Search

Your search keyword '"Rostomyan T"' showing total 8 results
Start Over Author "Rostomyan T" Publisher springer
8 results on '"Rostomyan T"'

1. Single π0 production off neutrons bound in deuteron with linearly polarized photons

Author

Mullen, C., Gardner, S., Glazier, D. I., Kay, S. J. D., Livingston, K., Strakovsky, I. I., Workman, R. L., Abt, S., Achenbach, P., Afzal, F., Ahmed, Z., Akondi, C. S., Annand, J. R. M., Bashkanov, M., Beck, R., Biroth, M., Borisov, N. S., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Fegan, S., Ferretti-Bondy, M. I., Ghosal, D., Gorodnov, I., Gradl, W., Günther, M., Gurevic, G., Heijkenskjöld, L., Hornidge, D., Huber, G. M., Jermann, N., Kaeser, A., Korolija, M., Kashevarov, V. L., Krusche, B., Kulikov, V. V., Lazarev, A., Lutterer, S., MacGregor, I. J. D., Manley, D. M., Martel, P. P., Martemianov, M. A., Meier, C., Miskimen, R., Mocanu, M., Mornacchi, E., Neganov, A., Oberle, M., Ostrick, M., Otte, P., Paudyal, D., Pedroni, P., Powell, A., Prakhov, S. N., Reicherz, G., Ron, G., Rostomyan, T., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Wagner, S., Walford, N. K., Watts, D. P., Werthmüller, D., Wettig, J., Witthauer, L., Wolfes, M., Zachariou, N., and Publica

Subjects
deuteron, polarization, N(1440), partial wave, Nuclear Theory, photon: energy, Delta(1232), beam: asymmetry, Mainz Linac, kinematics, isospin: symmetry, calorimeter, electron: beam, pi0: photoproduction, Nuclear Experiment, photon: beam, Crystal Ball
Abstract

The quasifree γ→d→π0n(p) photon beam asymmetry, Σ, has been measured at photon energies, Eγ, from 390 to 610 MeV, corresponding to center of mass energy from 1.271 to 1.424 GeV, for the first time. The data were collected in the A2 hall of the MAMI electron beam facility with the Crystal Ball and TAPS calorimeters covering pion center-of-mass angles from 49∘ to 148∘. In this kinematic region, polarization observables are sensitive to contributions from the Δ(1232) and N(1440) resonances. The extracted values of Σ have been compared to predictions based on partial-wave analyses (PWAs) of the existing pion photoproduction database. Our comparison includes the SAID, MAID and Bonn–Gatchina analyses; while a revised SAID fit, including the new Σ measurements, has also been performed. In addition, isospin symmetry is examined as a way to predict π0n photoproduction observables, based on fits to published data in the channels π0p, π+n and π-p.

Published
2021

2. Experimental study of the γp→K0Σ+, γn→K0Λ, and γn→K0Σ0 reactions at the Mainz Microtron

Author

Akondi, C. S., Bantawa, K., Manley, D. M., Abt, S., Achenbach, P., Afzal, F., Aguar-Bartolomé, P., Ahmed, Z., Annand, J. R. M., Arends, H. J., Bashkanov, M., Beck, R., Biroth, M., Borisov, N., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Downie, E. J., Drexler, P., Ferretti Bondy, M. I., Gardner, S., Glazier, D. I., Gorodnov, I., Gradl, W., Günther, M., Gurevich, D., Kay, S., Heijkenskjöld, L., Hornidge, D., Huber, G. M., Käser, M., Kashevarov, V. L., Korolija, M., Krusche, B., Lazarev, A., Livingston, K., Lutterer, S., McGeorge, J. C., MacGregor, I. J. D., Martel, P. P., Middleton, D. G., Miskimen, R., Mornacchi, E., Mushkarenkov, A., Mullen, C., Neganov, A., Neiser, A., Oberle, M., Ostrick, M., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Powell, A., Prakhov, S. N., Ron, G., Rostomyan, T., Sarty, A., Sfienti, C., Sokhoyan, V., Spieker, K., Steffen, O., Strakovsky, I. I., Strub, Th., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu. A., Walford, N. K., Watts, D. P., Wagner, S., Werthmüller, D., Wettig, J., Witthauer, L., and Wolfes, M.

Abstract

This work measured dσ/dΩ for neutral kaon photoproduction reactions from threshold up to a c.m. energy of 1855MeV, focussing specifically on the γp→K0Σ+, γn→K0Λ, and γn→K0Σ0 reactions. Our results for γn→K0Σ0 are the first-ever measurements for that reaction. These data will provide insight into the properties of N∗ resonances and, in particular, will lead to an improved knowledge about those states that couple only weakly to the πN channel. Integrated cross sections were extracted by fitting the differential cross sections for each reaction as a series of Legendre polynomials and our results are compared with prior experimental results and theoretical predictions.

Published
2019

3. The $\eta^{\prime}$η-carbon potential at low meson momenta

Author

Nanova, M., Friedrich, S., Brinkmann, K. -T., Crede, V., Drexler, P., Eberhardt, H., Elsner, D., Frommberger, F., Funke, Ch., Gottschall, M., Grüner, M., Gutz, E., Metag, V., Hammann, Ch., Hannappel, J., Hartmann, J., Hillert, W., Hoffmeister, Ph., Honisch, Ch., Jude, T., Kaiser, D., Kalischewski, F., Keshelashvili, I., Paryev, E. Ya., Klein, F., Koop, K., Krusche, B., Lang, M., Makonyi, K., Messi, F., Müller, J., Müllers, J., Piontek, D., Rostomyan, T., Afzal, F. N., Schaab, D., Schmidt, Ch., Schmieden, H., Schmitz, R., Seifen, T., Sokhoyan, V., Sowa, C., Spieker, K., Thiel, A., Thoma, U., Bayadilov, D., Triffterer, T., Urban, M., van Pee, H., Walther, D., Wendel, Ch., Werthmüller, D., Wiedner, U., Wilson, A., Witthauer, L., Wunderlich, Y., Bantes, B., Zaunick, H. -G., Beck, R., Becker, M., and Böse, S.

Subjects
Nuclear Theory, High Energy Physics::Experiment, ddc:530, Nuclear Experiment
Abstract

The production of η′ mesons in coincidence with forward-going protons has been studied in photon-induced reactions on 12C and on a liquid hydrogen (LH2) target for incoming photon energies of 1.3-2.6 GeV at the electron accelerator ELSA. The η′ mesons have been identified via the η′→π0π0η→6γ decay registered with the CBELSA/TAPS detector system. Coincident protons have been identified in the MiniTAPS BaF2 array at polar angles of 2∘≤θp≤11∘. Under these kinematic constraints the η′ mesons are produced with relatively low kinetic energy (≈150 MeV) since the coincident protons take over most of the momentum of the incident-photon beam. For the C-target this allows the determination of the real part of the η′-carbon potential at low meson momenta by comparing with collision model calculations of the η′ kinetic energy distribution and excitation function. Fitting the latter data for η′ mesons going backwards in the center-of-mass system yields a potential depth of V=−(44±16(stat)±15(syst)) MeV, consistent with earlier determinations of the potential depth in inclusive measurements for average η′ momenta of ≈1.1 GeV/c. Within the experimental uncertainties, there is no indication of a momentum dependence of the η′-carbon potential. The LH2 data, taken as a reference to check the data analysis and the model calculations, provide differential and integral cross sections in good agreement with previous results for η′ photoproduction off the free proton.

Published
2018

4. Determination of the scalar polarizabilities of the proton using beam asymmetry Σ3 in Compton scattering

Author

Sokhoyan, V., Downie, E. J., Mornacchi, E., McGovern, J. A., Krupina, N., Afzal, F., Ahrens, J., Akondi, C. S., Annand, J. R. M., Arends, H. J., Beck, R., Braghieri, A., Briscoe, W. J., Cividini, F., Collicott, C., Costanza, S., Denig, A., Dieterle, M., Ferretti, M., Gardner, S., Garni, S., Glazier, D. I., Glowa, D., Gradl, W., Gurevich, G., Hamilton, D., Hornidge, D., Huber, G. M., Käser, A., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lensky, V., Linturi, J., Lisin, V., Livingston, K., MacGregor, I.J.D., Macrae, R., Manley, D. M., Martel, P. P., Middleton, D. G., Miskimen, R., Mushkarenkov, A., Neiser, A., Oberle, M., Ortega Spina, H., Ostrick, M., Ott, P., Otte, P. B., Oussena, B., Paudyal, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Rostomyan, T., Sarty, A., Schumann, S., Spieker, K., Steffen, O., Strakovsky, I. I., Strandberg, B., Strub, T., Supek, I., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Wagner, S., Watts, D. P., Wettig, J., Witthauer, L., Werthmüller, D., Wolfes, M., and Zana, L.

Subjects
Nuclear Theory, Physics::Accelerator Physics, Physics::Atomic Physics, Nuclear Experiment
Abstract

The scalar dipole polarizabilities, αE1αE1 and βM1βM1 , are fundamental properties related to the internal dynamics of the nucleon. The currently accepted values of the proton polarizabilities were determined by fitting to unpolarized proton Compton scattering cross section data. The measurement of the beam asymmetry Σ3Σ3 in a certain kinematical range provides an alternative approach to the extraction of the scalar polarizabilities. At the Mainz Microtron (MAMI) the beam asymmetry was measured for Compton scattering below pion photoproduction threshold for the first time. The results are compared with model calculations and the influence of the experimental data on the extraction of the scalar polarizabilities is determined.

Published
2017

5. Photon asymmetry measurements of γp → π0p for\ud Eγ = 320–650 MeV

Author

Gardner, S., Howdle, D., Sikora, M.H., Wunderlich, Y., Abt, S., Achenbach, P., Afzal, F., Aguar-Bartolome, P., Ahmed, Z., Annand, J.R.M., Arends, H.J., Bantawa, K., Bashkanov, M., Beck, R., Biroth, M., Borisov, N.S., Braghieri, A., Briscoe, W.J., Cherepnya, S., Cividini, F., Costanza, S., Collicott, C., Demissie, B.T., Denig, A., Dieterle, M., Downie, E.J., Drexler, P., Ferretti-Bondy, M.I., Filkov, L.V., Glazier, D.I., Garni, S., Gradl, W., Günther, M., Gurevich, G.M., Hall Barrientos, P., Hamilton, D., Heid, E., Hornidge, D., Huber, G.M., Jahn, O., Jude, T.C., Käser, A., Kay, S., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Linturi, J.M., Lisin, V., Livingston, K., Lutterer, S., MacGregor, I.J.D., Macrae, R., Mancell, J., Manley, D.M., Martel, P.P., McGeorge, J.C., McNicoll, E.F., Middleton, D.G., Miskimen, R., Mullen, C., Mushkarenkov, A., Neganov, A.B., Neiser, A., Nikolaev, A., Oberle, M., Ostrick, M., Owens, R.O., Otte, P.B., Oussena, B., Paudyall, D., Pedroni, P., Polonski, A., Prakhov, S., Rajabi, A., Robinson, J., Rosner, G., Rostomyan, T., Sarty, A., Schumann, S., Sokhoyan, V., Spieker, K., Steffen, O., Sfienti, C., Strakovsky, I.I., Strandberg, B., Strub, Th., Supek, I., Tarbert, C.M., Thiel, A., Thiel, M., Thomas, A., Unverzagt, M., Usov, Yu.A., Watts, D.P., Werthümller, D., Wettig, J., Wolfes, M., Witthauer, L., and Zana, L.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

High-statistics measurements of the photon asymmetry Σ for the γp → π0p reaction have been\ud made in the center-of-mass energy range W = 1214–1450 MeV. The data were measured with the MAMI\ud A2 real photon beam and Crystal Ball/TAPS detector systems in Mainz, Germany. The results significantly\ud improve the existing world data and are shown to be in good agreement with previous measurements, and\ud with the MAID, SAID, and Bonn-Gatchina predictions. We have also combined the photon asymmetry\ud results with recent cross-section measurements from Mainz to calculate the profile functions, Σˇ (= σ0Σ), and perform a moment analysis. Comparison with calculations from the Bonn-Gatchina model shows\ud that the precision of the data is good enough to further constrain the higher partial waves, and there\ud is an indication of interference between the very small F-waves and the N(1520)3/2− and N(1535)1/2−\ud resonances.

Published
2016

6. Photoproduction of ηπ pairs off nucleons and deuterons

Author

Käser, A., Müller, F., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Bartolome, P. A., Beck, R., Braghieri, A., Briscoe, W. J., Cherepnya, S., Costanza, S., Dieterle, M., Downie, E. J., Drexler, P., Fil’kov, L. V., Fix, A., Garni, S., Glazier, D. I., Hamilton, D., Hornidge, D., Howdle, D., Huber, G. M., Jaegle, I., Jude, T. C., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J.D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., McGeorge, J.C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D. G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D., Starostin, A., Strub, Th., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Walford, N. K., Watts, D. P., Werthmüller, D., and Witthauer, L.

Subjects
Nuclear Theory, Nuclear Experiment, QC
Abstract

Quasi-free photoproduction of πηπη -pairs has been investigated from threshold up to incident photon energies of 1.4 GeV, respectively up to photon-nucleon invariant masses up to 1.9 GeV. Total cross sections, angular distributions, invariant-mass distributions of the πηπη and meson-nucleon pairs, and beam-helicity asymmetries have been measured for the reactions γp→pπ0ηγp→pπ0η , γn→nπ0ηγn→nπ0η , γp→nπ+ηγp→nπ+η , and γn→pπ−ηγn→pπ−η from nucleons bound inside the deuteron. For the γpγp initial-state data for free protons have also been analyzed. Finally, the total cross sections for quasi-free production of π0ηπ0η pairs from nucleons bound in 3 He nuclei have been investigated in view of final state interaction (FSI) effects. The experiments were performed at the tagged photon beam facility of the Mainz MAMI accelerator using an almost 4 ππ covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. The shapes of all differential cross section data and the asymmetries are very similar for protons and neutrons and agree with the conjecture that the reactions are dominated by the sequential Δ⋆3/2−→ηΔ(1232)→πηNΔ⋆3/2−→ηΔ(1232)→πηN decay chain, mainly with Δ(1700)3/2−Δ(1700)3/2− and Δ(1940)3/2−Δ(1940)3/2− . The ratios of the magnitude of the total cross sections also agree with this assumption. However, the absolute magnitudes of the cross sections are reduced by FSI effects with respect to free

Published
2016

7. Photoproduction of π0-pairs off protons and off neutrons

Author

Dieterle, M., Oberle, M., Ahrens, J., Annand, J. R. M>, Arends, H. J., Bantawa, K., Bartolome, P. A., Beck, R., Bekrenev, V., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Downie, E. J., Drexler, P., Fil’kov, L. V., Fix, A., Garni, S., Glazier, D. I., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Huber, G. M., Jahn, O., Jude, T. C., Käser, A., Kashevarov, V. L., Keshelashvili, I., Kondratiev, R., Korolija, M., Krusche, B., Lisin, V., Livingston, K., MacGregor, I. J. D., Maghrbi, Y., Mancell, J., Manley, D. M., Marinides, Z., McGeorge, J. C., McNicoll, E., Mekterovic, D., Metag, V., Micanovic, S., Middleton, D. G., Mushkarenkov, A., Nikolaev, A., Novotny, R., Ostrick, M., Otte, P., Oussena, B., Pedroni, P., Pheron, F., Polonski, A., Prakhov, S., Robinson, J., Rostomyan, T., Schumann, S., Sikora, M. H., Sober, D. I., Starostin, A., Strub, Th., Supek, I., Thiel, M., Thomas, A., Unverzagt, M., Walford, N. K., Watts, D. P., Werthmüller, D., and Witthauer, L.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

Total cross sections, angular distributions, and invariant-mass distributions have been measured for the photoproduction of π0π0 pairs off free protons and off nucleons bound in the deuteron. The experiments were performed at the MAMI accelerator facility in Mainz using the Glasgow photon tagging spectrometer and the Crystal Ball/TAPS detector. The accelerator delivered electron beams of 1508 and 1557MeV, which produced bremsstrahlung in thin radiator foils. The tagged photon beam covered energies up to 1400MeV. The data from the free proton target are in good agreement with previous measurements and were only used to test the analysis procedures. The results for differential cross sections (angular distributions and invariant-mass distributions) for free and quasi-free protons are almost identical in shape, but differ in absolute magnitude up to 15%. Thus, moderate final-state interaction effects are present. The data for quasi-free neutrons are similar to the proton data in the second resonance region (final-state invariant masses up to ≈1550 MeV), where both reactions are dominated by the N(1520)3/2−→Δ(1232)3/2+π decay. At higher energies, angular and invariant-mass distributions are different. A simple analysis of the shapes of the invariant-mass distributions in the third resonance region is consistent with strong contributions of an N⋆→Nσ decay for the proton, while the reaction is dominated by a sequential decay via a Δπ intermediate state for the neutron. The data are compared to predictions from the Two-Pion-MAID model and the Bonn-Gatchina coupled-channel analysis.

Published
2015

8. Measurements of 12C(→γ,pp) photon asymmetries for\ud Eγ= 200–450 MeV

Author

Robinson, J., MacGregor, I.J.D., Annand, J.R.M., Aguar-Bartolomé, P., Akasoy, L. K., Arends, H. J., Azimov, Y.I., Bantawa, K., Beck, R., Bekrenev, V.S., Berghäuser, H., Braghieri, A., Branford, D., Briscoe, W.J., Brudvik, J., Cherepnya, S., Codling, R.F.B., Demissie, B.T., Dieterle, M., Downie, E.J., Drexler, P., Fil’kov, L.V., Glazier, D.I., Gregor, R., Hamilton, D., Heid, E., Hornidge, D., Howdle, D., Jahn, O., Jude, T.C., Kashevarov, V.L., Keshelashvili, I., Kondratiev, R., Korolija, M., Kotulla, M., Koulbardis, A.A., Kruglov, S.P., Krusche, B., Lisin, V., Livingston, K., Manley, D.M., McGeorge, J.C., McNicoll, E.F., Metag, V., Middleton, D.G., Mushkarenkov, A., Nefkens, B.M.K., Nikolaev, A., Novotny, R., Oberle, M., Ostrick, M., Owens, R.O., Otte, P.B., Oussena, B., Pedroni, P., Polonski, A., Prakhov, S., Rosner, G., Rostomyan, T., Schumann, S., Sikora, M.H., Sober, D.I., Starostin, A., Strakovsky, I.I., Suarez, I.M., Supek, I., Tarbert, C.M., Thiel, M., Thomas, A., Unverzagt, M., Watts, D.P., Werthmueller, D., and Witthauer, L.

Subjects
Nuclear Theory, Nuclear Experiment
Abstract

The 12C (→γ ,pp) reaction has been studied in the photon energy range 200-450 MeV at the Mainz microtron MAMI-C, where linearly polarised photons were energy-tagged using the Glasgow-Mainz Tagged Photon Spectrometer and protons were detected in the Crystal Ball detector. The photon asymmetry Σ has been measured over a wider Eγ range than previous measurements. The strongest asymmetries were found at low missing energies where direct emission of nucleon pairs is expected. Cuts on the difference in azimuthal angles of the two ejected protons increased the magnitude of the observed asymmetries. At low missing energies the Σ data exhibit a strong angular dependence, similar to deuteron photodisintegration.

Published
2013

Catalog

Books, media, physical & digital resources
See catalog results