119224580
Gauge invariance and QCD twist-3 factorization for single spin asymmetries
A bstractThe collinear factorization at twist-3 for Drell-Yan processes is studied with the motivation to solve the discrepancy in literature about the single spin asymmetry in the lepton angular distribution, and to show how QCD gauge invariance is realized in the hadronic tensor. The obtained result here agrees with our early result derived with a totally different approach. In addition to the asymmetry we can construct another two observables to identify the spin effect. We show that the gauge invariance of different contributions in the hadronic tensor is made in different ways by summing the effects of gluon exchanges. More interestingly is that we can show that the virtual correction to one structure function of the hadronic tensor, hence to some weighted SSA observables, is completely determined by the quark form factor. This will simplify the calculation of higher order corrections. The corresponding result in semi-inclusive DIS is also given for the comparison with Drell-Yan processes.
118575585
QCD evolutions of twist-3 chirality-odd operators
We study the scale dependence of twist-3 distributions defined with chirality-odd quark-gluon operators. To derive the scale dependence we explicitly calculate these distributions of multi-patron states instead of a hadron. Taking one-loop corrections into account we obtain the leading evolution kernel in the most general case. In some special cases the evolutions are simplified. We observe that the obtained kernel in general does not get simplified in the large-N-c limit in contrast to the case of those twist-3 distributions defined only with chirality-odd quark operators. In the later, the simplification is significant. (C) 2012 Elsevier B.V. All rights reserved.
119108158
Azimuthal Dependence of DIS with Spin-1 Target
We study DIS with a spin-1 hadron or a nucleus polarized in arbitrary direction. The differential cross-section in this case will have an azimuthal dependence. We derive the dependence by including contributions from twist-2- and twist-3 QCD operators. The twist-3 contribution is computed at tree-level. A spin-1 hadron or nucleus can have nonzero tensor polarization. We find that all structure functions related to the tensor-polarization of the initial hadron can be extracted by study the azimuthal dependence. A nonzero result of the structure functions of a nucleus from experiment will indicate nontrivial inner structure of the nucleus.
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.
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.
135204416
Searching for new green wavelength shifters in polystyrene
A series of commercially available fluorescent compounds was tested as wavelength shifters in polystyrene for the tile/fiber SDC calorimeter. The objective was to find a green-fluorescing compound with short decay time (3--7 ns). Transmittance, fluorescence, and decay time measurements were performed in order to characterize each compound in polystyrene. These samples were also studies for radiation-induced damage.
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.
121554245
Coumarins as wavelength shifters in polystyrene
Abstract A series of commercially available coumarins was tested as wavelength shifters in polystyrene for a tile/fiber calorimeter application. The objective was to find a compound that when incorporated in a polystyrene matrix absorbed in the 400–450 nm wavelength range, fluoresced in the green region of the visible spectrum ( λ em = 450−550 nm), and exhibited both short decay time and high quantum yield. Transmittance, fluorescence, and decay time determinations were performed in order to characterize each coumarin in polystyrene. Two coumarins (C510 and C515) were found to have faster decay times (∼8 ns vs. 12 ns) and superior light output (100–120%) compared to the commonly-used green wavelength shifter, K-27.