Calibration of the DAMPE Plastic Scintillator Detector and its on-orbit performance

The DArk Matter Particle Explorer(DAMPE) is a space-borne apparatus for detecting the highenergy cosmic-ray-like electrons, γ-rays, protons and heavy ions. The Plastic Scintillator Detector(PSD)is the top-most sub-detector of the DAMPE. The PSD is designed to measure the charge of incident highenergy particles and it also serves as a veto detector for discriminating γ-rays from charged particles. In this paper, a PSD on-orbit calibration procedure is described, which includes the five steps of pedestal, dynode correlation, response to minimum-ionizing particles, light attenuation function and energy reconstruction.A method for reconstructing the charge of incident high energy cosmic-ray particles is introduced. The detection efficiency of each PSD strip is verified to be above 99.5%; the total efficiency of the PSD for charged particles is above 99.99%.

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.

Characterisation of Photocathodes Based on Pb Thin Film Deposited by UV Pulsed Laser Ablation

This work deals with the deposition of lead （Pb） thin films by the UV pulsed laser ablation technique, for their further use as photocathode devices in superconducting radio frequency guns. Scanning electron microscopy and atomic force microscopy analyses were performed to study the morphological features of Pb thin films deposited on Si （100） and Nb substrates. The films showed a granular structure with a nearly fully covered surface only for that one deposited on Nb substrate. X-ray diffraction measurements indicate the growth of polycrystalline Pb thin films with a preferential orientation along （111） planes. Results of the photoemission performance of Pb thin film deposited on Nb substrate showed a very encouraging average value of quantum efficiency of 6 x 10-5 through a single-photon absorption process, promoting further studies in the realisation of Pb photocathodes by this technique.

Quantum hydrodynamics of a single particle

Semiconductor devices are strong competitors in the race for the development of quantum computational systems.In this work,we interface two semiconductor building blocks of different dimensionalities with complementary properties:(1)a quantum dot hosting a single exciton and acting as a nearly ideal single-photon emitter and(2)a quantum well in a 2D microcavity sustaining polaritons,which are known for their strong interactions and unique hydrodynamic properties,including ultrafast real-time monitoring of their propagation and phase mapping.In the present experiment,we can thus observe how the injected single particles propagate and evolve inside the microcavity,giving rise to hydrodynamic features typical of macroscopic systems despite their genuine intrinsic quantum nature.In the presence of a structural defect,we observe the celebrated quantum interference of a single particle that produces fringes reminiscent of wave propagation.While this behavior could be theoretically expected,our imaging of such an interference pattern,together with a measurement of antibunching,constitutes the first demonstration of spatial mapping of the self-interference of a single quantum particle impinging on an obstacle.