T.S. Wang

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...

Study of the

Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

p\vec{d} \to n\{pp\}_{s}

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%.

charge-exchange reaction using a polarised deuterium target

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.

Deuterium depth distribution study in Yb

Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

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

Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

Study of the

Abstract The vector and tensor analysing powers, A y and A y y , of the p d → → n { p p } s charge-exchange reaction have been measured at a beam energy of 600 MeV at the COSY-ANKE facility by using an unpolarised proton beam incident on an internal storage cell target filled with polarised deuterium gas. The low energy recoiling protons were measured in a pair of silicon tracking telescopes placed on either side of the target. Putting a cut of 3 MeV on the diproton excitation energy ensured that the two protons were dominantly in the S 0 1 state, here denoted by { p p } s . The polarisation of the deuterium gas was established through measurements in parallel of proton–deuteron elastic scattering. By analysing events where both protons entered the same telescope, the charge-exchange reaction was measured for momentum transfers q ≥ 160 MeV / c . These data provide a good continuation of the earlier results at q ≤ 140 MeV / c obtained with a polarised deuteron beam. They are also consistent with impulse approximation predictions with little sign evident for any modifications due to multiple scatterings. These successful results confirm that the ANKE deuteron charge-exchange programme can be extended to much higher energies with a polarised deuterium target than can be achieved with a polarised deuteron beam.

p\stackrel{\to }{d}\to n{\left\{pp\right\}}_{s}

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.