Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron

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

doi:10.1016/j.physletb.2013.03.021

Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron

M. Oberle, B. Krusche^*, J. Ahrens, J. R. M. Annand, H. J. Arends, K. Bantawa, P. A. Bartolome, R. Beck, V. Bekrenev, H. Berghaeuser, A. Braghieri, D. Branford, W. J. Briscoe, J. Brudvik, S. Cherepnya, B. Demissie, M. Dieterle, E. J. Downie, P. Drexler, L. V. Fil'kovA. Fix, D. I. Glazier, E. Heid, D. Hornidge, D. Howdle, G. M. Huber, O. Jahn, I. Jaegle, T. C. Jude, A. Kaeser, V. L. Kashevarov, I. Keshelashvili, R. Kondratiev, M. Korolija, S. P. Kruglov, 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. McNicoll, D. Mekterovic, V. Metag, S. Micanovic, D. G. Middleton, A. Mushkarenkov, B. M. K. Nefkens, A. Nikolaev, R. Novotny, M. Ostrick, B. Oussena, P. Pedroni, F. Pheron, A. Polonski, S. N. Prakhov, J. Robinson, G. Rosner, T. Rostomyan, S. Schumann, M. H. Sikora, D. I. Sober, A. Starostin, I. Supek, M. Thiel, A. Thomas, M. Unverzagt, D. P. Watts, D. Werthmueller, L. Witthauer, F. Zehr

^*Corresponding author for this work

School of Physics and Astronomy

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

Abstract / Description of output

Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions (gamma) over right arrowp -> p pi(0)pi(0) and (gamma) over right arrowd -> (n)p pi(0)pi(0), (gamma) over right arrowd -> (p)n pi(0)pi(0) off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Decay photons from the pi(0) mesons, recoil protons, and recoil neutrons were detected in the 4 pi covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons. This demonstrates that the free-nucleon behavior of such observables can be extracted from measurements with quasi-free nucleons, which is the only possibility for the neutron. Contrary to expectations, the measured asymmetries are very similar for reactions off protons and neutrons. The results are compared to the predictions from the Two-Pion MAID reaction model and (for the proton) also to the Bonn-Gatchina coupled channel analysis. (C) 2013 Elsevier B.V. All rights reserved.

Original language	English
Pages (from-to)	237-243
Number of pages	7
Journal	Physics Letters B
Volume	721
Issue number	4-5
DOIs	https://doi.org/10.1016/j.physletb.2013.03.021
Publication status	Published - 25 Apr 2013

Keywords / Materials (for Non-textual outputs)

DOUBLE-PION-PHOTOPRODUCTION
TOTAL CROSS-SECTION
DOUBLE PI(0) PHOTOPRODUCTION
TAGGED PHOTON SPECTROMETER
2ND RESONANCE REGION
BARYON RESONANCES
PARTIAL-WAVE
MICROTRON
THRESHOLD
MAMI

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10.1016/j.physletb.2013.03.021

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Oberle, M., Krusche, B., Ahrens, J., Annand, J. R. M., Arends, H. J., Bantawa, K., Bartolome, P. A., Beck, R., Bekrenev, V., Berghaeuser, H., Braghieri, A., Branford, D., Briscoe, W. J., Brudvik, J., Cherepnya, S., Demissie, B., Dieterle, M., Downie, E. J., Drexler, P., ... Zehr, F. (2013). Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron. Physics Letters B, 721(4-5), 237-243. https://doi.org/10.1016/j.physletb.2013.03.021

@article{156215983a26488080bb2596df025719,

title = "Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron",

abstract = "Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions (gamma) over right arrowp -> p pi(0)pi(0) and (gamma) over right arrowd -> (n)p pi(0)pi(0), (gamma) over right arrowd -> (p)n pi(0)pi(0) off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Decay photons from the pi(0) mesons, recoil protons, and recoil neutrons were detected in the 4 pi covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons. This demonstrates that the free-nucleon behavior of such observables can be extracted from measurements with quasi-free nucleons, which is the only possibility for the neutron. Contrary to expectations, the measured asymmetries are very similar for reactions off protons and neutrons. The results are compared to the predictions from the Two-Pion MAID reaction model and (for the proton) also to the Bonn-Gatchina coupled channel analysis. (C) 2013 Elsevier B.V. All rights reserved.",

keywords = "DOUBLE-PION-PHOTOPRODUCTION, TOTAL CROSS-SECTION, DOUBLE PI(0) PHOTOPRODUCTION, TAGGED PHOTON SPECTROMETER, 2ND RESONANCE REGION, BARYON RESONANCES, PARTIAL-WAVE, MICROTRON, THRESHOLD, MAMI",

author = "M. Oberle and B. Krusche and J. Ahrens and Annand, {J. R. M.} and Arends, {H. J.} and K. Bantawa and Bartolome, {P. A.} and R. Beck and V. Bekrenev and H. Berghaeuser and A. Braghieri and D. Branford and Briscoe, {W. J.} and J. Brudvik and S. Cherepnya 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 E. Heid and D. Hornidge and D. Howdle and Huber, {G. M.} and O. Jahn and I. Jaegle and Jude, {T. C.} and A. Kaeser and Kashevarov, {V. L.} and I. Keshelashvili and R. Kondratiev and M. Korolija and Kruglov, {S. P.} 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 E. McNicoll and D. Mekterovic and V. Metag and S. Micanovic and Middleton, {D. G.} and A. Mushkarenkov and Nefkens, {B. M. K.} and A. Nikolaev and R. Novotny and M. Ostrick 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 Sober, {D. I.} and A. Starostin and I. Supek and M. Thiel and A. Thomas and M. Unverzagt and Watts, {D. P.} and D. Werthmueller and L. Witthauer and F. Zehr",

year = "2013",

month = apr,

day = "25",

doi = "10.1016/j.physletb.2013.03.021",

language = "English",

volume = "721",

pages = "237--243",

journal = "Physics Letters B",

issn = "0370-2693",

publisher = "Elsevier",

number = "4-5",

}

Oberle, M, Krusche, B, Ahrens, J, Annand, JRM, Arends, HJ, Bantawa, K, Bartolome, PA, Beck, R, Bekrenev, V, Berghaeuser, H, 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, Heid, E, Hornidge, D, Howdle, D, Huber, GM, Jahn, O, Jaegle, I, Jude, TC, Kaeser, A, Kashevarov, VL, Keshelashvili, I, Kondratiev, R, Korolija, M, Kruglov, SP, Kulbardis, A, Lisin, V, Livingston, K, MacGregor, IJD, 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, BMK, Nikolaev, A, Novotny, R, Ostrick, M, Oussena, B, Pedroni, P, Pheron, F, Polonski, A, Prakhov, SN, Robinson, J, Rosner, G, Rostomyan, T, Schumann, S, Sikora, MH, Sober, DI, Starostin, A, Supek, I, Thiel, M, Thomas, A, Unverzagt, M, Watts, DP, Werthmueller, D, Witthauer, L & Zehr, F 2013, 'Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron', Physics Letters B, vol. 721, no. 4-5, pp. 237-243. https://doi.org/10.1016/j.physletb.2013.03.021

TY - JOUR

T1 - Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron

AU - Oberle, M.

AU - Krusche, B.

AU - Ahrens, J.

AU - Annand, J. R. M.

AU - Arends, H. J.

AU - Bantawa, K.

AU - Bartolome, P. A.

AU - Beck, R.

AU - Bekrenev, V.

AU - Berghaeuser, H.

AU - Braghieri, A.

AU - Branford, D.

AU - Briscoe, W. J.

AU - Brudvik, J.

AU - Cherepnya, 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 - Heid, E.

AU - Hornidge, D.

AU - Howdle, D.

AU - Huber, G. M.

AU - Jahn, O.

AU - Jaegle, I.

AU - Jude, T. C.

AU - Kaeser, A.

AU - Kashevarov, V. L.

AU - Keshelashvili, I.

AU - Kondratiev, R.

AU - Korolija, M.

AU - Kruglov, S. P.

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.

AU - Mekterovic, D.

AU - Metag, V.

AU - Micanovic, S.

AU - Middleton, D. G.

AU - Mushkarenkov, A.

AU - Nefkens, B. M. K.

AU - Nikolaev, A.

AU - Novotny, R.

AU - Ostrick, M.

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. I.

AU - Starostin, A.

AU - Supek, I.

AU - Thiel, M.

AU - Thomas, A.

AU - Unverzagt, M.

AU - Watts, D. P.

AU - Werthmueller, D.

AU - Witthauer, L.

AU - Zehr, F.

PY - 2013/4/25

Y1 - 2013/4/25

N2 - Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions (gamma) over right arrowp -> p pi(0)pi(0) and (gamma) over right arrowd -> (n)p pi(0)pi(0), (gamma) over right arrowd -> (p)n pi(0)pi(0) off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Decay photons from the pi(0) mesons, recoil protons, and recoil neutrons were detected in the 4 pi covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons. This demonstrates that the free-nucleon behavior of such observables can be extracted from measurements with quasi-free nucleons, which is the only possibility for the neutron. Contrary to expectations, the measured asymmetries are very similar for reactions off protons and neutrons. The results are compared to the predictions from the Two-Pion MAID reaction model and (for the proton) also to the Bonn-Gatchina coupled channel analysis. (C) 2013 Elsevier B.V. All rights reserved.

AB - Beam-helicity asymmetries have been measured at the MAMI accelerator in Mainz for the photoproduction of neutral pion pairs in the reactions (gamma) over right arrowp -> p pi(0)pi(0) and (gamma) over right arrowd -> (n)p pi(0)pi(0), (gamma) over right arrowd -> (p)n pi(0)pi(0) off free protons and off quasi-free nucleons bound in the deuteron for incident photon energies up to 1.4 GeV. Circularly polarized photons were produced from bremsstrahlung of longitudinally polarized electrons and tagged with the Glasgow magnetic spectrometer. Decay photons from the pi(0) mesons, recoil protons, and recoil neutrons were detected in the 4 pi covering electromagnetic calorimeter composed of the Crystal Ball and TAPS detectors. After kinematic reconstruction of the final state, excellent agreement was found between the results for free and quasi-free protons. This demonstrates that the free-nucleon behavior of such observables can be extracted from measurements with quasi-free nucleons, which is the only possibility for the neutron. Contrary to expectations, the measured asymmetries are very similar for reactions off protons and neutrons. The results are compared to the predictions from the Two-Pion MAID reaction model and (for the proton) also to the Bonn-Gatchina coupled channel analysis. (C) 2013 Elsevier B.V. All rights reserved.

KW - DOUBLE-PION-PHOTOPRODUCTION

KW - TOTAL CROSS-SECTION

KW - DOUBLE PI(0) PHOTOPRODUCTION

KW - TAGGED PHOTON SPECTROMETER

KW - 2ND RESONANCE REGION

KW - BARYON RESONANCES

KW - PARTIAL-WAVE

KW - MICROTRON

KW - THRESHOLD

KW - MAMI

U2 - 10.1016/j.physletb.2013.03.021

DO - 10.1016/j.physletb.2013.03.021

M3 - Article

SN - 0370-2693

VL - 721

SP - 237

EP - 243

JO - Physics Letters B

JF - Physics Letters B

IS - 4-5

ER -

Measurement of the beam-helicity asymmetry I-circle dot in the photoproduction of pi(0)-pairs off the proton and off the neutron

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Keywords / Materials (for Non-textual outputs)

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