Search

With more accurate measurement method for gas samples, cross sections of the 14N(n,α0,1)11B reactions were measured at 24 energy points in the 4.5–11.5 MeV neutron energy region based on the 4.5 MV Van de Graaff accelerator at Peking University and the HI-13 tandem accelerator of China Institute of Atomic Energy (CIAE). The average neutron fluence (Φ) through the gas sample was obtained through the combination of a highly enriched 238U3O8 sample and the simulation based on SuperMC. The cross sections of the 14N(n,α0)11B reaction measured using the gas sample and the solid samples are in agreement with each other. R-matrix analysis was carried out for the n + 14N system using code RAC in the neutron energy region below 30 MeV. A possible valley structure in both the excitation functions of the 14N(n,α0,1)11B reactions in the 10–11 MeV neutron energy region was found for the first time. [ABSTRACT FROM AUTHOR]

Due to the excellent radiation hardness and high–temperature endurance, diamond detectors are suitable for intense neutron measurements and promising for neutron diagnostics of scientific fusion devices. In the present work, simultaneous measurement of energy spectrum and fluence of neutrons using a diamond detector was realized for the first time. The absolute response matrix of the diamond detector was simulated based on detailed analysis of the nuclear reactions and the proper selection of nuclear reaction data. Neutron energy spectra as well as neutron fluences for 5.0, 5.5, 8.5, 9.5 and 10.5 MeV neutrons from d–d reaction were measured using the diamond detector based on the absolute response matrix. The measured neutron energy spectra and neutron fluences are reasonable compared with those detected using a EJ-309 liquid scintillator and a 238U fission chamber, respectively, which verifies the reliability of the present work. Furthermore, the energy spectrum and fluence of a 14.2 MeV d–t neutron source were also measured using the diamond detector. The present work demonstrates the ability of simultaneous measurement of energy spectrum and fluence as well as for both d–d and d–t neutrons using a diamond detector, which is of great significance for neutron diagnostics of scientific fusion devices. [ABSTRACT FROM AUTHOR]

• The neutron energy response of Cs 2 7LiYCl 6 :Ce (CLYC-7) scintillation detector was investigated, and the figures-of-merit (FOM), response function, and neutron energy resolution at different neutron energies were obtained. • The Monte Carlo method was used to simulate the particle transport within the CLYC-7 scintillator and investigate the energy response curves of different particles. • The response function was applied to the CLYC-7 scintillation detector, and it was used to measure the D-D fusion neutron spectrum on EAST. During plasma experiments on EAST (Experimental Advanced Superconducting Tokamak), the discharges heated with neutral beam injection (NBI) for plasma results in the production of 2.45 MeV deuterium-deuterium (D-D) fusion neutrons. In order to measure the energy spectrum of D-D fusion neutrons, a new Cs 2 7LiYCl6:Ce (CLYC-7) crystal with 7Li-enrichment has been developed and fabricated into a CLYC-7 scintillation detector. Before utilizing this detector for studying neutron energy spectra, it is crucial to explore the response function of the detector within a relevant neutron energy range. Therefore, the detector has been experimented using the 4.5 MeV electrostatic accelerator at Peking University to investigate its response to fast neutrons, energy resolution, and pulse discrimination capability in the neutron energy range 2.07 MeV–5.51 MeV. The neutron reactions occurring within the CLYC-7 scintillator were simulated using MCNPX, focusing on the reactions 35Cl(n,p) and 35Cl(n,α), as well as the energy response curve and the contributions of different particles (protons, alphas) to the neutron spectrum. The experimental results were successfully validated on EAST, where the 2.45 MeV fusion neutron energy spectrum was measured. That demonstrates the ability of the CLYC-7 scintillation detector to diagnose the fusion neutron energy spectrum for deuterium plasma discharge. [ABSTRACT FROM AUTHOR]

Cross sections of the 12C(n , n +3 α) reaction are of great significance in understanding the nuclear reaction mechanism and in the applications of nuclear technology. However, large differences (≈ 200%) exist in the 12C(n , n +3 α) cross section data of measurements and evaluations. Using a single crystal chemical vapor deposited (sCVD) diamond detector as an active target, cross sections of the 12C(n , n + 3 α) and 12C(n , α 0) 9 Be reactions were measured simultaneously in the neutron energy region of 9.50 – 14.67 MeV. The present cross sections of the 12C (n , α 0) 9 Be reaction are consistent with the results of the latest measurement, which confirms the reliability of this work. The measurement results of the 12C(n , n +3 α) reaction with uncertainties smaller than 15% contribute to effectively clarify the discrepancies of the measurements and evaluations. To our knowledge, this is the first time to measure the 12C(n , n +3 α) cross sections using the diamond detector as an active target. Our method can be used in the future measurements to constrain the 12C(n , n +3 α) excitation function in a much wider neutron energy region. R -matrix analysis was carried out for n+12C system using the RAC code in the neutron energy region below 30 MeV. Systematic and reliable calculation results are obtained for various reaction channels. • The measured 12C(n , α 0)9Be cross sections are consistent with the results of the latest measurement. • The uncertainties of the measured 12C(n , n +3 α) cross sections are smaller than 15%. • The present 12C(n , n +3 α) cross sections are helpful to effectively clarify the existing discrepancies (≈ 200%). • This is the first time to measure the 12C(n , n +3 α) cross sections using a diamond detector as an active target. • R -matrix analysis was carried out for n+12C system using the RAC code in the neutron energy region below 30 MeV. [ABSTRACT FROM AUTHOR]