arXiv subjects

Ximeng Chen

Publications and source records attributed to Ximeng Chen.

4 recordsLinked to original sources

arXiv2017

Production and decay of K-shell hollow krypton in collisions with 52 - 197 MeV/u bare xenon ions

X-ray spectra of K-shell hollow krypton atoms produced in single collisions with 52 - 197 MeV/u Xe54+ ions are measured in a heavy-ion storage ring equipped with an internal gas-jet target. Energy shifts of the Kα_1,2^s, Kα_1,2^(h,s), and K\b{eta}_1,3^s transitions are obtained. Thus, the average number of the spectator L-vacancies presented during the x-ray emission is deduced. From the relative intensities of the Kα_1,2^s and Kα_1,2^(h,s) transitions, the ratio of K-shell hollow krypton to singly K-shell ionized atoms is determined to be 14 - 24%. In the considered collisions, the K-vacancies are mainly created by the direct ionization which cannot be calculated within the perturbation descriptions. The experimental results are compared with a relativistic coupled channel calculation performed within the independent particle approximation.

physics.atom-ph↗

arXiv2013

Charge Sharing Effect on 600 μm Pitch Pixelated CZT Detector for Imaging Applications

We are currently investigating the spatial resolution of highly pixelated Cadmium Zinc Telluride (CZT) detector for imaging applications. A 20 mm {\times} 20 mm {\times} 5 mm CZT substrate was fabricated with 600 μm pitch pixels (500 μm anode pixels with 100 μm gap) and coplanar cathode. Charge sharing between two pixels was studied using collimated 122 keV gamma ray source. Experiments show a resolution of 125 μm FWHM for double-pixel charge sharing events when the 600 μm pixelated and 5 mm thick CZT detector biased at -1000 V. In addition, we analyzed the energy response of the 600 μm pitch pixelated CZT detector.

physics.ins-det↗

arXiv2013

Unfolding the fast neutron spectra of a BC501A liquid scintillation detector using GRAVEL method

Accurate knowledge of the neutron energy spectra is useful in basic research and applications. The overall procedure of measuring and unfolding the fast neutron energy spectra with BC501A liquid scintillation detector is described. The recoil proton spectrum of Am-Be neutrons was obtained experimentally. With the NRESP7 code, the response matrix of detector was simulated. Combining the recoil proton spectrum and response matrix, the unfolding of neutron spectra was performed by GRAVEL iterative algorithm. A MatLab program based on the GRAVEL method was developed. The continuous neutron spectrum of Am-Be source and monoenergetic neutron spectrum of D-T source have been unfolded successfully and are in good agreement with their standard reference spectra. The unfolded Am-Be spectrum are more accurate than the spectra unfolded by artificial neural networks in recent years.

physics.ins-det↗

arXiv2013

Study of n-γ discrimination in low energy range (above 40 keVee) by charge comparison method with a BC501A liquid scintillation detector

A VME-based experiment system for n-γ discrimination using the charge comparison method was established. A data acquisition program for controlling the programmable modules and processing data online via VME64X bus was developed through the use of LabVIEW. The two-dimensional (2D) scatter plots of the charge in the slow component vs. the total charge of recorded pulses from Am-Be and Cf neutron sources were presented. The 2D scatter plots of the energy vs. the ratio of the charge in the slow component to the total charge of the pulses were presented at the meantime. The quality of n-γ discrimination was checked by the figure-of-merit, and the results showed good performance of n-γ discrimination at low energy range. Neutrons and γ-rays were separated above 50 keVee (electron-equivalent energy). The quality of n-γ discrimination have been improved compared with others' results at 5 energies (150, 250, 350, 450, 550 keVee).

physics.ins-det↗