Determination of the number of ψ' events at BES Ⅲ

The number of ψ' events accumulated by the BESⅢ experiment from March 3 through April 14, 2009, is determined by counting inclusive hadronic events. The result is 106.41×(1.00±0.81%)×106 . The error is systematic dominant; the statistical error is negligible.     

Determination of the number of ψ(3686)events at BESⅢ

The numbers of ψ(3686) events accumulated by the BESⅢ detector for the data taken during 2009 and2012 are determined to be(107.0±0.8)×10~6 and(341.1±2.1)×10~6, respectively, by counting inclusive hadronic events,where the uncertainties are systematic and the statistical uncertainties are negligible. The number of events for the sample taken in 2009 is consistent with that of the previous measurement. The total number of ψ(3686) events for the two data taking periods is(448.1±2.9)×10~6.     

Determination of the number of J/ψ events with inclusive J/ψ decays

A measurement of the number of J/ψ events collected with the BESⅢ detector in 2009 and 2012 is performed using inclusive decays of the J/ψ. The number of J/ψ events taken in 2009 is recalculated to be(223.7±1.4)×10~6, which is in good agreement with the previous measurement, but with significantly improved precision due to improvements in the BESⅢ software. The number of J/ψ events taken in 2012 is determined to be(1086.9±6.0)×10~6. In total, the number of J/ψ events collected with the BESⅢ detector is measured to be(1310.6±7.0)×106, where the uncertainty is dominated by systematic effects and the statistical uncertainty is negligible.     

Determination of event start time at BESⅢ

The principle of the method for the BESⅢ event start time determination and the code construction are described. The investigation of influence of the noise, the method of rejecting noise and the performance checking by the Monte Carlo physics data sample are also presented. The preliminary results got from the Monte Carlo simulation are presented, the reconstruction efficiency of J/ψ→ anything events at noise level 0~60% can achieve above 99%, and the error rate is below 1%.     

Determination of the number of J/ψ events with J/ψ → inclusive decays

The number of J/ψ events collected with the BES0 detector at the BEPC/ from June 12 to July 28, 2009 is determined to be (225:3±2:8)×10⁶ using J/ψ → inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.     

Cross Section of Heavy Ion Reaction （14.5 MeV/u） ^132Xe ＋ Bi

We investigate the cross section of the heavy ion reaction （14.5 MeV/u） ^132Xe ＋ Bi by using a CR-39 plastic track detector. The target-detector assembly is exposed at UNILAC beam facility of GSI, Germany. After etching under appropriate etching conditions, the detector is scanned for multipronged events produced as a result of interactions of projectile ions with target atoms. The elastic events are separated from binary events and used for the determination of the quarter-point angle. The quarter-point angle obtained is used to determine the total reaction cross section. The total experimental reaction cross section is determined by using statistics of inelastic events of two-pronged and higher multiplicity events. The experimental reaction cross sections determined by using elastic and inelastic data observed in the reaction under study are found to be in good agreement with the theoretically calculated value of reaction cross section using a sharp cutoff model.     

Phenomenon of Energy Concentration in High-Energy Family Events of Cosmic Rays

The phenomenon of energy concentration in high-energy family events of cosmic rays in studied by comparing the results of family events of total visible energies 1000-400TeV observed in the Kanbala emulsion chamber experiment with the Monte Carlo simulation data,The simulation is made by the program CORSIKA in which QGSJET is applied as the hadronic interaction model,and the chemical composition of primary cosmic rays is obtained from the rigidity-cut model and the extrapolation of new results of direct measurements.This shows that the whole distribution tendency of the rate of energy concentration of simulated family events is basically consistent with that of the experiment.     

Robust H∞ observer-based of a class of complex control for synchronization dynamical networks

This paper is concerned with the robust Hoo synchronization problem for a class of complex dynamical networks by applying the observer-based control. The proposed feedback control scheme is developed to ensure the asymptotic stability of the augmented system, to reconstruct the non-measurable state variables of each node and to improve the H∞ performance related to the synchronization error and observation error despite the external disturbance. Based on the Lyapunov stability theory, a synchronization criterion is obtained under which the controlled network can be robustly stabilized onto a desired state with a guaranteed H∞ performance. The controller and the observer gains can be given by the feasible solutions of a set of linear matrix inequalities （LMIs）. The effectiveness of the proposed control scheme is demonstrated by a numerical example through simulation.     

Robust H_∞ observer-based control for synchronization of a class of complex dynamical networks

This paper is concerned with the robust H∞ synchronization problem for a class of complex dynamical networks by applying the observer-based control. The proposed feedback control scheme is developed to ensure the asymptotic stability of the augmented system, to reconstruct the non-measurable state variables of each node and to improve the H∞ performance related to the synchronization error and observation error despite the external disturbance. Based on the Lyapunov stability theory, a synchronization criterion is obtained under which the controlled network can be robustly stabilized onto a desired state with a guaranteed H∞ performance. The controller and the observer gains can be given by the feasible solutions of a set of linear matrix inequalities (LMIs). The effectiveness of the proposed control scheme is demonstrated by a numerical example through simulation.     

Error analysis on dihedral angle of corner-cube reflectors in Fourier transform spectrometer北大核心CSCD

Fourier transform spectrometer is an important spectral analysis instrument. To research the influence of the dihedral angle error of corner-cube reflectors on interference quality of oscillating Fourier transform spectrometer, the theoretical analysis and computer simulation were carried out. According to the oscillating Fourier transform spectrometer model, the mathematical expressions of the interference intensity and modulation depth with dihedral angle error were deduced. The tolerance of dihedral angle was determined by the modulation depth criterion. The optical design software Zemax was used to establish the model for simulation and verify the results of theoretical derivation. According to the modulation depth criterion, the tolerance of dihedral angle obtained by the theoretical model is 2.52″, and that obtained by the Zemax simulation is 2.38″. The error is 0.14″, which is acceptable. The analysis results show that the established theoretical model is reasonable, which has certain reference value for the design and installation of oscillating Fourier transform spectrometers. © 2022 Editorial office of Journal of Applied Optics. All rights reserved.     

Current sensor based on an atomic magnetometer for DC application

A DC current sensor based on an optically pumped atomic magnetometer is proposed.It has a high linearity in a wide operation range,since the magnetometer measures the absolute magnitude of the magnetic field produced by the current to be measured.The current sensor exhibits a high accuracy with a non-moment solenoid and magnetic shielding to suppress the influence from the environment.The absolute error of the measured current is below 0.08 m A when the range is from 7.5 m A to 750 m A.The relative error is 5.54×10^-5 at 750 m A.     

An Approach to Extract the Spin Transfer to ∧in Polarized Proton--Proton Collision

We introduce an approach to extract the spin transfer to A in polarized proton-proton collision, based on the relation between single spin asymmetry and the polarization of A production. With 4 × 10^6 ∧ events simulated for a PHENIX detector system, DLL = 0.1598 ± 0.0343 is retrieved by the approach and it agrees very well with the input value of 0.1429. The approach is further tested and confirmed with ‘bunch shuffling＇ method for the simulated events as well as experimental events collected at PHENIX in 2003. It is concluded that one can correctly extract the spin transfer without detailed understanding of acceptance correction even if the correction is significantly large in PHENIX experiment by using the approach described here. The method can be generally used for spin transfer study.     

Study of the online event filtering algorithm for BESⅢ

The results of a study of event tagging strategies for elementary physics processes in the τ-charm region are presented. The algorithm for online event filtering is optimized by adopting the information provided by different sub-detectors according to their strengths and capacities. The algorithm is tested with various generated physics and background events. The results indicate that the algorithm satisfies the requirements of BESⅢ physics analysis and its     

Accurate and rapid error estimation on global gravitational field from current GRACE and future GRACE Follow-On missions

Firstly, the new combined error model of cumulative geoid height influenced by four error sources, including the inter-satellite range-rate of an interferometric laser (K-band) ranging system, the orbital position and velocity of a global positioning system (GPS) receiver and non-conservative force of an accelerometer, is established from the perspectives of the power spectrum principle in physics using the semi-analytical approach. Secondly, the accuracy of the global gravitational field is accurately and rapidly estimated based on the combined error model; the cumulative geoid height error is 1.985× 10^-1~m at degree 120 based on GRACE Level 1B measured observation errors of the year 2007 published by the US Jet Propulsion Laboratory (JPL), and the cumulative geoid height error is 5.825× 10^ - 2~m at degree 360 using GRACE Follow-On orbital altitude 250~km and inter-satellite range 50 km. The matching relationship of accuracy indexes from GRACE Follow-On key payloads is brought forward, and the dependability of the combined error model is validated. Finally, the feasibility of high-accuracy and high-resolution global gravitational field estimation from GRACE Follow-On is demonstrated based on different satellite orbital altitudes.     

Optimized 481 Mb/s visible light communication system using phosphorescent white LED

We demonstrate a visible light communication system based on DC-biased optical orthogonal frequency-division multiplexing（DCO-OFDM） and achieve a bit rate of 481 Mb/s at a communication distance of 65 cm by employing single 1 W commercial phosphorescent light-emitting diode（LED）. The average bit error rate of the received data is 2.3×10-3, which is below the forward error correction limit, 3.8×10-3. The effect of signal clipping in DCO-OFDM system is studied and resource allocation algorithms are utilized. At least 13% capacity improvement can be obtained by suitable signal clipping and resource allocation.     

Spatial Characteristics of Head-Related Transfer Function

The spatial characteristics of head-related transfer functions (HRTFs) are studied by a spatial Fourier analysis.A law of the HRTF spatial sampling in different elevation planes is obtained, and the corresponding spatial interpolating method used to recover the continuous HRTF is proposed. The method is valid, for the average error between the measured and interpolated HRTFs in the horizontal plane is about 0.5%. These results provide guidance for the discrete spatial measurement of HRTFs.     

MEASUREMENT OF POWER FLOW IN VIBRATIONAL STRUCTURE

The evaluation of power flow in vibrational structure is treated theorettaly,experimentally and bycomputer simulaion.It is shown that the bending wave power can be messured with two transducers,as longas the error caused by near-field is known well.The method is very similar to the sound power measurement inair.The error caused by this way is calculated.Comparison between measured and theoretical results showsthat in thin rods the bending wave power can be calculated with the accuracy better than 2 dB.At lowfrequencies the limiting factor is the near-field influence,at high frequencies it is the transducer separation,the mass loading by the transducers and the phase difference,etc..     

Non-crossover sub-Doppler DAVLL in selective reflection scheme

We demonstrate a non-crossover sub-Doppler dichroic atomic vapor laser locking(DAVLL) in selective reflection scheme, which allows us to obtain a modulation-free laser locking with wide tuneable range. The dependence of peak-to-peak amplitude, tuneable range and the slope near the zero-crossing point of error signal on the frequency shift induced by the magnetic fields are studied. The adjustable error signal by the varying external magnetic field can offer the laser locking from the order of tens MHz to hundreds MHz. The ultimate dither of locked laser frequency is less than 0.5 MHz. The square root of Allan variance of the error signals reaches a minimum of 3 × 10-10 for an averaging time of 130 s.     

Monte Carlo Simulation on Energy Deposition of Low-Energy Electrons in Liquid Water

A Monte Carlo approach to simulate the transport and energy deposition of low energy electrons (E0≤10keV) in liquid water is presented. The elastic scattering of electrons is described by Mott cross section, which is derived from the relativistic wave equation of Dirac. The inelastic scattering model of electrons is based on the dielectric response theory with exchange effect included. A new method of sampling various inelastic scattering events is proposed in the simulation. Using the approach stated, the spatial distribution of inelastic scattering events and energy deposition of electrons in liquid water are computed and the results are compared with other theoretical studies.     

Boundary evaluation and error correction on pseudorandom spread spectrum photon counting system

The Cramer–Rao lower bound on range error is modeled for pseudo-random ranging systems using Geiger-mode avalanche photodiodes. The theoretical results are shown to agree with the Monte Carlo simulation, satisfying boundary evaluations. Experimental tests prove that range errors caused by the fluctuation of the number of photon counts in the laser echo pulse leads to the range drift of the time point spread function. The function relationship between the range error and the photon counting ratio is determined by using numerical fitting.Range errors due to a different echo energy is calibrated so that the corrected range root mean square error is improved to 1 cm.