甚大面积伽马射线空间望远镜计划

高能伽马射线探测是研究极端天体物理的主要途径之一.空间高能伽马射线探测具有覆盖波段宽、时间连续性好、能量分辨率高等突出优势.在成功研发并运行我国首颗天文卫星—"悟空"号(DArk Matter Particle Explorer,DAMPE)的基础上,紫金山天文台联合国内的多家单位提议研制甚大面积伽马射线空间望远镜(Very Large Areagamma-ray Space Telescope,VLAST),该望远镜在GeV-TeV能段接受度高达10 m^(2)·sr,并具有强的MeV-GeV波段探测能力,其综合性能预期比费米卫星的大面积伽马望远镜(Fermi-LAT(Large Area Telescope))提升10倍之上.重点介绍了VLAST的主要科学目标,探测器的初步配置及预期性能指标.

“火眼金睛”揭示宇宙奥秘—悟空号卫星取得七大科技成果

1引言天文观测表明,宇宙中广泛存在暗物质,约占宇宙总质能的1/4,是我们已知普通物质的5倍。然而自20世纪30年代以来,科学家仅能通过引力在宏观尺度观测暗物质,其物理性质至今仍不为人所知。另一个世纪谜题是高能宇宙射线的起源、加速机制,宇宙线所关联的极端加速和极端相互作用等问题使其在物理学中备受关注。这两大科学问题都被列为美国国家研究委员会(NRC)遴选出的21世纪11个宇宙物理学重大科学问题之中[1]。除此之外,高能伽马射线是探索极端宇宙的重要探针之一,有助于揭示宇宙中极端天体的性质,了解其中蕴藏的物理过程和规律。

Comparison of Proton Shower Developments in the BGO Calorimeter of the Dark Matter Particle Explorer between GEANT4 and FLUKA Simulations

The DArk Matter Particle Explorer(DAMPE)is a satellite-borne detector for high-energy cosmic rays and y-rays.To fully understand the detector performance and obtain reliable physical results,extensive simulations of the detector are necessary.The simulations are particularly important for the data analysis of cosmic ray nuclei,which relies closely on the hadronic and nuclear interactions of particles in the detector material.Widely adopted simulation softwares include the GEANT4 and FLUKA,both of which have been implemented for the DAMPE simulation tool.Here we describe the simulation tool of DAMPE and compare the results of proton shower properties in the calorimeter from the two simulation softwares.Such a comparison gives an estimate of the most significant uncertainties of our proton spectral analysis.

Off line software for the DAMPE experiment

A software system has been developed for the DArk Matter Particle Explorer（DAMPE） mission, a satellite-based experiment. The DAMPE software is mainly written in C＋＋ and steered using a Python script. This article presents an overview of the DAMPE offline software, including the major architecture design and specific implementation for simulation, calibration and reconstruction. The whole system has been successfully applied to DAMPE data analysis. Some results obtained using the system, from simulation and beam test experiments, are presented.

Energy correction for the BGO calorimeter of DAMPE using an electron beam

The DArk Matter Particle Explorer is an orbital indirect dark matter search experiment which measures the spectra of photons, electrons and positrons originating from deep space. The electromagnetic calorimeter （ECAL）, made of bisnmth germinate （BGO）, is one of tile key sub-detectors of DAMPE, and is designed for energy measurement with a large dynamic range from 5 GeV to 10 TeV. In this paper, methods for energy correction are discussed, in order to reconstruct the primary energy of the incident electrons. Different methods are chosen for the appropriate energy ranges. The correction results of Geant4 simulation and beam test data （at CERN） are presented.

Temperature effects on MIPs in the BGO calorimeters of DAMPE

In this paper, we present a study of temperature effects on BGO calorimeters using proton MIPs collected in the first year of operation of DAMPE. By directly comparing MIP calibration constants used by the DAMPE data production pipe line, we find an experimental relation between the temperature and signal amplitudes of each BGO bar： a general deviation of -1.162%/℃, and -0.47%/℃ to -1.60%/℃ statistically for each detector element. During 2016, DAMPE＇s temperature changed by ~8℃ due to solar elevation angle, and the corresponding energy scale bias is about 9%. By frequent MIP calibration operation, this kind of bias is eliminated to an acceptable value.