Preface

A variety of mesomorphic side-chain polysiloxanes were synthesized by using hydrosilylation reaction withdicyclopentadienylplatinum (Ⅱ) (DPPC) as the catalyst. The mesogenic groups are derivatives of stilbene with cyano or nitrotail groups. The products were characterized by DSC, X-ray deffraction and polarizing optical microscopy (POM). All thepolymers were found to have relatively low T_g and can form a smectic liquid crystal phase.

Feasibility study of cosmic-ray componentsmeasurement by using a scintillating fiber tracker in space

Purpose The application of traditional silicon strip detectors in space experiments often suffers from heat and power consumption limitations when a large area has to be instrumented.Recently,a scintillating fiber detector with SiPM readout was proposed and adopted by ground high-energy experiments.Its excellent performance in track measurement and mechanical flexibility makes it a prospective candidate for large-area tracking detectors in the next-generation space experiments.This paper mainly focuses on its performance in cosmic-ray charge measurement.Methods A fast Geant4 simulation for a single tracker module was developed and compared with the beam test results.The non-uniformity of the detector response was studied.Moreover,a full tracker simulation using a variety of typical cosmic ray nuclei was implemented.The performance of a fiber tracker with multiple layers was evaluated.Results and conclusion The comparison between the simulation results and the beam test data of protons and helium nuclei shows a good agreement.The non-uniformity study reveals the strong dependence of the detector signal on the position and inclination angle of the incident particles.Then,a corresponding correction algorithm was developed and applied in the following data analysis.The preliminary result shows that the charge measurement capability of the fiber tracker composed of 9 XY superlayers is comparable to that of the AMS-02 inner tracker,which consists of 7 layers of double-sided silicon micro-strip ladders.This paper discusses the feasibility of using fiber trackers to measure cosmic ray charges and provide a guide for the optimization of detector design.

A preliminary simulation study of influence of backsplash on the plastic scintillator detector design in HERD experiment

Background The plastic scintillator detector(PSD)is one of the detectors in the high energy cosmic radiation detection(HERD)facility,which is designed for gamma-ray detection and a redundant charge measurement.Backsplash will lead to a decrease in PSD’s performance of gamma-ray detection and charge measurement,which should be carefully considered.Purpose Two preliminary segmentation schemes of the PSD and two veto strategies have been proposed to suppress the backsplash effect.In this paper,we focus on the influence of the backsplash caused by gamma rays.The gamma-ray trigger efficiency and identification efficiency were studied in the case of different cell sizes and veto strategies,which can provide guidance on the PSD design.Methods A Monte Carlo simulation based on Geant4 has been performed.To simplify the simulation,the PSD is segmented into 1 cm3 cubes which can be easily aggregated into cells with different sizes during analysis.Results and conclusion Side_Veto can be used as a baseline design of veto strategy,whereas Smart_Veto can be selected as an upgraded design.Both the PSD bar cell with a width of less than 11 cm and the PSD tile cell with a width of less than 20 cm can achieve a sufficiently high gamma-ray trigger efficiency(>80%),which realizes the primary goal of the PSD.Meanwhile,both the PSD bar cell with a width of less than 3 cm and the PSD tile cell with a width of less than 20 cm can ensure a sufficiently high gamma-ray identification efficiency(>80%)for photons up to 800 GeV.