Production of Ultra Cold Neutrons by a Doppler Shifter with Pulsed Neutrons at J-PARC
Production of Ultra Cold Neutrons by a Doppler Shifter with Pulsed Neutrons at J-PARC
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J-PARC 的脉冲中子多普勒频移器产生超冷中子
DOI：
10.1088/1742-6596/528/1/012030
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and T. Yoshioka
中科院分区：
文献类型：
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作者：
K. Mishima;S. Imajo;M. Hino;T. Ino;Y. Iwashita;R. Katayama;M. Kitaguchi;T. Oda;H. M. Shimizu;M. Utsuro;S. Yamashita;and T. Yoshioka
超冷中子(UCN)是动能在几百纳电子伏特左右的中子。动能如此之小的中子可以被困在物质容器或磁场中。由于这些独特的特性，碳纳米管被用于一些重要的基础物理实验。多普勒移位器是一种产生UCN的装置，它通过在以入射中子一半速度移动的镜子上的反射使UCN减速。利用四层单色超镜反射速度约为68m/S的中子[1，Hino et al.(2010)]，制作了一台多普勒频移器，并使用J-PARC脉冲中子源工作。多普勒移位器的一个重要特点是使用脉冲中子束。与连续中子束不同，可以通过选择脉冲中子束中的时间片来选择中子速度。因此，在J-PARC的情况下，UCN产量提高了~80倍。我们利用多普勒移位器成功地制备了UCN：测量的UCN产生率与模拟结果一致。
Ultracold neutrons (UCNs) are neutrons whose kinetic energy is around a few hundred nanoelectronvolts. Neutrons with such small kinetic energy can be trapped in a material vessel or magnetic fields. Because of these unique characteristics, UCNs are used for some important experiments of fundamental physics. The Doppler shifter is a device to produce UCN by slowing them down by the reflection on a mirror moving with half of the velocity of incoming neutrons. A Doppler shifter using a quadruple-stack of monochromatic supermirrors that reflects neutrons with a velocity around 68m/s [1, Hino et al.(2010)] was fabricated, and operated with a pulsed neutron source of J-PARC. An important feature of the Doppler shifter is the use of a pulsed neutron beam. Unlike in continuous neutron beams, the neutron velocity can be selected by choosing a time slice in a pulsed neutron bunch. Thus the UCN production improves by~ 80 times in the case of J-PARC. We successfully produced the UCNs by the Doppler shifter: the measured UCN production rate is consistent with the simulations.