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1. chinaXiv:201711.02297 [pdf]

The low temperature performance of CsI(Na) crystals for WIPMs direct searchesI

Xuan Zhang; Xilei Sun; Junguang Lu; Pin Lv
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

Previous studies showed that CsI(Na) crystals have signi cantly di erent wave- forms between alpha and gamma scintillations. In this work, the light yield and PSD capability of CsI(Na) scintillators as a function of the temperature down to 80 K has been studied. As temperature drops, the fast component rises and the slow component decreases. By cooling the CsI(Na) crystals, the light yield of high ionization events are enhanced signi cantly, while the light yield of background gamma events are suppressed. At 110 K, CsI(Na) crystal achieves the optimal balance between low threshold and good background re- jection performance. The di erent responses of CsI(Na) to gamma and alpha at di erent temperatures are explained with self-trapped and activator lumines- cence centers.

submitted time 2017-11-10 Hits1110Downloads589 Comment 0

2. chinaXiv:201711.02307 [pdf]

Study of linearity of LYSO crystal for HERD calorimeter

Zheng Quan; Zhi-gang Wang; Ming Xu; Yong-wei Dong; Jun-jing Wang; Guang-peng An; Xin Liu; Tian-wei Bao; Li Zhang; Rui-jie Wang; Jun-guang Lv; Bo-bing Wu; Shuang-nan Zhang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

The High Energy cosmic Radiation Detection (HERD) facility is a space mission designed for detecting cosmic ray (CR) electrons, γ-rays up to tens of TeV and CR nuclei from proton to iron up to several PeV. The main instrument of HERD is a 3-D imaging calorimeter (CALO) composed of nearly ten thousand cubic LYSO crystals. A large dynamic range of single HERD CALO Cell (HCC) is necessary to achieve HERD’s PeV observation objectives, which means that the response of HCC should maintain a good linearity from minimum ionizing particle (MIP) calibration to PeV shower maximum. In order to study the linearity of HCC over such a large energy range, a beam test has been implemented at the E2 and E3 beam lines of BEPC. High intensity pulsed electron beam provided by E2 line are used for producing high energy density within HCC; π+/proton provided by E3 line are used for HCC calibration. The results show that no saturation e?ect occurs and the linearity of HCC is better than 10% from 30 MeV (1 MIP) to 1.1×103 TeV (energy density is 93 TeV/cm3), which can meet the requirement mentioned above.

submitted time 2017-11-10 Hits1689Downloads861 Comment 0

3. chinaXiv:201711.02310 [pdf]

A Novel Collimation Method for Large Hadron Colliders

Ye Zou; Jianquan Yang; Jingyu Tang
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

This paper proposes a novel collimation method for large hadron colliders by arranging betatron and momentum collimation systems in the same insertion to improve the overall cleaning efficiency. The method has the potential of avoiding beam losses at the downstream dispersion suppression section following the conventional betatron collimation section, which is caused by those particles with single diffractive scattering at the collimators. Evident beam loss in arc sections should be avoided to protect the superconducting magnets from quenching, especially when the stored beam energy is up to hundreds of MJ level or even higher in modern proton-proton collider. Our studies show that it is beneficial to arrange the momentum collimation system just after the betatron collimation system so that it can clean the particles with lower momentum due to the single diffractive scattering in the betatron collimators. This method is being applied to the future proton-proton collider SPPC. Preliminary multi-particle simulations are presented with the Merlin code.

submitted time 2017-11-10 Hits912Downloads430 Comment 0

4. chinaXiv:201711.02319 [pdf]

Puzzle of the Λc spectrum

Qi-Fang Lu; Yubing Dong; Xiang Liu; Takayuki Matsuki
Subjects: Physics >> General Physics: Statistical and Quantum Mechanics, Quantum Information, etc.

There is a puzzle in the +c family, i.e., one member with JP = 3/2+ is missing in a L = 2 multiplet which the heavy quark effective theory predicts, and JP’s of c(2765)+ and c(2940)+ are unknown. Using a light diquark picture to calculate baryon masses, we study possible assignments of two c’s with unknown JP and the missing +c with 3/2+ for L = 2, and we find the most probable possibility that the peak corresponding to c(2880)+ actually includes a missing member with spin 3/2+ for L = 2 and that quantum numbers of c(2765)+ and c(2940)+ are 2S (1/2+) and 2P(1/2?), respectively.

submitted time 2017-11-10 Hits1340Downloads726 Comment 0

5. chinaXiv:201703.00628 [pdf]

Simulation of positron backscattering on Al, Cu, Ag and Au targets using GEANT4 code

Xin Lai; Xiaopan Jiang; Xingzhong Cao; Xi Zhang; Zhiming Zhang; Xuexiang Cao; Gang Xiang; Baoyi Wang; Long Wei
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

In this paper, backscattering of 3-50 keV positrons on Al, Cu, Ag and Au metallic targets has been systematically investigated using GEANT4 code. The dependence of positron backscattering coefficients on atomic number Z, target thickness, incident energy and angles has been discussed comprehensively. Besides, positron backscattering spectra for those metallic targets at different discrete scattering angles were also studied to provide theoretical basis of the most appropriate scattering angle selected for simulation parameters and specified applied measurement techniques. The impact of atomic number Z of targets on positron backscattering spectra was investigated as well. Simulation results are in reasonable agreement with previous experiment data and theoretical work.

submitted time 2017-03-26 Hits14116Downloads1646 Comment 0

6. chinaXiv:201703.00622 [pdf]

On uncertainty of the beam energy measurement in e+e? collision using Compton Backscattering.

X. H. Mo
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The beam energy is measured in e+e- collision by using Compton Backscattering. The uncertainty of this measurement process is studied by virtue of analytical formulas, and the special effects of variant energy spread and energy drift on the systematic uncertainty estimation are also studied with Monte Carlo sampling technique. These quantitative conclusions are especially important for understanding the uncertainty of beam energy measurement system.

submitted time 2017-03-26 Hits13619Downloads1426 Comment 0

7. chinaXiv:201703.00621 [pdf]

On two cryogenic systems of high purity germanium detector

Zhang Jian-Yong; Cai Xiao; MO Xiao-Hu
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

Two cryogenic systems of high purity germanium detector, liquid nitrogen and mechanical coolers, are expound, together with explanations of merits and demerits for each kind of cooling methods. The resolutions of detector to the characteristic lines of 152Eu under different cooling conditions are studied. The laboratory results indicate that the mechanical cooler (X-Cooler II) is an ideal replacement candidate for the liquid nitrogen cooler that is being utilized by BEMS at BEPC-II.

submitted time 2017-03-26 Hits13553Downloads1559 Comment 0

8. chinaXiv:201703.00615 [pdf]

Study of the data taking strategy for a high precision τ mass measurement

Y.K.Wang; J.Y.Zhang; X.H.Mo; C.Z.Yuan
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

To achieve a high precision τ mass measurement at BESIII, two free para-meters (mτ and ε) and three parameters (mτε and σBG)fittings are simulated using sampling technique. For two parameters fitting, two points should be taken, the one is near the threshold of τ+τ- production to determine mτ , the other point is at 3.595 GeV to determine e±ciency. The ratio of luminosity at the two points is 3 to 1. For three parameters fitting, one point should be added at the low energy region with about 10% of the total luminosity. The optimal ratio of luminosity at the other two points is still 3 to 1.

submitted time 2017-03-26 Hits13144Downloads1319 Comment 0

9. chinaXiv:201703.00612 [pdf]

Measurement of radiation dose at the north interaction point of BEPCII

Mo Xiaohu; Zhang Jianyong; Zhang Tianbao; Zhang Qinjiang; Achasov Mikhail; Fu Chengdong; Muchnoi Nikolay; Qin Qing; Qu Huamin; Wang Yifang; Wu Jingming; Xu Jinqiang; Yu Boxiang
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The technique details for measuring radiation dose are expounded. The results of radiation levels of gamma and neutron are presented and the corresponding radiation shielding is discussed based on the simplified estimation. In addition, the radiation level of photon as background for the future experiment is measured by NaI(Tl) detector.

submitted time 2017-03-26 Hits12679Downloads1047 Comment 0

10. chinaXiv:201703.00609 [pdf]

Significance of Energy Scale for Physics at BESIII

C. D. Fu; X. H. Mo
Subjects: Physics >> Condensed Matter: Structural, Mechanical and Thermal Properties

The effects of absolute energy calibration on BESIII physics are discussed in detail, which mainly involve the effects on τ mass measurement, cross section scan measurement, and generic error determination in other measurements.

submitted time 2017-03-26 Hits11451Downloads1049 Comment 0

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