First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons

Dieterle, M. and Witthauer, L. and Cividini, F. and Abt, S. and Achenbach, P. and Adlarson, P. and Afzal, F. and Ahmed, Z. and Akondi, C. S. and Annand, J. R. M. and Arends, H. J. and Bashkanov, M. and Beck, R. and Biroth, M. and Borisov, N. S. and Braghieri, A. and Briscoe, W. J. and Costanza, S. and Collicott, C. and Denig, A. and Downie, E. J. and Drexler, P. and Ferretti-Bondy, M. I. and Gardner, S. and Garni, S. and Glazier, D. I. and Glowa, D. and Gradl, W. and Gunther, M. and Gurevich, G. M. and Hamilton, D. and Hornidge, D. and Huber, G. M. and Kaser, A. and Kashevarov, V. L. and Kay, S. and Keshelashvili, I. and Kondratiev, R. and Korolija, M. and Krusche, B. and Lazarev, A. B. and Linturi, J. M. and Lisin, V. and Livingston, K. and Lutterer, S. and MacGregor, I. J. D. and Mancell, J. and Manley, D. M. and Martel, P. P. and Metag, V. and Meyer, W. and Miskimen, R. and Mornacchi, E. and Mushkarenkov, A. and Neganov, A. B. and Neiser, A. and Oberle, M. and Ostrick, M. and Otte, P. B. and Paudyal, D. and Pedroni, P. and Polonski, A. and Prakhov, S. N. and Rajabi, A. and Reicherz, G. and Ron, G. and Rostomyan, T. and Sarty, A. and Sfienti, C. and Sikora, M. H. and Sokhoyan, V. and Spieker, K. and Steffen, O. and Strakovsky, I. I. and Strub, Th. and Supek, I. and Thiele, A. and Thiel, M. and Thomas, A. and Unverzagth, M. and Usov, Yu. A. and Wagner, S. and Walford, N. K. and Watts, D. P. and Werthmueller, D. and Wettig, J. and Wolfes, M. and Zana, L.. (2017) First measurement of the polarization observable E and helicity-dependent cross sections in single π0 photoproduction from quasi-free nucleons. Physics Letters B, 770. pp. 523-531.

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Abstract

The double-polarization observable E and the helicity-dependent cross sections and have been measured for the first time for single photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry E since the and components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry E measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.

Faculties and Departments:	05 Faculty of Science > Departement Physik > Former Organization Units Physics > Hadronenphysik (Krusche)
UniBasel Contributors:	Krusche, Bernd
Item Type:	Article, refereed
Article Subtype:	Research Article
Publisher:	Elsevier
ISSN:	0370-2693
e-ISSN:	1873-2445
Note:	Publication type according to Uni Basel Research Database: Journal article
Language:	English
Identification Number:	doi: 10.1016/j.physletb.2017.04.079 isi: 000404196500066
edoc DOI:	10.5451/unibas-ep58458
Last Modified:	15 Jan 2018 13:48
Deposited On:	15 Jan 2018 13:48

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