95842495
The Beijing ISOL initial conceptual design report
Abstract Peking University (PKU) and China Institute of Atomic Energy (CIAE) are jointly proposing to construct a large science facility, temporarily called “Beijing ISOL”. This facility aims at both basic science and application goals, and is based on the double driver system, namely reactor driving and intense deuteron-beam driving. On the basic science side, the radioactive ion beams produced from the isotope separation online (ISOL) device will be used to study the new physics and technologies at the limit of nuclear stability. On the other side regarding to the applications, the facility will be devoted to material research for the nuclear energy system by using typically the intense neutron and ion beams. In the whole process of design, construction and operation, an opening policy will be pursued, and the domestic and international cooperation will be emphasized. Through this project, a joint research and education mode will be established.
119215240
Neutron energy spectrum measurements with a compact liquid scintillation detector on EAST
A neutron detector based on EJ301 liquid scintillator has been employed at EAST to measure the neutron energy spectrum for D-D fusion plasma. The detector was carefully characterized in different quasi-monoenergetic neutron fields generated by a 4.5 MV Van de Graaff accelerator. In recent experimental campaigns, due to the low neutron yield at EAST, a new shielding device was designed and located as close as possible to the tokamak to enhance the count rate of the spectrometer. The fluence of neutrons and ?-rays was measured with the liquid neutron spectrometer and was consistent with 3He proportional counter and NaI(Tl) ?-ray spectrometer measurements. Plasma ion temperature values were deduced from the neutron spectrum in discharges with lower hybrid wave injection and ion cyclotron resonance heating. Scattered neutron spectra were simulated by the Monte Carlo transport Code, and they were well verified by the pulse height measurements at low energies.
118079649
Cross-section measurement and analysis for the Sm-149 (n, alpha) Nd-146 reaction at 6.0 MeV
We have measured the $^{149}\mathrm{Sm}(n,\ensuremath{\alpha})^{146}\mathrm{Nd}$ cross section at 6.0 MeV to be $0.12\ifmmode\pm\else\textpm\fi{}0.018$ mb. This is the first reported result for this cross section in the MeV region and so should be helpful for constraining nuclear data evaluations (which differ by a factor of 40 for this reaction at this energy) and for testing and improving nuclear models. The experiment was performed at the at the 4.5-MV Van de Graaff accelerator of Peking University. Neutrons were produced via the $^{2}\mathrm{H}(d,n)^{3}\mathrm{He}$ reaction using a deuterium gas target, and absolute neutron flux was determined with a small $^{238}\mathrm{U}$ fission chamber. Alpha particles were detected using a two-section gridded ionization chamber in which two large-area $^{149}\mathrm{Sm}{}_{2}{\mathrm{O}}_{3}$ samples were placed back-to-back so that the cross section and forward/backward ratio were measured for nearly the entire 4$\ensuremath{\pi}$ solid angle. The data were compared to statistical-model predictions using the code talys. Good agreement between the measured and theoretical cross sections could be obtained with a small modification of the $\ensuremath{\alpha}$-optical potential parameters from their default values in talys. However, we were not able to reproduce the measured forward/backward ratio. In addition, using the previously reported $^{147}\mathrm{Sm}(n,\ensuremath{\alpha})^{144}\mathrm{Nd}$ cross section at 6.0 MeV together with our new result, good agreement was found between the measured and predicted cross-section ratio for these two isotopes. Finally, none of the existing evaluated data libraries are in agreement with our new data to within the experimental uncertainties.
119182289
Single spin asymmetry in lepton angular distribution of Drell-Yan processes
A bstractWe study the single spin asymmetry in the lepton angular distribution of Drell-Yan processes in the framework of collinear factorization. The asymmetry has been studied in the past and different results have been obtained. In our study we take an approach different than that used in the existing study. We explicitly calculate the transverse-spin dependent part of the differential cross-section with suitable parton states. Because the spin is transverse, one has to take multi-parton states for the purpose. Our result agrees with one of the existing results. A possible reason for the disagreement with others is discussed.
120119782
Calculation of half-lives of cluster decay by using proximity potential with a new universal function
Abstract The half-lives of cluster decays are calculated using proximity potential model with a new universal function, and compared to the experimentally measured values and the theoretical ones of liquid drop model. The results of the present calculations show reasonable agreement with the experimental data as well as the half-life calculations of liquid drop model. In the present work, it is certified that proximity potential model with the new universal function can be used successfully to calculate the half-lives of cluster decays for heavy nuclei.
120110625
Study of the universal function of nuclear proximity potential between α and nuclei from density-dependent nucleon-nucleon interaction
The universal function of proximity potential between α and nuclei is systematically studied from the double-folding model with the density-dependent nucleon-nucleon interaction (CDM3Y6) by analyzing different target nuclei with Z = 48–92. The analytical formula of universal function is obtained at s0 > −1 by fitting all of the calculated values. Using this formula we calculate the half-lives of α decay for heavy nuclei in comparison with the values of the experimental data. It is shown that the half-lives of the α decay calculated from the presently obtained universal function in proximity potential can keep within a factor of 3 with the experimental data.
55019383
Gamma-irradiation of coumarins in a polystyrene matrix
Abstract Polystyrene samples doped with commercially available coumarin derivatives were prepared and tested as wavelength shifters for plastic scintillation applications. Radiation damage studies were performed utilizing a 60 Co source. Transmittance and light yield measurements were recorded before and after irradiation (100 kGy), and after annealing of the samples. All samples experienced losses in transmittance and light yield as a result of radiation-induced damage to the polymer and in some cases, the dopant. None of the coumarins examined in this study outperformed the commonly-used green wavelength shifter, K-27, after irradiation.
120893139
Calculation of {alpha} preformation for nuclei near N=162 and N=184
The {alpha} preformation factor and the penetration probability are carefully analyzed for heavy and superheavy even-even nuclei. The penetration probability of an {alpha} cluster in the parent nucleus is calculated within the WKB approximation, whereas the nuclear potential between an {alpha} cluster and the daughter nucleus is obtained in the frame of a double-folding model with a density-dependent nucleon-nucleon interaction, in which the zero-range exchange term is supplemented. The {alpha} preformation factors in different shell regions are compared. It is shown that shell effects play an important role in {alpha} preformation. The preformation factor can supply information on the nuclear structure, and the penetration probability mainly determines the {alpha}-decay half-life. The results indicate that the deformed-subshell region at N=162 is different from that at N=152, and Z=114 and N=184 may lie in the closed-shell region.