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The DArk Matter Particle Explorer (DAMPE) is a general purposed satelliteborne high energy γ−ray and cosmic ray detector, and among the scientific objectives of DAMPE are the searches for the origin of cosmic rays and an understanding of Dark Matter particles. As one of the four detectors in DAMPE, the Plastic Scintillator Detector (PSD) plays an important role in the particle charge measurement and the photons/electrons separation. The PSD has 82 modules, each consists of a long organic plastic scintillator bar and two PMTs at both ends for readout, in two layers and covers an overall active area larger than 82 cm × 82 cm. It can identify the charge states for relativistic ions from H to Fe, and the detector efficiency for Z=1 particles can reach 0.9999. The PSD has been successfully launched with DAMPE on Dec. 17, 2015. In this paper, the design, the assembly, the qualification tests of the PSD and some of the performance measured on the ground have been described in detail.

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Shallow levels in arsenic-doped Hg1−xCdxTe grown by molecular beam epitaxy have been investigated by temperature- and excitation power-dependent modulated photoluminescence spectroscopy. The ionization energies of the shallow levels of AsTe, AsHg, and the AsHg–VHg complex are preliminarily determined to be about 11.0, 8.5, and 33.5meV, respectively. Correspondingly, the forming energy of the AsHg–VHg complex has been deduced to be approximately 10.5meV. The results could be used as guidelines for the material growth or the fabrication of related devices.

Environmentally friendly synthesis of carbon nanoprticles (C‐NPs) from folic acid (FA) is realized with the assistance of microplasma. TEM shows that the synthesized FA C‐NPs are amorphous and of diameter around 47 nm. The produced FA C‐NPs exhibit an excitation independent emission around 445 nm with the fluorescence quantum yield 13% at excitation wavelength of 370 nm. X‐ray photoelectron spectroscopy (XPS) shows the FA C‐NPs are composed of carbon (64.15%), nitrogen (6.04%), and oxygen (29.81%). Raman spectroscopy shows that the intensity ratio between the sp3 and sp2 hybridizations of Carbon is 0.35. UV‐Vis absorption, Fourier Transform Infrared Spectroscopy (FTIR), and Nuclear Magnetic Resonance (NMR) spectra provide a deep insight into the fluorescence of FA C‐NPs. With plasma processing of FA, carbon atoms are involved in sp2 hybridization and amine (NH2), NH and COOH groups are converted into ROOCNHCOOR group. As a consequence, the electron donating ability of aromatic ring is enhanced, which plays an important role in the fluorescence of FA C‐NPs. Finally, the promising application of FA C‐NPs in bioimaging is also demonstrated by fluorescence labeling of MCF‐7 cancer cells.

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Modulated photoluminescence spectra have been performed to investigate the impurity activation in MBE-grown As-doped Hg1−𝑥Cd𝑥Te (𝑥 ≈ 0.3). The results show that the doped As mainly acting as donors in the as-grown samples can be fully activated as AsTe by two-stage anneals of 285 ∘ C/16 h + 240 ∘ C/48 h, of which the ionization energy has been determined to be about 10.5 meV, slightly smaller than that of intrinsic VHg (about 14.5 meV). However, the higher activation temperature (e.g. 400 ∘ C) at the first-stage can produce large numbers of excessive VHg and seriously deteriorate the quality of epilayers. This could give a brief guideline for preparing extrinsic p-type HgCdTe materials or devices.