Implementation of Neutron Reflection with Nano-Dispersed Media in Geant4
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mplementation of Neutron Reflection with Nano-Dispersed Media in Geant4 Mostafa Jamalipoura, *, Luca Zaninib, and Giuseppe Gorinia aDepartment
of Physics, University of Milano-Bicocca, Milano, 20126 Italy Spallation Source ERIC, Lund, 221 00 Sweden *e-mail: [email protected]
bEuropean
Received June 27, 2019; revised July 29, 2019; accepted August 10, 2019
Abstract—A study has been carried out in order to see the feasibility of using nanodiamond particles as a reflector for cold and very cold neutrons in Geant4. Nanodiamond particles have a large scattering angle probability against very cold neutrons compared to the other materials due their high optical potential. This unique feature makes this powder a prominent candidate to be used as a reflector for very cold neutrons. Moreover, they can also be implemented for quasi-specular reflection of cold neutrons at small incidence angles due to multiple small-angle scattering of neutrons from nano-sized inhomogeneities in the scattering potential. A new process in Geant4 has been prepared in order to add cross sections of nanodiamond particles to the predefined processes. The geometry of previous experiments carried out in order to observe the reflection of nanodiamond particles has been developed in Geant4 in order to validate the implementation. The results show that there is a good agreement between the new method implemented in Geant4 and experimental data. Keywords: neutron reflection, small-angle scattering, low-energy neutrons, Geant4 DOI: 10.1134/S1027451020070174
INTRODUCTION The scattering of low-energy neutrons is of interest for fundamental physics [1]. It has already been shown that for low-energy neutrons, namely cold, very cold and ultra cold neutrons, nanodiamond particles can be a remarkable reflector [2–4]. Very cold neutrons can be trapped in nanodiamond particles due to the large scattering probability, while cold neutrons can be reflected at small incident angles due to multiple-scattering. Cold neutrons have the energy in a range 0.1–5 meV, while very cold neutrons have the energies of 0.5 μeV–0.1 meV. Neutrons with smaller energies are called ultra cold, which can be scattered at any incident angle. Cold neutrons are reflected from flat surfaces if the incident angle of the neutron is small enough so that the perpendicular component of neutron velocity is less than the critical velocity. Cold neutrons have a broad range of application in sciences [5, 6]. It has already been shown that the critical velocity of nanodiamond particles is the highest available velocity among materials. Therefore, they have the highest scattering efficiency for very cold and cold neutrons [3, 7].
along with other predefined processes in order to insert new parameters related to nanodiamond particle characteristics. The size distribution for nanodiamond particles, composition, and cross sections have been modeled in order to update the neutron position when entering the nano-dispersed media. Shell impurities have also been defined in order to take into ac
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