Production of ultra cold neutrons by a doppler shifter with pulsed neutrons at J-PARC

International Workshop on Neutron Optics and Detectors

Mishima, K.^1 ; Imajo, S.^2 ; Hino, M.^3 ; Ino, T.^4 ; Iwashita, Y.^5 ; Katayama, R.^6 ; Kitaguchi, M.^7,8 ; Oda, T.^9 ; Shimizu, H.M.^7 ; Utsuro, M.^10 ; Yamashita, S.^1 ; Yoshioka, T.^11

International Center for Elementary Particle Physics, University of Tokyo, Tokyo 113-0033, Japan^1

Department of Physics, Kyoto University, Kyoto 606-8502, Japan^2

Research Reactor Institute, Kyoto University, Osaka, Kumatori, 590-0494, Japan^3

KEK, High Energy Accelerator Research Organization, Tsukuba, Japan^4

Institute for Chemical Research, Kyoto University, Kyoto 611-0011, Uji, Japan^5

Department of Physics, University of Tokyo, Tokyo 113-0033, Japan^6

Department of Physics, Nagoya University, Nagoya 464-8602, Japan^7

Center of Experimental Studies, Nagoya University, Nagoya 464-8602, Japan^8

Department of Nuclear Engineering, Kyoto University, Kyoto 615-8530, Japan

(10) Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047, Japan

(11) Research Center for Advanced Particle Physics, Kyushu University, Fukuoka 812- 8581, Japan^9

关键词: Fundamental physics;    Important features;    Neutron velocity;    Production rates;    Pulsed neutron;    Pulsed neutron beams;    Pulsed neutron sources;    Ultra-cold neutrons;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/528/1/012030/pdf
DOI  :  10.1088/1742-6596/528/1/012030

来源: IOP

【 摘 要 】

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.