用金属镓测量太阳中微子俘获率。III：2002- 2007年数据采集期的结果
Measurement of the solar neutrino capture rate with gallium metal. III: Results for the 2002--2007 data-taking period
摘要：
1989年12月，俄美合作的SAGE实验开始用金属镓靶测量太阳中微子俘获率。从那时起，测量一直在继续，只有几次短暂的中断。我们在这里给出了SAGE自2001年12月最后一次发表数据摘要以来的实验改进。假设太阳中微子的产生率在数据收集期间是恒定的，对截至2007年12月的168次提取的综合分析给出了能量超过233 keV的太阳中微子的捕获率为65.4（+3.1）（-3.0）（stat）（+2.6）（-2.8）（syst）SNU。所有三个Ga太阳中微子实验（SAGE、Gallex和GNO）结果的加权平均值现在是66.1 +/- 3.1 SNU，其中统计和系统不确定性已被正交组合。在最近的数据收集期间，使用反应堆产生的37 Ar中微子源进行了新的SAGE测试。在这个实验中观察到的速率与计算出的速率之比，再加上之前三次使用Ga的51 Cr中微子源实验中测得的速率，为0.87 +/- 0.05。对这个低结果的一个可能的解释是，71 Ge中最低的两个激发态俘获中微子的截面被高估了。如果我们假设这些横截面为零，那么包括中微子振荡的标准太阳模型预测Ga的总捕获率在63-66 SNU的范围内，不确定性约为4%，与实验吻合良好。我们推导出质子-质子聚变反应在太阳中产生的中微子流的电流值为（6.0 +/-0.8）× 10^（10）/（cm ^2 s），这与标准太阳模型预测的pp流值很好地吻合.最后，我们表明，数据是一致的假设，太阳中微子的生产率是恒定的时间。
英文摘要：
The Russian-American experiment SAGE began to measure the solar neutrino capture rate with a target of gallium metal in Dec. 1989. Measurements have continued with only a few brief interruptions since that time. We give here the experimental improvements in SAGE since its last published data summary in Dec. 2001. Assuming the solar neutrino production rate was constant during the period of data collection, combined analysis of 168 extractions through Dec. 2007 gives a capture rate of solar neutrinos with energy more than 233 keV of 65.4 (+3.1)(-3.0) (stat) (+2.6)(-2.8) (syst) SNU. The weighted average of the results of all three Ga solar neutrino experiments, SAGE, Gallex, and GNO, is now 66.1 +/- 3.1 SNU, where statistical and systematic uncertainties have been combined in quadrature. During the recent period of data collection a new test of SAGE was made with a reactor-produced 37Ar neutrino source. The ratio of observed to calculated rates in this experiment, combined with the measured rates in the three prior 51Cr neutrino-source experiments with Ga, is 0.87 +/- 0.05. A probable explanation for this low result is that the cross section for neutrino capture by the two lowest-lying excited states in 71Ge has been overestimated. If we assume these cross sections are zero, then the standard solar model including neutrino oscillations predicts a total capture rate in Ga in the range of 63-66 SNU with an uncertainty of about 4%, in good agreement with experiment. We derive the current value of the neutrino flux produced in the Sun by the proton-proton fusion reaction to be (6.0 +/- 0.8) x 10^(10)/(cm^2 s), which agrees well with the pp flux predicted by the standard solar model. Finally, we show that the data are consistent with the assumption that the solar neutrino production rate is constant in time.
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