, Perotti, M, Indelicato, C, Magrini, C, Giorgetti, G, Capitani, G, Viti, C, Marian N. M., Perotti M., Indelicato C., Magrini C., Giorgetti G., Capitani G., Viti C., Marian, N, Perotti, M, Indelicato, C, Magrini, C, Giorgetti, G, Capitani, G, Viti, C, Marian N. M., Perotti M., Indelicato C., Magrini C., Giorgetti G., Capitani G., and Viti C.

Abstract

The present study aims to apply the principles of circular economy, using special inorganic waste (in particular, red gypsum muds from a TiO2 plant in Tuscany, Italy) to produce ceramic materials for the construction and building industries. Red gypsum (RG) muds produced during more than 10 years of industrial processing were chemically and mineralogically characterized by X-ray fluorescence spectrometry (XRF), X-ray powder diffraction (XRPD), scanning electron microscopy with energy dispersive X-ray spectrometer (SEM/EDS), and thermal analyses (TA). The analyses testify that RG waste production is chemically and mineralogically constant over time, and therefore suitable to be used as a secondary raw material in industrial ceramic production. Ceramic specimens have been realized using an extremely high amount of the RG waste (up to 70%) and characterized using the same chemical-mineralogical techniques, revealing that anhydrite, pyroxene, and Fe/Ti oxides are the main crystalline phases, embedded in a glassy compact matrix. Overall results indicate that the production of ceramic materials could represent a definitive and sustainable solution for the problematic management of the large volumes of RG waste deriving from TiO2 plants.

Published
2023

22. Recycling detoxified cement asbestos slates in the production of ceramic sanitary wares

Author

Bernasconi, A, Pellegrino, L, Vergani, F, Campanale, F, Marian, N, Galimberti, L, Perotti, M, Viti, C, Capitani, G, Bernasconi A., Pellegrino L., Vergani F., Campanale F., Marian N. M., Galimberti L., Perotti M., Viti C., Capitani G., Bernasconi, A, Pellegrino, L, Vergani, F, Campanale, F, Marian, N, Galimberti, L, Perotti, M, Viti, C, Capitani, G, Bernasconi A., Pellegrino L., Vergani F., Campanale F., Marian N. M., Galimberti L., Perotti M., Viti C., and Capitani G.

Abstract

The recycling of cement asbestos slates (CASs) thermally treated in air at 1100 °C as secondary raw material in the production of Vitreous China (VC) sanitary wares has been investigated. Deactivated cement asbestos powder (DCAP) has been used in individual substitutions (5 wt%) of quartz and feldspar. The single raw materials, the ceramic technological properties before and after firing, and the phases and microstructure evolution during firing have been investigated with a variety of techniques, including those commonly used for production quality checks and instrumental methods for mineralogical analyses. DCAP acts as flux rather than as inert in the firing process, promoting greification. Although the substituted samples have some critical aspects that need to be addressed before processing, such as the presence of sulphate salts that increase the dispersant demand and the colour of the fired ceramic body, the overall technological properties are comparable to those of normal production, suggesting the possible reuse of DCAP powder in the production of sanitary wares.

Published
2023

23. A comparison of two approaches to screen the filtration properties of Materials during the COVID-19 Emergency Time

Author

Capitani, G, Ferrero, L, Capitani G., Ferrero L., Capitani, G, Ferrero, L, Capitani G., and Ferrero L.

Abstract

Determination of the filtration efficiency (even to nanosize) of several textiles was carried out during emergency time at the beginning of the COVID-19 pandemic lockdown in order to perform a fast screening of materials candidate for facial masks. At this purpose, a double strategy was adopted in Milan scanning electron microscopy investigation and a classical filtration test of ambient aerosol. The latter was used in order to mimic as much as possible the capability to filter ambient aerosol that might contain COVID-19. The two methods were compared to investigate their capability to identify only textiles characterized by a filtration efficiency higher than 90% (thus candidate for facial mask production). Results showed filtration efficiency above 90% for promising candidate textiles as well as poor filtration capabilities (below 60%) of other textiles, enabling a fast screening of the materials from different Italian factories.

Published
2023

24. Reevaluation of the parton distribution of strange quarks in the nucleon

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avetissian, A., Avetisyan, E., Belostotski, S., Blok, H. P., Borissov, A., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Etzelmüller, E., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., García, J. Garay, Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Hartig, M., Hasch, D., Hoek, M., Holler, Y., Hristova, I., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Ma, B. -Q., Mahon, D., Manaenkov, S. I., Mao, Y., Marianski, B., Marukyan, H., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Stahl, M., Statera, M., Steffens, E., Steijger, J. J. M., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

An earlier extraction from the HERMES experiment of the polarization-averaged parton distribution of strange quarks in the nucleon has been reevaluated using final data on the multiplicities of charged kaons in semi-inclusive deep-inelastic scattering obtained with a kinematically more comprehensive method of correcting for experimental effects. General features of the distribution are confirmed, but the rise at low x is less pronounced than previously reported.

Published
2013
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25. Transverse target single-spin asymmetry in inclusive electroproduction of charged pions and kaons

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

Single-spin asymmetries were investigated in inclusive electroproduction of charged pions and kaons from transversely polarized protons at the HERMES experiment. The asymmetries were studied as a function of the azimuthal angle $\psi$ about the beam direction between the target-spin direction and the hadron production plane, the transverse hadron momentum relative to the direction of the incident beam, and the Feynman variable $x_F$. The $\sin(\psi)$ amplitudes are positive for positive pions and kaons, slightly negative for negative pions and consistent with zero for negative kaons, with particular transverse-momentum but weak $x_F$ dependences. Especially large asymmetries are observed for two small subsamples of events, where also the scattered electron was recorded by the spectrometer., Comment: 10 pages, 5 figures

Published
2013

26. Beam-helicity asymmetry in associated electroproduction of real photons $ep \to e\gamma \pi N$ in the $\Delta$-resonance region

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Blok, H. P., Böttcher, H., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Etzelmüller, E., Fabbri, R., Frullani, S., Gapienko, G., Gapienko, V., García, J. Garay, Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Hartig, M., Hasch, D., Holler, Y., Hristova, I., Ivanilov, A., Jackson, H. E., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Lu, X. -G., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Mao, Y., Marianski, B., Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Stahl, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zagrebelnyy, V., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The beam-helicity asymmetry in associated electroproduction of real photons, $ep\to e\gamma \pi N$, in the $\Delta$(1232)-resonance region is measured using the longitudinally polarized HERA positron beam and an unpolarized hydrogen target. Azimuthal Fourier amplitudes of this asymmetry are extracted separately for two channels, $ep\to e\gamma \pi^0 p$ and $ep\to e\gamma \pi^+ n$, from a data set collected with a recoil detector. All asymmetry amplitudes are found to be consistent with zero., Comment: 17 pages, 4 figures, (minor changes wit respect to previous arXiv version)

Published
2013
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27. The HERMES Recoil Detector

Author

Airapetian, A., Aschenauer, E. C., Belostotski, S., Borissov, A., Borisenko, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capitani, G. P., Carassiti, V., Ciullo, G., Clarkson, A., Contalbrigo, M., De Leo, R., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Guler, H., Gregor, I. M., Hartig, M., Hill, G., Hoek, M., Holler, Y., Hristova, I., Jo, H. S., Kaiser, R., Keri, T., Kisselev, A., Krause, B., Krauss, B., Lagamba, L., Lehmann, I., Lenisa, P., Lu, S., Lu, X. -G., Lumsden, S., Mahon, D., de la Ossa, A. Martinez, Murray, M., Mussgiller, A., Nowak, W. -D., Naryshkin, Y., Osborne, A., Pappalardo, L. L., Perez-Benito, R., Petrov, A., Pickert, N., Prahl, V., Protopopescu, D., Reinecke, M., Riedl, C., Rith, K., Rosner, G., Rubacek, L., Ryckbosch, D., Salomatin, Y., Schnell, G., Seitz, B., Shearer, C., Shutov, V., Statera, M., Steijger, J. J. M., Stenzel, H., Stewart, J., Stinzing, F., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Varanda, M., Veretennikov, D., Vilardi, I., Vikhrov, V., Vogel, C., Yaschenko, S., Ye, Z., Yu, W., Zeiler, D., and Zihlmann, B.

Subjects
Physics - Instrumentation and Detectors, High Energy Physics - Experiment
Abstract

For the final running period of HERA, a recoil detector was installed at the HERMES experiment to improve measurements of hard exclusive processes in charged-lepton nucleon scattering. Here, deeply virtual Compton scattering is of particular interest as this process provides constraints on generalised parton distributions that give access to the total angular momenta of quarks within the nucleon. The HERMES recoil detector was designed to improve the selection of exclusive events by a direct measurement of the four-momentum of the recoiling particle. It consisted of three components: two layers of double-sided silicon strip sensors inside the HERA beam vacuum, a two-barrel scintillating fibre tracker, and a photon detector. All sub-detectors were located inside a solenoidal magnetic field with an integrated field strength of 1 T. The recoil detector was installed in late 2005. After the commissioning of all components was finished in September 2006, it operated stably until the end of data taking at HERA end of June 2007. The present paper gives a brief overview of the physics processes of interest and the general detector design. The recoil detector components, their calibration, the momentum reconstruction of charged particles, and the event selection are described in detail. The paper closes with a summary of the performance of the detection system., Comment: 50 pages, 72 figures

Published
2013
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28. Multiplicities of charged pions and kaons from semi-inclusive deep-inelastic scattering by the proton and the deuteron

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Izotov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Ma, B. -Q., Mahon, D., Maiheu, B., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

Multiplicities in semi-inclusive deep-inelastic scattering are presented for each charge state of \pi^\pm and K^\pm mesons. The data were collected by the HERMES experiment at the HERA storage ring using 27.6 GeV electron and positron beams incident on a hydrogen or deuterium gas target. The results are presented as a function of the kinematic quantities x_B, Q^2, z, and P_h\perp. They represent a unique data set for identified hadrons that will significantly enhance our understanding of the fragmentation of quarks into final-state hadrons in deep-inelastic scattering.

Published
2012
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29. Beam-helicity asymmetry arising from deeply virtual Compton scattering measured with kinematically complete event reconstruction

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Etzelmüller, E., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Gregor, I. M., Guler, H., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Krauss, B., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Lu, S., Lu, X., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Osborne, A., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubacek, L., Rubin, J., Ryckbosch, D., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shearer, C., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steijger, J. J. M., Stewart, J., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

The beam-helicity asymmetry in exclusive electroproduction of real photons by the longitudinally polarized HERA positron beam scattering off an unpolarized hydrogen target is measured at HERMES. The asymmetry arises from deeply virtual Compton scattering and its interference with the Bethe--Heitler process. Azimuthal amplitudes of the beam-helicity asymmetry are extracted from a data sample consisting of $ep\rightarrow ep\gamma$ events with detection of all particles in the final state including the recoiling proton. The installation of a recoil detector, while reducing the acceptance of the experiment, allows the elimination of background from $ep\rightarrow eN\pi\gamma$ events, which was estimated to contribute an average of about 12% to the signal in previous HERMES publications. The removal of this background from the present data sample is shown to increase the magnitude of the leading asymmetry amplitude by 0.054 +/- 0.016 to -0.328 +/- 0.027 (stat.) +/- 0.045 (syst.).

Published
2012
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30. Azimuthal distributions of charged hadrons, pions, and kaons produced in deep-inelastic scattering off unpolarized protons and deuterons

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Frullani, S., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Stancari, M., Statera, M., Steijger, J. J. M., Stewart, J., Stinzing, F., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment, Nuclear Experiment
Abstract

The azimuthal cos{\phi} and cos2{\phi} modulations of the distribution of hadrons produced in unpolarized semi-inclusive deep-inelastic scattering of electrons and positrons off hydrogen and deuterium targets have been measured in the HERMES experiment. For the first time these modulations were determined in a four-dimensional kinematic space for positively and negatively charged pions and kaons separately, as well as for unidentified hadrons. These azimuthal dependences are sensitive to the transverse motion and polarization of the quarks within the nucleon via, e.g., the Cahn, Boer-Mulders and Collins effects.

Published
2012
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31. Beam-helicity and beam-charge asymmetries associated with deeply virtual Compton scattering on the unpolarised proton

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hoek, M., Holler, Y., Imazu, Y., Jackson, H. E., Jo, H. S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Lorenzon, W., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Beam-helicity and beam-charge asymmetries in the hard exclusive leptoproduction of real photons from an unpolarised hydrogen target by a 27.6 GeV lepton beam are extracted from the HERMES data set of 2006-2007 using a missing-mass event selection technique. The asymmetry amplitudes extracted from this data set are more precise than those extracted from the earlier data set of 1996-2005 previously analysed in the same manner by HERMES. The results from the two data sets are compatible with each other. Results from these combined data sets are extracted and constitute the most precise asymmetry amplitude measurements made in the HERMES kinematic region using a missing-mass event selection technique., Comment: (minor changes only compared to arXiv version 1)

Published
2012
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32. Measurement of the virtual-photon asymmetry A2 and the spin-structure function g2 of the proton

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Schüler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

A measurement of the virtual-photon asymmetry A_2(x,Q^2) and of the spin-structure function g_2(x,Q^2) of the proton are presented for the kinematic range 0.004 < x < 0.9 and 0.18 GeV^2 < Q^2 < 20 GeV^2. The data were collected by the HERMES experiment at the HERA storage ring at DESY while studying inclusive deep-inelastic scattering of 27.6 GeV longitudinally polarized leptons off a transversely polarized hydrogen gas target. The results are consistent with previous experimental data from CERN and SLAC. For the x-range covered, the measured integral of g_2(x) converges to the null result of the Burkhardt-Cottingham sum rule. The x^2 moment of the twist-3 contribution to g_2(x) is found to be compatible with zero.

Published
2011
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33. Multidimensional Study of Hadronization in Nuclei

Author

HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Düren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gapienko, G., Gapienko, V., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Grigoryan, L., Hadjidakis, C., Hartig, M., Hasch, D., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikás, L., Lehmann, I., Lenisa, P., Ruiz, A. López, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfré, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Petrosyan, A., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schäfer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stewart, J., Stinzing, F., Taroian, S., Truty, R., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Hadron multiplicities in semi-inclusive deep-inelastic scattering were measured on neon, krypton and xenon targets relative to deuterium at an electron(positron)-beam energy of 27.6 GeV at HERMES. These ratios were determined as a function of the virtual-photon energy nu, its virtuality Q2, the fractional hadron energy z and the transverse hadron momentum with respect to the virtual-photon direction pt . Dependences were analysed separately for positively and negatively charged pions and kaons as well as protons and antiprotons in a two-dimensional representation. Compared to the one-dimensional dependences, some new features were observed. In particular, when z > 0.4 positive kaons do not show the strong monotonic rise of the multiplicity ratio with nu as exhibited by pions and negative kaons. Protons were found to behave very differently from the other hadrons.

Published
2011
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34. Measurement of double-spin asymmetries associated with deeply virtual Compton scattering on a transversely polarized hydrogen target

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hartig, M., Hasch, D., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lapikas, L., Lehmann, I., Lenisa, P., Ruiz, A. Lopez, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., de la Ossa, B. Marianski A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Schaefer, A., Schnell, G., Schueler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stinzing, F., Taroian, S., Terkulov, A., Truty, R., Trzcinski, A., Tytgat, M., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Zagrebelnyy, V., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Double-spin asymmetries in exclusive electroproduction of real photons from a transversely polarized hydrogen target are measured with respect to the product of target polarization with beam helicity and beam charge, and with respect to the product of target polarization with beam helicity alone. The asymmetries arise from the deeply virtual Compton scattering process and its interference with the Bethe--Heitler process. They are related to the real part of the same combination of Compton form factors as that determining the previously published transverse target single-spin asymmetries through the imaginary part. The results for the double-spin asymmetries are found to be compatible with zero within the uncertainties of the measurement, and are not incompatible with the predictions of the only available GPD-based calculation., Comment: 9 pages, 4 figures, and 3 tables

Published
2011
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35. Inclusive Measurements of Inelastic Electron and Positron Scattering from Unpolarized Hydrogen and Deuterium Targets

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hill, G., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lamb, R., Lapikas, L., Lehmann, I., Lenisa, P., Linden-Levy, L. A., Ruiz, A. Lopez, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Pickert, N., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schaefer, A., Schnell, G., Schueler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stenzel, H., Stewart, J., Stinzing, F., Taroian, S., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, H., Ye, Z., Yen, S., Yu, W., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Results of inclusive measurements of inelastic electron and positron scattering from unpolarized protons and deuterons at the HERMES experiment are presented. The structure functions $F_2^p$ and $F_2^d$ are determined using a parameterization of existing data for the longitudinal-to-transverse virtual-photon absorption cross-section ratio. The HERMES results provide data in the ranges $0.006\leq x\leq 0.9$ and 0.1 GeV$^2\leq Q^2\leq$ 20 GeV$^2$, covering the transition region between the perturbative and the non-perturbative regimes of QCD in a so-far largely unexplored kinematic region. They are in agreement with existing world data in the region of overlap. The measured cross sections are used, in combination with data from other experiments, to perform fits to the photon-nucleon cross section using the functional form of the ALLM model. The deuteron-to-proton cross-section ratio is also determined., Comment: 38 pages, 11 Figures, 9 Tables; Fig. 9 modified, Ref. [46] added, minor textual additions on pages 12 and 17

Published
2011
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36. Ratios of Helicity Amplitudes for Exclusive rho-0 Electroproduction

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hill, G., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lamb, R., Lapikas, L., Lehmann, I., Lenisa, P., Linden-Levy, L. A., Ruiz, A. Lopez, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Pickert, N., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schaefer, A., Schnell, G., Schueler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stinzing, F., Taroian, S., Terkulov, A., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Wang, S., Yaschenko, S., Yen, S., Yu, W., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Exclusive rho^0-meson electroproduction is studied in the HERMES experiment, using a 27.6 GeV longitudinally polarized electron/positron beam and unpolarized hydrogen and deuterium targets in the kinematic region 0.5 GeV^2 < Q^2 < 7.0 GeV^2, 3.0 GeV < W < 6.3 GeV, and -t' < 0.4 GeV^2. Real and imaginary parts of the ratios of the natural-parity-exchange helicity amplitudes T_{11} (\gamma^*_T --> \rho_T), T_{01} (\gamma^*_T --> \rho_L), T_{10} (\gamma^*_L --> \rho_T), and T_{1-1} (\gamma^*_{-T} -->\rho_T) to T_{00} (\gamma^*_L --> \rho_L) are extracted from the data. For the unnatural-parity-exchange amplitude U_{11}, the ratio |U_{11}/T_{00}| is obtained. The Q^2 and t' dependences of these ratios are presented and compared with perturbative QCD predictions., Comment: 27 pages, 8 tables, 13 figures; minor textual changes on pages 2, 3,9, 10, 11, and some changes to the list of references

Published
2010
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37. Measurement of azimuthal asymmetries associated with deeply virtual Compton scattering on a longitudinally polarized deuterium target

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hill, G., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Jackson, H. E., Jgoun, A., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Krauss, B., Kravchenko, P., Krivokhijine, V. G., Lagamba, L., Lamb, R., Lapikas, L., Lehmann, I., Lenisa, P., Linden-Levy, L. A., Ruiz, A. Lopez, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Movsisyan, A., Muccifora, V., Murray, M., Mueller, D., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Pickert, N., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schaefer, A., Schnell, G., Schueler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stenzel, H., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Trzcinski, A., Tytgat, M., Vandenbroucke, A., Van der Nat, P. B., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, Z., Yen, S., Yu, W., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Azimuthal asymmetries in exclusive electroproduction of a real photon from a longitudinally polarized deuterium target are measured with respect to target polarization alone and with respect to target polarization combined with beam helicity and/or beam charge. The asymmetries appear in the distribution of the real photons in the azimuthal angle $\phi$ around the virtual photon direction, relative to the lepton scattering plane. The asymmetries arise from the deeply virtual Compton scattering process and its interference with the Bethe-Heitler process. The results for the beam-charge and beam-helicity asymmetries from a tensor polarized deuterium target with vanishing vector polarization are shown to be compatible with those from an unpolarized deuterium target, which is expected for incoherent scattering dominant at larger momentum transfer. Furthermore, the results for the single target-spin asymmetry and for the double-spin asymmetry are found to be compatible with the corresponding asymmetries previously measured on a hydrogen target. For coherent scattering on the deuteron at small momentum transfer to the target, these findings imply that the tensor contribution to the cross section is small. Furthermore, the tensor asymmetry is found to be compatible with zero., Comment: 33 pages, 7 figures, 7 tables; minor textual changes on pages 5 and 27, additional Table 2 added on page 10

Published
2010
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38. Effects of transversity in deep-inelastic scattering by polarized protons

Author

HERMES collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Bacchetta, A., Belostotski, S., Bianchi, N., Blok, H. P., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Elschenbroich, U., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hill, G., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Izotov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Lagamba, L., Lamb, R., Lapikas, L., Lehmann, I., Lenisa, P., Linden-Levy, L. A., Ruiz, A. Lopez, Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Pickert, N., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schaefer, A., Schnell, G., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stenzel, H., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Trzcinski, A., Tytgat, M., van der Nat, P. B., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, H., Ye, Z., Yen, S., Yu, W., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Single-spin asymmetries for pions and charged kaons are measured in semi-inclusive deep-inelastic scattering of positrons and electrons off a transversely nuclear-polarized hydrogen target. The dependence of the cross section on the azimuthal angles of the target polarization (phi_S)and the produced hadron (phi) is found to have a substantial sin(phi+phi_S) modulation for the production of pi+, pi- and K+. This Fourier component can be interpreted in terms of non-zero transversity distribution functions and non-zero favored and disfavored Collins fragmentation functions with opposite sign. For pi0 and K- production the amplitude of this Fourier component is consistent with zero., Comment: 7 pages, 3 figures

Published
2010
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39. Exclusive Leptoproduction of Real Photons on a Longitudinally Polarised Hydrogen Target

Author

The HERMES Collaboration, Airapetian, A., Akopov, N., Akopov, Z., Aschenauer, E. C., Augustyniak, W., Avakian, R., Avetissian, A., Avetisyan, E., Ball, B., Belostotski, S., Bianchi, N., Blok, H. P., Boettcher, H., Borissov, A., Bowles, J., Brodski, I., Bryzgalov, V., Burns, J., Capiluppi, M., Capitani, G. P., Cisbani, E., Ciullo, G., Contalbrigo, M., Dalpiaz, P. F., Deconinck, W., De Leo, R., De Nardo, L., De Sanctis, E., Diefenthaler, M., Di Nezza, P., Dueren, M., Ehrenfried, M., Elbakian, G., Ellinghaus, F., Fabbri, R., Fantoni, A., Felawka, L., Frullani, S., Gabbert, D., Gapienko, G., Gapienko, V., Garibaldi, F., Gavrilov, G., Gharibyan, V., Giordano, F., Gliske, S., Golembiovskaya, M., Hadjidakis, C., Hartig, M., Hasch, D., Hill, G., Hillenbrand, A., Hoek, M., Holler, Y., Hristova, I., Imazu, Y., Ivanilov, A., Izotov, A., Jackson, H. E., Jo, H. S., Joosten, S., Kaiser, R., Karyan, G., Keri, T., Kinney, E., Kisselev, A., Kobayashi, N., Korotkov, V., Kozlov, V., Kravchenko, P., Krivokhijne, V. G., Lagamba, L., Lamb, R., Lapikas, L., Lehmann, I., Lenisa, P., Linden-Levy, L. A., Lopez~Ruiz, A., Lorenzon, W., Lu, X. -G., Lu, X. -R., Ma, B. -Q., Mahon, D., Makins, N. C. R., Manaenkov, S. I., Manfre, L., Mao, Y., Marianski, B., de la Ossa, A. Martinez, Marukyan, H., Miller, C. A., Miyachi, Y., Movsisyan, A., Muccifora, V., Murray, M., Mussgiller, A., Nappi, E., Naryshkin, Y., Nass, A., Negodaev, M., Nowak, W. -D., Pappalardo, L. L., Perez-Benito, R., Pickert, N., Raithel, M., Reimer, P. E., Reolon, A. R., Riedl, C., Rith, K., Rosner, G., Rostomyan, A., Rubin, J., Ryckbosch, D., Salomatin, Y., Sanftl, F., Schaefer, A., Schnell, G., Schueler, K. P., Seitz, B., Shibata, T. -A., Shutov, V., Stancari, M., Statera, M., Steffens, E., Steijger, J. J. M., Stenzel, H., Stewart, J., Stinzing, F., Taroian, S., Terkulov, A., Trzcinski, A., Tytgat, M., Vandenbroucke, A., van der Nat, P. B., Van Haarlem, Y., Van Hulse, C., Veretennikov, D., Vikhrov, V., Vilardi, I., Vogel, C., Wang, S., Yaschenko, S., Ye, H., Ye, Z., Yen, S., Yu, W., Zeiler, D., Zihlmann, B., and Zupranski, P.

Subjects
High Energy Physics - Experiment
Abstract

Polarisation asymmetries are measured for the hard exclusive leptoproduction of real photons from a longitudinally polarised hydrogen target. These asymmetries arise from the deeply virtual Compton scattering and Bethe-Heitler processes. From the data are extracted two asymmetries in the azimuthal distribution of produced real photons about the direction of the exchanged virtual photon: A_UL with respect to the target polarisation and A_LL with respect to the product of the beam and target polarisations. Results for both asymmetries are compared to the predictions from a generalised parton distribution model. The sin(phi) and cos(0*phi) amplitudes observed respectively for the A_UL and A_LL asymmetries are compatible with the sizeable predictions from the model. Unexpectedly, a sin(2*phi) modulation in the A_UL asymmetry with a magnitude similar to that of the sin(phi) modulation is observed., Comment: 18 pages, 2 figures, 5 tables

Published
2010
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40. Compton Scattering by the Proton using a Large-Acceptance Arrangement

Author

Wolf, S., Lisin, V., Kondratiev, R., Massone, A. M., Galler, G., Ahrens, J., Arends, H. -J., Beck, R., Camen, M., Capitani, G. P., Grabmayr, P., Härter, F., Hehl, T., Jennewein, P., Kossert, K., L'vov, A. I., Molinari, C., Ottonello, P., Owens, R. O., Peise, J., Preobrajenskij, I., Proff, S., Robbiano, A., Sanzone, M., Schumacher, M., Schmitz, M., and Wissmann, F.

Subjects
Nuclear Experiment, High Energy Physics - Experiment, High Energy Physics - Phenomenology
Abstract

Compton scattering by the proton has been measured using the tagged-photon facility at MAMI (Mainz) and the large-acceptance arrangement LARA. The new data are interpreted in terms of dispersion theory based on the SAID-SM99K parameterization of photo-meson amplitudes. It is found that two-pion exchange in the t-channel is needed for a description of the data in the second resonance region. The data are well represented if this channel is modeled by a single pole with mass parameter m(sigma)=600 MeV. The asymptotic part of the spin dependent amplitude is found to be well represented by pi-0-exchange in the t-channel. A backward spin-polarizability of gamma(pi)=(-37.1+-0.6(stat+syst)+-3.0(model))x10^{-4}fm^4 has been determined from data of the first resonance region below 455 MeV. This value is in a good agreement with predictions of dispersion relations and chiral pertubation theory. From a subset of data between 280 and 360 MeV the resonance pion-photoproduction amplitudes were evaluated leading to a E2/M1 multipole ratio of the p-to-Delta radiative transition of EMR(340 MeV)=(-1.7+-0.4(stat+syst)+-0.2(model))%. It was found that this number is dependent on the parameterization of photo-meson amplitudes. With the MAID2K parameterization an E2/M1 multipole ratio of EMR(340 MeV)=(-2.0+-0.4(stat+syst)+-0.2(model))% is obtained.

Published
2001
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41. Compton Scattering by the Proton

Author

Galler, G., Lisin, V., Kondratiev, R., Massone, A. M., Wolf, S., Ahrens, J., Arends, H. -J., Beck, R., Camen, M., Capitani, G. P., Grabmayr, P., Hall, S. J., Härter, F., Hehl, T., Jennewein, P., Kossert, K., L'vov, A. I., Molinari, C., Ottonello, P., Peise, J., Preobrajenski, I., Proff, S., Robbiano, A., Sanzone, M., Schumacher, M., Schmitz, M., and Wissmann, F.

Subjects
Nuclear Experiment, High Energy Physics - Phenomenology
Abstract

Compton scattering by the proton has been measured over a wide range covering photon energies 250 MeV < E_\gamma < 800 MeV and photon scattering angles 30^0 < \theta^{lab}_\gamma < 150^0, using the tagged-photon facility at MAMI (Mainz) and the large-acceptance arrangement LARA. The data are in good agreement with the dispersion theory based on the SAID-SM99K parameterization of photo-meson amplitudes. From the subset of data between 280 and 360 MeV the resonance pion-photoproduction amplitudes were evaluated leading to the multipole E2/M1 ratio EMR(340 MeV) =(-1.6 \pm 0.4(stat+syst) \pm 0.2(model)%. From all data below 455 MeV the proton's backward spin polarizability was determined to be \gamma_\pi=(-37.9 \pm 0.6(stat+syst) \pm 3.5(model))x10^{-4}fm^4.

Published
2001
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42. Single-Crystal Elasticity of Antigorite at High Pressures and Seismic Detection of Serpentinized Slabs

Author

Satta, N, Grafulha Morales, L, Criniti, G, Kurnosov, A, Boffa Ballaran, T, Speziale, S, Marquardt, K, Capitani, G, Marquardt, H, Satta N., Grafulha Morales L. F., Criniti G., Kurnosov A., Boffa Ballaran T., Speziale S., Marquardt K., Capitani G. C., Marquardt H., Satta, N, Grafulha Morales, L, Criniti, G, Kurnosov, A, Boffa Ballaran, T, Speziale, S, Marquardt, K, Capitani, G, Marquardt, H, Satta N., Grafulha Morales L. F., Criniti G., Kurnosov A., Boffa Ballaran T., Speziale S., Marquardt K., Capitani G. C., and Marquardt H.

Abstract

The subduction of serpentinized slabs is the dominant process to transport “water” into Earth's mantle, and plays a pivotal role for subduction dynamics. Antigorite, the most abundant serpentine mineral in subduction settings, may imprint a seismic signature on serpentinized slabs, making them seismically distinguishable from the dry, non-serpentinized ones. However, the complete single-crystal elasticity of antigorite has not been experimentally constrained at high pressures, hindering the use of seismological approaches to detect serpentinization in subducting slabs. Here, we report the full elastic stiffness tensor of antigorite by single-crystal Brillouin spectroscopy and X-ray diffraction up to 7.71(5) GPa. We use our results to model seismic properties of antigorite-bearing rocks and show that their seismological detectability depends on the geometrical relation between seismic wave paths and foliation of serpentinized rocks. In particular, we demonstrate that seismic shear anisotropy shows low sensitivity to serpentinization for a range of relevant geometries.

Published
2022

43. Nanostructured 3C-SiC on Si by a network of (111) platelets: a fully textured film generated by intrinsic growth anisotropy

Author

Vanacore, G, Chrastina, D, Scalise, E, Barbisan, L, Ballabio, A, Mauceri, M, La Via, F, Capitani, G, Crippa, D, Marzegalli, A, Bergamaschini, R, Miglio, L, Vanacore G. M., Chrastina D., Scalise E., Barbisan L., Ballabio A., Mauceri M., La Via F., Capitani G., Crippa D., Marzegalli A., Bergamaschini R., Miglio L., Vanacore, G, Chrastina, D, Scalise, E, Barbisan, L, Ballabio, A, Mauceri, M, La Via, F, Capitani, G, Crippa, D, Marzegalli, A, Bergamaschini, R, Miglio, L, Vanacore G. M., Chrastina D., Scalise E., Barbisan L., Ballabio A., Mauceri M., La Via F., Capitani G., Crippa D., Marzegalli A., Bergamaschini R., and Miglio L.

Abstract

In this paper, we address the unique nature of fully textured, high surface-to-volume 3C-SiC films, as produced by intrinsic growth anisotropy, in turn generated by the high velocity of the stacking fault growth front in two-dimensional (111) platelets. Structural interpretation of high resolution scanning electron microscopy and transmission electron microscopy data is carried out for samples grown in a hot-wall low-pressure chemical vapour deposition reactor with trichlorosilane and ethylene precursors, under suitable deposition conditions. By correlating the morphology and the X-ray diffraction analysis we also point out that twinning along (111) planes is very frequent in such materials, which changes the free-platelet configuration.

Published
2022

44. Thermal decomposition of cement–asbestos at 1100 °C: how much “safe” is “safe”?

Author

Vergani, F, Galimberti, L, Marian, N, Giorgetti, G, Viti, C, Capitani, G, Vergani F., Galimberti L., Marian N. M., Giorgetti G., Viti C., Capitani G. C., Vergani, F, Galimberti, L, Marian, N, Giorgetti, G, Viti, C, Capitani, G, Vergani F., Galimberti L., Marian N. M., Giorgetti G., Viti C., and Capitani G. C.

Abstract

The products of cement–asbestos treated in air at 1100 °C were characterized by a multi-methodological approach to determine: (i) the effective deactivation of harmful asbestos fibers; (ii) the mineralogy and microstructure of the inert product and its possible use as a secondary raw material (SRM); and (iii) any potential health hazard of the SRM. For this purpose, energy-dispersive X-ray fluorescence spectrometry (EDXRF), X-ray powder diffraction (XRPD), scanning, and transmission electron microscopy (SEM and TEM) analyses were performed. The powdered SRM was also analyzed by dynamic laser scattering and solution leaching experiments, to determine grain size distribution and possible elements release. Our results confirm the deactivation of crocidolite and chrysotile asbestos fibers, but at the same time evidence a significant fraction of nanoparticles in the SRM and some critical releases of SO42–, F– and Cr6+ in solution. Both the nanoparticle fraction and the critical elemental release may pose human health concern and adversely affect potential applications of the SRM. Strategies to control the grain size distribution through adjusted thermal treatment conditions and microwave-assisted grinding operations are discussed. Possible routes to safely reuse the SRM are indicated.

Published
2022

45. Laboratory Simulation of Space Weathering on Silicate Surfaces in the Water Environment

Author

Murri, M, Capitani, G, Fasoli, M, Monguzzi, A, Calloni, A, Bussetti, G, Malaspina, N, Campione, M, Murri M., Capitani G., Fasoli M., Monguzzi A., Calloni A., Bussetti G., Malaspina N., Campione M., Murri, M, Capitani, G, Fasoli, M, Monguzzi, A, Calloni, A, Bussetti, G, Malaspina, N, Campione, M, Murri M., Capitani G., Fasoli M., Monguzzi A., Calloni A., Bussetti G., Malaspina N., and Campione M.

Abstract

Silicate nanoparticles occur in various astrophysical environments where they experience substantial processing due to events such as grain-grain collisions and irradiation. However, the structure and chemical evolution together with the origin of these grains are still poorly understood and intensively debated. For this purpose, we performed liquid-phase nanosecond pulsed laser ablation on olivine single crystals to (i) simulate space weathering in a water environment (e.g., hydrous or volatile-rich bodies) and (ii) study the chemical and structural evolution of both the target surface and the ablated material. In particular, optical spectroscopy analyses have been performed on the ablated material and correlated with high-resolution transmission electron microscopy and diffraction, whereas compositional variations of the ablated target surface were determined by X-ray photoelectron spectroscopy. Our results show that the target material is enriched in Fe and depleted in Mg after the ablation process, with the water environment triggering the oxidation of Fe2+ into Fe3+ in a region confined at the solid-liquid interface and thus promoting the formation of magnetite on the sample surface. On the other hand, in the ablated material we find olivine crystalline fragments with shock features together with Mg-rich crystalline nanoparticles. Notably, no metallic iron nanoparticles have been detected in the ablated material. Our simulation of space weathering in the water environment revealed structural and chemical changes which are expected to give rise to distinctive features in the reflectance spectra when compared to those from airless bodies of the inner solar system.

Published
2022

47. Flotation Sludges from Precious Metal Recovery Processes: From Waste to Secondary Raw Material in Ceramics

Author

Perotti, M, Iacoviello, F, Marian, N, Indelicato, C, Capitani, G, Salvini, R, Zampini, M, Viti, C, Perotti, Matteo, Iacoviello, Francesco, Marian, Narcisa M., Indelicato, Carlo, Capitani, Giancarlo, Salvini, Riccardo, Zampini, Marco, Viti, Cecilia, Perotti, M, Iacoviello, F, Marian, N, Indelicato, C, Capitani, G, Salvini, R, Zampini, M, Viti, C, Perotti, Matteo, Iacoviello, Francesco, Marian, Narcisa M., Indelicato, Carlo, Capitani, Giancarlo, Salvini, Riccardo, Zampini, Marco, and Viti, Cecilia

Abstract

In this study, we investigated flotation muds (FM) deriving from the recovery processes of precious metals contained in e-waste (wastes from electronics) and exhausted catalysts. FM consist of an amorphous phase, corresponding to a Ca- and Al-rich silicatic glass, potentially usable as a secondary raw material (SRM) to obtain a final ceramic product (CFM). A high FM amount was used in our ceramic tests, and suitably mixed with variable percentages of other phases. Chemical analysis, phase composition, microstructure, pore pattern and technological properties of the new ceramic products were determined using different analytical techniques, including bulk XRF, XRD, SEM-EDS and µCT. The CFM product predominantly consists of nepheline, pyroxene and wollastonite as the main crystalline phases, with a minor amorphous phase occurring as a compact interstitial matrix. The ceramic product has a porous interconnected microstructure. Nevertheless, this microstructure does not negatively affect the mechanical properties of the ceramic product, as testified by the geo-mechanical tests, revealing good properties in terms of bending and uniaxial strength. These preliminary results point out that FM recycling is feasible, at least at the laboratory scale.

Published
2023

49. TEM-EDS microanalysis: Comparison among the standardless, Cliff & Lorimer and absorption correction quantification methods

Author

Conconi, R, Ventruti, G, Nieto, F, Capitani, G, Conconi, R, Ventruti, G, Nieto, F, and Capitani, G

Abstract

Available quantification methods for energy dispersive X-ray microanalysis in transmission electron microscopy, such as the standardless method (SLM), the Cliff-Lorimer approximation (CLA) and the absorption correction method (ACM), are compared. As expected, the CLA and ACM give superior results with respect to the SLM. As far as absorption can be considered negligible, CLA and ACM perform similarly. However, starting from mass-thickness of the order of 22 × 10−6 g/cm2, absorption become significant and the ACM gives better results. More accurate analyses can be obtained with the ACM if distinct kO/Si factors are determined for light and heavy minerals, respectively, placing a divide at 2.90 g/cm3. Caution must be used when k-factors are derived indirectly from minerals with very different structure/chemistry, suggesting that separate k-factors data sets are required for accurate EDS quantification, at least for the major and diverse broad classes of minerals. Element diffusion of monovalent cations and channelling effects may represent a complication, especially in very anisotropic minerals such as phyllosilicates, where these two phenomena may occur together.

Published
2023

50. Syn-exhumation Pervasive Brittle Deformation in the Voltri (Nw Italy) Serpentinite: the Chrysotile-cemented Acquasanta Breccia

Author

Barale, L, Piana, F, Avataneo, C, Botta, S, Capitani, G, Cossio, R, Marcelli, I, Petriglieri, J, Tallone, S, Turci, F, Compagnoni, R, Petriglieri, JR, Barale, L, Piana, F, Avataneo, C, Botta, S, Capitani, G, Cossio, R, Marcelli, I, Petriglieri, J, Tallone, S, Turci, F, Compagnoni, R, and Petriglieri, JR

Abstract

This paper sheds light on syn-exhumation, pervasive cataclastic processes occurred on competent serpentinites of a metaophiolitic sub-unit of the Voltri Massif. The reported data highlight the importance of the compositional and structural heterogeneities within the ophiolite-bearing exhumation channels, since the observed pervasive cataclastic processes affected only the more competent rock bodies of the metaophiolitic unit, giving origin to a serpentinite breccia, named as Acquasanta Breccia. This breccia is cemented by random-oriented chrysotile fibers that give rise to a very uncommon microstructure, as highlighted by optical microscopy, Micro-Raman spectroscopy, SEM-EDS and TEM investigations. The Acquasanta Breccia underwent a sequence of syn-exhumation tectonic events, accompanied by the onset of different generations and types of chrysotile, which occur both in veins and in the rock matrix. The breccia records the intermediate and late stages of the exhumation of the Voltri meta-ophiolites, which occurred after the development of the retrograde greenschist-facies foliation and before the late shallower faulting events.

Published
2023

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