Study of 48Ca Double Beta Decay

48Ca双β衰变研究

• 批准号: 14204026
• 负责人: KISHIMOTO Tadafumi
• 金额: $ 34.44万
• 依托单位: Osaka University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (A)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2004
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14204026/
• 关键词: Neutrino; Double beta decay; Majorana mass; Lepton number non-conservation; Low radioactivity; CaF2; Scintillator; Underground laboratory; シンチレーション光

The observation of double beta decay demonstrates the violation of Lepton Number conservation. It is a key experiment to answer the question why our universe is matter dominated. This research project aims at studying the double beta decay of 48Ca for which the CANDLES detector system, which features CaF2 crystals, is under construction. This year is the final year of the research. It is fortunate that our request to continue the research approved and our final year becomes the starting year of the basic Research S which roughly doubles our budget.We have achieved the following this year.1. We constructed vessel and oil purification system. We now have almost all elements of the detector.2. Newly designed PMT's are immersed in pire water and endurance test was performed. We found some problem and fixed it.3. We studied best arrangement of PMT for given number of PMT's.4. Additional CaF2 crystals were purchased. We studied radioactive background level and found that all of them are OK.5 … More . The almost unique background which is serious to this experiment is the successive decay of beta and alpha particles that may give background at the Q value region. The observation of pulse shape will give us information to discriminate the background for which we studied characteristics of 500 MHz flash ADC.6. Although we are working at Oto cosmo observatory near Osaka University, the CANDLES detector system becomes so large that Oto will have difficulty to accommodate the detector. We had discussion with ICRR and we decided to install the CANDLES III at Kamioka underground laboratory.7. We organized US-Japan seminar on "Double beta decay and neutrino masses" at Maui Hawaii from September 16-20, 2005. In this seminar we discussed current status of study of double beta decay. It helped to have recognition of our experiment.We are currently studying characteristic of the detector we constructed at Osaka University. After that study we will move the detector system to underground laboratory and start data taking. Less

双贝塔衰变的观察证明了轻子数守恒定律的违反。这是回答为什么我们的宇宙是物质主导的问题的一个关键实验，该研究项目旨在研究 48Ca 的双贝塔衰变，其中 CANDLES 探测器系统。幸运的是，我们继续研究的请求获得批准，我们的最后一年成为基础研究 S 的起始年，这大约使我们的预算增加了一倍。实现了以下这个1.我们建造了容器和油净化系统。2.新设计的PMT浸入水中并进行了耐久性测试。3.我们研究了。给定数量的 PMT 的最佳排列。4. 我们研究了放射性背景水平，发现它们都正常。5 … 更多 。 β 和 α 粒子的衰变可能会在 Q 值区域提供背景，但脉冲形状的观察将为我们提供区分背景的信息，我们研究了 500 MHz 闪存 ADC 的特性。6。在大阪大学附近，CANDLES 探测器系统变得如此之大，以至于 Oto 难以容纳探测器。我们与 ICRR 进行了讨论，我们决定在 Kamioka 地下实验室安装 CANDLES III。7。 “双β衰变和中微子质量”于2005年9月16日至20日在夏威夷毛伊岛举行。在这次研讨会上我们讨论了双β衰变的研究现状，这有助于我们的实验得到认可。我们目前正在研究探测器的特性。我们在大阪大学建造了该研究之后，我们将把探测器系统移至地下实验室并开始采集数据。

项目成果

Background rejection using FADC for double beta decay experiments

使用 FADC 进行双 β 衰变实验的背景抑制

• 发表时间: 2004
• 期刊: Proc. of the Mini-workshop on Kaon Experiments and Detectors
• 作者: S.Umhehara

A.Sakaguchi et al.: "Structure of ^<13>_λC Hypernucleus Studied by the (K^-,π^-,γ)Reaction"Nucl.Phys.A. 721. 979-982 (2003)

A. Sakaguchi 等：“通过 (K^-,π^-,γ) 反应研究^<13>_λC 超核的结构”Nucl.Phys.A. 721. 979-982 (2003)

S.Yoshida et al.: "Search for Wimps with NaI(Tl) Detectors at Oto Cosmo Observatory"Nuclear Physics A. 721. 1056-1059 (2003)

S.Yoshida 等人：“在 Oto Cosmo 天文台用 NaI(Tl) 探测器搜索 Wimps”核物理 A. 721. 1056-1059 (2003)

Neutron spectrum measurement for dark matter search in Oto Cosmo Observatory

奥托宇宙天文台用于暗物质搜索的中子能谱测量

• 发表时间: 2004
• 期刊: Annual Report 2004 Osaka University Laboratory of Nuclear Studies
• 作者: Gouda;N.;Tsujimoto;T.;Kobayashi;Y.;Nakajima;T.;Matsuhara;H.;Yano;T.;Yasuda;N.;Kan-Ya;Y.;Yamada;Y.;Ueno;M.;T.Kobayashi
• 通讯作者: T.Kobayashi

Magnetic Field Dependence of Large Photomultipliers used in CANDLES-III

CANDLES-III 中使用的大型光电倍增管的磁场依赖性

• 发表时间: 2004
• 期刊: Annual Report 2004 Osaka University Laboratory of Nuclear Studies
• 作者: Gouda;Naoteru;Tsujimoto;Takuji;Kobayashi;Yukiyasu;Nakajima;Tadashi;Yasuda;Naoki;Kan-Ya;Yukitoshi;Matsuhara;Hideo;Yano;Taihei;Yamada;Yoshiyuki;Ueno;Munetaka;I.Sugai et al.;S.Yoshida
• 通讯作者: S.Yoshida