A novel 1D-ACAR measurement method based on continuous crystal array detector

Abstract

BackgroundAngular correlation of annihilation radiation (ACAR) is a high-precision (sub-milliradian level) method for studying Fermi momentum and Fermi energy in metals. However, there are some disadvantages in traditional 1D-ACAR experimental device, such as complex device structure and long spectrum formation.PurposeThis study aims to propose a new 1D-ACAR measuring method with improved efficiency based on continuous LYSO crystal array detectors without angle scanning.MethodsContinuous LYSO crystal array and silicon photomultiplier (SiPM) array were used to form detector array, and the truncated center-of-gravity (TCOG) method was adopted as basic location algorithm. Based on the dependence of angular resolution of the array detector completely on its spatial resolution, Geant4 was employed to simulate the continuous crystal array detector (CCAD) to optimize detector structure and location algorithm. Both the array cell width and crystal size were optimized to increase the most possible resolution.ResultsSimulation results show that the angular resolution of the detector can be improved by forming photoelectric conversion array with suitable width of SiPM and increasing the size of continuous crystal. When the width of SiPM array unit is 1 mm and the crystal size is 30 mm (length)×35 mm (width), the angular resolution of CCAD is 0.84 mrad, reaching the angle resolution level of the 1D-ACAR experimental device. Angle resolution of CCAD can be further improved by increasing the crystal size.ConclusionsThe 1D-ACAR experimental device based on the CCAD can greatly shorten the long-time of spectrum formation without decreasing the angle resolution.

Keywords

• acar
• continuous crystal
• location algorithm
• position resolution