Xin Wu

Design of the readout electronics for the DAMPE Silicon Tracker detector

The Silicon Tracker (STK) is a detector of the DAMPE satellite to measure the incidence direction of high energy cosmic ray. It consists of 6 X-Y double layers of silicon micro-strip detectors with 73,728 readout channels. Its a great challenge to readout the channels and process the huge volume of data in the critical space environment. 1152 Application Specific Integrated Circuits (ASIC) and 384 ADCs are adopted to readout the detector channels. The 192 Tracker Front-end Hybrid (TFH) modules and 8 identical Tracker Readout Board (TRB) modules are designed to control and digitalize the front signals. In this paper, the design of the readout electronics for STK and its performance will be presented in detail.

The test results of the Silicon Tungsten Tracker of DAMPE

V. Gallo∗1, G. Ambrosi2, R. Asfandiyarov1, P. Azzarello1, P. Bernardini3,4, B. Bertucci2,5, A. Bolognini2,5, F. Cadoux1, M. Caprai2, I. De Mitri3,4, M. Domenjoz1, Y. Dong6, M. Duranti2,5, R. Fan6, P. Fusco7,8, F. Gargano7, K. Gong6, D. Guo6, C. Husi1, M. Ionica2,5, D. La Marra1, F. Loparco7,8, G. Marsella3,4, M.N. Mazziotta7,, A. Nardinocchi2,5, L. Nicola1, G. Pelleriti1, W. Peng6, M. Pohl1, V. Postolache2, R. Qiao6, A. Surdo4, A. Tykhonov1, S. Vitillo1, H. Wang6, M. Weber1, D. Wu6, X. Wu1, F. Zhang6

Internal alignment and position resolution of the silicon tracker of DAMPE determined with orbit data

Abstract The DArk Matter Particle Explorer (DAMPE) is a space-borne particle detector designed to probe electrons and gamma-rays in the few GeV to 10 TeV energy range, as well as cosmic-ray proton and nuclei components between 10 GeV and 100 TeV. The silicon–tungsten tracker–converter is a crucial component of DAMPE. It allows the direction of incoming photons converting into electron–positron pairs to be estimated, and the trajectory and charge (Z) of cosmic-ray particles to be identified. It consists of 768 silicon micro-strip sensors assembled in 6 double layers with a total active area of 6.6 m 2 . Silicon planes are interleaved with three layers of tungsten plates, resulting in about one radiation length of material in the tracker. Internal alignment parameters of the tracker have been determined on orbit, with non-showering protons and helium nuclei. We describe the alignment procedure and present the position resolution and alignment stability measurements.

Offline software for the DAMPE experiment

A software framework has been developed for the DArk Matter Particle Explorer (DAMPE) mission, a satellite based experiment. The software framework of DAMPE is mainly written in C++, while the application under this framework is steered in Python script. The framework is comprised of four principal parts: event data module which contains all reconstruction and simulation information based on ROOT input/output (I/O) streaming; a collection of processing models which are used to process each event data, called as algorithms; service module, a series of common tools which provide general functionalities like data communication between algorithms; and event filters. This article presents an overview of the DAMPE offline software framework, and the major architecture design choices during the development. The whole system has been applied to DAMPE data analysis successfully, based on which some results from simulation and beam test experiments are also shown in this article.

Experimental verification of the HERD prototype at CERN SPS

The High Energy cosmic-Radiation Detection (HERD) facility is one of several space astronomy payloads of the cosmic light house program onboard Chinas Space Station, which is planned for operation starting around 2020 for about 10 years. Beam test with a HERD prototype, to verify the HERD specifications and the reading out method of wavelength shifting fiber and image intensified CCD, was taken at CERN SPS in November, 2015. The prototype is composed of an array of 5*5*10 LYSO crystals, which is 1/40th of the scale of HERD calorimeter. Experimental results on the performances of the calorimeter are discussed.

In-orbit Performance of the Silicon-Tungsten Tracker of the DAMPE Mission

The DArk Matter Particle Explorer (DAMPE) is a high energy astroparticle satellite mission designed to detect electron, photon and cosmic rays with high precision for Dark Matter search, cosmic ray flux and composition measurement and gamma-ray astronomy. One of the key components of the DAMPE payload is the Silicon-Tungsten Tracker (STK), consisting of 6 tracking planes, each plane is made of 2 orthogonal layers of single-sided silicon micro-strip detectors. Three layers of 1 mm thick tungsten plates are interleaved with the tracking planes to serve as photon converter. Besides precise track reconstruction for charge particles and converted photons, the STK will also measure the charge of the incoming cosmic ray, and provide pre-shower information to improve particle identification. nAfter intensive design, prototyping, test and production efforts by the STK collaboration, the construction of the STK has been completed in April 2015 and successfully integrated into the DAMPE payload in June 2015, after passing the environmental acceptance test. The DAMPE satellite was launched on December 17th 2015. nAfter the launch the STK has been commissioned rapidly in orbit and has ben functioning extremely well since, which allows it to play a key role in the first physics results coming out of the DAMPE collaboration.xa0 In this contribution, a brief overview on the development, qualification and beam tests of the STK Engineering and Qualification Model and the Flight Model will be provided. Then the STK in-orbit calibration and performance will be presented in details, including the noise behavior, the thermal and mechanical stability, the alignment procedure, the position resolution, and the tracking efficiency.

In-flight performance of the DAMPE silicon tracker

Abstract DAMPE (DArk Matter Particle Explorer) is a spaceborne high-energy cosmic ray and gamma-ray detector, successfully launched in December 2015. It is designed to probe astroparticle physics in the broad energy range from few GeV to 100 TeV. The scientific goals of DAMPE include the identification of possible signatures of Dark Matter annihilation or decay, the study of the origin and propagation mechanisms of cosmic-ray particles, and gamma-ray astronomy. DAMPE consists of four sub-detectors: a plastic scintillator strip detector, a Silicon–Tungsten tracKer–converter (STK), a BGO calorimeter and a neutron detector. The STK is composed of six double layers of single-sided silicon micro-strip detectors interleaved with three layers of tungsten for photon conversions into electron–positron pairs. The STK is a crucial component of DAMPE, allowing to determine the direction of incoming photons, to reconstruct tracks of cosmic rays and to estimate their absolute charge (Z). We present the in-flight performance of the STK based on two years of in-flight DAMPE data, which includes the noise behavior, signal response, thermal and mechanical stability, alignment and position resolution.

A novel 3-D calorimeter for the high energy cosmic-radiation detection (HERD) facility onboard China's future space station

The High Energy cosmic-Radiation Detection (HERD) facility is a flagship and landmark scientific experiment onboard Chinas Space Station, planned for operation starting around 2025 for about 10 years. The main instrument of HERD is a 3-D calorimeter (CALO) sensitive to incident gamma-rays and particles from five sides. With this design, the effective geometric factor of HERD is more than one order of magnitude larger than that of previous missions. CALO is made of about 7,500 cubes of LYSO crystals, corresponding to about 55 radiation lengths and 3 nuclear interaction lengths, respectively. The crystal signals are transferred by wavelength shifting fibers and read out by ISCMOS devices. Energy deposition in each crystal is then derived by summing up about 400 CMOS pixels and with necessary correction for light saturation. Both a low range ISCMOS and a high range one are required to meet the requirement of a large dynamic range of at least 10 million. The prototype of CALO has been tested successfully in November 2015 at CERN, which leads to an improved design of CALO.

First observations of Pulsars with the DArk Matter Particle Explorer

The DArk Matter Particle Explorer (DAMPE) is a satellite-borne particle detector used to study High Energy Cosmic Rays and High Energy Gamma-Rays. It was successfully launched on the 17th of December 2015 from the Jiuquan Launching Center into a sun-synchronous orbit at an altitude of 500 km. The instrument consists of a BGO Electromagnetic Calorimeter for electron/proton separation; a silicon tracker inter-spaced with tungsten for pair conversion of Gamma-Rays; a plastic scintillator detector which is used both as an anti-coincidence detector and for charge measurements and a neutron detector. During the first year of the mission, DAMPE has scanned the full sky at least once, thereby revealing several bright gamma-ray sources. We present an initial analysis on the brightest pulsars observed in an energy range from 1 GeV to 100 GeV together with an outlook on future developments. Comparisons with measurements performed by other instruments will be presented.

Reconstruction software of the silicon tracker of DAMPE mission

DAMPE is a satellite-borne experiment aimed to probe astroparticle physics in the GeV-TeV energy range. The Silicon tracker (STK) is one of the key components of DAMPE, which allows the reconstruction of trajectories (tracks) of detected particles. The non-negligible amount of material in the tracker poses a challenge to its reconstruction and alignment. In this paper we describe methods to address this challenge. We present the track reconstruction algorithm and give insight into the alignment algorithm. We also present our CAD-to-GDML converter, an in-house tool for implementing detector geometry in the software from the CAD drawings of the detector.