Phys. Rev. Lett.
103,
012301
(2009)
[6 pages]
Measurement of the Differential Cross Section for the Reaction γn→π-p from Deuterium
W. Chen et al. The CLAS Collaboration
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W. Chen1, T. Mibe2, D. Dutta3, H. Gao1, J. M. Laget7,4, M. Mirazita5, P. Rossi5, S. Stepanyan4, I. I. Strakovsky6, M. J. Amaryan27, M. Anghinolfi20, H. Bagdasaryan27,*, M. Battaglieri20, M. Bellis10, B. L. Berman6, A. S. Biselli15,29, C. Bookwalter17, D. Branford14, W. J. Briscoe6, W. K. Brooks34,4, V. D. Burkert4, S. L. Careccia27, D. S. Carman4, L. Casey11, P. L. Cole19,4, P. Collins8, V. Crede17, A. Daniel2, N. Dashyan37, R. De Vita20, E. De Sanctis5, A. Deur4, S. Dhamija16, R. Dickson10, C. Djalali32, G. E. Dodge27, D. Doughty12,4, H. Egiyan25,36, P. Eugenio17, G. Fedotov31, A. Fradi21, M. Garçon7, G. P. Gilfoyle30, K. L. Giovanetti23, F. X. Girod7,†, W. Gohn13, R. W. Gothe32, K. A. Griffioen36, M. Guidal21, H. Hakobyan34,37, C. Hanretty17, N. Hassall18, D. Heddle12,4, K. Hicks2, M. Holtrop25, C. E. Hyde27,28, Y. Ilieva32, D. G. Ireland18, B. S. Ishkhanov31, E. L. Isupov31, H. S. Jo21, J. R. Johnstone18, K. Joo13,35, D. Keller2, M. Khandaker26, P. Khetarpal29, W. Kim24, A. Klein27, F. J. Klein11,4, L. H. Kramer16,4, V. Kubarovsky4, S. E. Kuhn27, S. V. Kuleshov22, V. Kuznetsov24, K. Livingston18, H. Y. Lu32, N. Markov13, M. E. McCracken10, B. McKinnon18, C. A. Meyer10, T Mineeva13, V. Mokeev31,4, B. Moreno21, K. Moriya10, P. Nadel-Turonski11, R. Nasseripour32,‡, S. Niccolai21, I. Niculescu23,6, M. R. Niroula27, M. Osipenko20,31, A. I. Ostrovidov17, K. Park32,24, S. Park17, S. Anefalos Pereira5, O. Pogorelko22, S. Pozdniakov22, J. W. Price9, S. Procureur7, D. Protopopescu18, B. A. Raue16,4, G. Ricco20, M. Ripani20, B. G. Ritchie8, G. Rosner18, F. Sabatié7,27, M. S. Saini17, J. Salamanca19, C. Salgado26, R. A. Schumacher10, Y. G. Sharabian4,37, D. I. Sober11, D. Sokhan14, S. S. Stepanyan24, S. Strauch32, M. Taiuti20, D. J. Tedeschi32, S. Tkachenko27, M. Ungaro13, M. F. Vineyard33,30, D. P. Watts18,§, L. B. Weinstein27, D. P. Weygand4, M. H. Wood32, A. Yegneswaran4, J. Zhang27, and B. Zhao13 (The CLAS Collaboration)
1Duke University, Durham, North Carolina 27708, USA
2Ohio University, Athens, Ohio 45701, USA
3Mississippi State University, Mississippi State, Mississippi 39762, USA
4Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA
5INFN, Laboratori Nazionali di Frascati, 00044 Frascati, Italy
6The George Washington University, Washington, D.C. 20052, USA
7CEA-Saclay, Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France
8Arizona State University, Tempe, Arizona 85287-1504, USA
9California State University, Dominguez Hills, Carson, California 90747, USA
10Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
11Catholic University of America, Washington, D.C. 20064, USA
12Christopher Newport University, Newport News, Virginia 23606, USA
13University of Connecticut, Storrs, Connecticut 06269, USA
14Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
15Fairfield University, Fairfield, Connecticut 06824, USA
16Florida International University, Miami, Florida 33199, USA
17Florida State University, Tallahassee, Florida 32306, USA
18University of Glasgow, Glasgow G12 8QQ, United Kingdom
19Idaho State University, Pocatello, Idaho 83209, USA
20INFN, Sezione di Genova, 16146 Genova, Italy
21Institut de Physique Nucleaire ORSAY, Orsay, France
22Institute of Theoretical and Experimental Physics, Moscow, 117259, Russia
23James Madison University, Harrisonburg, Virginia 22807, USA
24Kyungpook National University, Daegu 702-701, Republic of Korea
25University of New Hampshire, Durham, New Hampshire 03824-3568, USA
26Norfolk State University, Norfolk, Virginia 23504, USA
27Old Dominion University, Norfolk, Virginia 23529, USA
28Université Blaise Pascal, Laboratoire de Physique Corpusculaire CNRS/IN2P3 F-63177 Aubière, France
29Rensselaer Polytechnic Institute, Troy, New York 12180-3590, USA
30University of Richmond, Richmond, Virginia 23173, USA
31Skobeltsyn Nuclear Physics Institute, Skobeltsyn Nuclear Physics Institute, 119899 Moscow, Russia
32University of South Carolina, Columbia, South Carolina 29208, USA
33Union College, Schenectady, New York 12308, USA
34Universidad Técnica Federico Santa María, Casilla 110-V Valparaíso, Chile
35University of Virginia, Charlottesville, Virginia 22901, USA
36College of William and Mary, Williamsburg, Virginia 23187-8795, USA
37Yerevan Physics Institute, 375036 Yerevan, Armenia
Received 6 March 2009; published 1 July 2009
We report a measurement of the differential cross section for the γn→π-p process from the CLAS detector at Jefferson Laboratory in Hall B for photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles (θc.m.) between 50° and 115°. We confirm a previous indication of a broad enhancement around a c.m. energy (√s) of 2.1 GeV at θc.m.=90° in the scaled differential cross section s7dσ/dt and a rapid falloff in a center-of-mass energy region of about 400 MeV following the enhancement. Our data show an angular dependence of this enhancement as the suggested scaling region is approached for θc.m. from 70° to 105°.
© 2009 The American Physical Society
URL:
http://link.aps.org/doi/10.1103/PhysRevLett.103.012301
DOI:
10.1103/PhysRevLett.103.012301
PACS:
25.10.+s, 13.60.Le, 24.85.+p, 25.20.−x
*Current address: University of Virginia, Charlottesville, Virginia 22901, USA †Current address: Thomas Jefferson National Accelerator Facility, Newport News, Virginia 23606, USA ‡Current address: The George Washington University, Washington, DC 20052, USA §Current address: Edinburgh University, Edinburgh EH9 3JZ, United Kingdom
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