The strangeness photoproduction process has been intensively studied based on the high-quality data of the charged kaon channel, γ + p + K+ + A(Σ0). On the other hand, there was no reliable data for the neutral kaon channel γ+n + K0+A(Σ0). The theoretical investigations suffer seriously from the lack of the data. A Substantial effort has been made to measure the γ+ n → K0 + A process in the K: → Π+ Π- decay channel, using a liquid deuterium target and a tagged photon beam (Eγ = 0.8-1.1 GeV) in the threshold region at Laboratory of Nuclear Science (LNS), Tohoku University. We have taken exploratory data quite successfully with use of Neutral Kaon Spectrometer (NKS) at LNS-Tohoku in 2003 and 2004. The data is compared theoretical models and it indicates a hint that the KO differential cross section has a backward peak in the energy region. The second generation of the experiment, named NKS2, is designed to extend the NKS experiment by considerably upgrading the original neutral kaon spectrometer, fully replacing the spectrometer magnet, tracking detectors and all the trigger counters. The new spectrometer NKS2 has significantly larger acceptance for neutral kaons compared with NKS, particularly covering forward angles and much better invariant mass resolution. The estimated acceptance of NKS2 is three (ten) times larger for K:(A) than that of NKS. The spectrometer is newly constructed and installed at LNS, Tohoku University in 2005. The deuterium target data was taken with the tagged photon beam in 2006-2007. We will report recent results of NKS2 in this paper. Additionally, a status of the upgrade project that gives us larger acceptance and capability of K +A coincidence measurement will be repsented.
|ホスト出版物のタイトル||Hadron and Nuclear Physics 09|
|ホスト出版物のサブタイトル||Osaka University, Japan, 16-19 November 2009|
|出版社||World Scientific Publishing Co.|
|出版ステータス||Published - 2010 1月 1|
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