2011 Vol. 35, No. 7

Particle and field theory
Uncertainty study of DS-(D-)→γlν (l=e,μ) decays determined by wave function
HOU Zhao-Yu, GUO Peng, WU Wen-Wang
2011, 35(7): 603-607. doi: 10.1088/1674-1137/35/7/001
Wave function is important for determining decay constants fDS- and fD-. Using the 5 types of D meson wave functions in the heavy quark limit, we studied the uncertainties of radiative pure-leptonic decays of DS-(D-) mesons. The branching ratios are (1.025390—1.706812) × 10-5 and (0.953498—1.576725) × 10-6 for DS- and D- decays, respectively, which are sensitive to the type of wave function.
Two loop low temperature corrections to electron self energy
Mahnaz Q, Samina S
2011, 35(7): 608-611. doi: 10.1088/1674-1137/35/7/002
We recalculate the two loop corrections in the background heat bath using real time formalism. The procedure of the integrations of loop momenta with dependence on finite temperature before the momenta without it has been followed. We determine the mass and wavefunction renormalization constants in the low temperature limit of QED, for the first time with this preferred order of integrations. The correction to electron mass and spinors in this limit is important in the early universe at the time of primordial nucleosynthesis as well as in astrophysics.
particle and nuclear astrophysics and cosmology
Unruh-Verlinde temperature and energy of (2+1)-dimensional matter coupled black hole via entropic force
HAN Yi-Wen, BAO Zhi-Qing, HONG Yun
2011, 35(7): 612-615. doi: 10.1088/1674-1137/35/7/003
Verlinde's recent work, which shows that gravity may be explained as an entropic force caused by the changes in information associated with the positions of material bodies, is extended to study the Unruh-Verlinde temperature and energy of a static spherically symmetric charged black hole. The results indicate that the Unruh-Verlinde temperature is equal to the Hawking temperature at the event horizon. The energy is dependent on the radius of the screen, which is also a consequence of the Gauss' laws of gravity and electrostatics.
A new parametric equation of state and quark stars
NA Xue-Sen, XU Ren-Xin
2011, 35(7): 616-621. doi: 10.1088/1674-1137/35/7/004
It is still a matter of debate to understand the equation of state of cold matter with supra-nuclear density in compact stars because of unknown non-perturbative strong interaction between quarks. Nevertheless, it is speculated from an astrophysical view point that quark clusters could form in cold quark matter due to strong coupling at realistic baryon densities. Although it is hard to calculate this conjectured matter from first principles, one can expect that the inter-cluster interaction will share some general features with the nucleon-nucleon interaction successfully depicted by various models. We adopt a two-Gaussian component soft-core potential with these general features and show that quark clusters can form stable simple cubic crystal structure if we assume that the wave function of quark clusters have a Gaussian form. With this parametrization, the Tolman-Oppenheimer-Volkoff equation is solved with reasonably constrained parameter space to give mass-radius relations of crystalline solid quark stars. With baryon number densities truncated at 2n0 at surface and the range of the interaction fixed at 2 fm we can reproduce similar mass-radius relations to that obtained with bag model equations of state. The maximum mass ranges from 0.5M to 3M. The recently measured high pulsar mass ( 2M) is then used to constrain the parameters of this simple interaction potential.
Nuclear and ion Physics
A study of meson-meson potential in the chiral quark model
LI Ming-Tao, DONG Yu-Bing, ZHANG Zong-Ye
2011, 35(7): 622-628. doi: 10.1088/1674-1137/35/7/005
An effective potential in a meson-meson system is discussed based on the SU(3) chiral constituent quark model, and the analytic form of the potential is explicitly given. In addition, the effective potential is employed to study the bound state problem of ωφ, which is related to the new resonance of f0(1810) observed in BESⅡ very recently.
Exploring nuclear symmetry energy with isospin dependence in neutron skin thickness of nuclei
LIU Min, LI Zhu-Xia, WANG Ning, ZHANG Feng-Shou
2011, 35(7): 629-634. doi: 10.1088/1674-1137/35/7/006
We propose an alternative way to constrain the density dependence of the symmetry energy from the neutron skin thickness of nuclei which shows a linear relation to both the isospin asymmetry and the nuclear charge with a form of Z2/3. The relation of the neutron skin thickness to the nuclear charge and isospin asymmetry is systematically studied with the data from antiprotonic atom measurement, and with the extended Thomas-Fermi approach incorporating the Skyrme energy density functional. An obviously linear relationship between the slope parameter L of the nuclear symmetry energy and the isospin asymmetry dependent parameter of the neutron skin thickness can be found, by adopting 70 Skyrme interactions in the calculations. Combining the available experimental data, the constraint of -20 MeV L 82 MeV on the slope parameter of the symmetry energy is obtained. The Skyrme interactions satisfying the constraint are selected.
Detection Technology and Methods
Preparation of a silicon micro-strip nuclear radiation detector by a two-step annealing process
LI Hai-Xia, LI Zhan-Kui, WANG Fang-Cong, WANG Zhu-Sheng, WANG Xiu-Hua, LI Chun-Yan
2011, 35(7): 635-637. doi: 10.1088/1674-1137/35/7/007
The annealing process for boron implantation is a crucial step during large size nuclear radiation detector fabrication. It can reduce the lattice defects and the projection straggling. A two-step annealing process for boron implantation was developed instead of a one-step annealing process, and the reverse body resistance of a silicon micro-strip detector was significantly increased, which means that the performance of the detector was improved.
A study of the active thermal control for the high energy detector on the HXMT
ZHANG Yi-Fei, LI Yan-Guo, WU Bo-Bing, ZHANG Yong-Jie, DONG Yong-Wei, SUN Jian-Chao, ZHAO Dong-Hua, XING Wen, CHAI Jun-Ying, KANG Shi-Xiu, SONG Li-Ming
2011, 35(7): 638-641. doi: 10.1088/1674-1137/35/7/008
A thermal control system (TCS) based on the resistance heating method is designed for the High Energy Detector (HED) on the Hard X-ray Modulation Telescope (HXMT). The ground-based experiments of the active thermal control for the HED with the TCS are performed in the ambient temperature range from -15 to 20 ℃ by utilizing the pulse width to monitor the interior temperature of a NaI(Tl) crystal. Experimental results show that the NaI(Tl) crystal's interior temperature is from 17.4 to 21.7 ℃ when the temperature of the PMT shell is controlled within (20±3) ℃ with the TCS in the interesting temperature range, and the energy resolution of the HED is maintained at 16.2% @ 122 keV, only a little worse than that of 16.0% obtained at 20 ℃. The average power consumption of the TCS for the HED with a low-emissivity shell is about 4.3 W, which is consistent with the simulation.
Study of radiation background at the north crossing point of the BEPCⅡ in collision mode
MO Xiao-Hu, ZHANG Jian-Yong, ZHANG Qing-Jiang, Achasov Mikhail, CAI Xiao, FU Cheng-Dong, Harris Fred, LIU Qian, Muchnoi Nikolay, QIN Qing, QU Hua-Min, WANG Yi-Fang, XU Jin-Qiang, ZHANG Tian-Bao
2011, 35(7): 642-655. doi: 10.1088/1674-1137/35/7/009
Understanding the radiation background at the north crossing point (NCP) in the tunnel of BEPCII is crucial for the performance safety of the High Purity Germanium (HPGe) detector, and in turn of great significance for long-term stable running of the energy measurement system. Therefore, as the first step, a NaI(Tl) detector is constructed to continuously measure the radiation level of photons as background for future experiments. Furthermore, gamma and neutron dosimeters are utilized to explore the radiation distribution in the vicinity of the NCP where the HPGe detector will be located. Synthesizing all obtained information, the shielding for neutron irradiation is studied based on model-dependent theoretical analysis.
Fluence rate linear response limit of a scintillators to γ-rays
GUAN Xing-Yin, SONG Zhao-Hui, HAN He-Tong
2011, 35(7): 656-659. doi: 10.1088/1674-1137/35/7/010
Scintillation detectors based on LSO, CeF and PbWO are the main candidates for measuring γ-rays in a mixed γ/n pulsed radiation field with high intensity. An experiment using the Lissajous figure method to study the high fluence rate response behavior of three kinds of commonly used scintillators is introduced in this paper. The result shows that the fluence rate linear response limit of LSO and CeF is 1.9×1019 and 2.1×1018MeV/(cm2·s), respectively, and the PbWO scintillator still maintains linear response when the fluence rate of γ-ray is up to 2.0 × 1020 MeV/(cm2·s).
Effects due to a Pu-C source on a HPGe detector and the corresponding neutron shielding
ZHANG Jian-Yong, FU Cheng-Dong, MO Xiao-Hu, ZHANG Zi-Liang, LI Dao-Wu, WANG Bao-Yi
2011, 35(7): 660-667. doi: 10.1088/1674-1137/35/7/011
A gamma spectrum of a Pu-C source is measured using a p-type HPGe detector, whose three peaks (full energy, single-escape and double-escape peak) can be used as a calibration source for the beam energy measurement system of BEPCII. The effect of fast neutron damage on the energy resolution of the HPGe detector is studied, which indicates that the energy resolution begins to deteriorate when the detector is subject to 2×107 n/cm2 fastneutrons. The neutron damage mechanism and detector repair methods are reviewed. The Monte Carlo simulation technique is utilized to study the shielding of the HPGe detector from the fast neutron radiation damage, which is of great significance for the future commissioning of the beam energy measurement system.
Neutron beam monitor based on a boron-coated GEM
ZHOU Jian-Rong, SUN Zhi-Jia, LIU Ben, WANG Yan-Feng, YANG Gui-An, ZHOU Liang, XU Hong, DONG Jing, YANG Lei, LI Yi
2011, 35(7): 668-674. doi: 10.1088/1674-1137/35/7/012
A new thermal neutron beam monitor with a Gas Electron Multiplier (GEM) is developed to meet the needs of the next generation of neutron facilities. A prototype chamber has been constructed with two 100 mm×100 mm GEM foils. Enriched boron-10 is coated on one surface of the aluminum cathode plate as the neutron convertor. 96 channel pads with an area of 8 mm×8 mm each are used for fast signal readout. In order to study the basic characteristics of a boron-coated GEM, several irradiation tests were carried out with α source 239Pu and neutron source 241Am(Be). The signal induced by the neutron source has a high signal-to-noise ratio. A clear image obtained from α source 239Pu is presented, which shows that the neutron beam monitor based on a boron-coated GEM has a good two-dimensional imaging ability.
Radiation emission from the “Rhodotron-TT200” cavity
Farshid Tabbakh, Mahmud Borhani
2011, 35(7): 675-678. doi: 10.1088/1674-1137/35/7/013
In this paper, the X-rays emitted from the Rhodotron-TT200 cavity have been studied in depth. We found that the Bremsstrahlung interaction is the only contribution of X-ray generation important to safety. The X-ray dose rate in the Rhodotron vault is calculated for normal conditions based on MCNP4C results. The presented calculation shows good agreement with the experimental measurements, which consequently confirms the reliability of the calculation for use in shielding design and other safety aspects.
CSNS H- ion source test stand
WU Xiao-Bing, OUYANG Hua-Fu, CHI Yun-Long, HE Wei, HUANG Tao, LI Gang, LIU Ying-Man, LU Yan-Hua, XU Tao-Guang, ZHANG Jun-Song, ZHANG Hua-Shun, ZHAO Fu-Xiang
2011, 35(7): 679-683. doi: 10.1088/1674-1137/35/7/014
The Penning surface plasma source is adopted as the China Spallation Neutron Source (CSNS) H- ion source. The designed energy and beam current of the source are 50 keV and 20 mA, respectively, with a normalized root mean square (norm. rms.) emittance of 0.2 πmm·mrad. The construction of a H- ion source test stand has been completed, and the commissioning of the source is in progress. Stable H- ion beams with energy of 50 keV and current up to 50 mA are attained. Emittance measurement for the H- beam is being prepared.
Design and end chamfer simulation of PEFP beam line curved dipole magnets
ZHU Ying-Shun, YANG Mei, ZHANG Zhuo, CHEN Wan, YIN Bao-Gui, SHI Cai-Tu, KANG Wen
2011, 35(7): 684-688. doi: 10.1088/1674-1137/35/7/015
The design, fabrication and field measurement of 11 DC curved dipole magnets for the PEFP Beam Line have been completed. In this paper, a design method for a complex end chamfer using OPERA-3D is proposed. The conventional method for estimating chamfer shape is extended and applied to a curved dipole magnet by a coordinate transformation. Using the interface with CAD software, the complex end chamfer is modeled and fully determined by 3D simulation to meet the field uniformity requirement. The magnetic field measurement results are in good agreement with the simulation. The design considerations, field simulation results, end chamfer development process and measurement results are presented in detail.
Synchrotron radiation,applications of nuclear techniquees,etc
Study on the chemical composition features of Longquan celadon excavated from the Chuzhou site of Huai'an City in Jiangsu Province by EDXRF
LI Li, FENG Song-Lin, FENG Xiang-Qian, XU Qing, YAN Ling-Tong, MA Bo, HUO Hua
2011, 35(7): 689-694. doi: 10.1088/1674-1137/35/7/016
A mass of Longquan celadon shards were excavated from the Chuzhou site of Huai'an City in Jiangsu Province, China. These celadon shards were fired during the period of the Late Yuan Dynasty to the Tianshun era of the Ming Dynasty, as identified by archaeologists at Nanjing Museum. In order to research the chemical composition features of this ancient celadon porcelain, energy dispersive X-ray fluorescence (EDXRF) for non-destructive analysis was used to determine the chemical composition of the porcelain body and glaze in these shards. The results indicate that Ti and Fe in the body of Longquan celadon are characteristic elements which can distinguish porcelain produced during the Late Yuan Dynasty from those produced in the Ming Dynasties. The results of the principal component analysis (PCA) show that different body and glaze raw materials were used for the production of porcelain in different periods and the raw materials of the body and glaze are also different for various vessel shapes. The chemical compositions in the porcelain body of civilian ware are slightly different. The imperial and civilian Longquan celadon porcelains produced during the Hongwu era to the Tianshun era of the Ming Dynasty are distinguishable by the MnO, Fe2O3, Rb2O and SrO content in their porcelain glaze.
Z charmoniumlike mesons
Arafat Gabareen, Stephen Lars
2011, 35(7): 695-702. doi: 10.1088/1674-1137/35/7/017
A brief review of the experimental situation concerning the electrically charged charmoniumlike meson candidates, Z-, is presented.