The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 k...The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.展开更多
Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation...Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation effect research.Method A series of detectors were built for different experiments,including beam monitoring,beam profile measurement,neutron induced secondaries(fission fragments,light charged particles and gamma)cross section measurement,and neutron resonance radiography,etc.A common digitization electronics and a cluster-based DAQ were developed for these detector systems.Most detectors have been employed at Back-n and serviced for experiments from the beginning of the beamline running.Results and conclusion As an overview of detectors of Back-n,the details of the detector design and the experiment performing are described in this paper.Some developing systems,e.g.,MTPC and B-MCP,are also included.展开更多
文摘The 13C(, n)16O reaction is the key neutron source reaction for the main s-process nucleosynthesis[1]. Theimportant energy range (Gamow window) for the 13C( , n)16O reaction during the s-process spans from 140 to230 keV in the center of mass frame. Because of the Coulomb barrier, the cross sections drop exponentially asmeasurement approaches the Gamow window energies. Limited by cosmic ray background and the available beamintensity, the ground-based measurements are limited to energies above 280 keV. Therefore, the extrapolationbased on R-matrix calculation and/or in-direct measurement is the current method to estimate the cross sectionsfor astrophysical interest with limited precision. Moreover, due to the existence of sub-threshold resonances, thereare rather large uncertainties associated with the extrapolated cross sections which limit the precision of the currentreaction rate and thus prevent us from a complete understanding of the nucleosynthesis of heavy elements.
基金support provided by the National KeyR&DProgram of China(Grant No.2016YFA0401600).
文摘Purpose Back-n is a white neutron beamline at China spallation neutron source,which was established in the year of 2018.It is a powerful facility for nuclear data measurement,neutron detector calibration,and radiation effect research.Method A series of detectors were built for different experiments,including beam monitoring,beam profile measurement,neutron induced secondaries(fission fragments,light charged particles and gamma)cross section measurement,and neutron resonance radiography,etc.A common digitization electronics and a cluster-based DAQ were developed for these detector systems.Most detectors have been employed at Back-n and serviced for experiments from the beginning of the beamline running.Results and conclusion As an overview of detectors of Back-n,the details of the detector design and the experiment performing are described in this paper.Some developing systems,e.g.,MTPC and B-MCP,are also included.
