Study of Hyperon-Nucleon Interaction

超子-核相互作用的研究

基本信息

批准号：
12304013
负责人：
IMAI Kenichi
金额：
$ 26万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-12304013/
关键词：
Hyperon Hypernuclei Strangeness Time Projection Chamber Exotic hadrons QCD ハイベロン

项目摘要

We have made several discoveries in hypernuclear physics. During the analysis of the nuclear emulsion obtained by KEK-E373 experiment, we found several double hypernuclei. One is ^6He_ΛΛ nucleus and its mass was precisely determined. From the binding energy of the two Λ of this nucleus, ΛΛ interaction was determined to be weakly attractive for the first time. The result is quite important to construct models of baryon-baryon was interaction. The high precision γray spectroscopy of hypernuclei has provided very rich physics results. Recent measurements with Hyperball for ^7Li,^9Be and ^<16>O hypernuclei have almost determined ΛN spin-dependent interaction, such as spin-spin, spin-orbit and tensor interaction. Especially, spin-orbit interaction determimed by a level splitting of 40kev of spin doublet states of ^9Be hypernucleus was found very weak compared to the nucleon-nucleon case by almost two orders of magnitude.At KEK-PS, we have performed an experiment (E522) with a 1.66GeV/c K- b … More eam to study a possible H-dibaryon resonance and ΞN interaction. We took a largest data for (K-,K+) reactions with a scintillating fiber active target. We have analyzed counter data and visual data obtained by the scintillating fiber. About 40k (K-,K+) reactions were scanned with computer-aided scanning system. Among them we have obtained about 200 events which show emission of two Λ from the (K-K+) reaction vertices. The invariant mass spectrum of the two Λ shows a peak near the threshold which may suggest the existence of H-dibaryon resonance.We have constructed a Time Projection Chamber (TPC) for the study of hyperon resonances with Laser Compton γ beam at Spring-8. The characteristics of the TPC is that a target is located inside the TPC. This makes it possible to detect decays of low energy hyperons which has only a few cm flight length. The primary goal is to measure Λ(1405) with nuclear targets to clarify its structure. We have studied the properties of the TPC with cosmic rays. We have obtained the position resolution of 300μm and 500μm in Θ and z directions, respectively. In the end of 2003, we installed the TPC in a superconducting solenoid and started data taking together with a forward spectrometer with the γbeam. The TPC has been successfully operated at the beam rate of 10^6 Hz. Preliminary analysis shows that charged particle tracks are clearly recorded by the TPC. Less

我们在超核物理方面取得了多项发现，在对KEK-E373实验获得的核乳状液进行分析时，我们发现了几个双超核，其中之一是^6He_ΛΛ核，并且根据两个Λ的结合能精确确定了它的质量。该核的ΛΛ相互作用首次被确定为弱吸引力，其结果对于构建重子-重子相互作用模型具有重要意义。超核的γ射线能谱提供了非常丰富的物理结果，最近用Hyperball对^7Li、^9Be和^16O超核进行的测量几乎确定了ΛN自旋相关的相互作用，例如自旋-自旋、自旋-轨道和张量相互作用。特别是，由 ^9Be 超核自旋双重态的 40kev 能级分裂决定的自旋轨道相互作用与核子-核子情况几乎相差两个数量级。在 KEK-PS，我们用 1.66GeV/c K- b … More 进行了一项实验 (E522)，以研究可能的 H-二重子共振和 ΞN 相互作用。与闪烁光纤活性目标的（K-，K+）反应的最大数据我们分析了闪烁光纤获得的计数器数据和视觉数据。利用计算机辅助扫描系统对(K-,K+)反应进行了扫描，其中我们获得了大约200个事件，这些事件显示了(K-K+)反应顶点的两个Λ的发射。两个Λ的不变质谱显示了a。在阈值附近出现峰值，这可能表明氢二重子共振的存在。我们在 Spring-8 上构建了一个时间投影室（TPC），用于研究激光康普顿 γ 光束的超子共振。 TPC的特点是目标位于TPC内部，这使得可以检测飞行长度只有几厘米的低能超子的衰变，主要目标是用核目标测量Λ(1405)以澄清其。我们用宇宙射线研究了TPC的特性，我们在θ和z方向上分别获得了300μm和500μm的位置分辨率。 2003年，我们将TPC安装在超导螺线管中，并开始与带有γ束的前向谱仪一起采集数据。TPC已在10^6 Hz的束流速率下成功运行。初步分析表明，带电粒子轨迹被清晰地记录下来。更少的TPC。