Determination of the Atmospheric Neutrino Flux by the Observation of Atmospheric Gamma

通过大气伽马观测测定大气中微子通量

• 批准号: 09440110
• 负责人: KASAHARA Katsuaki
• 金额: $ 7.17万
• 依托单位: Shibaura Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1997
• 资助国家: 日本
• 起止时间: 1997 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-09440110/
• 关键词: Atmospheric Neutrinos; Neutrino Oscillation; Scintillating Fiber; Atmospheric Gamma Rays; Cosmic Rats; Kamioka Experiment; Atmospheric Muons; MuonNeutrino Deficit; 大気電子

First year: We have upgraded the trigger system of the BETS originally designed for the observation of primary cosmic electrons; a multi trigger system was realized by which we can observe gamma rays with different trigger conditions simultaneously.Second year: We selected Mt. Norikura Observatory of Tokyo University (〜2800 m) as a site where we could do an observation meaningful for the calibration of atmospheric neutrino calculations as well as the test of the detector, We made 3 week observation. The trigger rate was coincident with the calculation within 2〜3%. However, the vertical flux of the gamma rays was deviated from the calculation. This contradiction was now well resolved by improving the data analysis method.Third year: 1) The observation is at the balloon altitudes so that a number of charged particles are expected to enter from the side of the detector. To reject such particles, we added 4 plastic scintillator plates of size 30cmx 5cmx 1.5cm around the top part of the det … More ector, For read-out, we embedded 8 thin fibers in each plate and they are read by a small PMT. 2) The balloon was launched at Sanriku Balloon Center on Sep., 2, 1999 and recovered after 〜10 hour flight. The trigger rates from the sea level to 25 km were nicely coincident with a calculation and thus proved that both of the calculation and detector were well operating. We realized quasi level flight(〜30 min) at 15.3, 18.5, 21.2, and 24.7km above sea level, 3) The energy spectrum was obtained at these altitudes, and they are converted into the vertical flux. The spectrum was well approximated by a power at 3 to 30 GeV. The vertical fluxes at 15 to 21 km were well reproduced by the calculations using the BESS measured primary intensity. However, the observation gave a larger flux than the calculation above 25 km, This seems to be due to the lack of anti-coincidence scintillator at some part of the detector; at higher altitudes, more primary protons are expected and they can enter the detector as if neutral particles from the gap where there is no scintillator. These protons could be rejected by employing image analysis and preliminary result showed we could to it. In year 2000, we are adding anti-coincidence scintillator and making a balloon observation again. Using these results and the muons spectrum at various altitudes, we expect we can reduce a reliable neutrino flux. Less

第一年：我们对原设计用于观测初级宇宙电子的BETS的触发系统进行了升级，实现了多触发系统，可以同时观测不同触发条件的伽马射线。第二年：我们选择了Mt.东京大学纪仓天文台（海拔2800米）作为一个可以进行大气中微子计算校准和探测器测试的观测点，我们进行了为期3周的观测。触发率与计算值在2 ~ 3%范围内符合。然而，伽马射线的垂直通量偏离了计算。现在，通过改进数据分析方法，这个矛盾得到了很好的解决。第三年：1）在气球高度进行观测，预计会有大量带电粒子从探测器侧面进入。为了排除这些颗粒，我们在探测器的顶部周围添加了4个尺寸为30 cm × 5cm × 1.5cm的塑料闪烁体板。 ...更多信息 对于读出，我们在每个板中嵌入8根细纤维，并且它们由小PMT读取。2)这只气球于9月9日在三陆气球中心升空，1999年2月2日，经过10个小时的飞行后恢复。从海平面到25 km的触发率与计算结果吻合较好，证明了计算和探测器的工作良好。在海拔15.3，18.5，21.2和24.7km处实现了准水平飞行（约30 min）。该谱很好地近似了3至30 GeV的功率。利用BESS测量的初级强度计算15 - 21 km的垂直通量，得到了较好的再现。然而，在25 km以上的观测给出了比计算更大的通量，这似乎是由于在探测器的某些部分缺乏反符合闪烁体;在更高的海拔，预计更多的初级质子，它们可以像中性粒子一样从没有闪烁体的差距进入探测器。用图象分析方法可以排除这些质子，初步结果表明我们可以排除这些质子。2000年，我们又增加了反符合闪烁体，进行了气球观测。利用这些结果和不同高度的μ子谱，我们期望我们可以减少一个可靠的中微子流量。少

项目成果

S.Torii et al: "The baloon-borne electron telescope with scintilating fibers (BETS)"Nucl. Int.and Meth. A. (in press). (2000)

S.Torii 等人：“带有闪烁纤维的气球载电子望远镜（BETS）”Nucl。

S. Torii et al: "The Baloon-borne electron telescope withscintilating fibers(BETS)"Nucl. Inst. and Meth. A. (in press). (2000)

S. Torii 等人：“带有闪烁纤维的气球载电子望远镜（BETS）”Nucl。

M. Hond et al: "Calculation of Atmospheric Neutrino and the Sensitivity of Angular Dependences to Various Models"Proc. of the 26th Int. Cosmic Ray Conf. Utah. 2. 180-183 (1999)

M. Hond 等人：“大气中微子的计算和角度依赖性对各种模型的敏感性”Proc。

M.Hond et al: "Calculation of Atmospheric Neutrino and Sensitivity of Angular Dependences to Various Models"Proc of the 26th Int. Cosmic Ray Conf. Utah. Vol.2. 180-183 (1999)

M.Hond 等人：“大气中微子的计算和角度依赖性对各种模型的敏感性”第 26 届国际会议论文集。

M.Hond et al: "Calculation of Atmospheric Neutrino and the Sensitivity of Angular Dependences to Various Models"Proc.of the 26th Int.Cosmic Ray Conf.Utah. 2. 180-183 (2000)

M.Hond 等人：“大气中微子的计算和角度依赖性对各种模型的敏感性”第 26 届国际宇宙射线会议犹他州会议记录。