L. Yu

Observation of the Superheavy Nuclide 271 Ds

With the recent commissioning of a gas-filled recoil separator at Institute of Modern Physics (IMP) in Lanzhou, the decay properties of (271)Ds (Z = 110) were studied via the Pb-208(Ni-64, n) reaction at a beam energy of 313.3MeV. Based on the separator coupled with a position sensitive silicon strip detector, we carried out the energy-position-time correlation measurements for the implanted nucleus and its subsequent decay alphas. One alpha-decay chain for (271)Ds was established. The.. energy and decay time of the (271)Ds nucleus were measured to be 10.644 MeV and 96.8 ms, which are consistent with the values reported in the literature.

Directed and elliptic flows in heavy ion collisions at intermediate energies

A theoretical investigation of directed and elliptic flows for different light particles and fragments in collisions of 40Ca + 40Ca and 112Sn + 112Sn is conducted below 100 MeV/nucleon in the isospin-dependent quantum molecular dynamics model. With increasing incident energy, the directed flow rises from negative to positive, while the elliptic flow decreases with the increasing incident energies. The directed flow for 40Ca + 40Ca system is not sensitive to the nuclear equation of states (EOS), but the directed flow for 112Sn + 112Sn system is sensitive to the EOS. However, the elliptic flows for both 40Ca + 40Ca and 112Sn + 112Sn systems are not sensitive to EOS. A study of the dependence of directed and elliptic flows on fragment charge (mass) is also performed. The information on EOS can be extracted by investigating the directed flow at intermediate energies when the combined mass is large or small.

An improved method of energy calibration for position-sensitive silicon detectors *

Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced.The energy resolution of the 8.088 Me V α decay of213 Rn is determined to be about 87 ke V(FWHM), which is better than the result of the traditional method, 104 ke V(FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances.Energy calibration of resistive charge division-based position-sensitive silicon detectors is achieved by parabolic fitting in the traditional method, where the systematic variations of vertex and curvature of the parabola with energy must be considered. In this paper we extend the traditional method in order to correct the fitting function, simplify the procedure of calibration and improve the experimental data quality. Instead of a parabolic function as used in the traditional method, a new function describing the relation of position and energy is introduced. The energy resolution of the 8.088 MeV α decay of 213Rn is determined to be about 87 keV (FWHM), which is better than the result of the traditional method, 104 keV (FWHM). The improved method can be applied to the energy calibration of resistive charge division-based position-sensitive silicon detectors with various performances.

Experiment for synthesis of neutron- deficient protactinium isotopes

The complete fusion reaction 40 Ca+ 175 Lu was studied at a beam energy of 5.1 MeV u �1 . Evaporation residues recoiled from the target were separated from the primary beam by the gas-filled recoil separator SHANS and then implanted into the focal plane detection system. Based on the energy-positiontime correlation measurement, neutron-deficient nuclei − 208 213 Ac, 212 Pa and 211 Th produced in this reaction were identified. Previously reported decay properties of the ground state in 212 Pa were confirmed and improved values of − + 5.1 1.7 ms and 8.250(20) MeV for the half-life and α-particle energy of 212 Pa were obtained. No correlated decay chain arising from 211 Pa was observed and an upper limit for the cross section of 211 Pa was estimated.