T. H. Huang

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.

A NEW ESTIMATE OF B (RHO , OMEGA ) + GAMMA IN THE LIGHT-CONE QCD SUM RULE

We propose a new estimate of the process B(,)+ by using the light-cone QCD sum rule. The aim is to choose the chiral quark current operators in order to eliminate the uncertainty arising from the chiral-even operators in the correlator. In the case of neglecting the corrections from the -meson mass, the sum rules for form factors are obtained, which are valid to twist-three accuracy. The resulting branching ratios are consistent with the experimental data.We propose a new estimate of the process B(,)+ by using the light-cone QCD sum rule. The aim is to choose the chiral quark current operators in order to eliminate the uncertainty arising from the chiral-even operators in the correlator. In the case of neglecting the corrections from the -meson mass, the sum rules for form factors are obtained, which are valid to twist-three accuracy. The resulting branching ratios are consistent with the experimental data.

Observation of superheavy nuclide 271Ds based on the Gas-filled separator at IMP

A gas-filled recoil separator was designed and built newly at Institute of Modern Physics (IMP) in Lanzhou. With the recent commissioning of the separator, the decay properties of 271Ds were studied via the 208Pb (64Ni, n) reaction at a beam energy of 313.3 MeV. One α-decay chain for 271Ds was established in total. The experimental result is consistent with the values reported in the literature.

Observation of a new transition in the {beta}-delayed neutron decay of {sup 18}N

A new transition is reported in the beta-delayed neutron decay of {sup 18}N. The observed neutron energy is 3.78{+-}0.05 MeV with a branching ratio of 0.05{+-}0.03%, which corresponds to an excitation energy of 12.05{+-}0.05 MeV in the daughter nucleus {sup 18}O. The log ft value of this transition is 5.24{+-}0.3, which, together with the previously reported electron scattering data, determines the J{sup {pi}} value of this level to be 1{sup -}. The experimental data are compared to the shell model calculations in different model spaces.

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.

Experimental study of the {beta}-delayed neutron decay of {sup 21}N

The first spectroscopic study for the beta decay of N-21 is carried out based on beta-n, beta-gamma, and beta-n-gamma coincidence measurements. The neutron-rich N-21 nuclei are produced by the fragmentation of the E/A=68.8 MeV Mg-26 primary beam on a thick Be-9 target and are implanted into a thin plastic scintillator that also plays the role of beta detector. The time of flight of the emitted neutrons following the beta decay are measured by the surrounding neutron sphere and neutron wall arrays. In addition, four clover germanium detectors are used to detect the beta-delayed gamma rays. Thirteen new beta-delayed neutron groups are observed with a total branching ratio of 90.5 +/- 4.2%. The half-life for the beta decay of N-21 is determined to be 82.9 +/- 7.5 ms. The level scheme of O-21 is deduced up to about 9 MeV excitation energy. The experimental results for the beta decay of N-21 are compared to the shell-model calculations.