2006 Fiscal Year Final Research Report Summary
Development of hypernuclear gamma-ray spectroscopy
| Project/Area Number |
15204014
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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| Research Institution | Tohoku University |
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Principal Investigator |
TAMURA Hirokazu Tohoku University, Graduate School of Science, Professor, 大学院理学研究科, 教授 (10192642)
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| Co-Investigator(Kenkyū-buntansha) |
FUJII Yu Tohoku University, Graduate School of Science, Research Associate, 大学院理学研究科, 助手 (30302079)
UKAI Mifuyu Cyclotron RI Center, Postdoctral fellow, 教育研究支援者 (30420053)
TAKAHASHI Toshiyuki High Energy Accelerator Research Organization, IPNS, Associate Professor, 素粒子原子核研究所, 助教授 (50281960)
KOIKE Takeshi Tohoku University, Graduate School of Science, Research Associate, 大学院理学研究科, 助手 (70396422)
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| Project Period (FY) |
2003 – 2006
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| Keywords | hypernuclei / gamma-ray spectroscopy / germanium (Ge) detector / Λ particle / ΛN interaction / baryon-baryon interactions |
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| Research Abstract |
1.Data analysis for hypernuclear g-ray spectroscopy on ^<16>O and ^<10>B target has been finished.
We observed ^<16>_ΛO(^-1→1^-,0^-) transition and determined the AN tensor interaction strength of T=0.03 MeV from the 26 keV spacing of the ground-state doublet. We also observed the ^<16>_ΛO(2^-→1^-) transition. From the ^<10>B target data, the ^<10>_ΛB ground-state doublet spacing was found to be less than 100 keV. We also observed the ^7_ΛLi(7/2^+→5/2^+) transition by γγ coincidence method, and assigned the spins in the ^9_ΛBe(3/2^+,5/2^+) doublet by observing the ^9_ΛBe(3/2^+→/2^+) transition.
2.Data analysis for the γ-ray spectroscopy experiment of hyperfragments from stopped K-absorption (KEK E509) has been done.
We observed the ^7_ΛLi E2 transition on ^<10>B and ^<12>C targets and determined its production rate.
3.We carried out data analysis for the 11_ΛB experiment (KEK E518) and observed six transitions. One of them was assigned as 1/2^+→5/2^+.
4.By adding six Clover-type Ge detectors to Hyperball, we constructed "Hyperball2", which doubled the efficiency.
5.Employing Hyperball2, we performed a γ-ray spectroscopy experiment on 11_ΛB and ^<12>_ΛC at the KEK-PS K6 line using the ^<12>C (π^+,K^+) reaction. In preliminary results, we observed the ^<11>_ΛB (7/2^+-5/2^+,262 keV) transition between the ground-state doublet and the ^<12>_ΛC (1^-_2→2-,2.67 MeV) transition from the core-excited 1^-_2state to one of the ground state doublet member.
6.From all of these data, we successfully determined all the four parameters on the spin-dependent ΛN interaction strengths as Δ=0.33(A>10), 0.43(A=7), S_Λ=-0.01,S_N=-0.4,T=0.03 MeV. It was also found that many hypernuclear level data can be explained by these four parameters with a few exceptions.
7,We are developing a waveform readout method of Ge detectors and faster background suppression counters using PWO for our further γ-ray spectroscopy experiments at J-PARC.
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