| Co-Investigator(Kenkyū-buntansha) |
A.MARGARIAN アルメニアYerevan研究所, 研究員
J.EADES スイスCERN研究所, 主任研究員
T.HENNINO フランスSaclay研究所, 教授
P.RADVANY フランスSaclay研究所, 教授
P.KIENLE 独GSI研究所, 教授
TANAKA Masahiko Institute for Nuclear study, University of Tokyo.Research Associate, 原子核研究所, 助手 (20013435)
TOKI Hiroshi Faculty of Science, Tokyo Metropolitan University. Professor, 理学部, 助教授 (70163962)
KUNO Yoshitaka National Laboratory for High Energy Physics. Associate Professor, 助教授
TAMURA Hirokazu Faculty of Science, University of Tokyo, Research Associate, 理学部, 助手 (10192642)
YAMAZAKI Toshimitsu Institute for Nuclear Study, University of Tokyo, Professor, 原子核研究所, 教授 (80011500)
MARGARIAN Amul Yerevan Physics Institute, Researcher
EADES John European Organization for Nuclear Research (CERN), Senior Researcher
HENNINO Thierry Laboratorie National Satyrne, Saclay. Professor
RADVANYI Pierre Laboratorie National Saturne, Saclay, Professor
KIENLE Paul Geselleshaft fu schwerionenforshung, Professor
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| Research Abstract |
The aim of this project is to search for deeply-bound pionic atoms, such as 1s and 2p states of pionic Pb, using a novel nuclear-reaction method. The study of such states using the conventional pionic X-ray spectroscopy is impossible, since pions will be absorbed by the nucleus before they can reach the deeply bound states.
We carried out Pb(d,2p) experiments using the SPES IV spectrometer at Saclay (France), Pb(n,d) experiments using the MRS spectrometer at TRIUMF (Canada), and Pb(d,^3He) experiments using the SPES I spectrometer at Saclay. Corresponding theoretical works have been done also.
1. (d,2p) reaction
The experiment reached the sensitivity with which we should be able to find the pionic-atom peak, if the formation cross section was as large as was theoretically predicted. However, no peak was observed.
2. (n,d) and (d,^3He) theory
The reason for the non-observation of peaks in the (d,2p) experiment was later understood through detailed theoretical works, and (n,d) or(d,^3He) reactions were found to be more suited for the production of deeply-bound pionic atoms.
3. (d,^3He) reaction
Data were taken at 3ﾟ in the laboratory frame. Theory guides us to go to smaller angles to increase the cross section, but due to experimental difficulties, we were unable to go to much smaller angles. No peak was identified in the spectrum, but as a by product, the pion production cross section for p(d,^3He)pi^0 was measured for the fist time.
4. (n,d) reaction
Near the pion production threshold, a structure, whose energy and cross section were consistent with theoretical prediction, was seen. However, the statistical significance was too small to draw strong conclusions, and the use of neutron beam makes it difficult to much improve the statistical accuracy.
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