The enhanced X-ray Timing and Polarimetry mission—eXTP

In this paper we present the enhanced X-ray Timing and Polarimetry mission—eXTP. eXTP is a space science mission designed to study fundamental physics under extreme conditions of density, gravity and magnetism. The mission aims at determining the equation of state of matter at supra-nuclear density, measuring effects of QED, and understanding the dynamics of matter in strong-field gravity. In addition to investigating fundamental physics, eXTP will be a very powerful observatory for astrophysics that will provide observations of unprecedented quality on a variety of galactic and extragalactic objects. In particular, its wide field monitoring capabilities will be highly instrumental to detect the electro-magnetic counterparts of gravitational wave sources.The paper provides a detailed description of:(1) the technological and technical aspects, and the expected performance of the instruments of the scientific payload;(2) the elements and functions of the mission, from the spacecraft to the ground segment.

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.