2006 Vol. 30, No. 12

Particle and field theory
Faddeev-Senjanovic Quantization of the Supersymmetrical Electrodynamic System
JIANG Yun-Guo, HUANG Yong-Chang
2006, 30(12): 1151-1155.
According to the method of path integral quantization for the canonical constrained system in Faddeev-Senjanovic scheme, we quantize the supersymmetrical electrodynamic system in general situation, and obtain the generating functional of Green function. Another first class constraint is obtained by making the linear combination of several primary constraints, the generator of gauge transformation is constructed, gauge transformations of all the different fields are deduced. Utilizing the consistency equation of gauge fixing condition to deduce another gauge fixing condition, we find that the secondary constraint of the system is an Euler-Lagrange equation which is just the conversation law of electric charge. Thus, we do not need to calculate the other secondary constraints step by step, and get no new constraints naturally. So, the Faddeev-Senjanovic path integral quantization of the supersymmetrical electrodynamic system is simplified.
A New KRR Parametrising Method of Superstring Models of AdS5\otimes S1, AdS5\otimes S5and AdS2\otimes S2
CAI Xiao-Lin, WANG Xiao-Hui, WANG Zhan-Yun, SONG Pei, SHI Kang-Jie
2006, 30(12): 1156-1164.
A new KRR parametrizing method of three typical superstring models of AdS5\otimes S1, AdS5\otimes S5and AdS2\otimes S2 is given, and combining with κ symmetry they have, their Cartan 1-forms, Maurer-Cartan equations, actions and motion equations are given.
Nuclear and ion Physics
Performance of the ALICE PHOS Front-End Electronics
YIN Zhong-Bao, ZHOU Dai-Cui
2006, 30(12): 1165-1170.
The physics requirements and the main characteristics of the current design of the front-end electronics (FEE) of ALICE photon spectrometer (PHOS) are discussed. A dedicated test facility has been established in Wuhan to evaluate the physics performance of PHOS FEE. The test results show that the current FEE prototype has met the physics requirements of the PHOS detector.
Cross Section Measurements for (n,2n), (n,p) and (n,α) Reactions on Germanium Isotopes at the Neutron Energy around 14MeV
PU Zhong-Sheng, GUAN Qiu-Yun, MA Jun, YAN Dong
2006, 30(12): 1171-1174.
Cross sections for 70Ge(n,2n)69Ge,76Ge(n,2n)75Ge, 70Ge(n,p)70Ga,72Ge(n,p)72Ga,73Ge(n,p)73Ga, 72Ge(n,α)69mZn and 74Ge(n,α)71mZn reactions were measured at the neutron energies from 13.5 to 14.6MeV using activation technique and γ-ray spectrometry. The neutron fluences was determined using the monitor reaction 93Nb(n, 2n) 92mNb and the neutron energies were measured by the method of cross section ratios for 90Zr(n,2n)89m+gZr to 93Nb(n,2n)92mNb reaction. The results of present work were compared with data published previously.
Entrance Channel Dependence of Production Cross Sections of Superheavy Nucleus 266Hs
LIU Zu-Hua, BAO Jing-Dong
2006, 30(12): 1175-1179.
For the 26Mg+244Cm, 27Al+243Am and 32S+238U systems, the capture cross sections and the formation of the compound nucleus 270Hs are calculated and compared. In the entrance channel, the projectile is captured after overcoming the Coulomb barrier that has a distribution due to the deformation of the target nucleus. After contact, the system is assumed to be injected into an "asymmetric fission valley'' by the neutron induced neck formation. The dynamic process of the composite nucleus in the "asymmetric fission valley'' is treated in a two-parameter Smoluchowski equation in which neutron flow and diffusion in elongation coordinates are taken into account. The compound nucleus configuration is achieved only for those events where the system has diffused over the conditional saddle-point in the "asymmetric fission valley''. Our results show that the Coulomb barrier in the entrance channel and the height of the conditional saddle-point in the "asymmetric fission valley'' have obvious influence in the processes of the capture and compound nucleus formation.
Detection Technology and Methods
Investigation of Feasibility of Measurement of Nuclear Fission Number by Using 3—5MeV γ-Rays
HU Guang-Chun, GONG Jian, LIU Xiao-Ya, XIONG Zong-Hua, HAO Fan-Hua, XIANG Yong-Chun, LI Run-Dong
2006, 30(12): 1180-1183.
A new method is established for measuring nuclear fission number. In this method, the gamma ray total counts of 3—5MeV energy region is utilized. In this paper, the feasibility of this method is verified by irradiation experiment of enriched uranium sample. The results show that this method can be used to measure number of nuclear fission. Compared with the result of general method, the uncertainty in the measurement of this method is less than 16%. It is of worth-while further research.
Physics Design and Study of the BSNS RCS Injection System
TANG Jing-Yu, QIU Jing, WANG Sheng, WEI Jie
2006, 30(12): 1184-1189.
With the Beijing Spallation Neutron Source (BSNS) accelerator in design, intense H beams are first accelerated by the linac and then injected in the rapid cycling synchrotron (RCS) for accumulation and further acceleration. The injection system uses H stripping and phase space painting method to fill the large ring acceptance with the linac beam of small emittance. The method is crucial to maintain low beam loss rate during the accumulation and initial acceleration. Different from the injection design of similar high-intensity accelerators in the world, the BSNS ring injection is accomplished by magnetic elements that are completely contained in a 9 meter-long uninterrupted space of near-zero dispersion. With the accumulated 1.9×1013 particles, space charge effects play a very important role. The 3D simulations including space charge effects have been carried out to optimize the injection design. This paper presents the physics design, computer simulation results and design optimization of the injection system.
An Alternative Lattice Design for ILC Damping Ring
SUN Yi-Peng, GAO Jie, GUO Zhi-Yu
2006, 30(12): 1190-1195.
The ILC damping rings should provide beams with very low natural emittances for the linear collider to reach the required luminosity, and at the same time, the damping rings also need to have a large acceptance to ensure good injection efficiency for high emittance, high energy spread beam from the positron source. Meeting the above requirements is a real challenge for the ILC damping ring lattice design. In order to reduce the cost for ILC damping rings, an alternative lattice different from the baseline configuration design has been done with modified FODO cells, and the total quadrupole number has been reduced by half. The new lattice has been optimised to have good dynamic apertures.
Synchrotron radiation,applications of nuclear techniquees,etc
Performance of Beijing Intense Slow Positron Beam
CAO Xing-Zhong, WANG Bao-Yi, WANG Ping, MA Yan-Yun, QIN Xiu-Bo, WEI Long
2006, 30(12): 1196-1199.
Beijing intense slow positron beam has been constructed successfully, which utilizes the pulsed electron beam of the BEPC LINAC with high energy to inject into the Ta target. The system will be used to expand the methodology research on positron beam and to study the defect of film materials. The running performance of DC positron beam will be introduced in this paper, such as the intensity, the energy spread and the beam size. As the main measurement method, Doppler broadening spectrum system of positron annihilation has also been accomplished.
Special Issue
Model of Geometric Neutrino Mixing and Leptogenesis
HE Xiao-Gang
2006, 30(12): 1200-1205.
I report results obtained recently in collaboration with on neutrino mixing (hep-ph/0507217). Current neutrino oscillation data are consistent with the neutrino mixing angles taking values sin2θ12=1/3, sin2θ23=1/2, and sin2θ13=0. We present a class of renormalizable gauge models which realize such a geometric mixing pattern naturally. These models, which are based on the non--Abelian discrete symmetry A4, place significant restrictions on the neutrino mass spectrum. It is shown that baryogenesis via leptogenesis occurs quite naturally, with a single phase (determined from neutrino oscillation data) appearing in leptonic asymmetry and in neutrinoless double beta decay.
Some Puzzles in B Physics
LI Hsiang-Nan
2006, 30(12): 1206-1210.
I discuss some puzzles observed in exclusive B meson decays: the large difference between the direct CP asymmetries of the B0→π+K± and B±→π0K± modes, and the small longitudinal polarization fraction of the B→φK* modes. These puzzles, being attributed to QCD uncertainty, may not be regarded as signals of new physics.
Regarding the Ground Scalar Mesons
LI De-Min, LIU Yun-Hu
2006, 30(12): 1211-1217.
Based on the main assumption that the a0(980) and D*sJ(2317) belong to the 1 3P0 qq multiplet, the masses of the states belong to the 1 3P0 qq multiplet are estimated in the quasi-linear Regge trajectory ansatz. In the framework of meson-meson mixing, it is suggested that the a0(980), K*0(1052), f0(1099) and f0(530) constitute the ground scalar meson nonet, and that the f0(1099) is composed mostly of ss while the f0(530) is mainly uu+dd. It is supposed that these states would likely correspond to the observed scalar states a0(980),κ(900), f0(980) and f0(600)/σ, respectively. Also, in the glueball-dominace picture, the mass of the ground scalar glueball is estimated to be about 1340MeV. The agreement between the present findings and those given by other different approaches is satisfactory.
ALICE Experiment at LHC and its Trigger Decision of PHOS
WANG Ya-Ping, CAI Xu
2006, 30(12): 1218-1221.
An overview of experimental status of A Large Heavy-Ion Collider Experiment(ALICE) in CERN/LHC program is given, and the trigger decision criterion of the Photon Spectrometer(PHOS) in ALICE experiment is studied deeply by Monte Carlo(MC) simulation.
Quark Number Density Susceptibilities in Lattice QCD
MENG Xiang-Fei, LIU Yu-Bin
2006, 30(12): 1222-1224.
We measured charge fluctuation and fermion number density susceptibility using lattice QCD with two light flavors of staggered quarks on 16×82×4 lattice. Below the critical temperature, we simulated them with the sub-volume for V=(2a)3×(8a)3, where \left(a=\kou\dfrac{1}{4T}\right). We find that new aspect is observation of volume dependence in the fluctuations. The charge fluctuation and fermion number density susceptibility vary with the volume for V. This suggests the existence of hadronic length scale in the charge fluctuation and fermion number density susceptibility. Above critical temperature, charge fluctuation and fermion number density susceptibility are almost volume independent for V≥(2a)3.
Detecting the Ambient Neutralino Dark Matter Particles at Accelerator
FENG Tai-Fu, LI Xue-Qian, MA Wen-Gan, WANG Jian-Xiong, ZHAO Gong-Bo
2006, 30(12): 1225-1229.
In this work, we present a new strategy to investigate the possibility of direct detection of the ambient neutralino matter at accelerator. We calculate the cross sections for both elastic and inelastic scattering processes of the dark matter particles with the beam particles at e+e and hadron colliders.
Isospin-Dependence of Nucleon Potential and Effective Mass in Relativistic Approach
MA Zhong-Yu, RONG Jian
2006, 30(12): 1230-1233.
The isospin-dependence of nucleon optical potentials and the nucleon effective mass is studied in the framework of the Dirac Brueckner Hartree-Fock (DBHF) approach. A new decomposition of the Dirac structure of the nuclear self-energy in the DBHF is extended to asymmetric nuclear matter calculations. The real part of the nucleon self-energy in asymmetric nuclear matter is calculated with the G-matrix in the Hartree-Fock approach, while the imaginary part is obtained from the polarization diagram. The nucleon vector effective mass is derived from the Schroedinger equivalent potentials. It is found that the neutron vector effective mass is larger than that of proton in the neutron-rich nuclear matter once the energy dependence of the nucleon potentials is considered.
Signature Inversion in the Odd-Odd Nuclei with Mass A~80
SHEN Shui-Fa, WANG Feng-Ge, PENG Nie, CHEN Heng-Gui, LU Hao, WU Yong-Peng
2006, 30(12): 1234-1237.
To understand the microscopic origin of the signature inversion in the yrast positive-parity bands of doubly odd Rb nuclei, as an example, we performed calculations using the projected shell model (PSM) to describe the energy spectra in 82Rb. It can be seen that the main features are reproduced in the calculations. This analysis shows clearly that the signature splitting and especially the signature inversion are reproduced only by a varying γ deformation with increasing spin.
Statistic Analysis of the Deposited Energy in Single Event Upset Induced by 10—20MeV Neutrons
LI Hua
2006, 30(12): 1238-1241.
Based on Monte Carlo simulations, the deposited energies in the single event upset induced by 10—20MeV neutrons in SRAM silicon chip are been statistically analysed. It can provide statistic information about the deposited energy for understanding the random process of the single event upset.
Theoretical Study of $\bf ^2H(d,\bm\upgamma)^4He$ at Low Energies
MA Yin-Qun, TIAN Yuan, MA Zhong-Yu
2006, 30(12): 1242-1245.
We study the astrophysical important 2 H(d,γ)4He reaction that allows for the D-state component of the colliding deuterons and D-components in 4He ground state in the framework of a phenomenological model. Our study reproduces the experimental reaction cross section at E<3MeV. Our results indicate a D-state admixture in the 4He ground state of 7.4%.