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arXiv 1403.0107physics.ins-detnucl-ex
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预测反应堆反中微子发射的Fission产物β谱测量方法

Method of Fission Product Beta Spectra Measurements for Predicting Reactor Anti-neutrino Emission

D. M. Asner, K. Burns, L. W. Campbell, B. Greenfield, M. S. Kos, J. L. Orrell, M. Schram, B. VanDevender, 1 L. S. Wood, D. W. Wootan

摘要:

在核反应堆的堆芯中发生的核裂变过程导致不稳定的、富含中子的裂变产物,其随后发生β衰变并发射电子反中微子。这些反应堆中微子从中微子的最初发现到目前中微子混合角的精确测量,一直服务于中微子物理学研究。对反应堆中微子的绝对通量和能谱的预测取决于一系列基于20世纪70年代和80年代测量的开创性论文。不断改进的反应堆中微子测量技术和最近重新考虑的预测和观察到的反应堆中微子通量之间的协议,促使重新审视潜在的β谱测量。提出了一种方法,该方法使用输送到工程目标的加速器质子束来产生定制的中子场,以再现存在于操作的核反应堆的堆芯中的中子能谱。放置在这个定制的中子通量中的主反应堆可裂变同位素的箔将最终从所产生的裂变产物中发射β粒子。在具有垂直磁场的时间投影室中测量这些β粒子提供了一组独特的系统考虑,用于与原始精液β谱测量进行比较。诸如伽马射线发射和辐照后放射化学分析等辅助测量将进一步限制每次裂变的β发射的绝对标准化。展开的β谱测量与这种方法到一个预测的反应堆中微子谱的要求进行了探讨。

英文摘要:

The nuclear fission process that occurs in the core of nuclear reactors results in unstable, neutron rich fission products that subsequently beta decay and emit electron anti-neutrinos. These reactor neutrinos have served neutrino physics research from the initial discovery of the neutrino to current precision measurements of neutrino mixing angles. The prediction of the absolute flux and energy spectrum of the emitted reactor neutrinos hinges upon a series of seminal papers based on measurements performed in the 1970s and 1980s. The steadily improving reactor neutrino measurement techniques and recent re-considerations of the agreement between the predicted and observed reactor neutrino flux motivates revisiting the underlying beta spectra measurements. A method is proposed to use an accelerator proton beam delivered to an engineered target to yield a neutron field tailored to reproduce the neutron energy spectrum present in the core of an operating nuclear reactor. Foils of the primary reactor fissionable isotopes placed in this tailored neutron flux will ultimately emit beta particles from the resultant fission products. Measurement of these beta particles in a time projection chamber with a perpendicular magnetic field provides a distinctive set of systematic considerations for comparison to the original seminal beta spectra measurements. Ancillary measurements such as gamma-ray emission and post-irradiation radiochemical analysis will further constrain the absolute normalization of beta emissions per fission. The requirements for unfolding the beta spectra measured with this method into a predicted reactor neutrino spectrum are explored.

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