Kaihong Fang

Cross-section measurement for the reactions producing short-lived nuclei induced by neutrons around 14 MeV

The cross-sections of 180W(n,2n)179mW, 186W(n,2n)185mW, 165Ho(n,2n)164mHo, 64Ni(n,alpha)61Fe, 165Ho(n,alpha)162Tb and 51V(n,p)51Ti reactions induced by neutrons around 14 MeV were measured using activation technique and calculated by a previously developed formula in this work. The neutron flux was determined using the monitor reactions 93Nb(n,2n)92mNb and 27Al(n,alpha)24Na, the neutron energies were measured with the method of cross-section ratios for 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reactions. The results of this work are compared with data published previously.

Screening Potential of 6Li(d,α)4He and 7Li(p,α)4He Reactions in Liquid Lithium

In order to investigate the screening effect of a nuclear reaction in a liquid metal environment, thick-target yields of the 6 Li(d,α) 4 He and 7 Li(p,α) 4 He reactions were measured using a liquid Li target for incident energies between 22.5 and 70 keV. The modified S ( E ) factor [ S * ( E )] for the liquid Li environment was deduced by dividing the measured yield by the energy integration of the penetration factor divided by the stopping power. It was shown that S * ( E ) for the liquid environment is considerably larger than that for the atomic/molecular environment for both reactions. The difference in the screening energy between the two environments was deduced to be Δ U = 235 ±63 ( 6 Li+d) and 140±82 eV ( 7 Li+p), although the screening energy for liquid Li has a large uncertainty with U liq ∼486–776 ( 6 Li+d) and 324–637 eV ( 7 Li+p) owing to the uncertainty of the astrophysical bare S ( E ) factors. This difference in the screening energy should be considered in such a way that, in liquid Li met...

Measurement of fission cross-section for the 232Th(n,f )141Ba reaction induced by neutrons around 14 MeV

In order to investigate the fission process in more detail, and to compare with the measurement of cumulative fission yields, the fission cross section of the (232)Th(n,x)(89)Rb reaction induced by 14 MeV neutron was measured using the activation technique. In our measurement the neutron flux was determined using the monitor (27)Al(n,α)(24)Na reaction, and the neutron energies were measured by the method of cross-section ratios of (90)Zr(n,2n)(89)Zr to (93)Nb(n,2n)(92m)Nb reactions. The cross sections were deduced as 14.0±0.9 mb at E(n)=14.7±0.3 MeV and 13.2±1.0 mb at E(n)=14.1±0.3 MeV.

Deuterium depth distribution study in Yb

The deuterium depth distribution for a , while beam implanted into ytterbium (Yb) at a temperature between 300 and 340 K was studied using the D(d,p)T reaction. By analyzing the proton yields, the deuterium depth distribution from the front surface to 500 nm depth was found. The results indicate that an equilibrium deuterium distribution region from the front surface to a depth approximately equal to the mean range of implanted deuterons was formed in Yb during the implantation. The deduced deuterium concentration in the equilibrium deuterium distribution region was D/Yb = 22%.

Reanalysis of the astrophysical S(E) factors of the 6Li(d,α)4He, 7Li(p,α)4He and 6Li(p,α)3He reactions

The experimental data of the Li-6(d,alpha)He-4, Li-7(p,alpha)He-4 and Li-6(p,alpha)He-3 reactions obtained by other groups are reanalyzed in this work to extract their respective astrophysical S(E) factors and the screening energies provided by different environments (LiF solid targets and molecular H-2 or D-2 gas targets). Different from previous authors who investigated these three reactions independently, we study them simultaneously, based on the hypothesis that the screening effects are independent of the isotopic effects and the fact that the screening effects depend on the environments. The present extracted astrophysical S(E) factors result in S-bare(0) = 20.5 +/- 0.5, 0.0616 +/- 0.0017 and 3.63 +/- 0.13 MeV b for the Li-6(d,alpha)He-4, Li-7(p,alpha)He-4 and Li-6(p,alpha)He-3 reactions, respectively. The screening energies are 310 +/- 109 and 218 +/- 38 eV for the LiF solid targets and molecular H-2 or D-2 gas targets, respectively. These deduced screening energies are smaller than that observed by Engstler et al, and the value of U-s = 218 +/- 38 eV for the molecular H-2 or D-2 gas targets coincides with the value of 186 eV estimated from the adiabatic limit, while the value of U-s = 310 +/- 109 eV for the LiF solid targets is still slightly larger than that estimated from theoretical predictions.

Measurement of cross-sections for 14 MeV neutron interaction with 175 Lu

The cross-sections for 14MeV neutron interaction with 175Lu were precisely measured by the neutron activation and off-line gamma ray technique. The neutron fluence was monitored by the accompanying α-particle of the T(d,n)α reaction, and the neutron energies were determined by using the cross-section ratio method of 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reactions. As a result, the cross-sections of 175Lu(n,2n)174mLu, 175Lu(n,2n)174gLu, 175Lu(n,p)175m+gYb and 175Lu(n,α)172Tm reactions have been deduced at En = 14.1 ± 0.3MeV, 14.5 ± 0.3MeV and 14.7 ± 0.3MeV, respectively. Meanwhile, the comparisons between this work and the date reported by other groups previously were also given. For the comparison, it was found that there were nonnegligible discrepancies among these experimental data, as well as for several databases. As a conclusion, present data seem to be more consistent with the database of ENDF/B-VII.1, but trend to be lower than those of JEFF-3.2 and FENDL-3.1b, except the 175Lu(n,2n)174m+gLu reaction which are all in agreement.

Effect of deuteron density distribution on the deduction of screening potential from the D(d,p)T reaction in Be metals

The D(d,p)T reaction in Be metal environments has been measured to investigate the electron screening effect in metals in an energy region of from 5.5 keV to 10 keV in a center of mass system (CMS) at a temperature of 121 K. The depth distribution of deuteron density in Be metals has an impact on the observed reaction yields. A model of deuteron density distribution in metal has been proposed to obtain the original yields. A screening energy of (116±46) eV has been obtained with the assumed deuteron density distribution model.