Study of Doubly Strangeness Nuclei

本研究的目的是利用圆柱探测器系统（CDS）和1.8 GeV/c的高强度k束（lO**6/sec）在BNL/AGS上寻找双λ超核。到目前为止，双超核的候选物质只有两种。我们的方法是在（K-, K+）反应中通过S=-2的类化合物态产生双λ超核，并通过CDS观察两个介子的连续衰变来检测它们。我们预计统计数字将比以前高出两个数量级。我们在去年完成了COS，测试实验表明CDS以及BNL/AGS的束线光谱仪系统性能良好。今年的数据是从9月到11月。初步分析表明，在双介子谱中存在许多相关动量区域的事件。我们希望在改进CDS的动量分辨率后，能够识别双- λ超核。我们的数据包含了级联超核、h粒子等S=-2核系统的信息，具有比以往更高的统计量，因此我们也将对这些有趣的话题给出新的结果。

The aim of this study is to search for double-lambda hypernuclei by using the Cylindrical Detector System (CDS) and a high intensity K-beam (lO**6/sec) with 1.8 GeV/c at BNL/AGS.There have been only two candidates for double-lambda hypernuclei so far studied. Our method is to produce double-lambda hypernuclei through a compound-like state with S=-2 in the (K-, K+) reaction and to detect them by observing sucessively decaying two pions with CDS.We expect higher statistics by two orders of magnitudes than before.We have completed COS in the last year and the test experiment showed a good performance of CDS as well as the beam-line spectrometer system at BNL/AGS.In this year we have accumulated the data from September through November . A preliminary anaysis shows that there are many events for relevant momentum regions in two-pions spectrum. We hope we can identify double -lambda hypernuclei after the improvement of the momentum resolution of CDS.Our data contains information concerning S=-2 nucler systems such as cascade hypernuclei, H-particle with higher statistics than before, so that we will also give new results about those interesting topics.