High resolution γ spectroscopy of hypernuclei with large Ge detector system

该研究项目的目标是构建一个齿轮球探测器，并通过keV分辨率测量高核i的g-转换，并打开高核物理学的新领域，称为高核的γ-光谱。After the R&D of the Ge detector and its fast electronics by using？-beams， we have constructed the Ge-ball detector called "Hyperball" with collaboration of Chinese physicists。它涉及14个纯60%的Ge晶体与BGO康普顿抑制剂。我们在KEK上进行了第一次与π束和观察到的γ转换的KEK进行了第一次与keV分辨率的超核。“Hyperball”is now wellknown by its great success.The M1 transition between the ground spin-doublet states （3/2 -> 1/2） of伊D17伊D1李伊D2 was measured to be 680 keV。这一分裂主要是为了γ N自旋-自旋相互作用。在实验中，因此，提供了关键数据来确定自旋-自旋相互作用。By using Doppler attenuation method， we measured B（E2） of the transition （5/2 -> l/2） of i D17 i i D2 i D2 for the first time。核尺寸的收缩是由γ粒子首先由此数据确认的。这一成功的主张是γ-光谱学的巨大潜力。The γ-transitions of Eye D19 Eye D2 Eye D2 Eye D2也在BNL的第二次实验中被观察到。他们来自双重国家（5/2， 3/2）到地面（1/2），几乎完全可以与Λ和核核之间的LS相互作用。初步数据显示，碎片只有30 keV那么小。这表明，γ N的LS交互比NN交互小100次。这个项目在其实现和初步结果中非常成功。The spectroscopy of hypernuclei is now established as a usable and great tool for the study of hypernuclei.

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.