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Your search keyword '"Nefkens, B. M. K."' showing total 36 results
Start Over Author "Nefkens, B. M. K." Journal physical review letters
36 results on '"Nefkens, B. M. K."'

1. Narrow Structure in the Excitation Function ofηPhotoproduction off the Neutron

Author

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

Published
2013
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2. Beam-Helicity Asymmetries in Double-Pion Photoproduction off the Proton

Author

Krambrich, D., primary, Zehr, F., additional, Fix, A., additional, Roca, L., additional, Aguar, P., additional, Ahrens, J., additional, Annand, J. R. M., additional, Arends, H. J., additional, Beck, R., additional, Bekrenev, V., additional, Boillat, B., additional, Braghieri, A., additional, Branford, D., additional, Briscoe, W. J., additional, Brudvik, J., additional, Cherepnya, S., additional, Codling, R., additional, Downie, E. J., additional, Dexler, P., additional, Glazier, D. I., additional, Grabmayr, P., additional, Gregor, R., additional, Heid, E., additional, Hornidge, D., additional, Jahn, O., additional, Kashevarov, V. L., additional, Knezevic, A., additional, Kondratiev, R., additional, Korolija, M., additional, Kotulla, M., additional, Krusche, B., additional, Kulbardis, A., additional, Lang, M., additional, Lisin, V., additional, Livingston, K., additional, Lugert, S., additional, MacGregor, I. J. D., additional, Manley, D. M., additional, Martinez, M., additional, McGeorge, J. C., additional, Mekterovic, D., additional, Metag, V., additional, Nefkens, B. M. K., additional, Nikolaev, A., additional, Pedroni, P., additional, Pheron, F., additional, Polonski, A., additional, Prakhov, S. N., additional, Price, J. W., additional, Rosner, G., additional, Rost, M., additional, Rostomyan, T., additional, Schumann, S., additional, Sober, D., additional, Starostin, A., additional, Supek, I., additional, Tarbert, C. M., additional, Thomas, A., additional, Unverzagt, M., additional, Walcher, Th., additional, and Watts, D. P., additional

Published
2009
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3. Incoherent Neutral Pion Photoproduction onC12

Author

Tarbert, C. M., primary, Watts, D. P., additional, Aguar, P., additional, Ahrens, J., additional, Annand, J. R. M., additional, Arends, H. J., additional, Beck, R., additional, Bekrenev, V., additional, Boillat, B., additional, Braghieri, A., additional, Branford, D., additional, Briscoe, W. J., additional, Brudvik, J., additional, Cherepnya, S., additional, Codling, R., additional, Downie, E. J., additional, Föhl, K., additional, Glazier, D. I., additional, Grabmayr, P., additional, Gregor, R., additional, Heid, E., additional, Hornidge, D., additional, Jahn, O., additional, Kashevarov, V. L., additional, Knezevic, A., additional, Kondratiev, R., additional, Korolija, M., additional, Kotulla, M., additional, Krambrich, D., additional, Krusche, B., additional, Lang, M., additional, Lisin, V., additional, Livingston, K., additional, Lugert, S., additional, MacGregor, I. J. D., additional, Manley, D. M., additional, Martinez, M., additional, McGeorge, J. C., additional, Mekterovic, D., additional, Metag, V., additional, Nefkens, B. M. K., additional, Nikolaev, A., additional, Novotny, R., additional, Owens, R. O., additional, Pedroni, P., additional, Polonski, A., additional, Prakhov, S. N., additional, Price, J. W., additional, Rosner, G., additional, Rost, M., additional, Rostomyan, T., additional, Schadmand, S., additional, Schumann, S., additional, Sober, D., additional, Starostin, A., additional, Supek, I., additional, Thomas, A., additional, Unverzagt, M., additional, Walcher, Th., additional, and Zehr, F., additional

Published
2008
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4. Test of Charge Conjugation Invariance

Author

Nefkens, B. M. K., primary, Prakhov, S., additional, Gårdestig, A., additional, Allgower, C. E., additional, Bekrenev, V., additional, Briscoe, W. J., additional, Clajus, M., additional, Comfort, J. R., additional, Craig, K., additional, Grosnick, D., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D., additional, Koulbardis, A., additional, Kozlenko, N., additional, Kruglov, S., additional, Lolos, G., additional, Lopatin, I., additional, Manley, D. M., additional, Manweiler, R., additional, Marušić, A., additional, McDonald, S., additional, Olmsted, J., additional, Papandreou, Z., additional, Peaslee, D., additional, Phaisangittisakul, N., additional, Price, J. W., additional, Ramirez, A. F., additional, Sadler, M., additional, Shafi, A., additional, Spinka, H., additional, Stanislaus, T. D. S., additional, Starostin, A., additional, Staudenmaier, H. M., additional, Supek, I., additional, and Tippens, W. B., additional

Published
2005
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5. Dynamics of theπ−p→π0π0nReaction forpπ−<750 MeV/c

Author

Craig, K., primary, Comfort, J. R., additional, Allgower, C. E., additional, Bekrenev, V., additional, Berger, E., additional, Briscoe, W. J., additional, Clajus, M., additional, Draper, B., additional, Grosnick, D., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D., additional, Koulbardis, A., additional, Kozlenko, N., additional, Kruglov, S., additional, Lolos, G. J., additional, Lopatin, I., additional, Manley, D. M., additional, Manweiler, R., additional, Marušić, A., additional, McDonald, S., additional, Nefkens, B. M. K., additional, Olmsted, J., additional, Papandreou, Z., additional, Peaslee, D., additional, Phaisangittisakul, N., additional, Prakhov, S., additional, Price, J. W., additional, Pulver, M., additional, Ramirez, A. F., additional, Sadler, M. E., additional, Shafi, A., additional, Spinka, H., additional, Stanislaus, S., additional, Starostin, A., additional, Supek, I., additional, Staudenmaier, H. M., additional, and Tippens, W. B., additional

Published
2003
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6. Properties of theΛ(1670)12−Resonance

Author

Manley, D. M., primary, Abaev, V. V., additional, Allgower, C. E., additional, Bekrenev, V., additional, Briscoe, W. J., additional, Clajus, M., additional, Comfort, J. R., additional, Craig, K., additional, Grosnick, D., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D. D., additional, Kulbardis, A. A., additional, Kozlenko, N. G., additional, Kruglov, S., additional, Lolos, G., additional, Lopatin, I. V., additional, Manweiler, R., additional, Marušić, A., additional, McDonald, S., additional, Nefkens, B. M. K., additional, Olmsted, J., additional, Papandreou, Z., additional, Peaslee, D. C., additional, Phaisangittisakul, N., additional, Prakhov, S., additional, Price, J. W., additional, Ramirez, A. F., additional, Sadler, M., additional, Shafi, A., additional, Spinka, H., additional, Stanislaus, T. D. S., additional, Starostin, A., additional, Staudenmaier, H. M., additional, Strakovsky, I. I., additional, Supek, I., additional, and Tippens, W. B., additional

Published
2001
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7. Determination of the Quadratic Slope Parameter inη→3π0Decay

Author

Tippens, W. B., primary, Prakhov, S., additional, Allgower, C. E., additional, Bekrenev, V., additional, Berger, E., additional, Briscoe, W. J., additional, Clajus, M., additional, Comfort, J. R., additional, Craig, K., additional, Efendiev, A., additional, Grosnick, D., additional, Holstein, B. R., additional, Huber, G. M., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D., additional, Koulbardis, A., additional, Kozlenko, N., additional, Kruglov, S., additional, Lolos, G. J., additional, Lopatin, I., additional, Manley, D. M., additional, Marušić, A., additional, Manweiler, R., additional, McDonald, S., additional, Nefkens, B. M. K., additional, Olmsted, J., additional, Papandreou, Z., additional, Phaisangittisakul, N., additional, Price, J. W., additional, Pulver, M., additional, Ramirez, A. F., additional, Sadler, M. E., additional, Shafi, A., additional, Spinka, H., additional, Stanislaus, S., additional, Starostin, A., additional, and Staudenmaier, H. M., additional

Published
2001
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8. Measurement ofπ0π0Production in the Nuclear Medium byπ−Interactions at0.408GeV/c

Author

Starostin, A., primary, Staudenmaier, H. M., additional, Allgower, C. E., additional, Bekrenev, V., additional, Berger, E., additional, Briscoe, W. J., additional, Clajus, M., additional, Comfort, J. R., additional, Craig, K., additional, Grosnick, D., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D., additional, Koulbardis, A., additional, Kozlenko, N., additional, Kruglov, S., additional, Kycia, T., additional, Lolos, G., additional, Lopatin, I., additional, Manley, D. M., additional, Manweiler, B., additional, Marušić, A., additional, McDonald, S., additional, Nefkens, B. M. K., additional, Olmsted, J., additional, Papandreou, Z., additional, Peaslee, D., additional, Peterson, R. J., additional, Phaisangittisakul, N., additional, Prakhov, S., additional, Pulver, M., additional, Ramirez, A. F., additional, Sadler, M., additional, Shafi, A., additional, Slaus, I., additional, Spinka, H., additional, Stanislaus, S., additional, Supek, I., additional, and Tippens, W. B., additional

Published
2000
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9. Search for theCPForbidden Decayη→4π0

Author

Prakhov, S., primary, Tippens, W. B., additional, Allgower, C., additional, Bekrenev, V., additional, Berger, E., additional, Briscoe, W. J., additional, Clajus, M., additional, Comfort, J. R., additional, Craig, K., additional, Grosnick, D., additional, Huber, G. M., additional, Isenhower, D., additional, Knecht, N., additional, Koetke, D., additional, Koulbardis, A., additional, Kozlenko, N., additional, Kruglov, S., additional, Kycia, T., additional, Lolos, G. J., additional, Lopatin, I., additional, Manley, D. M., additional, Marušić, A., additional, Manweiler, R., additional, McDonald, S., additional, Nefkens, B. M. K., additional, Olmsted, J., additional, Papandreou, Z., additional, Peaslee, D., additional, Peterson, G. J., additional, Phaisangittisakul, N., additional, Pulver, M., additional, Ramirez, A. F., additional, Sadler, M. E., additional, Shafi, A., additional, Šlaus, I., additional, Spinka, H., additional, Stanislaus, S., additional, Starostin, A., additional, Staudenmaier, H. M., additional, Supek, I., additional, and Wong, C. W., additional

Published
2000
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10. Measurement of the branching ratio for the decay η→μ+μ−

Author

Kessler, R. S., primary, Abegg, R., additional, Baldisseri, A., additional, Boudard, A., additional, Briscoe, W., additional, Fabbro, B., additional, Garçon, M., additional, Hermes, E. A., additional, Jacobs, W. W., additional, Lytkin, L., additional, Mayer, B., additional, Nefkens, B. M. K., additional, Niebuhr, C., additional, Petrov, A. M., additional, Poitou, J., additional, Saudinos, J., additional, Tippens, B., additional, Tomasi-Gustafsson, E., additional, van der Schaaf, A., additional, van Oers, W. T. H., additional, Vigdor, S. E., additional, Wang, M., additional, and White, D., additional

Published
1993
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11. Measurement of the spin-rotation parametersAandRforπ+p→π+p andπ−p→π−p scattering from 471 to 625 MeV/c

Author

Barlow, D. B., primary, Kessler, R. S., additional, Kim, G. J., additional, Nefkens, B. M. K., additional, Pillai, C., additional, Price, J. W., additional, Wightman, J. A., additional, Hall, S., additional, Lane, D. W., additional, Loe, S. R., additional, Morton, L. K., additional, Sadler, M. E., additional, Adrian, S. D., additional, Briscoe, W. J., additional, Kramer, L. H., additional, Mokhtari, A., additional, Petrov, A. M., additional, Seftor, C. J., additional, Taragin, M. F., additional, Davis, J. F., additional, and Supek, I., additional

Published
1989
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16. Left-Right Asymmetry in Inverseπ−Photoproduction from a Transversely Polarized Proton Target

Author

Kim, G. J., primary, Adrian, S. D., additional, Arends, J., additional, Briscoe, W. J., additional, Eichon, A. D., additional, Engelage, J., additional, Graessle, S., additional, Nefkens, B. M. K., additional, Ohashi, Y., additional, Sadler, M. E., additional, Seftor, C. J., additional, Sober, D. I., additional, Taragin, M., additional, and Ziock, H. J., additional

Published
1986
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17. Measurement ofp+d→He3+γand Comparison with the Inverse Reaction

Author

Nefkens, B. M. K., primary, Bauer, Th. S., additional, Baba, K., additional, Boudard, A., additional, Briscoe, W. J., additional, Bruge, G., additional, Faure, J. L., additional, Gosset, J., additional, Hegerath, A., additional, Lugol, J. C., additional, Silverman, B. H., additional, and Terrien, Y., additional

Published
1980
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20. Experimental Investigation ofCPViolation inKe30Decays

Author

Verhey, L. J., primary, Nefkens, B. M. K., additional, Abashian, A., additional, Abrams, R. J., additional, Carpenter, D. W., additional, Mischke, R. E., additional, Smith, J. H., additional, Thatcher, R. C., additional, and Wattenberg, A., additional

Published
1966
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28. Measurements of double-polarized compton scattering asymmetries and extraction of the proton spin polarizabilities.

Author

Martel PP, Miskimen R, Aguar-Bartolome P, Ahrens J, Akondi CS, Annand JR, Arends HJ, Barnes W, Beck R, Bernstein A, Borisov N, Braghieri A, Briscoe WJ, Cherepnya S, Collicott C, Costanza S, Denig A, Dieterle M, Downie EJ, Fil'kov LV, Garni S, Glazier DI, Gradl W, Gurevich G, Hall Barrientos P, Hamilton D, Hornidge D, Howdle D, Huber GM, Jude TC, Kaeser A, Kashevarov VL, Keshelashvili I, Kondratiev R, Korolija M, Krusche B, Lazarev A, Lisin V, Livingston K, MacGregor IJ, Mancell J, Manley DM, Meyer W, Middleton DG, Mushkarenkov A, Nefkens BM, Neganov A, Nikolaev A, Oberle M, Ortega Spina H, Ostrick M, Ott P, Otte PB, Oussena B, Pedroni P, Polonski A, Polyansky V, Prakhov S, Rajabi A, Reicherz G, Rostomyan T, Sarty A, Schrauf S, Schumann S, Sikora MH, Starostin A, Steffen O, Strakovsky II, Strub T, Supek I, Thiel M, Tiator L, Thomas A, Unverzagt M, Usov Y, Watts DP, Witthauer L, Werthmüller D, and Wolfes M

Abstract

The spin polarizabilities of the nucleon describe how the spin of the nucleon responds to an incident polarized photon. The most model-independent way to extract the nucleon spin polarizabilities is through polarized Compton scattering. Double-polarized Compton scattering asymmetries on the proton were measured in the Δ(1232) region using circularly polarized incident photons and a transversely polarized proton target at the Mainz Microtron. Fits to asymmetry data were performed using a dispersion model calculation and a baryon chiral perturbation theory calculation, and a separation of all four proton spin polarizabilities in the multipole basis was achieved. The analysis based on a dispersion model calculation yields γ(E1E1)=-3.5±1.2, γ(M1M1)=3.16±0.85, γ(E1M2)=-0.7±1.2, and γ(M1E2)=1.99±0.29, in units of 10(-4)  fm(4).

Published
2015
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29. Measurement of the transverse target and beam-target asymmetries in η meson photoproduction at MAMI.

Author

Akondi CS, Annand JR, Arends HJ, Beck R, Bernstein A, Borisov N, Braghieri A, Briscoe WJ, Cherepnya S, Collicott C, Costanza S, Downie EJ, Dieterle M, Fix A, Fil'kov LV, Garni S, Glazier DI, Gradl W, Gurevich G, Hall Barrientos P, Hamilton D, Hornidge D, Howdle D, Huber GM, Kashevarov VL, Keshelashvili I, Kondratiev R, Korolija M, Krusche B, Lazarev A, Lisin V, Livingston K, MacGregor IJ, Mancel J, Manley DM, Martel P, McNicoll EF, Meyer W, Middleton D, Miskimen R, Mushkarenkov A, Nefkens BM, Neganov A, Nikolaev A, Oberle M, Ostrick M, Ortega H, Ott P, Otte PB, Oussena B, Pedroni P, Polonski A, Polyanski VV, Prakhov S, Reicherz G, Rostomyan T, Sarty A, Schumann S, Steffen O, Strakovsky II, Strub T, Supek I, Tiator L, Thomas A, Unverzagt M, Usov YA, Watts DP, Werthmüller D, Witthauer L, and Wolfes M

Abstract

We present new data for the transverse target asymmetry T and the very first data for the beam-target asymmetry F in the γ[over →]p[over →]→ηp reaction up to a center-of-mass energy of W=1.9  GeV. The data were obtained with the Crystal-Ball/TAPS detector setup at the Glasgow tagged photon facility of the Mainz Microtron MAMI. All existing model predictions fail to reproduce the new data indicating a significant impact on our understanding of the underlying dynamics of η meson photoproduction. The peculiar nodal structure observed in existing T data close to threshold is not confirmed.

Published
2014
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30. Neutron skin of (208)pb from coherent pion photoproduction.

Author

Tarbert CM, Watts DP, Glazier DI, Aguar P, Ahrens J, Annand JR, Arends HJ, Beck R, Bekrenev V, Boillat B, Braghieri A, Branford D, Briscoe WJ, Brudvik J, Cherepnya S, Codling R, Downie EJ, Foehl K, Grabmayr P, Gregor R, Heid E, Hornidge D, Jahn O, Kashevarov VL, Knezevic A, Kondratiev R, Korolija M, Kotulla M, Krambrich D, Krusche B, Lang M, Lisin V, Livingston K, Lugert S, MacGregor IJ, Manley DM, Martinez M, McGeorge JC, Mekterovic D, Metag V, Nefkens BM, Nikolaev A, Novotny R, Owens RO, Pedroni P, Polonski A, Prakhov SN, Price JW, Rosner G, Rost M, Rostomyan T, Schadmand S, Schumann S, Sober D, Starostin A, Supek I, Thomas A, Unverzagt M, Walcher T, Zana L, and Zehr F

Abstract

Information on the size and shape of the neutron skin on (208)Pb is extracted from coherent pion photoproduction cross sections measured using the Crystal Ball detector together with the Glasgow tagger at the MAMI electron beam facility. On exploitation of an interpolated fit of a theoretical model to the measured cross sections, the half-height radius and diffuseness of the neutron distribution are found to be c(n)=6.70±0.03(stat.)  fm and a(n)=0.55±0.01(stat.)(-0.03)(+0.02)(sys.)  fm, respectively, corresponding to a neutron skin thickness Δr(np)=0.15±0.03(stat.)(-0.03)(+0.01)(sys.)  fm. The results give the first successful extraction of a neutron skin thickness with an electromagnetic probe and indicate that the skin of (208)Pb has a halo character. The measurement provides valuable new constraints on both the structure of nuclei and the equation of state for neutron-rich matter.

Published
2014
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31. Photoproduction of π0 mesons off neutrons in the nucleon resonance region.

Author

Dieterle M, Keshelashvili I, Ahrens J, Annand JR, Arends HJ, Bantawa K, Bartolome PA, Beck R, Bekrenev V, Braghieri A, Branford D, Briscoe WJ, Brudvik J, Cherepnya S, Demissie B, Downie EJ, Drexler P, Fil'kov LV, Fix A, Glazier DI, Hamilton D, Heid E, Hornidge D, Howdle D, Huber GM, Jaegle I, Jahn O, Jude TC, Käser A, Kashevarov VL, Kondratiev R, Korolija M, Kruglov SP, Krusche B, Kulbardis A, Lisin V, Livingston K, MacGregor IJ, Maghrbi Y, Mancell J, Manley DM, Marinides Z, Martinez M, McGeorge JC, McNicoll E, Mekterovic D, Metag V, Micanovic S, Middleton DG, Mushkarenkov A, Nefkens BM, Nikolaev A, Novotny R, Oberle M, Ostrick M, Oussena B, Pedroni P, Pheron F, Polonski A, Prakhov SN, Robinson J, Rosner G, Rostomyan T, Schumann S, Sikora MH, Sober D, Starostin A, Supek I, Thiel M, Thomas A, Unverzagt M, Watts DP, Werthmüller D, and Witthauer L

Abstract

Precise angular distributions have been measured for the first time for the photoproduction of π0 mesons off neutrons bound in the deuteron. The effects from nuclear Fermi motion have been eliminated by a complete kinematic reconstruction of the final state. The influence of final-state-interaction effects has been estimated by a comparison of the reaction cross section for quasifree protons bound in the deuteron to the results for free protons and then applied as a correction to the quasifree neutron data. The experiment was performed at the tagged photon facility of the Mainz Microtron MAMI with the Crystal Ball and TAPS detector setup for incident photon energies between 0.45 and 1.4 GeV. The results are compared to the predictions from reaction models and partial-wave analyses based on data from other isospin channels. The model predictions show large discrepancies among each other and the present data will provide much tighter constraints. This is demonstrated by the results of a new analysis in the framework of the Bonn-Gatchina coupled-channel analysis which included the present data.

Published
2014
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32. Measurement of the 1H(γ, p)π0 reaction using a novel nucleon spin polarimeter.

Author

Sikora MH, Watts DP, Glazier DI, Aguar-Bartolomé P, Akasoy LK, Annand JR, Arends HJ, Bantawa K, Beck R, Bekrenev VS, Berghäuser H, Braghieri A, Branford D, Briscoe WJ, Brudvik J, Cherepnya S, Codling RF, Demissie BT, Downie EJ, Drexler P, Fil'kov LV, Freehart B, Gregor R, Hamilton D, Heid E, Hornidge D, Howdle DA, Jaegle I, Jahn O, Jude TC, Kashevarov VL, Keshelashvili I, Kondratiev R, Korolija M, Kotulla M, Koulbardis AA, Kruglov SP, Krusche B, Lisin V, Livingston K, MacGregor IJ, Maghrbi Y, Manley DM, Marinides Z, Martinez M, McGeorge JC, McKinnon B, McNicoll EF, Mekterovic D, Metag V, Micanovic S, Middleton DG, Mushkarenkov A, Nefkens BM, Nikolaev A, Novotny R, Ostrick M, Otte PB, Oussena B, Pedroni P, Pheron F, Polonski A, Prakhov S, Robinson J, Rosner G, Rostomyan T, Schumann S, Sober DI, Starostin A, Strakovsky II, Suarez IM, Supek I, Thiel M, Thomas A, Unverzagt M, Werthmüller D, Workman RL, Zamboni I, and Zehr F

Abstract

We report the first large-acceptance measurement of polarization transfer from a polarized photon beam to a recoiling nucleon. The measurement pioneers a novel polarimetry technique, which can be applied to many other nuclear and hadron physics experiments. The commissioning reaction of 1H(γ, p)π0 in the range 0.4

Published
2014
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33. Narrow structure in the excitation function of η photoproduction off the neutron.

Author

Werthmüller D, Witthauer L, Keshelashvili I, Aguar-Bartolomé P, Ahrens J, Annand JR, Arends HJ, Bantawa K, Beck R, Bekrenev V, Braghieri A, Branford D, Briscoe WJ, Brudvik J, Cherepnya S, Demissie B, Dieterle M, Downie EJ, Drexler P, Fil'kov LV, Fix A, Glazier DI, Hamilton D, Heid E, Hornidge D, Howdle D, Huber GM, Jaegle I, Jahn O, Jude TC, Käser A, Kashevarov VL, Kondratiev R, Korolija M, Kruglov SP, Krusche B, Kulbardis A, Lisin V, Livingston K, MacGregor IJ, Maghrbi Y, Mancell J, Manley DM, Marinides Z, Martinez M, McGeorge JC, McNicoll EF, Metag V, Middleton DG, Mushkarenkov A, Nefkens BM, Nikolaev A, Novotny R, Oberle M, Ostrick M, Oussena B, Pedroni P, Pheron F, Polonski A, Prakhov SN, Robinson J, Rosner G, Rostomyan T, Schumann S, Sikora MH, Sober D, Starostin A, Supek I, Thiel M, Thomas A, Unverzagt M, and Watts DP

Abstract

The photoproduction of η mesons off nucleons bound in 2H and 3He has been measured in coincidence with recoil protons and recoil neutrons for incident photon energies from threshold up to 1.4 GeV. The experiments were performed at the Mainz MAMI accelerator, using the Glasgow tagged photon facility. Decay photons from the η→2γ and η→3π0 decays and the recoil nucleons were detected with an almost 4π electromagnetic calorimeter combining the Crystal Ball and TAPS detectors. The data from both targets are of excellent statistical quality and show a narrow structure in the excitation function of γn→nη. The results from the two measurements are consistent, taking into account the expected effects from nuclear Fermi motion. The best estimates for position and intrinsic width of the structure are W=(1670±5)  MeV and Γ=(30±15)  MeV. For the first time precise results for the angular dependence of this structure have been extracted.

Published
2013
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34. Accurate test of chiral dynamics in the γp→π0p reaction.

Author

Hornidge D, Aguar Bartolomé P, Annand JR, Arends HJ, Beck R, Bekrenev V, Berghäuser H, Bernstein AM, Braghieri A, Briscoe WJ, Cherepnya S, Dieterle M, Downie EJ, Drexler P, Fernández-Ramírez C, Filkov LV, Glazier DI, Hall Barrientos P, Heid E, Hilt M, Jaegle I, Jahn O, Jude TC, Kashevarov VL, Keshelashvili I, Kondratiev R, Korolija M, Koulbardis A, Krambrich D, Kruglov S, Krusche B, Laffoley AT, Lisin V, Livingston K, MacGregor IJ, Mancell J, Manley DM, McNicoll EF, Mekterovic D, Metag V, Micanovic S, Middleton DG, Moores KW, Mushkarenkov A, Nefkens BM, Oberle M, Ostrick M, Otte PB, Oussena B, Pedroni P, Pheron F, Polonski A, Prakhov S, Robinson J, Rostomyan T, Scherer S, Schumann S, Sikora MH, Starostin A, Supek I, Thiel M, Thomas A, Tiator L, Unverzagt M, Watts DP, Werthmüller D, and Witthauer L

Abstract

A precision measurement of the differential cross sections dσ/dΩ and the linearly polarized photon asymmetry Σ≡(dσ⊥-dσ∥)/(dσ⊥+dσ∥) for the γp→π0p reaction in the near-threshold region has been performed with a tagged photon beam and almost 4π detector at the Mainz Microtron. The Glasgow-Mainz photon tagging facility along with the Crystal Ball/TAPS multiphoton detector system and a cryogenic liquid hydrogen target were used. These data allowed for a precise determination of the energy dependence of the real parts of the S- and all three P-wave amplitudes for the first time and provide the most stringent test to date of the predictions of chiral perturbation theory and its energy region of agreement with experiment.

Published
2013
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35. Dynamics of the pi(-)p-->pi(0)pi(0)n reaction for p(pi(-))<750 MeV/c.

Author

Craig K, Comfort JR, Allgower CE, Bekrenev V, Berger E, Briscoe WJ, Clajus M, Draper B, Grosnick D, Isenhower D, Knecht N, Koetke D, Koulbardis A, Kozlenko N, Kruglov S, Lolos GJ, Lopatin I, Manley DM, Manweiler R, Marusić A, McDonald S, Nefkens BM, Olmsted J, Papandreou Z, Peaslee D, Phaisangittisakul N, Prakhov S, Price JW, Pulver M, Ramirez AF, Sadler ME, Shafi A, Spinka H, Stanislaus S, Starostin A, Supek I, Staudenmaier HM, and Tippens WB

Abstract

Data are presented for the reaction pi(-)p-->pi(0)pi(0)n in the range from threshold to p(pi(-))=750 MeV/c. The systematics of the data and multipole analyses are examined for sensitivity to a f(0)(600) ("sigma") meson. A one-pion-exchange mechanism is found to be very weak, or absent. The reaction appears to become dominated by sequential pi(0) decays through the Delta(1232) resonance as the beam momentum increases, along with substantial interference effects from several competing mechanisms.

Published
2003
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36. Properties of the Lambda(1670)(1-)/2 resonance.

Author

Manley DM, Abaev VV, Allgower CE, Bekrenev V, Briscoe WJ, Clajus M, Comfort JR, Craig K, Grosnick D, Isenhower D, Knecht N, Koetke DD, Kulbardis AA, Kozlenko NG, Kruglov S, Lolos G, Lopatin IV, Manweiler R, Marusić A, McDonald S, Nefkens BM, Olmsted J, Papandreou Z, Peaslee DC, Phaisangittisakul N, Prakhov S, Price JW, Ramirez AF, Sadler M, Shafi A, Spinka H, Stanislaus TD, Starostin A, Staudenmaier HM, Strakovsky II, Supek I, and Tippens WB

Abstract

Recently the Crystal Ball Collaboration measured precise new data for the near-threshold reaction K(-)p-->etaLambda, which is dominated by formation of the Lambda(1670)1 / 2(-). In this Letter, we present results of a unitary, multichannel analysis that incorporates the new Crystal Ball data. For our preferred fit, we obtain mass M = 1673+/-2 MeV, width Gamma = 23+/-6 MeV, and elasticity x = 0.37+/-0.07. This elasticity is significantly larger than previously recognized. Resonance parameters of our preferred fit are in striking agreement with the quark-model predictions of Koniuk and Isgur.

Published
2002
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