Lu Hong

Performance of the muon detector A under TIBET III array

In order to observe gamma rays in the 100 TeV energy region, the 4500 m(2) underground muon detector array using water Cherenkov technique is constructed, forming the TIBET III+MD hybrid array. Because the showers induced by primary gamma rays contain much fewer muons than those induced by primary hadrons, significant improvement of the gamma ray sensitivity for TIBET III+MD array is expected. In this paper, the design and performance of the MD-A detector with large Tyvek bag is reported.

Updated study on multi-TeV cosmic-ray modulation with the Tibet III air shower array using the east-west method

We study the sidereal and solar time modulation of multi-TeV cosmic rays using the east-west method with Tibet III air shower array data taken from November 1999 to December 2008. The statistics are twice the amount used in our previous paper. In this analysis, the amplitude of the observed sidereal time modulation is about 0.1%, and the modulation shows an excess from about 4 to 7 hours and a deficit around 12 hours in local sidereal time. The sidereal time modulation has a weak dependence on the primary energy of the cosmic rays. However, the solar time modulation shows a large energy dependence. We find that the solar time modulation is fairly consistent with the prediction of the Compton-Getting effect for high-energy samples (6.2 TeV and 12.0 TeV), but exceeds the prediction for the low-energy sample (4.0 TeV). Such a discrepancy may be due to the solar modulation or the characteristics of the experimental device in the near threshold energy.

Comparative studies of silicon photomultipliers and traditional vacuum photomultiplier tubes

Silicon photomultipliers (SiPMs) are a new generation of semiconductor-based photon counting devices with the merits of low weight, low power consumption and low voltage operation, promising to meet the needs of space particle physics experiments. In this paper, comparative studies of SiPMs and traditional vacuum photomultiplier tubes (PMTs) have been performed regarding the basic properties of dark currents, dark counts and excess noise factors. The intrinsic optical crosstalk effect of SiPMs was evaluated.

Design and simulations for the detector based on DSSSD

The present paper describes the design and simulation results of a position-sensitive charged particle detector based on the Double Sided Silicon Strip Detector (DSSSD). Also, the characteristics of the DSSSD and its testing result were are discussed. With the application of the DSSSD, the position-sensitive charged particle detector can not only give particle flux and energy spectra information and identify different types of charged particles, but also measure the location and angle of incident particles. As the detector can make multiparameter measurements of charged particles, it is widely used in space detection and exploration missions, such as charged particle detection related to earthquakes, space environment monitoring and solar activity inspection.

Design and performance study of the LEPD silicon tracker onboard the CSES satellite

The low energy particle detector (LEPD) is one of the main payloads onboard the China seismic electromagnetic satellite (CSES). The detector is designed to ascertain space electrons (0.1–10 MeV) and protons (2–50 MeV). It has the capability of identifying the electrons and protons, to measure the energy spectrum and the incident angle of the particles. The LEPD is made up of a silicon tracker system, a CsI (Tl) mini-calorimeter, an anti-coincidence system made by plastic scintillator, as well as electronics and a data acquisition system (DAQ). The tracker is also a kind of ΔE-E telescope; it consists of two layers of double-sided silicon strip detectors (DSSD). The signals emerging from the silicon tracker can be read out by two pieces of application specific integrated circuit (ASIC), which also can generate an event trigger for the LEPD. The functions of the DSSD system in the LEPD for charged particles were tested by 241Am @5.486 MeV α particles. The results show that the DSSD system works well, and has high performance to detect charged particles and measure the position of incident particles.

Design of electronics of LEPD principle prototype onboard the CEMES satellite

The Low Energy Particle Detector (LEPD) is one of the main payloads onboard China Electromagnetic Monitoring Experimental Satellite (CEMES). The detector is designed to identify the electrons and protons, to measure the energy spectrum and the incident angle of the particles. LEPD is made up of a silicon tracker, a CsI (TI) mini-calorimeter, an anticoincidence system made by plastic scintillator, as well as electronics and data acquisition system (DAQ). The front-end electronics are designed individually to process their output signals, such as two Double-sided Silicon Strip Detectors (DSSD), CsI (TI) mini-calorimeter and plastic scintillator. The DAQ is a very important part of the electronics, which used to select effective case and keep the scientific data in an appropriate size. In addition, limited current circuit and self-check circuit are also designed to deal with the Single Event Effects (SEE), especially the Single Event Lock (SEL).

An updated search of steady TeV γ-ray point sources in northern hemisphere using the Tibet air shower array*

Using the data taken from Tibet II High Density (HD) Array (1997 February1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV γ−ray point sources has now been updated by a factor of 2.8 improved statistics. From 0.0 to 60.0 in declination (Dec) range, no new TeV γ−ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV γ−ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits. Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China. Department of Physics, Hebei Normal University, Shijiazhuang 050016, China. Department of Mathematics and Physics, Tibet University, Lhasa 850000, China. Department of Physics, Shandong University, Jinan 250100, China. Institute of Modern Physics, Southwest Jiaotong University, Chengdu 610031, China. Department of Physics, Yunnan University, Kunming 650091, China. National Center for Space Weather, China Meteorological Administration, Beijing 100081, China. Physics Department and Tsinghua Center for Astrophysics, Tsinghua University, Beijing 100084, China. Center of Space Science and Application Research, Chinese Academy of Sciences, Beijing 100080, China.Using the data taken from Tibet II High Density (HD) Array (1997 February–1999 September) and Tibet-III array (1999 November–2005 November), our previous northern sky survey for TeV γ-ray point sources has now been updated by a factor of 2.8 improved statistics. From 0.0° to 60.0° in declination (Dec) range, no new TeV γ-ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV γ-ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits.

Search for the Multi-TeV Gamma Rays from the Shell-Like SNR G40.5–0.5 Using the Tibet Air Shower Array

Using observation data of the Tibet air shower array in different periods, a region with the highest excess of 4.4 σ in the multi-TeV was detected from the SNR G40.5-0.5 direction, although statistically insignificant yet. The position of the highest excess is located around the EGRET unidentified source 3EG J1903+0550.