White Star Production by pi-Meson in Nuclear Emulsion

本研究的目的是研究核乳剂中白星的产生特征。我们利用核乳胶和反杂化系统在欧洲核子核反应堆中进行了介子-中微子和陶子-中微子之间的中微子振荡实验，得到的信号是主要衰变拓扑为很短扭结的牛粒子，它是由介子中微子振荡而来的陶子中微子在荷电作用下与核乳胶相互作用产生的。在通常的中性电流相互作用中，我们原则上不能区分介子产生的tau扭结衰变和类扭结白星过程。在1995财年到1996财年的两年时间里，《核乳剂中介子产生白星》的研究得到了教育部科学研究助学金(B)(2)类的支持，这就是我们在完成中微子振荡实验时需要知道的一个背景。…更多名词，科学、体育和文化。现报告本次调查结果如下：1995财年、1996财年的进度时序项目；(FY1995)(1)核乳剂的形状、厚度、所需的板数由梁上暴露的测试组件来决定。(2)核乳剂支架的设计和制造，用于在曝光时相对固定乳胶板，并保持光束密度恒定。(3)将上述乳胶架与硅条探测器和其他计数器组件组装在一起，并测量相对位置。(4)通过连接数据采集电路对乳胶架组件进行测试，并同时完成必要的软件开发。(1996财年)(5)将乳剂计数器系统曝光在KEK的负pion上。(6)曝光后，目前已全部研制完成，并完成了全自动扫描测量的准备工作，总体上测量情况非常顺利，但在细节上也出现了一些新的问题，即需要非常复杂的测量仪器操作和功能。由于这些原因，本会计年度的计量和分析工作不可能完成。但目前已取得初步效果，计划在几个月内全面完成测试分析工作。较少

In this investigation, the purpose is a study of white star production features in nuclear emulsion. We are performing the neutrino oscillation experiment between muon-neutrino and tau-neutrino by using nuclear emulsion and counter hybrid system in CERN.The signal to be obtained, is tau particle which main decay topology is very short kink and which is produced in charged current interaction with nuclear emulsion by tau neutrino oscillated from muon neutrino. In principle, we can not distiguish between tau kink decay and kink like white star process produced by pion in usual neutral current interacion. Therefore, this rises as background and it is necessitated to know the white kink process probability in completion our neutrino oscillation experiment.During the 2 year term from FY1995 through FY1996, the investigation titled as "White Star Production by pi-Meson in Nuclear Emulsion" was supported in category of "Grant-in-Aid for Scientific Research (B) (2)" by The Ministry of Educatio … More n, Science, Sports and Culture. This investigation results have been reported here.The followings are time sequential item of progress in FY1995, FY1996 ;(FY1995)(1) The nuclear emulsion shape, thickness, the number of plates needed were decided by fabricating test modules exposed on beam.(2) The nuclear emulsion holder was designed and fabricated, which is used to fix the emulsion plates relatively in a exposure and keep the beam density to be constant.(3) The emulsion holder mensioned above was assembled with Silicon Strip Detectors and other counter componets and surveyed the relative positions.(4) THe emulsion holder assembly was tested by connecting with data taking circuits and necessitating software developement was completed in same time.(FY1996)(5) The emulsion-counter system was exposed on negative pion in KEK.(6) After exposure, all amulsion plates are developped and preparation of measurement by automatic scanner was completed.The global situation of measurement is very smooth but there appeare some new probiems in detail i.e. very complicated operation and function of measuring apparatus are needed. By these reasons, the completetion of measrement and analysis in this fiscal year becomes to be impossible. But at present, the preliminary results concerned to initial purpose has been obtained and in several months the measurement and analysis is planned to be finished comletely. Less