Grant-in-Aid for international Scientific Research
|Allocation Type||Single-year Grants|
|Research Institution||University of Tokyo|
HAYANO Ryugo University of Tokyo, Graduate school of Science, Associate Professor, 大学院・理学系研究科, 助教授 (30126148)
R Seki カリフォルニア州大, 教授
G Mason ビクトリア大学, 教授
M Salomon TRIUMF研究所, 上級研究員
S Yen TRIUMF研究所, 研究員
A Olin TRIUMF研究所, 上級研究員
L Lee マニトバ大学, 助手
YONEZAWA Yasushige Tsukuba College of Technology, Research Associate, 助手 (40248753)
OUTA Haruhiko University of Tokyo, INS,Research Associate, 原子核研究所, 助手 (60221818)
IWASAKI Masahiko University of Tokyo, Faculty of Science, Research Associate, 理学部, 助手 (60183745)
SEKI R. California State University, Professor
MASON G. University of Victoria, Professor
SALOMON M. TRIUMF,Senior Researcher
YEN S. TRIUMF,Researcher
OLIN A. TRIUMF,Senior Researcher
LEE L. Manitoba University, Research Associate
SEKI R. カリフォルニア州立大学, 教授
MASON G. Victoria大学, 教授
BEER G. Victoria大学, 教授
SALOMON M. TRIUMF, 研究員
YEN S. TRIUMF, 研究員
OLIN A. TRIUMF, 上級研究員
LEE L. TRIUMF, 研究員
GILL D.R. TRIUMF, 上級研究員
|Project Period (FY)
1993 – 1994
Completed(Fiscal Year 1994)
|Budget Amount *help
¥6,500,000 (Direct Cost : ¥6,500,000)
Fiscal Year 1994 : ¥3,000,000 (Direct Cost : ¥3,000,000)
Fiscal Year 1993 : ¥3,500,000 (Direct Cost : ¥3,500,000)
|Keywords||High Energy Physics / Strong Interaction / Exotic Atoms / X-ray spectroscopy / K-meson / QCD / 中間子 / ストレンジネス / 半導体検出器|
Strong interaction at low energy was studied by measuring X-rays of kaonic hydrogen atoms. The experiment was set up at the 12 GeV proton synchrotron of KEK.
The importance of this experiment has long been recognized, and there were 3 previous trialsin late 70's and early 80's. However, due to experimental difficulties and due also to the small flux of kaon beam, nobody has succeeded in the observation of the kaonic hydrogen X-rays.
In order to overcome difficulties, due to the large background caused by beam particles, and also to the small X-ray yields, we developed novel methods to suppress the X-ray background, and to enhance the signal to noise ratio.
Namely, background was suppressedby i) measuring the reaction vertex, and by selecting the events originating from the hydrogen target, and ii) by applying event tagging to select events with 2 charged pions in the final state. We also developed a novel X-ray detector system consisting of 60 Si (Li) crystals, operating in a low-temperature hydrogen gas. The use of gas target, instead of liquid, should help improve signal to background ratio.
In the first year, we concentrated on the detector development and construction. The Japanese group worked mostly on the hydrogen target, beam counters, Si (Li) detectors, and on the infrastructure in general. The Canadian team worked on the development and construction of the cylindrical vertex chambers and water Cherenkov detectors, both of which were essential in reducing the background. The completed detectors were transported to KEK,and were assembled there.
In 1994, we started to debug the system using the kaon beam, and by the end of 1994 we started to take data. Preliminary analysis exhibited that we have succeeded in observing the kaonic hydrogen X-rays, although we need to collect higher statistics in order to draw final conclusions.