A novel X-ray tube spectra reconstruction method based on transmission measurements

A novel X-ray tube spectrum reconstruction method has been proposed based on transmission measurements. Aluminum bars of varying lengths attenuate the X-rays to different levels. The detectors are of lutetium yttrium oxyorthosilicate scintillator and silicon photomultiplier. With the detected X-ray intensities, the X-ray spectrum is unfolded using the least square method. The detectors, aluminum bars, and collimating apertures are integrated in a detection module made of lead. Its response to X-ray is calculated by Monte Carlo codes Geant4. Due to the high photon flux, the detectors work in current mode.The electronics system, consisting of 24-bit high-precision ADCs with 144 KSPS sampling rate and field programmable gate array, makes the data acquisition process effective and precise. Measurements on a 70-k Vp tungsten anode X-ray were taken to verify the method. The unfolded spectrum agrees well with the simulated spectrum,demonstrating that the method is reliable and practical.

Correction and verification of HL-2A Tokamak Bonner sphere spectrometer in monoenergetic neutron fields from 100 keV to 5 MeV

A real-time Bonner sphere spectrometer(BSS)has been developed for spectral neutron measurements with the HL-2A Tokamak.To correct and verify the accuracy of the neutron spectrum from the BSS,the BSS system was calibrated using monoenergetic neutron beams in the energy range of 100 keV–5 MeV.The response function of the BSS was corrected based on the calibration results,and the corrected BSS system was verified by unfolding monoenergetic neutron spectra.Fusion neutron spectra on the HL-2A have been obtained from the calibrated BSS system for the first time.

Verification of a fusion neutron diagnostic Bonner sphere spectrometer on measurement of a ^(241)Am–Be neutron source

A Bonner sphere spectrometer(BSS) was developed for neutron diagnostic on HL_2A Tokamak.It contains eight polyethylene spheres embedded with SP9~3 He proportional counter.Before setting up on the Tokamak experimental hall,a verification experiment was arranged on a^(241)Am–Be neutron source to test its spectrometry capability.The neutron response functions were calculated by Monte Carlo code Geant4 to simulate the real measurement environments.By least square method,the neutron spectrum was finally unfolded on log domain from0.1 e V to 11 Me V.It has a remarkable consistency to the ISO 8529-1 standard^(241)Am–Be neutron spectrum.This shows that the BSS is effective and reliable for neutron spectrum determination.

Geant4 simulation of multi-sphere spectrometer response function and the detection of 241Am–Be neutron spectrum

This paper is aimed at detecting the neutron spectrum of^(241)Am–Be, a widely used neutron source, with the SP9 ~3He proportional counter, which is a multi-sphere spectrometer system of eight thermal neutron detectors embedded in eight polyethylene(PE) spheres of varying diameters. The transport processes of a neutron in the multi-sphere spectrometer are simulated using the Geant4 code. Two sets of response functions of the PE spheres are obtained for calculating the^(241)Am–Be neutron spectrum.Response Function 1 utilizes the thermal neutron scattering model G4 Neutron HPThermal Scattering for neutron energies of ≤4 eV, and Response Function 2 has no thermal treatment. Neutron spectra of an^(241)Am–Be neutron source are measured and compared to those calculated by using the response functions. The results show that response function with thermal treatment is more accurate and closer to the real spectrum.