Search for Exotic Nuclear Ultra-Rare Process and Ultra-Lowbackground Nuclear Spectroscopy

寻找奇异核超稀有过程和超低本底核光谱

• 批准号: 02452024
• 负责人: OHSUMI Hideaki
• 金额: $ 5.12万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (B)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-02452024/
• 关键词: Ultra-Lowbackground; Ultra rare process nuclear spectroscopy; Super Heavy Charged Particle; Charge non-conserving Decay; Dark Matter; 極低バックグランド; グ-クマタ-; WIMP

The nuclear exotic ultra-rare decays and the possibility of the existence of exotic particles have been investigated by means of ultra rare process nuclear spectroscopy with ultra low background detectors. Abstracts studied are as follows :1. Super heavy charged particle X- have been searched by using ^<100>Mo nucleus. We studied the exotic nuclear beta decay ^<100>MoX^- -> ^<100>TcX^- -> ^<100>RuX^-. The exotic decay was studied by using ultra low background Ge detector. The upper limit of the creation of such exotic nucleus ^<100>MoX^- is found to be 2.84.10^<-26> 1/sec/nucleus.2. The charge non-conserving processes (CNC) were studied by exotic CNC beta decay of ^<100>Mo ->^<100>Tc+nu+ nu (a) and the CNC nuclear excitation of ^<127>I+e_K -> ^<127>I^*+nu (b). The possibility of the process (a) was investigated by measuring gamma-ray of the doughter of ^<100>Tc. The lower limit of the CNC beta decay is 1.1・10^<18>yr, which means the upper limit of the CNC coupling constant *^2_*(G_<cnc … More >/G_F)^2<2.3・10^<-20>. The CNC process (b) was studied by searching for the gamma decay from the first excited state of ^<127>I. Lower lirffit of the mean life was obtained 5.8・10^<23>yr, which means the upper limit of the coupling constant *^2_* (G_<cnc>/G_F)^2 < 1.1・10^<-24>.3. Dark matter (DM), if there is in our galaxy, may interact to a nucleus in the detector via elastic collision. An ultralow background large volume NaI detector was used to search DAI candidates. As both ^<23>Na and ^<127>I nucleus in the NaI detector has a nonzero spin, NaI detector is very suitable to search for the DM candidates with only axdal vector couplings. In addition, the cross section of DM candidates with spin independent couplings is roughly proportional to the the square of the neutron number, ^<127>I nucleus is very effective to the detection of DM candidates with spin independent couplings. The pulse height effect of the recoil nucleon due to the DM scattering in the NaI detector have been directly measured by using neutron scattering. Our data shows the most stringent upper limit on the maximum halo density of the both candidate of Dirac neutrino and Majorana neutrino with mass heavier than about 10OGeV. Less

利用超低本底探测器的超稀有过程核谱，研究了核奇异超稀有衰变和奇异粒子存在的可能性。主要研究内容如下：1。用^<100>Mo原子核寻找了超重带电粒子X-。我们研究了奇异核衰变^<100>MoX^- -> ^<100>TcX^- -> ^<100>RuX^-。利用超低本底锗探测器对奇异衰变进行了研究。这种奇异核^<100>MoX^-产生的上限为2.84.10^<-26> 1/sec/ nucleus2。采用奇异的CNC β衰变（^<100>Mo ->^<100>Tc+nu+ nu (a)）和CNC核激发（^<127>I+e_K ->^< 127>I^*+nu (b)）研究了电荷非守恒过程（CNC）。通过测量^<100>Tc的子粒子的伽马射线，研究了过程(a)的可能性。CNC β衰变的下限为1.1·10^<18>yr，这意味着CNC耦合常数*^2_*(G_< CNC…More >/G_F)^2<2.3·10^<-20>的上限。通过寻找^<127>I的第一激发态的伽马衰变来研究CNC过程(b)。平均寿命的下限为5.8·10^<23>yr，即耦合常数*^2_* (G_<cnc>/G_F)^2 < 1.1·10^<-24>.3的上限。暗物质（DM），如果在我们的星系中存在，可能通过弹性碰撞与探测器中的原子核相互作用。采用超低本底大体积NaI检测器对DAI候选者进行搜索。由于NaI探测器中的^<23>Na和^<127>I核都具有非零自旋，因此NaI探测器非常适合搜索只有轴向矢量耦合的DM候选体。此外，具有自旋不依赖耦合的候选DM的截面大致与中子数的平方成正比，^<127>I核对具有自旋不依赖耦合的候选DM的检测非常有效。用中子散射法直接测量了在NaI探测器中DM散射引起的反冲核子的脉冲高度效应。我们的数据显示了质量大于10OGeV的狄拉克中微子和马约拉纳中微子的最大光晕密度的最严格上限。少

项目成果

H.Ohsumi,K.Fushimi,H.Ejiri,H.Kinoshita,K.Okada,H.Sono,T.Shima and J.Tanaka: "Laboratory Limits on Dark Matter by using a Large Volume Lowbackground NaI Detector" 投稿準備中(Physical Review C).

H.Ohsumi、K.Fushimi、H.Ejiri、H.Kinoshita、K.Okada、H.Sono、T.Shima 和 J.Tanaka：“使用大体积低背景 NaI 探测器对暗物质的实验室限制”准备提交（物理审查C）。

H.Ejiri,M.Kawasuki,H.Kinoshita,H.Ohsumi,K.Okada,H.Sano and E.Takasugi: "Limits on charge nonconservation studied by nuclear excitation of ^<127>I" Physical Review C. 44. 502-505 (1991)

H.Ejiri、M.Kawasuki、H.Kinoshita、H.Ohsumi、K.Okada、H.Sano 和 E.Takasugi：“通过 ^<127>I 的核激发研究电荷非守恒的极限”物理评论 C. 44。

H. Ohsumi, K. Fushimi, H. Ejiri, H. Kinoshita, K. Okada, H. Sano, T. Shima and J. Tanaka: "Laboratory Limits on Dark Matter by using a Large Volume Lowbackground NaI Detector"

H. Ohsumi、K. Fushimi、H. Ejiri、H. Kinoshita、K. Okada、H. Sano、T. Shima 和 J. Tanaka：“使用大体积低本底 NaI 探测器对暗物质的实验室限制”

H.Ejiri,M.Kawasaki,H.Kinoshita,H.Ohsum,K.Okada,H.Sano and E.Takasugi: "Limits on charge nonconservation studied by nuclear excitation of ^<127>I" Physical Review C. 44. 502-505 (1991)

H.Ejiri、M.Kawasaki、H.Kinoshita、H.Ohsum、K.Okada、H.Sano 和 E.Takasugi：“通过 ^<127>I 的核激发研究电荷非守恒的极限”物理评论 C. 44。

H. Ejiri, M. Kawasaki, H. Kinoshita, H. Ohsumi, K. Okada, H. Sano and E. Takasugi: "Limits on charge nonconservation studied by nuclear excitation of ^<127>I" Physical Review C. 44. 502-505 (1991)

H. Ejiri、M. Kawasaki、H. Kinoshita、H. Ohsumi、K. Okada、H. Sano 和 E. Takasugi：“通过 ^<127>I 核激发研究的电荷非守恒极限”物理评论 C. 44。