Study of the nu_<mu>-deficit in the atmospheric neutriono fluxes. (Study of the origin of neutrino mass.)

大气中微子通量中nu_<mu>-缺陷的研究。

• 批准号: 03101002
• 负责人: TOTSUKA Yoji
• 金额: $ 153.6万
• 依托单位: The University of Tokyo
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Specially Promoted Research
• 财政年份: 1991
• 资助国家: 日本
• 起止时间: 1991 至 1994
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-03101002/
• 关键词: Atomspheric neutrinos; Neutrino oscillations; Muon-neutrino; Eletron-neutrino; Tau-neutrino; Neutrino mass; タウニュートリノ質量; ニュートリノ; ニュ-トリノ; 大気ニュ-トリノ; ミュ-ニュ-トリノ; ニュ-トリノ質量

In 1994, a beam experiment was carried out to study the efficiency of separating electrons and muons, and to study various detector effects related to the nu_<mu>-deficit in the atmospheric neutrino fluxes. The result from this experiment showed that the efficiency of separating electrons and muons was 98% as expected by our Monte Carlo simulation. This result suggests that the atmospheric nu_<mu>-deficit is probably related to a real physics such as neutrino oscillations.The total number of atmospheric neutrino events was nearly doubled during this research period. The observed (nu_<mu>/nu_e) ratio relative to the expected one, (nu_<mu>/nu_e) _<Data>/ (nu_<mu>/nu_e) _<MC>, was 0.60<plus-minus>0.055 (stat.)<plus-minus>0.05 (syst.) at the sub-Gev energy range. The statistical significance of the nu_<mu>-deficit was about 5sigma.We also studied the atmospheric neutrino fluxes in the multi-GeV energy range. We observed nu_<mu>-deficit in this energy range too. The observed zenith-angle dependence of the nu_<mu>/nu_e ratio in this energy range was not uniform and was consistent with the expectation from neutrino oscillations.From those studies, we concluded that neutrino oscillations might account for the atmospheric netrino data. The mass of either nu_<mu>mu or nutau might be about 0.1 eV.

1994年，进行了一项横梁实验，以研究分离电子和兆子的效率，并研究与Nu_ <mu> - 缺陷相关的各种检测器效应。该实验的结果表明，通过我们的蒙特卡洛模拟预期，分离电子和万物的效率为98％。该结果表明，大气NU_ <mu> - 缺陷可能与中微子振荡等实际物理学有关。在此研究期间，大气中微子事件的总数几乎翻了一番。相对于预期的（nu_ <mu>/nu_e）_ <data>/（nu_ <mu>/nu_e）_ <mc>，观察到的（nu_ <mu>/nu_e）比率为0.60 <plus-minus> 0.055（Stat。）<Plus-Minus> 0.05（Syst。）在子GEV能量范围内。 NU_ <mu> - 缺陷的统计显着性约为5Sigma。我们还研究了多GEV能量范围内的大气中微子通量。我们也观察到nu_ <mu>在此能量范围内。在此能量范围内，观察到的NU_ <mu>/NU_E比的Zenith-angle依赖性并不均匀，并且与中微子振荡的期望一致。从这些研究中，我们得出结论，中微子振荡可能解释了大气Netrino数据。 nu_ <mu> mu或nutau的质量可能约为0.1 eV。

项目成果

Y.Fukuda, et al.: "Atmospheric nu_<mu>/nue Ratio in the Multi-GeV Energy Range" Physics Letters B. 335. 237-245 (1994)

Y.Fukuda 等人：“多 GeV 能量范围内的大气 nu_<mu>/nue 比率”《物理快报》B. 335. 237-245 (1994)

Y.Fukuda et al: "Search for low-energy neutrinos from galactic gamma-ray sources" The AstroophysicaI Journal. 435. 225-229 (1994)

Y.Fukuda 等人：“从银河伽马射线源中寻找低能中微子”《天体物理学杂志》。

Y.Totsuka: High-Energy Physics. Iwanami, 218 (1992)

Y.Totsuka：高能物理学。

戸塚洋二: "素粒子物理" 岩波書店, 218 (1992)

户冢洋二：《粒子物理学》岩波书店，218（1992）

Y.Fukuda et al: "Atmospheric νμ/νe ratio in the multi-GeV energe range" Physics Letters B. 335. 237-245 (1994)

Y. Fukuda 等人：“多 GeV 能量范围内的大气 νμ/νe 比率”《物理快报》B. 335. 237-245 (1994)