Quasifree photoproduction of eta mesons off protons and neutrons

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

doi:10.1103/PhysRevC.90.015205

Quasifree photoproduction of eta mesons off protons and neutrons

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

^*Corresponding author for this work

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract / Description of output

Differential and total cross sections for the quasifree reactions gamma p -> eta p and gamma n -> eta n have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes eta -> 2 gamma and eta -> 3 pi(0) -> 6 gamma and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The eta-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the S-11(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy W = (1670 +/- 5) MeV with an intrinsic width of Gamma approximate to 30 MeV.

Original language	English
Article number	015205
Number of pages	21
Journal	Physical Review C
Volume	90
Issue number	1
DOIs	https://doi.org/10.1103/PhysRevC.90.015205
Publication status	Published - 25 Jul 2014

Keywords / Materials (for Non-textual outputs)

NEAR-THRESHOLD PHOTOPRODUCTION
TAGGED PHOTON SPECTROMETER
EXCLUSIVE MEASUREMENT
BARYON RESONANCES
NARROW STRUCTURE
BEAM ASYMMETRY
QUARK-MODEL
DEUTERON
MICROTRON
ELECTROPRODUCTION

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10.1103/PhysRevC.90.015205

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Werthmueller, D., Witthauer, L., Keshelashvili, I., Aguar-Bartolome, P., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Beck, R., Bekrenev, V., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Costanza, S., Demissie, B., Dieterle, M., Downie, E. J., ... Watts, D. P. (2014). Quasifree photoproduction of eta mesons off protons and neutrons. Physical Review C, 90(1), Article 015205. https://doi.org/10.1103/PhysRevC.90.015205

@article{740971287e3747c3bbf9853118551d99,

title = "Quasifree photoproduction of eta mesons off protons and neutrons",

abstract = "Differential and total cross sections for the quasifree reactions gamma p -> eta p and gamma n -> eta n have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes eta -> 2 gamma and eta -> 3 pi(0) -> 6 gamma and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The eta-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the S-11(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy W = (1670 +/- 5) MeV with an intrinsic width of Gamma approximate to 30 MeV.",

keywords = "NEAR-THRESHOLD PHOTOPRODUCTION, TAGGED PHOTON SPECTROMETER, EXCLUSIVE MEASUREMENT, BARYON RESONANCES, NARROW STRUCTURE, BEAM ASYMMETRY, QUARK-MODEL, DEUTERON, MICROTRON, ELECTROPRODUCTION",

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

year = "2014",

month = jul,

day = "25",

doi = "10.1103/PhysRevC.90.015205",

language = "English",

volume = "90",

journal = "Physical Review C",

issn = "0556-2813",

publisher = "American Physical Society",

number = "1",

}

Werthmueller, D, Witthauer, L, Keshelashvili, I, Aguar-Bartolome, P, Ahrens, J, Annand, JRM, Arends, HJ, Bantawa, K, Beck, R, Bekrenev, V, Braghieri, A, Branford, D, Briscoe, WJ, Brudvik, J, Cherepnya, S, Costanza, 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, Kaeser, A, Kashevarov, VL, Kondratiev, R, Korolija, M, Kruglov, SP, Krusche, B, Kulbardis, A, Lisin, V, Livingston, K, MacGregor, IJD, Maghrbi, Y, Mancell, J, Manley, DM, Marinides, Z, Martinez, M, McGeorge, JC, McNicoll, EF, Metag, V, Middleton, DG, Mushkarenkov, A, Nefkens, BMK, Nikolaev, A, Novotny, R, Oberle, M, Ostrick, M, Otte, PB, 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 2014, 'Quasifree photoproduction of eta mesons off protons and neutrons', Physical Review C, vol. 90, no. 1, 015205. https://doi.org/10.1103/PhysRevC.90.015205

TY - JOUR

T1 - Quasifree photoproduction of eta mesons off protons and neutrons

AU - Werthmueller, D.

AU - Witthauer, L.

AU - Keshelashvili, I.

AU - Aguar-Bartolome, P.

AU - Ahrens, J.

AU - Annand, J. R. M.

AU - Arends, H. J.

AU - Bantawa, K.

AU - Beck, R.

AU - Bekrenev, V.

AU - Braghieri, A.

AU - Branford, D.

AU - Briscoe, W. J.

AU - Brudvik, J.

AU - Cherepnya, S.

AU - Costanza, S.

AU - Demissie, B.

AU - Dieterle, M.

AU - Downie, E. J.

AU - Drexler, P.

AU - Fil'kov, L. V.

AU - Fix, A.

AU - Glazier, D. I.

AU - Hamilton, D.

AU - Heid, E.

AU - Hornidge, D.

AU - Howdle, D.

AU - Huber, G. M.

AU - Jaegle, I.

AU - Jahn, O.

AU - Jude, T. C.

AU - Kaeser, A.

AU - Kashevarov, V. L.

AU - Kondratiev, R.

AU - Korolija, M.

AU - Kruglov, S. P.

AU - Krusche, B.

AU - Kulbardis, A.

AU - Lisin, V.

AU - Livingston, K.

AU - MacGregor, I. J. D.

AU - Maghrbi, Y.

AU - Mancell, J.

AU - Manley, D. M.

AU - Marinides, Z.

AU - Martinez, M.

AU - McGeorge, J. C.

AU - McNicoll, E. F.

AU - Metag, V.

AU - Middleton, D. G.

AU - Mushkarenkov, A.

AU - Nefkens, B. M. K.

AU - Nikolaev, A.

AU - Novotny, R.

AU - Oberle, M.

AU - Ostrick, M.

AU - Otte, P. B.

AU - Oussena, B.

AU - Pedroni, P.

AU - Pheron, F.

AU - Polonski, A.

AU - Prakhov, S. N.

AU - Robinson, J.

AU - Rosner, G.

AU - Rostomyan, T.

AU - Schumann, S.

AU - Sikora, M. H.

AU - Sober, D.

AU - Starostin, A.

AU - Supek, I.

AU - Thiel, M.

AU - Thomas, A.

AU - Unverzagt, M.

AU - Watts, D. P.

PY - 2014/7/25

Y1 - 2014/7/25

N2 - Differential and total cross sections for the quasifree reactions gamma p -> eta p and gamma n -> eta n have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes eta -> 2 gamma and eta -> 3 pi(0) -> 6 gamma and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The eta-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the S-11(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy W = (1670 +/- 5) MeV with an intrinsic width of Gamma approximate to 30 MeV.

AB - Differential and total cross sections for the quasifree reactions gamma p -> eta p and gamma n -> eta n have been determined at the MAMI-C electron accelerator by using a liquid deuterium target. Photons were produced via bremsstrahlung from the 1.5 GeV incident electron beam and energy tagged with the Glasgow photon tagger. Decay photons of the neutral decay modes eta -> 2 gamma and eta -> 3 pi(0) -> 6 gamma and coincident recoil nucleons were detected in a combined setup of the Crystal Ball and the TAPS calorimeters. The eta-production cross sections were measured in coincidence with recoil protons, recoil neutrons, and in an inclusive mode without a condition on recoil nucleons, which allowed a check of the internal consistency of the data. The effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final-state invariant mass and possible nuclear effects on the quasifree cross section were investigated by a comparison of free and quasifree-proton data. The results, which represent a significant improvement in statistical quality compared to previous measurements, agree with the known neutron-to-proton cross-section ratio in the peak of the S-11(1535) resonance and confirm a peak in the neutron cross section, which is absent for the proton, at a center-of-mass energy W = (1670 +/- 5) MeV with an intrinsic width of Gamma approximate to 30 MeV.

KW - NEAR-THRESHOLD PHOTOPRODUCTION

KW - TAGGED PHOTON SPECTROMETER

KW - EXCLUSIVE MEASUREMENT

KW - BARYON RESONANCES

KW - NARROW STRUCTURE

KW - BEAM ASYMMETRY

KW - QUARK-MODEL

KW - DEUTERON

KW - MICROTRON

KW - ELECTROPRODUCTION

U2 - 10.1103/PhysRevC.90.015205

DO - 10.1103/PhysRevC.90.015205

M3 - Article

SN - 0556-2813

VL - 90

JO - Physical Review C

JF - Physical Review C

IS - 1

M1 - 015205

ER -

Quasifree photoproduction of eta mesons off protons and neutrons

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Keywords / Materials (for Non-textual outputs)

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