Filtered neutron technique was applied for producing quasi-monoenergetic neutron beams of 24 keV, 54 keV, 133 keV and 148 keV at the horizontal neutron channel No. 4 of the Dalat Nuclear Research Reactor. The study on...Filtered neutron technique was applied for producing quasi-monoenergetic neutron beams of 24 keV, 54 keV, 133 keV and 148 keV at the horizontal neutron channel No. 4 of the Dalat Nuclear Research Reactor. The study on physical characteristics of these beam lines has been carried out for efficient applications in neutron capture experiments. The filtered neutron spectrum of each beam has been simulated by Monte-Carlo method and experimentally measured by a gas-filled protonrecoil spectrometer. The neutron fluxes of these filtered beams were measured by the activation technique with standard foils of 197Au, using a high efficient HPGe digital gamma-ray spectrometer.展开更多
External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Alumi...External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Aluminum, Nickel and Vanadium are used to obtain the mono-energetic neutron beams of 24 and 59 keV, with low level of Gamma and slow neutron background. A computer code and Monte-Carlo simulation technique were applied to optimize the filter configurations and to deduce the neutron energy distributions in the filtered beams. A hydrogen-filled proton recoil detector and the activation method with Gold foils were used to measure the neutron energy spectrum and flux of each beam at sample position. The results of experimental neutron fluxes are 6.1 × 105 and 5.3 × 105 n/cm2/s for 24 and 59 keV beams, respectively.展开更多
In this paper,we present the performance of a recently developed in-situ spin-exchange optically pumped^(3)He-neutron spin filter system at the China Spallation Neutron Source(CSNS).The system achieved a^(3)He polariz...In this paper,we present the performance of a recently developed in-situ spin-exchange optically pumped^(3)He-neutron spin filter system at the China Spallation Neutron Source(CSNS).The system achieved a^(3)He polarization of over 74%at the beamline BL-20.Analysis of neutron transmission experiment results reveals a neutron polarization of>90%and an average transmission of 27%for 2.2Åneutrons,which were maintained for a duration of 120 h of beam time.To the best of our knowledge,this is the first in-situ hyperpolarized^(3)He system incorporated on a neutron beamline in China.This technology is expected to provide stable,wide-angle,and highly polarized neutrons at the CSNS for materials research and fundamental neutron physics.展开更多
文摘Filtered neutron technique was applied for producing quasi-monoenergetic neutron beams of 24 keV, 54 keV, 133 keV and 148 keV at the horizontal neutron channel No. 4 of the Dalat Nuclear Research Reactor. The study on physical characteristics of these beam lines has been carried out for efficient applications in neutron capture experiments. The filtered neutron spectrum of each beam has been simulated by Monte-Carlo method and experimentally measured by a gas-filled protonrecoil spectrometer. The neutron fluxes of these filtered beams were measured by the activation technique with standard foils of 197Au, using a high efficient HPGe digital gamma-ray spectrometer.
文摘External filtered neutron beams have been developed at the horizontal radial channels No. 4 of Dalat research reactor. In the material composition of the neutron filters, the primary material components of Iron, Aluminum, Nickel and Vanadium are used to obtain the mono-energetic neutron beams of 24 and 59 keV, with low level of Gamma and slow neutron background. A computer code and Monte-Carlo simulation technique were applied to optimize the filter configurations and to deduce the neutron energy distributions in the filtered beams. A hydrogen-filled proton recoil detector and the activation method with Gold foils were used to measure the neutron energy spectrum and flux of each beam at sample position. The results of experimental neutron fluxes are 6.1 × 105 and 5.3 × 105 n/cm2/s for 24 and 59 keV beams, respectively.
基金supported by the National Key Research and Development Program of China(Grant No.2020YFA0406000)National Natural Science Foundation of China(Grant No.11875265)+2 种基金Scientific Instrument Developing Project of the Chinese Academy of Sciences(Grant No.ZDKYYQ20190004)Guangdong Basic and Applied Basic Research Foundation(Grant No.2019B1515120079)Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents(Grant No.20191122)。
文摘In this paper,we present the performance of a recently developed in-situ spin-exchange optically pumped^(3)He-neutron spin filter system at the China Spallation Neutron Source(CSNS).The system achieved a^(3)He polarization of over 74%at the beamline BL-20.Analysis of neutron transmission experiment results reveals a neutron polarization of>90%and an average transmission of 27%for 2.2Åneutrons,which were maintained for a duration of 120 h of beam time.To the best of our knowledge,this is the first in-situ hyperpolarized^(3)He system incorporated on a neutron beamline in China.This technology is expected to provide stable,wide-angle,and highly polarized neutrons at the CSNS for materials research and fundamental neutron physics.
