Investigation of the neutronic performance of cold moderators with JESSICA

The legacy of the experimental hadron physics programme at COSY

“…In the framework of a specific reaction model [282], the data are best described by a moderately attractive K − -nucleus potential of depth ≈ 60 MeV for an average kaon momentum ≈ 0.5 GeV/c. 9 The pd → 3 He X( 3 H X ′ ) family of reactions Despite the pd → 3 He X( 3 H X ′ ) reactions generally involving large momentum transfers, they have the big experimental advantage of requiring the measurement of only one charged particle, 3 He or 3 H, in the final state in order to reconstruct X through the missing mass in the reaction. For this reason there have been numerous studies of such reactions over the years.…”

“…The general physics interest is much greater in the two near-threshold measurements, carried out simultaneously at COSY-11 [172] and ANKE [173], where values of the dp → 3 He η cross section were extracted at many energies with robust relative normalizations. In both experiments, only the recoiling 3 He was detected and the η-meson identified through the peak in the missing-mass distribution.…”

“…100 are consistent with s-wave production but, in order to put extra constraints on the theoretical modeling, data are required away from the threshold region where higher partial waves may play a role. The decay photons are, of course, very well measured in the WASA central detector but the 4 He identification and measurement in the WASA forward detector was less effective than in the IUCF setup and some 3 He may have been falsely identified as 4 He. In addition, in common with many meson production experiments, the missing-mass peaks become less pronounced as one moves away from threshold.…”

“…This hodoscope was already used in the study of the pd → 3 He K + K − reaction [33]. High above threshold the acceptance for a pd → 3 He X + X − event is low, even for small 3 He angles, because one of the mesons X would miss the MOMO detector. On the other hand, very close to threshold there are significant losses of events from mesons escaping through the central hole.…”

“…This review is concerned with the hadronic physics programme at COSY and so it omits any discussion of the extensive studies of spallation and nuclear breakup studies carried out by the Nessi [2], Jessica [3], and PISA [4] collaborations, especially in the first few years of COSY. The results in these early stages are summarized by an internal report in 2003 "10 years of COSY" and this shows the dominance of the experiments that were launched quickly, most notably COSY-11.…”