Authors:Li Cheng-Bo; Wen Qun-Gang, Zhou Shu-Hua, Jiang Zong-Jun, Fu Yuan-Yong, Zhou Jing, Meng Qiu-Ying Wang Xiao-Lian First page: 054001 Abstract: The Coulomb barrier and electron screening cause difficulties in directly measuring nuclear reaction
cross sections of charged particles at astrophysical energies. The Trojan-horse method (THM) has
been introduced to solve the difficulties as a powerful indirect tool. In order to understand
experimental spectra better, Geant4 is employed to simulate the method. Validity and reliability of
simulation data are examined by comparing the experimental data with simulated results. The Geant4
simulation of THM improves data analysis and is beneficial to the design for future related
experiments. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Shu Neng-Chuan; Jia Min, Chen Yong-Jing Liu Ting-Jin First page: 054101 Abstract: Calculations of prompt fission neutron spectra (PFNS) from the 235 U(n, f) reaction were performed
with a semi-empirical method for E n = 7.0 and 14.7 MeV neutron energies. The total PFNS were
obtained as a superposition of (n,xnf) pre-fission neutron spectra and post-fission spectra of
neutrons which were evaporated from fission fragments, and these two kinds of spectra were taken as
an expression of the evaporation spectrum. The contributions of (n,xnf) fission neutron spectra on
the calculated PFNS were discussed. The results show that emission of one or two neutrons in the
(n,nf) or (n,2nf) reactions influences the PFNS shape, and the neutron spectra of the (n,xnf)
fission-channel are soft compared with the neutron spectra of the (n,f) fission channel. In
addition, analysis of the multiple-chance fission component showed that second-chance fission
dominates the PFNS with an incident neutron energy of 14.7 MeV whereas first-chance fission
dominates t... Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:H. Eslamizadeh First page: 054102 Abstract: The evaporation residue cross section anisotropy of the fission fragment angular distribution,
pre-scission neutron multiplicity and the pre-saddle and post-saddle contributions of the
pre-scission neutron multiplicity were analyzed within a stochastic approach based on one-, two- and
three-dimensional Langevin equations for the compound nucleus 224 Th formed via a complete fusion.
In these calculations, dissipation was generated through the chaos weighted wall and window friction
formula. Comparison of the theoretical results with the experimental data showed that
three-dimensional Langevin equations with dissipation generated through the chaos weighted wall and
window friction formula make it possible to reproduce satisfactorily the above-mentioned
experimental data. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Liu Lang First page: 054103 Abstract: The unitary correlation operator method (UCOM) and the similarity renormalization group theory (SRG)
are compared and discussed in the framework of the no-core Monte Carlo shell model (MCSM)
calculations for 3 H and 4 He. The treatment of spurious center-of-mass motion by Lawson's
prescription is performed in the MCSM calculations. These results with both transformed interactions
show good suppression of spurious center-of-mass motion with proper Lawson's prescription parameter
β c.m. values. The UCOM potentials obtain faster convergence of total energy for the ground state
than that of SRG potentials in the MCSM calculations, which differs from the cases in the no-core
shell model calculations (NCSM). These differences are discussed and analyzed in terms of the
truncation scheme in the MCSM and NCSM, as well as the properties of the potentials of SRG and UCOM. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Shi Wen-Xian; Chen Qi-Bo First page: 054105 Abstract: The spectroscopic properties and angular momentum geometry of the wobbling motion of a simple
triaxial rotor are investigated within the triaxial rotor model. The obtained exact solutions of
energy spectra and reduced quadrupole transition probabilities are compared to the approximate
analytic solutions from the harmonic approximation formula and Holstein-Primakoff formula. It is
found that the low lying wobbling bands can be well described by the analytic formulae. The
evolution of the angular momentum geometry as well as the K -distribution with respect to the
rotation and the wobbling phonon excitation are studied in detail. It is demonstrated that with the
increase of the wobbling phonon number, the triaxial rotor changes its wobbling motions along the
axis with the largest moment of inertia to the axis with the smallest moment of inertia. In this
process, a specific evolutionary track that can be used to depict the motion of a triaxial rotating
nucleus is proposed. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Chen Tian-Xiang; Li Cheng, Sun Yong-Jie, Chen Hong-Fang, Shao Ming, Tang Ze-Bo, Yang Rong-Xing, Zhou Yi Zhang Yi-Fei First page: 056003 Abstract: In order to test the performance of detector prototypes in a laboratory environment, we design and
build a large area (90 cm×52 cm) test platform for cosmic rays based on a well-designed Multi-gap
Resistive Plate Chamber (MRPC) with excellent time resolution and a high detection efficiency for
minimum ionizing particles. The time resolution of the MRPC module used is tested to be ∼80 ps, and
the position resolution along the strip is ∼5 mm, while the position resolution perpendicular to the
strip is ∼12.7 mm. The platform constructed by four MRPC modules can be used for tracking cosmic
rays with a spatial resolution of ∼6.3 mm, and provide a reference time ∼40 ps. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Cheng Peng; Pei Shi-Lun, Wang Jiu-Qing Li Zhi-Hui First page: 057002 Abstract: The ADS (Accelerator Driven subcritical System) driver linac in China is designed to run in CW
(Continuous Wave) mode with 10 mA designed beam current. In this scenario, the beam-induced
parasitic modes in the ADS driver linac may make the beam unstable or deteriorate the beam
performance. To evaluate the parasitic mode effect on the beam dynamics systematically, simulation
studies using the ROOT-based numerical code SMD have been conducted. The longitudinal beam
instability induced by the HOMs (High Order Modes) and SOMs (Same Order Modes) has little effect on
the longitudinal beam performance for the current ADS driver linac design based on the 10 MeV/325
MHz injector I from previous studies. Here the transverse parasitic mode (i.e., dipole HOM) effect
on the transverse beam performance at the ADS driver linac exit is investigated. To more reasonably
quantify the dipole mode effect, the multi-bunch effective emittance is introduced in this paper. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Geng Hao; Zhao Zhong-Jun Duan Yi-Xiang First page: 057003 Abstract: We experimentally studied ion behavior and interelectrode breakdown voltage. The ion behavior of a
drift tube directly influences the detection of ion intensity, and then influences the detection
sensitivity of a system. Interelectrode voltage and pressure directly influence the ion behavior.
Gas discharge between electrodes influences the adjustments required for interelectrode voltage. The
experimental results show: ion intensity increases exponentially with the increment of voltage
between drift electrodes; ion intensity decreases exponentially as pressure increases; with the
increment of pressure, the breakdown voltage at first decreases, and then increases; ion injection
has a significant influence on breakdown voltage, and this influence depends on the pressure and
shapes of the electrodes. We explain the results above through assumptions and by mathematical
methods. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:Bian Wen-Long; Ma Li-Zhen, Wu Wei, Yao Qing-Gao, Guan Ming-Zhi Du Jun-Jie First page: 057004 Abstract: A new 7.0 T asymmetric active shield superconducting magnet for Penning traps is proposed in this
work. The magnet has two field regions whose homogeneity is better than 0.5 ppm. Linear and
nonlinear methods are used for the asymmetric electromagnetic optimization. Stress analysis,
mechanical design and a quench protection system design are also introduced in this paper. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)

Authors:He Xiang; Zhao Feng-Li Wang Xiang-Jian First page: 057007 Abstract: Waveguide directional couplers working at 5.712/11.9924 GHz are developed. Even holes symmetrical to
the structure are drilled along the central line of the narrow-wall of the waveguide, which are used
to couple the electromagnetic power from the main-waveguide to the sub-waveguide. The final
prototypes have achieved satisfactory performances of high-power, ultra-high-vacuum and
high-directivity. The microwave measurement results are also qualified. Citation: Chinese Physics C PubDate: 2015-05-20T00:00:00Z Issue No:Vol. 39, No. 5 (2015)