2005 Vol. 29, No. 12

Particle and field theory
Decay Υ(3S)→Υ(1S)π+π-and a Possible bbqq State
GUO Fen-Kun1, 5, SHENG Peng-Nian1, 3, 4, JIAN Huan-Qing1, 2, 4, 6, PING Rong-Gang1, 2
2005, 29(12): 1121-1124.
The decay process \Upsilon(3S)\to\Upsilon(1S)ππ are re-visited using a Chiral Unitary Theory (ChUT) to include the important ππS wave final state interaction (FSI). It is found that when an additional intermediate state with JP=1 and I=1 is introduced, the ππ invariant mass spectrum and the cosθπ* distribution in the \Upsilon(3S)→\Upsilon(1S)ππ process can simultaneously be well-explained, and a good description for other bottomonium ππ transitions can be obtained consistently. As a result, the mass and the width of the intermediate state are predicted to be MX=10.08GeV and ΓX=0.655GeV, respectively. From the quark content analysis,this state should be a bbqq state.
Asymmetry of hadron production in pp(p) reaction
LI Xi-Ming, ZHAO Ning-Hua, LAN Jian-Sheng
2005, 29(12): 1125-1130.
The mean production probability of light flavor u, d and s quarks in the pp and p p reaction is calculated and discussed in this paper. It is found that the production probability depends on the energy and type of the reaction. As a result, the average yields of directly hadrons, the asymmetry of isospin, and the ratio of particle to antiparticle are all dependent on the energy and type of the reaction. In particular, we find that the ratio of banyon to antibaryon in pp reactions is larger than 1, which is consistent with the experiment results of heavy ion colliding.
particle and nuclear astrophysics and cosmology
Temperature Dependence of Electron Screening at Low Energy
ZENG Sheng1, F.Raiola2, B.Burchard2, C.Rolfs2, LIAN Gang1
2005, 29(12): 1131-1135.
For a deep understanding of the electron screening effects, we cooperated with the astrophysics group of Ruhr University to study the electron screening in the d(d,p)t reaction for the deuterated metals of groups 3 and 4 of the periodic table and the lanthanides, at a sample temperature T=200\textcelsius, using the D3+ beams provided by the 100kV accelerator of Dynamitron-Tandem-Laboratorium. The hydrogen solubility in the samples dropped to a level of a few percent (compared to T=20\textcelsius) and a large screening became observable. With the classical plasma model of Debye applied to the quasi-free metallic electrons, the deduced number of valence electrons per metallic atom agrees with the corresponding number from the Hall coefficient, for all metals investigated. Finally, we measured the screening for the metals Co and Pt as a function of sample temperature, in part between T=20\textcelsius and 340\textcelsius. The data agree with the Debye model; they represent the first observation of a temperature dependence of a nuclear cross section.
Generalize 't Hooft's Quantum State of the Black Hole Theory
BAI Hua, YAN Mo-Lin
2005, 29(12): 1136-1141.
Stating from 't Hooft's theory in which the black hole is treated as quantum states with high degeneracy with considerations of the quantum effect of the black hole and the Heisenberg uncertainty principle, we find out that the coordinations near horizon are noncommutative. Using the noncommutative field method, we study the non-extreme Reissner-Nordstr\"{o}m macro-black hole,and successfully calculate the black hole entropy and the Hawking temperature. We also predict the number of the dynamical freedom of the field and our quantum horizon model supports the Minimal Super-symmetric Standard Model.
Nuclear and ion Physics
Rotation and Decay of the Dinuclear System Formed in Dissipative Reaction of 19F+27Al
HAN Jian-Long1, WANG Qi1, DONG Yu-Chuan1, LI Song-Lin1, DUAN Li-Min1, WU He-Yu1, XU Hua-Gen1, CHEN Ruo-Fu1, 2, XU Hu-Shan1, BAI Zhen1, LI Zhi-Chang3, LU Xiu-Qin3, ZHAO Kui<s
2005, 29(12): 1142-1145.
Excitation functions of the reaction products B,C,N,O,F and Ne in the dissipative heavy ion collision of 19F+27Al have been measured at incident energies from 110.25MeV to 118.75MeV in step of 250keV. The energy coherent widths Γ of the products are extracted by using the energy autocorrelation functions. Taking into account the properties of both the rotation and decay in an intermediate dinuclear system formed in the reaction, the Ericson statistical theory in nuclear reaction has been developed and the evolution process of the dinuclear system is discussed.
Upper Limit of the Yield of Di-Omega in Central Au-Au Collision at Snn=200GeV with HIJING
SHAN Qing, WU Jian, WANG Xiao-Lian, CHEN Hong-Fang, ZHANG Yi-Fei, ZHANG Zi-Ping, SHAO Ming
2005, 29(12): 1146-1149.
According to the theoretical calculations on the cross section, the (ΩΩ)0+'s production including both the electromagnetic interaction process and the two-step process is studied with HIJING package. The production of the \noo is also simulated and calculated in this paper. The upper limit of the production rate of the (ΩΩ)0+ in the electromagnetic interaction process is (1.097±0.293)×10-10 per central Au-Au collision event at snn=200GeV, while (NΩ)022 is (0.894±0.005)×10-4.
Measurements of Cross Section for 160Gd(n,2n)159Gd and 158Gd(n,p)158Eu Reactions at the Neutron Energies of 13.5,14.1 and 14.6MeV
PU Zhong-Sheng, LI Zhi, MA Jun, LI Wei-Xue
2005, 29(12): 1150-1152.
The cross sections for (n, 2n) and (n, p) reactions were measured on Gadolinium isotopes at the neutron energies of 13.5—14.6MeV using activation technique. The cross section data for the reactions of 160Gd(n, 2n) 159Gd and 158Gd(n, p) 158Eu were reported.The cross sections of 160Gd(n, 2n) 159Gd reaction are (1940±83)mb, (2324±92)mb and (1983±77)mb at (13.5±0.2)MeV, (14.1±0.1)MeV and (14.6±0.2)MeV, respectively. The cross sections of 158Gd(n, p) 158Eu reaction are (1.9±0.1)mb, (2.1±0.1)mb and (3.5±0.1)mb at (13.5±0.2)MeV, (14.1±0.1)Mev and (14.6±0.2)MeV, respectively. The neutron fluences were determined by the cross sections of 93Nb(n, 2n) 92mNb reaction. The comparison was made between the present results and the previously published data.
Study on Pairing Energy Gap Parameter for O-isotopes in Relativistic Mean Field Theory
DING Bin-Gang1, 2, LU Ding-Hui1
2005, 29(12): 1153-1156.
In the framework of RMF theory, we study gap parameters for the pairing energy in the chain of O-isotopes. By examining the binding energies and the quadrupole deformations of nuclei, we find that the gap parameters, Λn and Λp,can simply be fixed to a value of 0.5 in this mass range, in accordance with satisfactory descriptions.
Dynamical Study on Fusion Mechanism near Coulomb Barrier
FENG Zhao-Qing1, JIN Gen-Ming1, 2, ZHANG Feng-Shou2, 3, FU Fen1, HUANG Xi1, 4
2005, 29(12): 1157-1161.
The isospin dependent quantum molecular dynamics model has been further developed by considering shell effect and the fusion mechanism near Coulomb barrier is studied by using the improved model. For light reaction system, the fusion excitation function can be described very well by using the improved model, which is consistent with the experimental data. At the same time, the experimental capture cross section for heavy reaction system can be reproduced basically.Especially for the region near or below barrier, it can also be described reasonably by using the improved model. As a further test for the model,the nucleus-nucleus interaction potential is also calculated, and compared with the proximity potential as well.
Rearrangement Contribution to Single Nucleon Potential in Hot Nuclear Matter and Three-body Force Effect
ZUO Wei1, LU Guang-Cheng1, LI Zeng-Hua1, 2, LUO Pei-Yan1
2005, 29(12): 1162-1166.
Based on the finite temperature Brueckner-Hartree-Fock approach including a microscopic three-body force, the rearrangement correction to the single nucleon potential in hot nuclear matter, and its density and temperature dependence have been investigated by using the hole-line expansion for the mass operator. It turns out that the rearrangement contribution due to ground state correlations is repulsive and it depends sensitively on both density and temperature. The rearrangement contribution becomes larger as the density increases and becomes smaller as the temperature rises up. The three-body force affects considerably the rearrangement contribution of the single nucleon potential and its effect increases with density. Inclusion of the three-body force in the calculation reduces the ground state correlations especially in the high density region and consequently makes the rearrangement contribution smaller.
Fusion Reactions Induced by Weakly Bound Projectile
LIU Zu-Hua
2005, 29(12): 1167-1169.
The effect of breakup on fusion for weakly bound projectiles 6Li and 9Be incident on 208Pb or 209Bi targets has been discussed by comparing experimental fusion excitation functions to the prediction of stranded theory. It is shown intuitively by this comparison that complete fusion of weakly bound projectile with heavy target is suppressed, whereas breakup has every little effect on the total fusion at energies above the barrier. The result indicates that partial fusion of weakly bound nuclei most likely takes place near the absorption region. By means of our observation, we have put forward a relationship between the cross sections of complete fusion and partial fusion.
Detection Technology and Methods
Raw Data Management System on GAUDI Framework
ZHANG Xiao-Mei, MA Qiu-Mei, WANG Zhe, WANG Da-Yong, YOU Zheng-Yun, MAO Ze-Pu, DENG Zi-Yan, QIU Jin-Fa, LIU Huai-Min, LI Wei-Dong, ZHANG Xue-Rao, MAO Ya-Jun, YUAN Ye, HUANG Xing-Tao, JIANG Lin-Li, ZANG Shi-Lei
2005, 29(12): 1170-1174.
The article describes the software package as a raw data management system which is mainly designed to convert persistent data in the form of a packed raw event byte stream into a form suitable for storage in the Transient Data Store of GAUDI. All its design and realizations are based on the GAUDI framework with Object-Oriented Design Patterns in C++, so the raw data management system is feasible and extensible.
Experimental Study on the Method of Deadtime Correction For HPGe Spectrometer System
ZHOU Feng-Qun1, 2, YANG Jing-Kang1, TUO Fei1, YI Yan-Ling1, KONG Xiang-Zhong1
2005, 29(12): 1175-1178.
A practical method of deadtime correction for HPGe γ spectrometer system was given.The relation between the percent deadtime and the correction of counting rate losses for HPGe γ spectrometer system was found by using a strong γ source.Therefore, the activity measurement can be implemented at relatively high count rate,with this γ spectrometer.
Experimental Study on Ion Beam Emittance of ECR Ion Source
SUN Liang-Ting, CAO Yun, FENG Yu-Cheng, LI Jin-Yu, ZHAO Hong-Wei, ZHANG Zi-Min, WANG Hui, MA Bao-Hua, HE Wei, ZHAO HUAN-Yu, GUO Xiao-Hong
2005, 29(12): 1179-1184.
With a recently developed electronic-sweep scanner system, we have done series of emittance study on ECR ion source. The electric-sweep scanner system was installed on the beam line of Lanzhou Electron Cyclotron Resonance Ion Source No. 3 experimental platform of Institute of Modern Physics. The influences of magnetic field, microwave, gas mixing and biased disc on the extracted ion beam emittance have been studied in detail. With the experimental results obtained and the empirical results of ion beam emittance and ECR plasma,some conclusions on the relationship between the source tunable parameters and electron cyclotron resonance plasma are made out, which might help understand the working regime of an ECR ion source. The typical results of the experiments and the derived conclusions are presented in this paper.
A New Physical Image on Backstreaming Ions
LONG Ji-Dong1, LIN Yu-Zheng1, SHI Jin-Shui2, YU Hai-Jun2
2005, 29(12): 1185-1189.
Backstreaming ions issue is a major concern for new generation radiography facilities based on LIA (linear induction accelerator). Its theory based on dynamics of single particle driving by beam charge field predicts that the ions could bring adverse effect on beam focus, resulting in degrade of radiography resolution. The predicted phenomena have not been observed until now. A new physical image on ions movement is presented here. Through analysis, it is found that an ions sheath transition zone could form between the target surface and the plasma. The sheath zone could counteract the beam space charge field applied on the positive ions. So using mass movement of diffusion to study ions behavior may be more proper. A verification experiments on the new image is also given in the end.
Analysis of Angular Distribution and Photon Yield from Bremsstrahlung Targets
GUO Bing-Qi, LI Quan-Feng, DU Tai-Bin, CHENG Cheng
2005, 29(12): 1190-1195.
Effects of electron beam parameters, including energy, radius and emittance, as well as target parameters, on bremsstrahlung exposure are discussed in this paper.With the energy of incident electrons varying from 2MeV to 50MeV, the forward yields at a distance of one meter from different targets, such as tungsten, copper, tantalum and aurum, are calculated by both analytical formula and MCNP4 Monte Carlo code. In addition, the relationship of X-ray dose to target and electron parameters is analyzed. The results agree well with published experimental and theoretical data,and may be a good reference for the design of this kind of X-ray source.
Thermal Structural Analysis and Test of the New Electron Gun for NEPCⅡ Linac
ZHOU Zu-Sheng, LIU Bo
2005, 29(12): 1196-1199.
The Beijing Electron Positron Collider Upgrade Project (BEPCⅡ) requires its injector linac to upgrade the beam energy and current. Hence the high emission current and low emittance electron gun must be newly designed and fabricated to meet the requirement of high positron beam current.This paper describes the temperature field distribution in the gun and the gun deformation caused by this distribution which is performed by using ANSYS. According to the real complex structure and the energy conversion inside the electron gun, we took conduction as the main energy conversion form after deep consideration and then got the temperature field. The coincidence between the temperature field and the structural deformation is also described. In this paper, the beam optics simulated by EGUN before and after structure deformation is discussed, and the valuable results have been obtained. The test results and simulation results are analyzed and compared.
Analysis on the arc Phenomenon of RF Circulator
HUANG Gui-Rong, GAO Hui, LIU Gong-Fa, lshang, WANG Jin-Xiang, FENG Lan-Lin
2005, 29(12): 1200-1204.
The characterization of the RF circulator of the Hefei Light Source is introduced. The arc phenomenon of circulator caused by RF harmonic or beam lost is analyzed in detail. In the case of the arc due to RF harmonic, the harmonic resonance on the RF transmission line has been observed from measurement. In the second case, the response of RF system to beam lost is described, and some related factors are discussed. A fast interlock circuit has been inserted into the RF system in order to protect the circulator.
Synchrotron radiation,applications of nuclear techniquees,etc
Diagnosis of the Output Characteristics of BSRF-3B3 Front End and Beamline
ZHAO Jia1, 2, CUI Ming-Qi1, ZHAO Yi-Dong1, TIAN Yu-Lian1, ZHOU Ke-Jin1, ZHENG Lei1, ZHU Jie1, SUN Li-Juan1, CHEN Kai1, MA Xiao-Yan1, HAN Yong1
2005, 29(12): 1205-1209.
All of the output characteristics of BSRF-3B3 beamline have achieved or surpassed the designed values after re-aligning and re-adjusting on-line. The flux is 7×1010phs/s/100mA and the best result of energy resolution (E/ΛE)is 5000@3.206keV at the station. The adjusting process, the diagnostic methods and the measured results of the output characteristics of both the front end and beamline are introduced in detail. The functions and shortages of double-wire BPM and fluorescence BPM for diagnosing and adjusting are analyzed.
Measurements of 41Ca in Biological Samples by AMS Using CaF2 Target
LI Shi-Hong, JIANG Shan, HE Ming, GUAN Yong-Jing, DONG Ke-Jun, WU Shao-Yong, YUAN Yuan, MI Sheng-Quan, LIU Shu-Tian, YUAN Jian
2005, 29(12): 1210-1213.
For determining numbers of 41Ca labeled biological samples, the analytical method of 41Ca/40Ca by Accelerator Mass Spectrometry (AMS) using CaF2 target was developed at the Beijing HI-13 AMS system. 41Ca in the biological samples and 41Ca standard samples were prepared to CaF2 with a more effective chemical separation and purification procedure. In the 41Ca AMS measurement, CaF3 negative ion was extracted from ion resource, 7+ charge state of particles was chosen after carbon foil stripping and accelerated at 8.5MV terminal voltage. 41Ca ions were finally recorded by an 140mbar P10 gas filled multi-anode ionization chamber detector. The results showed that 41Ca and the main isobar, 41K could be clearly identified in the two-dimensional density spectra, and the interference of 41K to 41Ca was eliminated with the very low 41K counting rate. The absolute measured values of 4 standard samples with 41Ca/40Ca in the range of 1.785×10-8—1.750×10-10 were in good linear relationship with the standard values (r2=0.997). After normalized with the 1.785×10-841Ca/40Ca standard, the measured values of S2 and S4 standard samples were in good agreement with the nominal values, however, the measured value of S3 deviated the nominal value largely. The 41Ca/40Ca of the biological blanks were estimated below 8.2×10-13.
The Study of Optimization of IMS Electric Field
WEI Yong-Bo, JIANG Da-Zheng
2005, 29(12): 1214-1218.
The Ion Mobility Spectrometry (IMS) has been known recently as an analytical technique to detect molecules of various materials in atmosphere pressure,especially those of hidden explosives and drugs .The design of the electric field is critical for resolution and performance of an IMS system. By electric field simulation and optimization, a better IMS spectrum was obtained.
Monte Carlo Simulation of High-energy Electron Beam Exposure in Resist
SONG Ying-Hui, ZHANG Yu-Lin, WEI Qiang, KONG Xiang-Dong
2005, 29(12): 1219-1224.
The complex scattering process of the high-energy(50keV≤E0≤100keV) electron beams with the Gaussian distribution in resist is simulated by Monte Carlo method with different energy range models. The backscatter coefficient of electrons and energy deposition distributions are presented under different exposure conditions. The simulation results are in good agreement with the experimental data. It is found that, in the energy range 50keV≤E0≤100keV, higher electron beam energy, thinner resist and lower substrate's atom number will cause lower proximity effect, which agrees with the corresponding experiment. The present results not only can help to optimize the exposure conditions in Electron Beam Lithography, but also supply more accurate data for proximity effect correction.