An improved evaluation of the neutron background in the PandaX-Ⅱ experiment

In dark matter direct detection experiments,neutron is a serious source of background,which can mimic the dark matter-nucleus scattering signals.In this paper,we present an improved evaluation of the neutron background in the PandaX-II dark matter experiment by a novel approach.Instead of fully relying on the Monte Carlo simulation,the overall neutron background is determined from the neutron-induced high energy signals in the data.In addition,the probability of producing a dark-matter-like background per neutron is evaluated with a complete Monte Carlo generator,where the correlated emission of neutron(s)andγ(s)in the(α,n)reactions and spontaneous fissions is taken into consideration.With this method,the neutron backgrounds in the Run 9(26-ton-day)and Run 10(28-ton-day)data sets of PandaX-II are estimated to be(0.66±0.24)and(0.47±0.25)events,respectively.     

Optical sensing systems for microfluidic devices: a review

This review deals with the application of optical sensing systems for microfluidic devices. In the “off-chip approach” macro-scale optical infrastructure is coupled, while the “on-chip approach” comprises the integration of micro-optical functions into microfluidic devices. The current progress of the use of both optical sensing approaches in microfluidic devices, as well as its applications is described. In all cases, sensor size and shape profoundly affect the detection limits, due to analyte transport limitation, not to signal transduction limitation. The micro- or nanoscale sensors are limited to picomolar-order detection for practical time scales. The review concludes with an assessment of future directions of optical sensing systems for integrated microfluidic devices.     

关于中值定理中值点的渐近性质

在［１］中，ＢｅｒｎａｒｄＪａｃｏｂｓｏｎ研究了Ｒｉｅｍａｎｎ积分第一中值定理的中值点的渐近性质·本文讨论Ｒｉｅｍａｎｎ积分第二中值定理和微分中值定理的中值点的渐近性质．     

A Semigroup Approach to Queueing Systems

We prove asymptotic stability of the solutions of equations describing a simple queueing system consisting of two machines separated by a finite storage buffer. Following an approach by G. Gupur, we apply the theory of C₀-semigroups and spectral theory of positive operators.     

Photon and positron generation by ultrahigh intensity laser interaction with electron beams

This study investigates the generation of high energy photons and positrons using focused ultrahigh intensity femtosecond laser pulses on a relativistic electron beam with a set of two-dimensional particle-in-cell simulations. We consider circularly and linearly polarized, single and spatially separated double laser pulses. We model both 500 MeV and 1 GeV electron beams. Higher positron production is obtained using circularly polarized laser pulses. Using double pulses, the focusing effect of the ponderomotive force confines the electrons to a small volume, generating additional energetic photons and positrons. The positron spectral distributions are effectively modified by these variations. When the electron beam energy is doubled, the number of positrons increased, while the cutoff energy remained nearly constant.     

Electron-positron pair production in the low-density approximation

Electron–positron pair creation is studied in the low-density approximation by solving the quantum Vlasov equation exactly and the mapping equation approximately. The simpler mapping equation is an approximate treatment of the quantum Vlasov equation in which the continuous external field is regarded as a series of delta kicks. Our study indicates that this new treatment is appropriate because the results of the two methods are in good agreement with each other. However, as the period number increases, interference and a complicated structure in the momentum distribution are observed. Furthermore, we also obtain the square power law relation of the number density to the applied electric field strength.     

Dynamic Analysis of a Deteriorating System with Single Vacation of a Repairman

Acta Mathematicae Applicatae Sinica, English Series - In this paper, we investigate a deteriorating system with single vacation of a repairman. The system is described by infinite...     

Semigroup method for a deteriorating system with multiple vacations of a repairman

Semigroup Forum - By using the method of functional analysis, especially $$C_0$$ -semigroup theory and spectral theory of linear operators we prove the well-posedness and the existence of a unique...     

A semigroup approach to the Gnedenko system with single vacation of a repairman

We investigate the Gnedenko system with one repairman who can take vacations. Our main focus is on the time asymptotic behaviour of the system. Using C ₀-semigroup theory for linear operators we first prove the well-posedness of the system and the existence of a unique positive dynamic solution given an initial value. Then by analysing the spectral distribution of the system operator and taking into account the irreducibility of the semigroup generated by the system operator we show that the dynamic solution converges strongly to the steady state solution. Thus we obtain asymptotic stability of the dynamic solution.     

A Search for Solar Axions and Anomalous Neutrino Magnetic Moment with the Complete Panda X-Ⅱ Data

We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^-12 for an axion mass less than 0.1 keV/c² and the neutrino magnetic moment μv<4.9×10^-11μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.