%0 Journal Article
%T Coherent photoproduction of eta-mesons off 3He - search for eta-mesic nuclei
%A F. Pheron
%A J. Ahrens
%A J. R. M. Annand
%A H. J. Arends
%A K. Bantawa
%A P. A. Bartolome
%A R. Beck
%A V. Bekrenev
%A H. Berghaeuser
%A B. Boillat
%A A. Braghieri
%A D. Branford
%A W. J. Briscoe
%A J. Brudvik
%A S. Cherepnya
%A B. Demissie
%A M. Dieterle
%A E. J. Downie
%A P. Drexler
%A D. I. Glazier
%A E. Heid
%A L. V. Fil'kov
%A D. Hornidge
%A D. Howdle
%A O. Jahn
%A I. Jaegle
%A T. C. Jude
%A V. L. Kashevarov
%A I. Keshelashvili
%A R. Kondratiev
%A M. Korolija
%A M. Kotulla
%A A. Kulbardis
%A S. P. Kruglov
%A B. Krusche
%A V. Lisin
%A K. Livingston
%A I. J. D. MacGregor
%A Y. Maghrbi
%A J. Mancell
%A D. M. Manley
%A Z. Marinides
%A M. Martinez
%A J. C. McGeorge
%A E. McNicoll
%A D. Mekterovic
%A V. Metag
%A S. Micanovic
%A D. G. Middleton
%A A. Mushkarenkov
%A B. M. K. Nefkens
%A A. Nikolaev
%A R. Novotny
%A M. Oberle
%A M. Ostrick
%A B. Oussena
%A P. Pedroni
%A A. Polonski
%A S. N. Prakhov
%A J. Robinson
%A G. Rosner
%A T. Rostomyan
%A S. Schumann
%A M. H. Sikora
%A D. I. Sober
%A A. Starostin
%A I. Supek
%A M. Thiel
%A A. Thomas
%A M. Unverzagt
%A D. P. Watts
%A D. Werthmueller
%A L. Witthauer
%A F. Zehr
%J Physics
%D 2012
%I arXiv
%R 10.1016/j.physletb.2012.01.075
%X Coherent photoproduction of $\eta$-mesons off $^3$He, i.e. the reaction $\gamma ^3{He}\rightarrow \eta ^3{He}$, has been investigated in the near-threshold region. The experiment was performed at the Glasgow tagged photon facility of the Mainz MAMI accelerator with the combined Crystal Ball - TAPS detector. Angular distributions and the total cross section were measured using the $\eta\rightarrow \gamma\gamma$ and $\eta\rightarrow 3\pi^0\rightarrow 6\gamma$ decay channels. The observed extremely sharp rise of the cross section at threshold and the behavior of the angular distributions are evidence for a strong $\eta {^3{He}}$ final state interaction, pointing to the existence of a resonant state. The search for further evidence of this state in the excitation function of $\pi^0$-proton back-to-back emission in the $\gamma ^3{He}\rightarrow \pi^0 pX$ reaction revealed a very complicated structure of the background and could not support previous conclusions.
%U http://arxiv.org/abs/1201.6517v1