High resolution γ spectroscopy of hypernuclei with large Ge detector system

使用大型 Ge 探测器系统进行超核高分辨率 γ 能谱

基本信息

批准号：
08239102
负责人：
IMAI Kenichi
金额：
$ 87.04万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research on Priority Areas
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-08239102/
关键词：
Hypernuclear Strangeness Crystal Ball γ-ray spectroscopy Fine Structure

项目摘要

The purpose of this research project was to construct a Ge-ball detector and to measure g-transitions of hypernuclei with keV resolution and to open the new field of hypernuclear physics, namely γ-spectroscopy of hypernuclei. After the R&D of the Ge detector and its fast electronics by using π-beams, we have constructed the Ge-ball detector called "Hyperball" with collaboration of Chinese physicists. It consists of 14 pure 60% Ge crystals with BGO Compton suppressors. We have carried out the first experiment at KEK with π-beam and observed γ transitions of hypernuclei with keV resolution for the first time. The "Hyperball" is now wellknown by its great success.The M1 transition between the ground spin-doublet states (3/2 -> 1/2) of ィイD17ィエD1LiィイD2ΛィエD2 was measured to be 690 keV. This splitting is mainly due to the ΛN spin-spin interaction. The experiment, therefore, provided a key data to determine the spin-spin interaction. By using Doppler attenuation method, we measured B(E2) of the transition (5/2 -> l/2) of ィイD17ィエD1LiィイD2ΛィエD2 for the first time. The shrinkage in the nuclear size by Λ particle was first confirmed by this data. This success claims the great ability of γ-spectroscopy of hypernuclei. The γ-transitions of ィイD19ィエD1BeィイD2ΛィエD2 were also observed in the second experiment done at BNL. They are they from the doublet states (5/2, 3/2) to the ground (1/2) which are almost purely due to the LS interaction between Λ and nucleon. The preliminary data shows that the splitting is as small as 30 keV. It indicates that the LS interaction of ΛN is about 100 times smaller than that of the NN interaction.This project was quite successful in its achievement and first results. The γ spectroscopy of hypernuclei is now established as a usable and great tool for the study of hypernuclei.

该研究项目的目的是构建Ge球探测器并以keV分辨率测量超核的g跃迁，并在Ge探测器和超核的研发之后开辟超核物理的新领域，即超核的γ能谱。凭借其快速电子学，我们与中国物理学家合作构建了名为“Hyperball”的Ge球探测器，它由14个纯60%的Ge组成。我们在 KEK 进行了第一个 π 光束实验，并首次以 keV 分辨率观察到了超核的 γ 跃迁。“Hyperball”现在以其巨大的成功而闻名。 D17D1LiD2ΛD2 的基态自旋双峰态 (3/2 -> 1/2) 测量为 690 keV。这种分裂主要是由于ΛN自旋-自旋相互作用。因此，实验提供了确定自旋-自旋相互作用的关键数据。通过使用多普勒衰减方法，我们测量了跃迁的B(E2)。 2 -> l/2) 的 D17D1LiD2ΛD2 的核尺寸的缩小首次被这一数据证实。声称超核 γ 能谱的强大能力在 BNL 进行的第二个实验中也观察到了 D19D1BeD2D2 的 γ 跃迁，它们是从双重态 (5/2 , 3/2) 到基态 (1/2) 的。）这几乎纯粹是由于 Λ 和核子之间的 LS 相互作用造成的。初步数据表明，分裂很小。 30 keV，这表明 ΛN 的 LS 相互作用比 NN 相互作用小 100 倍。该项目取得了相当成功的成果，并取得了初步成果。超核的 γ 能谱现在已成为一种可用且出色的工具。超核的研究。