Subjects: Physics >> Nuclear Physics submitted time 2024-05-17
Yan Zhang
Hao-Ran Zhang
Ren-Bo Wang
Ming-Yu Li
Rui Chen
Hai-Tao Wang
Xiang-Ting Meng
Shu-Min Zhou
Bin Tang
Abstract： A passive neutron multiplicity measurement device, FH-NCM/S1, based on field-programmable gate arrays (FPGAs), is developed specifically for measuring the mass of plutonium-240 (240Pu) in mixed oxide fuel. FHNCM/S1 adopts an integrated approach, combining the shift-register analysis mode with the pulse-position timestamp mode using an FPGA. The optimal effective length of the 3He neutron detector was determined to be 30 cm, and the thickness of the graphite reflector was ascertained to be 15 cm through MCNP simulations. After fabricating the device, calibration measurements were performed using a 252Cf neutron source; a detection efficiency of 43.07% and detector die-away time of 55.79 μs were observed. Nine samples of plutonium oxide were measured under identical conditions using the FH-NCM/S1 in shift-register analysis mode and a plutonium-waste multiplicity counter. The obtained double rates underwent corrections for detection efficiency(ε) and double gate fraction (f d), resulting in corrected double rates (Dc), which were used to validate the accuracy of the shift-register analysis mode. Furthermore, the device exhibited fluctuations in the measurement results, and within a single 20-s measurement, these fluctuations remained below 10%. After 30 cycles, the relative error in the mass of 240Pu was less than 5%. Finally, correlation calculations confirmed the robust consistency of both measurement modes. This study holds specific significance for the subsequent design and development of neutron multiplicity devices.
Subjects: Physics >> Geophysics, Astronomy, and Astrophysics Subjects: Astronomy >> Galaxy and Cosmology submitted time 2020-09-09
Abstract： Motivated by recent work on rotating black hole shadow [Phys. Rev. D101, 084029 (2020)], we investigate the shadow behaviors of rotating Hayward-de Sitter black hole for static observers at a finite distance in terms of astronomical observables. This paper uses the newly introduced distortion parameter in [arXiv:2006.00685] to describe the shadow's shape quantitatively. We show that the spin parameter would distort shadows and the magnetic monopole charge would increase the degree of deformation. At the same time, the distortion could be relieved because of the cosmological constant and the distortion would increase with the distance from the black hole. Besides, the spin parameter, magnetic monopole charge and cosmological constant increase will cause the shadow to shrink.
Peer Review Status:
Awaiting Review
Subjects: Physics >> The Physics of Elementary Particles and Fields submitted time 2020-09-06
Abstract： "
Peer Review Status:Awaiting Review
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