2002 Vol. 26, No. 09

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Particle and field theory
Calculation of Reactor Antineutrino Spectra in TEXONO
CHEN Dong-Liang, LI Jin, MAO Ze-Pu, WONG T
2002, 26(09): 889-894.
In the low energy reactor antineutrino physics experiments,either for the researches of antineutrino oscillation and antineutrino reactions,or for the measurement of abnormal magnetic moment of antineutrino,the flux and the spectra of reactor antineutrino must be described accurately. In this paper,the method of calculation of reactor antineutrino spectra was discussed detailedly. Furthermore,Based on the actual circumstances of NP2 reactors and the arrangement of detectors,the flux and the spectra of reactor antineutrino in TEXONO were worked out.
Quantum Mechanical Model with Nonlocal Potential
ZHANG De-Xing, CAI Shao-Hong
2002, 26(09): 895-899.
In this paper, using supersymmetric (SUSY) quantum mechanics, we discuss exactly solvable Quantum mechanical model with nonlocal potential. And we present a simple nonlocal presentation of exactly solvable local model, so exactly to obtain energy eigenfunctions and eignvalues.
Phase Difference and the Squeezing Property of the Superpositions of the q-Deformed Generalized Coherent States
LIANG Mai-Lin, YUAN Bing
2002, 26(09): 900-903.
It is shown that the possible higher squeezing order of the superposition state β>+eiφ βeiδ> of the generalized coherent states of the q deformed non-harmonic oscillator can be expressed as k≠2π n/δ,with n an integer and δ the phase difference between the two generalized coherent states. When δ=π,the order of squeezing can only be odd,which is just the result of the generalized even and odd coherent states of the q deformed non-harmonic oscillator;when δ takes other values,the squeezing order can be even. These results show that the parameter phase difference δ plays the key role in determining the possible squeezing order.
Nuclear and ion Physics
Single Event Effects Induced by 15.14 MeV/u 136Xe Ions
HOU Ming-Dong, ZHANG Qing-Xiang, LIU Jie, WANG Zhi-Guang, JIN Yun-Fan, ZHU Zhi-Yong, ZHEN Hong-Lou, LIU Chang-Long, CHEN Xiao-Xi, WEI Xin-Guo, ZHANG Lin, FAN You-Cheng
2002, 26(09): 904-908.
Single event effects induced by 15.14MeV/u 136Xe ions in different batches of 32k×8 bits static random access memory are studied. The incident angle dependences of the cross sections for single event upset and single event latchup are presented. The SEE cross sections are plotted versus energy loss instead of linear energy transfer value in sensitive region. The depth of sensitive volume and thickness of "dead" layer above the sensitive volume are estimated.
γ-Ray Anisotropy Measurement in Coincidence Mode
ZHENG Yong, ZHOU Xiao-Hong, LIU Min-Liang, LIU Zhong, HE Jian-Jun, GUO Ying-Xiang, LEI Xiang-Guo, ZHANG Yu-Hu, LUO Wan-Ju
2002, 26(09): 909-913.
In order to assign γ-ray multipolarity, a method of ADO ratios deduced from coincidence data has been described. The factors affecting the reliability of the ADO ratios have been discussed using an experimental detector configuration. The multipolarities for known γ-rays deduced by the ADO method are consistent with the previous results obtained from γ-ray angular distribution and DCO ratio measurements. This consistence proves that the ADO method is reliable. The advantages of the ADO method over the traditional DCO ratio measurement have been discussed.
Study of the Influence of Decay Data in Activation Reaction Cross Section
HUANG Xiao-Long, LU Han-Lin
2002, 26(09): 914-919.
The effect of the decay data on the measured activation cross section is investigated carefully and testified by several examples. These decay data include the half-life of the product, γ branching ratio of the product and decay scheme. Present work shows that these effects must be considered carefully when evaluating the activation reaction cross section. Sometimes they are main reason for causing the discrepancies among the experimental data.
Coincident Measurement between Neutron and Fragment in Reaction 17N+197Au
LI Xiang-Qing, HUA Hui, JIANG Dong-Xing, YE Yan-Lin, CHEN Tao, LI Zhi-Huan, GE Yu-Cheng, WANG Quan-Jin, WU He-Yu, JIN Gen-Ming, DUAN Li-Min, XIAO Zhi-Gang, WANG Hong-We
2002, 26(09): 920-925.
In the reaction induced by 33.4MeV/u 17N beam on 197Au, the coincident measurment between neutron and fragment was performed with the different combinations of 16 neutron detectors at 4°-83° and 14 telescopes at 2.3°-9.0°. Integrating the measured angular distributions of the different isotopes, the isotopic yield distributions of Z=3-6 elements are obtained. Based on the Abrasion-Ablation model, isotopic yield distributions are calculated using different density distributions for the projectile 17N and compared with the experiment data.
Probing Equilibration in HICs and Symmetry Energy by Using Isospin-Related Observables
LI Qing-Feng, LI Zhu-Xia
2002, 26(09): 926-932.
We have studied the equilibration with respect to isospin degree of freedom in four systems 96Ru+96Ru,96 Ru+96Zr,96Zr+96Ru,96Zr+96Zr at 100 MeV/u and 400MeV/u with isospin dependent QMD. It is proposed in this paper that the neutron-proton differential rapidity distribution is a sensitive probe to the degree of equilibration with respect to the isospin degree of freedom. By analyzing the average N/Z ratio of emitted nucleons, light charged particles (LCP) and intermediate mass fragments (IMF), it is found that there exists memory effect in multifragmentation process. The average N/Z ratio of IMF reduces largely as beam energy increases from 100MeV/u to 400MeV/u, which may result from the change of the behavior of the isotope distribution of IMF. The isotope distribution of IMF does also show certain memory effect at 100 MeV/u case but not at 400 MeV/u case. We also found the rapidity distribution of differential neutron-proton counting in neutron rich nucleus-nucleus collisions at intermediate energies is sensitive to the isospin dependent part of nuclear potential. In conclusion, based on these studies we have found it's an effective way to explore whether the final equilibration could be reached in intermediate HICs by constructing a set of isospin (a)symmetry nuclear-nuclear collision systems with same mass and different charge.
Effective Hyperon-Nucleon Interactions in the Relativistic Mean Field Theory
LV Hong-Feng, LONG Wen-Hui, MENG Jie, ZHOU Shan-Gui
2002, 26(09): 933-940.
The effective Λ nucleon interaction in single Λ hypernuclei is studied using the Relativistic Mean Field theory. Five sets of hyperon meson coupling parameters,for Λ-σ and Λ-ω interactions, are obtained by fitting the recent data of the binding energy of a Λ in the 1s state of 13Λ C,B1s1/2Λ. The detailed method is to fix one of the parameters to be a special value such as 2/3 or 1,or to suppose two of them be equal,and then the parameter sets are deduced. With these parameter sets determined from only this experimental quantity,we calculate the single particle spectra of Λ in single-Λ hypernuclei for a wide range of mass number from A=9 to A=208. The calculations reproduce the available data well.
Ground State Characteristics of the Light Nuclei with A≤6 on the Basis of the Translation Invariant Shell Model by Using Nucleon-Nucleon Interactions
2002, 26(09): 941-948.
Phenomenological nucleon-nucleon interactions consisting of central,tensor,spin-orbit and quadratic spin-orbit terms,with Gaussian radial dependence,are constructed by varying their parameters in order to obtain the best fit between the calculated and the experimental values of the binding energy,the root mean-square radius,the D-state probability,the magnetic dipole moment and the electric quadrupole moment of deuteron. The ground-state nuclear wave function of deuteron is expanded in terms of the translation invariant shell model basis functions corresponding to the number of quanta of excitation 0≤N≤10. Moreover,the binding energy,the root mean-square radius and the magnetic dipole moment of the nuclei 3H,4He,5He and 6Li are also calculated by using the new interactions. The wave functions of these nuclei are expanded in terms of the basis functions of the translation-invariant shell model with N=10 for the first two nuclei, N=7 for 5He and N=6 for 6Li. Furthermore,the role of the three body force is investigated for the triton nucleus. The obtained results are in good agreement with the corresponding experimental values.
Quantum Classical Correspondence in a 2-Dimensional Deformed Harmonic Oscillator System
LIU Fang, LI Jun-Qing, XING Yong-Zhong
2002, 26(09): 949-954.
The time evolution of expectation values of the basic dynamic variables in a quantum system under different effective Planck constant were compared with the exact values of the basic dynamic variables in classical system. It is found, for the regular motion, the difference comes from the quantum effect; for the chaotic motion, it comes from the dynamical effect and the destruction of the dynamical system. With these results, a correspondence between the quantum heterogeneity of the phase space and the Lyapunov exponent is made satisfactorily.
Two-Pion Interferometry at Small Relative Momentum in Ultrarelativistic Heavy Ion Collisions
CHEN Xiao-Fan, YANG Xue-Dong, CHEN Zhi-Lai, HAN Ling, WANG Qing-Dong
2002, 26(09): 955-958.
The relations between the pion source parameters in two models in ultrarelativistic heavy ion collisions are given using pion interferometry at small relative momentum. And comparisons are made with the experimental results of 200 A GeV O+Au collisions.
Detection Technology and Methods
A Precise Trigger Timing System
HUANG Sheng-Li, XU Zi-Zong, WANG Zhao-Min, WANG Xiao-Lian, LI Cheng, CHEN Hong-Fang, WU Jian, ZENG Hui
2002, 26(09): 959-963.
Four plastic scintillators coupled with three photo multiplier tubes (PMTs) were used to construct a preecise trigger timing system. When one charged particle passes through the system, the PMTs can measure its time information independently. By off line data analyzing, a precise trigger timing with resolution about 57ps has been gotten. This system can be used to research the time resolution of detectors.
Low Pressure Multiwire Proportional Chamber and Its Application to Radioactive Ion Beam Experiment
LI Zhi-Huan, CHEN Tao, YE Yan-Lin, JIANG Dong-Xing, HUA Hui, LI Xiang-Qing, WANG Quan-Jin, GE Yu-Cheng, PANG Dan-Yang, DI Zhen-Yu, TAN Ji-Lian, ZHANG Jin-Xia, FENG Ying
2002, 26(09): 964-970.
Radioactive ion beam is generally characterized by small beam intensity and big beam size. In order to carry on precise scattering and reaction experiments it is necessary to monitoring the incident angle and absolute number of the beam hitting the target. We therefore have designed and made up low pressure multiwire proportional chambers (LPMWPC) which have good beam transparency and are also adequate to be used in vacuum. Experiment test indicates that the position resolution of the chambers is about 0.5mm and the position determination efficiency is larger than 90% for the low Z particles at intermediate energies. This kind of chamber can then be used to detect the direction of the incident particle and to record the absolute number of the particles which really hit the target, or to detect the emitting angle of the outgoing particles.
Experimental Status of Ultra-high Energy Induced Nuclear Reactions
CAI Xu, ZHOU Dai-Mei
2002, 26(09): 971-990.
An overview of experimental status of the international collaboration on ultra-high energy induced nuclear reactions and the relative heavy-ion physics is given. It includes: 1. theoretical predictions of quark matter (quark gluon plasma), 2. the experiments of ultra-high energy heavy-ion collisions: (1) the BNL/AGS fixed target experiments, (2) the CERN/SPS fixed target experiments, (3) the BNL/RHIC colliding experiments, (4) the CERN/LHC colliding experiments.