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arXiv 1409.6969nucl-exastro-ph.HEphysics.ins-det
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反应堆反中微子改变~(22)Na衰变率的截面上限

Upper limit on the cross section for reactor antineutrinos changing 22Na decay rates

R. J. de Meijer, S. W. Steyn

摘要:

在本文中,我们提出了在核裂变反应堆的存在下,22钠衰变的长期观察结果。这些测量是在南非开普敦附近的Koeberg核电站的安全壳墙外和下面进行的。在此期间,反中微子通量的范围在5*10^11 ~ 1.6*10^13 cm^-2 s^-1之间。我们发现,符合求和技术提供了一个敏感的工具来测量的总衰减常数的变化,以及EC和β +衰变22 Na的第一个激发态在22 Ne之间的分支比。我们观察到反应堆开启和反应堆关闭之间计数率的相对变化等于(-0.51+/-0.11)*10^-4。在评估了可能的系统不确定性后,我们得出结论,这种效应要么是由于一个隐藏的仪器原因,要么是由于反中微子和22 Na核之间的相互作用。由于反中微子相互作用,22 Na衰变率的上限为~0.03 barn。

英文摘要:

In this paper we present results of a long-term observation of the decay of 22Na in the presence of a nuclear fission reactor. The measurements were made outside the containment wall of and underneath the Koeberg nuclear power plant near Cape Town, South Africa. Antineutrino fluxes ranged from ~5*10^11 to 1.6*10^13 cm^-2 s^-1 during this period. We show that the coincidence summing technique provides a sensitive tool to measure a change in the total decay constant as well as the branching ratio between EC and beta+ decay of 22Na to the first excited state in 22Ne. We observe a relative change in count rate between reactor-ON and reactor-OFF equal to (-0.51+/-0.11)*10^-4. After evaluating possible systematic uncertainties we conclude that the effect is either due to a hidden instrumental cause or due to an interaction between antineutrinos and the 22Na nucleus. An upper limit of ~0.03 barn has been deduced for observing any change in the decay rate of 22Na due to antineutrino interactions.

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