(EC/β+) Decay of 130Nd and 140Tb

Isotopes,¹³⁰Nd and ¹⁴⁰Tb were produced using enriched targets ⁹⁶Ru and ¹⁰⁶Cd, respectively,bombarded by ³⁶Ar ion beam. The two nuclides were identified and studied by a He-jet tape transport system in combination with "X-γ" and "γ-γ" coincidence measure- ments. The half-life of ¹³⁰Nd was determined to be (13±2)s. The EC/β⁺ decay scheme of 130Nd was proposed for the first time, and the spins and parties of the ground-state and observed low-lying states in the daughter nucleus ¹³⁰Pr were speculated tentatively. The previous simple EC/β⁺ decay scheme of ¹⁴⁰Tb was revised, and the spin-parity of its groundstate was assigned to be 7⁺.     

Calculation of astrophysical reaction rate of 82Ge(n,γ)83Ge

The neutron capture reaction on a neutron-rich near closed-shell nucleus ⁸²Ge may play an important role in the r-process following the fallout from nuclear statistical equilibrium in core-collapse supernovae. By carrying out a DWBA analysis for the experimental angular distribution of ⁸²Ge(d, p)⁸³Ge reaction we obtain the single particle spectroscopic factors, S_2,5/2 and S_0,1/2 for the ground and first excited states of ⁸³Ge=⁸²Ge⊙n, respectively. And then these spectroscopic factors are used to calculate the direct capture cross sections for the ⁸²Ge(n, γ)⁸³Ge reaction at energies of astrophysical interest. The optical potential for neutron scattering on unstable nucleus ⁸²Ge is not known experimentally. We employed a real folding potential which was calculated by using the proper ⁸²Ge density distribution and an effective nucleon-nucleon force DDM3Y. The neutron capture reactions on neutron-rich closed-shell nuclei are expected to be dominated by the direct capture to bound states. We will show that the direct capture rates on these nuclei are sensitive to the structure of the low-lying states.     

(EC+β+) Decay of 130Pm and 128Pr

¹³⁰Pm and ¹²⁸ Pr were produced by irradiation of ⁹⁶Ru with 171MeV ³⁶Ar beam,and a He-jet recoil tape transport system transported radioactivities to shielded reigon. Based on X-γ-t and γ-γ-t coincidence measurements ,the (EC+β⁺)decay scheme of ¹³⁰Pm was proposed for the first time and the (EC+β⁺)decay scheme of ¹²⁸Pr was revised.     

(EC+β+) Decay of 133Sm and 1.1s Isomer of 133Pr

By irradiation of an enriched target of ⁹⁶Ru with ⁴⁰Ca and using a helium-jet fast tape transport system in combination with X-γ and γ-γ coincidence measurements,the very neutron deficient isotope ¹³³Sm was produced and studied. A simple(EC+β⁺) decay scheme of Sm is proposed for the first time. A by product ¹³³Pr was produced simultaneously because of the ^98－102Ru contents of the ruthenium target. The half-life of an 11/2^－ low-lying isomeric state in ¹³³Pr has been measured to be (1.1±0.2)s. Using single-particle model,the reduced transition probabilities of the 11/2^－ isomers in ^{131,133,135,137}Pr are extracted from their experimental half-lives and compared with the Weisskopf estimate.     

A note on Ξc(3055)+ and Ξc(3123)+

The Babar Collaboration announced two new excited charmed baryons Ξ_c(3055)⁺ and Ξ_c(3123)⁺. We study their strong decays assuming they are D-wave states. Some assignments are excluded by comparing our numerical results with the experimental values of the total widths of Ξ_c(3055)⁺ and Ξ_c(3123)⁺. We also suggest some possible decay modes, which will be helpful to     

Calculation of prompt fission neutron spectra for 235U(n,f)

The prompt fission neutron spectra for the neutron-induced fission of ²³⁵U at E_n < 5 MeV are calculated using nuclear evaporation theory with a semi-empirical model, in which the nonconstant and constant temperatures related to the Fermi gas model are taken into account. The calculated prompt fission neutron spectra reproduce the experimental data well. For the n(thermal)+²³⁵U reaction, the average nuclear temperature of the fission fragment, and the probability distribution of the nuclear temperature, are discussed and compared with the Los Alamos model. The energy carried away by γ rays emitted from each fragment is also obtained and the results are in good agreement with the existing experimental data.     

First Study of Weak (EC+β+) Decay Branch for the Neutron-Deficient Isotoep 209Fr

²⁰⁹Fr has been produced by irradiation of ¹⁹⁷Au with ¹⁶O from SFC accelarator uia the fusion-evaporation 4n channel.The(EC+β⁺)decay of ²⁰⁹Fr has been studied by a He-jet tape transport system.The decay scheme is proposed for the first time based on γ-t,X-γ-t,γ-γ-t coincidece and γ-γ delay coincidence measurements,which takes account of 20 observed γ ray.Five members of low-lying states in ²⁰⁹Rn can be explained by the multi-plet [(²¹⁰Rn2⁺)(νf_5/2)^－1].The branching ratio for(EC+β⁺) decay of ²⁰⁹Fr has been estimated experimentaly to be(3.0±1.5)%.     

175Hf核ε衰变的IXK/Iγ(343keV)比值计算和分析及其辐射数据计算

简要地介绍了¹⁷⁵Hf核ε衰变的I_XK/I_γ(343keV)比值的计算方法与实验测量的比较与分析,并在此基础上,计算得到了P_γ(343keV)=0.869±0.004,还给出了¹⁷⁵Hf核ε衰变的辐射数据的计算与推荐     

Study of D0→π－l+νl Decay

In this paper, the D⁰→π^－l⁺ν_l decay process is studied by applying light-cone QCD sum rules. The form factor of D→π transition is calculated by choosing a correlation function with a chiral current to eliminate the effect caused by the uncertainty of the twist-3 function of the pion. Therefore the calculated result of the form factor is improved, and the branching ratio of the D⁰→π^－l⁺ν_l decay process is consistent with the new experimental data.     

Three Body Amplitude Analysis of the Process a2(1320)→π+π+π－

We analyze the decay amplitudes of the process a₂(1320)→π⁺π⁺π^－ using the tensor analysis method and show how to obtain three body amplitudes.     

Franck--Condon factors and r-Centroids for the A 1∑+u-X1∑+g Band System of 107,109Ag2: Comparison of the Observed and Calculated Absorption Band Strengths

Franck-Condon factors and r-centrolds for the, A^1 ∑^＋ u-X^1∑^＋ 9 band system of ^107,109Ag2 are computed using Morse and Rydberg-Klein-Rees potentials for both lower and upper electronic states. The differences between the two sets of results are typically in the third decimal place for transitions involving vibrational levels with ν＇ and ν＂ up to about 15. Somewhat larger deviations appear for higher vibrational levels, but both sets of results follow the same pattern, which is to match well with the relative absorption band strength distribution in our experimental spectrum. The relative absorption band strengths are calculated by assuming that the electronic transition moment has only a weak dependence on the internuclear distance r. Good agreement between our measured and calculated absorption band strength ratios is found, which provides an excellent test of the calculated Franck- Condon factors and relative absorption band strengths. The r-centrold value for the （ν＇ = 0, ν＂ = 0） band is found to be approximately equal to the average value of r＇ and r＇＇e , indicating that the potentials of both states are not significantly aaharmonic around their minimum regions.     

Finite Size Vertex Correction to the Strong Decay of ηc and χc States and a Determination of αs(mc)

In previous calculations of the strong decay of a charmonium,the first-order momentum dependence of the quark propagator is kept. It was found that the finite-size vertex correction to the Γ(J/ψ→3g) process is large. In this paper we calculate the two-gluon decay widths of η_c,χ_c0 and χ_c2 by including the full momentum dependence of the quark propagator. Comparing to the zero-order calculation we find that the finite-size vertex correction factor to the two-gluon decay widths of η_c is 1.32,and for the two gluon decays of χ_c0 and χ_c2,the vertex correction factors are 1.45 and 1.26, respectively. With the corrected decay widths Γ(η_c→2g) we extract the value as α_s(m_c)=0.28±0.05 which agrees with that calculated from the Γ(J/ψ→3g) process with the same correction. The finite-size vertex correction to the process Γ(η_c→3g) is not as large as that to the process Γ(J/ψ→3g).     

The Cross Section Measurement for the Reactions of 48,46Ti(n,p) 48,46Sc 50Ti(n,α) 47Ca and 58Ni (n,2n) 57Ni 58Ni(n,p)58m+gCo

The cross sections for the ⁵⁰Ti(n,α)⁴⁷Ca,⁴⁶Ti(n,p)⁴⁶Sc、⁴⁸Ti(n,p)⁴⁸Sc and ⁵⁸Ni(n,2n)⁵⁷Ni ⁵⁸Ni(n,p)^58m+gCo reactions have been measured by using the activation method relative to the cross sections of the ²⁷Al(n,α)²⁴Na reaction in the neutron energy range of 13.50—14.81MeV.The neutron energies were determined by the cross section ratios of the ⁹⁰Zr(n,2N) ^89m+gZr and ⁹³Nb (n,2n) ^92mNb reactions.The results obtained are compared with the published and to be published data of several authors.     

Microscopic Investigation of High-Spin States for Even-Even Nuclei(Ⅱ) Application to isotones 154Dy,156Er and 158Yb

With the effective interactions consisting of a pairing force,a quadrupole pairing force and a quadrupole-quadrupole force among valence nucleons,the microscopic approach based on the generalized Dyson expansion theory is applied in studying both the low-lying and high spin states for the isotones ¹⁵⁴Dy,¹⁵⁶Er and ¹⁵⁸Yb.In the truncated state space,the configurations(sd)N and (sd)N-1,+neutron-pair are assumed,respectively,for the low-lying and high spin states,although the same values of strength parameters are taken in the numerical calculations in the two subspaces.The calculated results are in good agreement with experiment,especially the data of first backbendings are reproduced satisfactorily.     

Analysis of Bs→φμ+μ- decay within supersymmetry

Motivated by the rst measurement on B(B_s→φμ⁺μ^-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic B_s→φμ⁺μ^- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(B_s→φμ⁺μ^-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δ_LL^u)₂₃ as well as (δ_LL,RR^u)₂₃ mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(B_s→φμ⁺μ^-), B(B→K^(*)μ⁺μ^-) and (B_s→φμ⁺μ^-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of B_s→φμ⁺μ^-are highly sensitive to the squark exchange contribution and the (δ_LL^u)₂₃ mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC.     

Fore-aft asymmetry of the 2H(n,γ)3H at very low energies

We have used the recent effective field theory (EFT) which is constructed from two-and three-nucleon interactions, using minimal substitution in the momentum dependence of these interactions. We present the calculations of the fore-aft asymmetry of γ-rays in the reaction ²H(n,γ)³H which are based on EFT up to next-to-next-to leading order (N²LO). The results are compared with the recently reported calculations and measurements of the fore-aft asymmetry of γ-rays from neutron-deuteron radiative capture. The calculated fore-aft asymmetry of the nd radiative capture process above deuteron breakup threshold is in good agreement with the available experimental data up to 20 MeV.     

Experimental Study of Resonance f2(1270) in the J/ψ Hadronic Decay

Based on the 2.5 million J/ψ's collected by the BES at BEPC,through the hadronic decay J/ψ→ωf₂(1270),f₂(1270)→π⁺π^－,ω→π⁺π^－π⁰,the properties of the resonance f₂(1270) are studied:its mass,width,and branching ratio.the angular distribution is fitted with maximum likelihood methood,determining its.J^PC=2⁺⁺ and giving in the first time the helicity amplitude ratios of this process as:x=0.99±0.29; y=－0.24±0.17; z₁=0.90±0.57;z₂=0.56±0.22.     

Analysis of Bs→φμ+μ- decay within supersymmetry

Motivated by the rst measurement on B(B_s→φμ⁺μ^-) by the CDF Collaboration, we study the supersymmetric e ects in semi-leptonic B_s→φμ⁺μ^- decay. In our evaluations, we analyze the dependences of the dimuon invariant mass spectrum and the forward-backward asymmetry on relevant supersymmetric couplings in the MSSM with and without R-parity. The analyses show that the new experimental upper limits of B(B_s→φμ⁺μ^-)from the LHCb Collaboration could further improve the bounds on sneutrino exchange couplings and (δ_LL^u)₂₃ as well as (δ_LL,RR^u)₂₃ mass insertion couplings. In addition, within the allowed ranges of relevant couplings under the constraints from B(B_s→φμ⁺μ^-), B(B→K^(*)μ⁺μ^-) and (B_s→φμ⁺μ^-), the dimuon forward-backward asymmetry and the di erential dimuon forward-backward asymmetry of B_s→φμ⁺μ^-are highly sensitive to the squark exchange contribution and the (δ_LL^u)₂₃ mass insertion contribution. The results obtained in this work will be very useful in searching for supersymmetric signals at the LHC.     

Experimental Study on 22Na(p,γ)23Mg Reaction

The reaction of ²²Na(p,γ)²³Mg has been investigated at the Radioactive Ion Beam Line in Lanzhou(RIBLL) using a radioactive beam ²³Al. The β⁺ delayed proton decay spectrum has been measured with the TOF-ΔE method and zero degree detectors. The half life of ²³Al is determined to be T_1/2=(476±45)ms by using a time scaler combined with the precision pulse generator,which is consistent with the other group's result of (470±30)ms. The known β⁺ delayed protons at E_r=0.216,0.278,0.438,0.479MeV have also observed in the experiment. The resonance strength of isospin analog state (IAS) is calculated. The resonance intensity of IAS is (11.4±6.0)meV. A new energy level of β⁺ delayed proton decay has been identified at E_x=8.916MeV,and their relative intensity also been obtained.