Structure of Heavy Λ hypernuclei with a high-resolution magnetic spectrometer

用高分辨率磁谱仪观察重Λ超核的结构

• 批准号: 13440084
• 负责人: NAGAE Tomofumi
• 金额: $ 6.85万
• 依托单位: High Energy Accelerator Research Organization
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-13440084/
• 关键词: Nuclean Physics; Hypermiclei; スペクトロスコピー

We have investigated the roduction, structure, and decay of Λ hypemuclei by using a high-resolution magnetic spectromerer. As for the production of hypermuclei, we used a new reaction of (π^-,Κ^+) rather than usually used (π^+,Κ^+) reactions. In this reaction,we cousk preduce neutron-rich Λ hypemuclei through the duble-charge exchange reaction. The result suggests the importance of virtual production og Σ hyperon in this reaction. We also invesitated real Σ production in a quasifree reaction to obtain the information of the Σ-Nucleus potentials in medum-heaby nuclei. The structure of a Λ hypemucleus with baryon uumber 89 was studied in detail. The energy levels of the ground state and excited states suggest that a Λ hyperon in the heavy hypernucleus has an effective mass of about 70% of the free Λ mass. In addition, the potential depth ovtained was 1-MeV deeper than so-far believed. In the non-mesonic weak decays of hypermuclei, we have succeeded to measure neutrons in high statistics with low backgrounds for the first time. The energy spectra of neutrons were nexpectedly smooth, which suggests the reaction mechanism of the non-mesonic weak decay should be reconsidered.For the extension of these invesigations, we have considered new hypermuclear experimental programs at the J-PARC which is now under construction. We have proposed several new experiments to the J-PARC.

我们利用高分辨率磁谱仪研究了Λ超核的产生、结构和衰变。对于超核的生成，我们采用了一种新的反应（π^-，Κ^+）而不是通常使用的反应（π^+，Κ^+）。在这个反应中，我们可以通过双电荷交换反应生成富中子Λ超核。结果表明，虚拟生产og Σ超子在该反应中的重要性。我们还研究了准自由反应中真实的Σ生成，以获得中重核中Σ-Nucleus势的信息。详细研究了重子数为89的Λ超核的结构。基态和激发态的能级表明，重超核中Λ超子的有效质量约为自由Λ质量的70%。此外，获得的潜在深度比目前认为的要深1-MeV。在超核的非介子弱衰变中，我们首次成功地在低背景下以高统计量测量了中子。中子能谱异常光滑，表明非介子弱衰变的反应机理需要重新考虑。为了延长这些研究，我们考虑在正在建设中的J-PARC进行新的超核实验项目。我们向J-PARC提出了几个新的实验。

项目成果

T.Nagae: "Progress in Hypernuclear Physics"European Physics Jurnal A. in press. (2003)

T.Nagae：“超核物理学进展”欧洲物理学杂志 A. 正在出版。

T.Nagae: "Progress in Hyperiruclear Physics"European Physics Journal A. (印刷中). (2003)

T.Nagae：“超核物理学进展”欧洲物理学杂志 A.（出版中）。

H.Hotchi et al.: "Spectrosoopy of medium-Heavy Λ hypernuclei via the (π^+,Κ^+) reaction"Physical Review C. Vol.64, No.4. 44302-1-44302-15 (2001)

H.Hotchi 等人：“通过 (π^+,Κ^+) 反应对中重 Λ 超核进行光谱分析”Physical Review C. Vol.64，No.4 (2001)。

H.Noumi et al.: "Sigma-Nucleus Potential in A=28"Physical Review Letters. Vol.89. 72301 (2002)

H.Noumi 等人：“A=28 中的西格玛核势”物理评论快报。

H.Hotchi et al.: "Spectroscopy of medium-heavy Λ hyperruclei via the Cπ^+, K^+1 reaction"Physical Review C. Vol.64, No.4. 044302-1-044302-15 (2001)

H.Hotchi 等人：“通过 Cπ^+、K^+1 反应进行中重 Λ 超核的光谱”Physical Review C. Vol.64，No.4 (2001)。