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Sako, Hiroyuki; Sugimura, Hitoshi; Ahn, J. K.*; Han, Y.*; Hasegawa, Shoichi; Hwang, S. H.*; Ichikawa, Yudai; Imai, Kenichi; Kiuchi, Ryuta*; Ozawa, Kyoichiro; et al.
Nuclear Instruments and Methods in Physics Research A, 763, p.65 - 81, 2014/11
Times Cited Count：5 Percentile：38.03(Instruments & Instrumentation)We developed a prototype TPC for an H-dibaryon search experiment at J-PARC. To investigate its performance, we conducted tests with Ar-CH
(90:10) and Ar-CF (95:5), where the former is mainly used. The detection efficiency was measured to be 98% at the beam rate up to 
cps/cm
, and 90% at the rate of 
cps/cm. Based on the measured horizontal resolution of 0.19-0.46 mm at the drift length of 5-20 cm, the position resolution of better than 0.3 mm is estimated in 1 T magnetic field. The ion backflow fraction was measured to be 5% and reduced up to 3% at the gain of 
. The horizontal position distortion due to ion backflow in the gate operation was suppressed within 
mm at the beam rates up to cps/cm. On the other hand, the distortion with the gate open was measured to be 
mm. The distortion in the final experiment is estimated to be 
mm.
Sako, Hiroyuki; Ahn, J. K.*; Baek, K. H.*; Bassalleck, B.*; Fujioka, H.*; Guo, L.*; Hasegawa, Shoichi; Hicks, K.*; Honda, R.*; Hwang, S. H.*; et al.
Journal of Instrumentation (Internet), 9(4), p.C04009_1 - C04009_10, 2014/04
Times Cited Count：3 Percentile：16.04(Instruments & Instrumentation)A TPC has been developed for J-PARC E42 experiment to search for H-dibaryon in (
, 
) reaction. An event with 2 
and 2 protons decaying from H-dibaryon is searched for inside the TPC. The TPC has octagonal prism shape drift volume with about 50 cm diameter with 55 cm drift length filled with Ar-CH (90:10) gas. At the end of the drift volume, 3-layer GEMs are equipped. In order to analyze momenta of produced particles, the TPC is applied with 1 T dipole magnetic field parallel to the drift electric field with a superconducting Helmholz magnet. In order to maximize the acceptance of H-dibaryon events, a diamond target is installed inside the TPC drift volume, in a cylindrical hole opened from the top to the middle of the drift volume. Since extremely high-rate beam is directly injected into the TPC drift volume to the target, a gating grid and GEMs are adopted to suppress positive-ion feedback.
H hypernucleus by the 
Li(
) reaction at 
- = 1.2 GeV/
Sugimura, Hitoshi; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Kiuchi, Ryuta; Ichikawa, Yudai; Hwang, S. H.*; Hasegawa, Shoichi; Tanida, Kiyoshi; J-PARC E10 Collaboration*
Physics Letters B, 729, p.39 - 44, 2014/02
Times Cited Count：31 Percentile：86.77(Astronomy & Astrophysics)We have carried out an experiment to search for a neutron-rich hypernucleus, 
H, by the Li(
,K
) reaction at p
= 1.2 GeV/c. The obtained missing-mass spectrum with an estimated energy resolution of 3.2 MeV (FWHM) showed no peak structure corresponding to the H hypernucleus neither below nor above the 
H+2n particle decay threshold. An upper limit of the production cross section for the bound H hypernucleus was estimated to be 1.2 nb/sr at 90% confidence level.
Imai, Kenichi; Ichikawa, Yudai; Hasegawa, Shoichi; Sako, Hiroyuki; Sato, Susumu; Kiuchi, Ryuta*; Hosomi, Kenji; Sugimura, Hitoshi; 36 of others*
Few-Body Systems, 54(7-10), p.1191 - 1194, 2013/08
Times Cited Count：11 Percentile：58.33(Physics, Multidisciplinary)In the J-PARC E27 experiment, we search for a bound state via the 
reaction at 1.7 GeV/c at the K1.8 beam line. The binding energy and decay width of the bound state can be obtained in the missing mass measurement with a good energy resolution of 2 MeV/c
. A range counter array (RCA) was constructed to detect the two high-momentum protons from the decay and to reduce the background such as quasi-free hyperon production. Recently, we have carried out a pilot run in June, 2012. The missing-mass spectrum has been obtained for the first time.
-atom X-raysSugimura, Hitoshi; Imai, Kenichi; Sako, Hiroyuki; Sato, Susumu; Adachi, Satoshi*; Tanida, Kiyoshi*; Kiuchi, Ryuta*; Joo, C. W.*
AIP Conference Proceedings 1388, p.602 - 604, 2011/10
Times Cited Count：0 Percentile：0.05(Astronomy & Astrophysics)no abstracts in English
-spectrometerSato, Susumu; Sako, Hiroyuki; Imai, Kenichi; Sugimura, Hitoshi; Adachi, Satoshi; Kiuchi, Ryuta*; Tanida, Kiyoshi*; Miwa, Koji*; Ozawa, Kyoichiro*
no journal, ,
no abstracts in English
Sako, Hiroyuki; Imai, Kenichi; Sato, Susumu; Sugimura, Hitoshi; Ichikawa, Yudai; Hasegawa, Shoichi; Shirotori, Kotaro; Kiuchi, Ryuta*; Honda, Ryotaro
no journal, ,
Recent Lattice-QCD calculations show the baryon-baryon potential corresponding to the H-dibaryon is attactive, and predicts H-dibaryon is either a weakly bound state or a resonance state. On the other hand, KEK-E224, E522 experiments observed a peak near the 
invariant mass spectrum, which suggests existence of H-dibaryon. However, due to low statistics and low mass resolution, they did not discover the evidence for H-dibaryon. We propose an experiment (P-42) to search for H-dibaryon at J-PARC with 
Kaon beams with improved statistics and mass resolutions. In this experiment, a dipole magnet spectrometer based on high-rate capable GEM-TPC is designed to reconstruct 2 protons and to 2 
s decaying from a H-dibaryon.
Imai, Kenichi; Kiuchi, Ryuta*
no journal, ,
We have developed Silicon Strip Detector (SSD) for measurements of particle tracks at J-PARC hadron facility. We reported performance of a prototype SSD in the past JPS meeting (2010 Spring), and recently we success the data suppression method by FPGA to reduce the data readout time and we have confirmed it works well during a test experiment at RCNP in 2011. In this presentation, we will report the performance of our SSD and the results of data suppression by FPGA.
Sato, Susumu; Sako, Hiroyuki; Hasegawa, Shoichi; Sugimura, Hitoshi; Ichikawa, Yudai; Ozawa, Kyoichiro; Kiuchi, Ryuta*; Hwang, S. H.*; Imai, Kenichi
no journal, ,
no abstracts in English
,
) reaction at J-PARC, 1Sako, Hiroyuki; Imai, Kenichi; Sato, Susumu; Hasegawa, Shoichi; Hwang, S. H.*; Sugimura, Hitoshi; Ichikawa, Yudai; Tanida, Kiyoshi; Kiuchi, Ryuta*; Ahn, J. K.*; et al.
no journal, ,
The H-dibaryon has been proposed as a stable 6-quark sate, and various experiments have been performed to search for it, but never been successful. KEK-PS E224 and E522 experiments observed peaks near the 
threshold in the invariant mass spectra although statistics is not enough. On the other hand, recent lattice QCD calculations predict the H is a shallow bound state or a resonance state. We proposed J-PARC E42 experiment to search for the H-dibaryon in (,) reaction with two-order higher statistics and higher mass resolutions.
Sako, Hiroyuki; Imai, Kenichi; Sato, Susumu; Hasegawa, Shoichi; Hwang, S. H.*; Sugimura, Hitoshi; Ichikawa, Yudai; Tanida, Kiyoshi; Kiuchi, Ryuta*
no journal, ,
J-PARC E42 is an experiment to search for the H-dibaryon in (,) reactions. The experimental setup consists of a larget solid angle TPC, a Helmholtz dipole magnet, and a spectrometer (Kurama). We have performed an experiment of a prototype TPC injecting a UV laser under magnetic field with the FM magnet in the J-PARC hadron facility hall. We have been also developing the second TPC which has the real size the pad plane and GEMs. In this presentation, we report the results of the prototype TPC and the status for the second TPC.
