A SIGNATURE FOR ISOSCALAR-SPIN TRANSITIONS IN ([d,d) SCATTERING

Three different signatures for isoscalar spin transitions in nuclei have been tested in the 12C(d,d)12C reaction at 400 MeV. These signatures have values close to zero for the natural parity states, and ranging from 0.22 to 0.50 for the ΔS=1 ΔT=0, 12.7 MeV state

3^3He Structure and Mechanisms of p3p^3He Backward Elastic Scattering

The mechanism of $p^3$He backward elastic scattering is studied. It is found that the triangle diagrams with the subprocesses $pd\to ^3$He$\pi^0$, $pd^*\to ^3$He$\pi^0$ and $p(pp)\to^3$He$\pi^+$, where $d^*$ and $pp$ denote the singlet deuteron and diproton pair in the $^1S_0$ state, respectively, dominate in the cross section at 0.3-0.8 GeV, and their contribution is comparable with that for a sequential transfer of a $np$ pair at 1-1.5 GeV. The contribution of the $d^*+pp$, estimated on the basis of the spectator mechanism of the $p(NN)\to ^3$He$\pi$ reaction, increases the $p^3$He$\to ^3$He$p$ cross section by one order of magnitude as compared to the contribution of the deuteron alone. Effects of the initial and final states interaction are taken into account.Comment: 17 pages, Latex, 4 postscript figures, expanded version, accepted by Physical Review

Single-neutron transfer from 11Be gs via the (p,d) reaction with a radioactive beam

The 11Be(p,d)10Be reaction has been performed in inverse kinematics with a radioactive 11Be beam of E/A = 35.3 MeV. Angular distributions for the 0+ ground state, the 2+, 3.37 MeV state and the multiplet of states around 6 MeV in 10Be were measured at angles up to 16 deg CM by detecting the 10Be in a dispersion-matched spectrometer and the coincident deuterons in a silicon array. Distorted wave and coupled-channels calculations have been performed to investigate the amount of 2+ core excitation in 11Be gs. The use of "realistic" 11Be wave functions is emphasised and bound state form factors have been obtained by solving the particle-vibration coupling equations. This calculation gives a dominant 2s component in the 11Be gs wave function with a 16% [2+ x 1d] core excitation admixture. Cross sections calculated with these form factors are in good agreement with the present data. The Separation Energy prescription for the bound state wave function also gives satisfactory fits to the data, but leads to a significantly larger [2 x 1d] component in 11Be gs.Comment: 39 pages, 12 figures. Accepted for publication in Nuclear Physics A. Added minor corrections made in proof to pages 26 and 3

Radium, Marie Curie and modern science

NESTE

Diffusion par fluorescence nucléaire du rayonnement γ de 75Se périodes des niveaux de 265 et 402 keV de 75As

Nuclear resonance fluorescence from the 265 keV excited state of 75As leads to a value of (2,3 ± 0,3) 10-11 sec for the half life of this level. No resonance fluorescence from the 402 keV level was observed and the half life of this level is therefore greater than 1,4 10 -11 sec. The variation of nuclear resonance intensity from the 265 keV level with the pressure of the gaseous source gives the value (1,5 ± 0,4) 10-9 sec for the half life of the 402 keV level. Electron capture branching ratios have been_reexamined and a weak (0,04 %) new transition leads to the 575 keV level of 75As.Aucun effet de diffusion résonnante n'a pu être observé dans le cas de la transition directe de 402 keV; par contre, le rayonnement de fluorescence nucléaire du niveau de 265 keV a été mis en évidence. Les périodes des niveaux de 402 keV et 265 keV ont été ainsi fixées respectivement a : τ1 > 1,4 10-11 sec et τ2 = (2,3 ± 0,3) 10-11 sec. L'étude systématique de l'intensité du rayonnement diffusé de 265 keV en fonction de la pression de la source gazeuse permet d'estimer à (1,5 ± 0,4) 10-9 sec la période du niveau de 402 keV. Les facteurs d'embranchements de capture électronique vers les différents niveaux de 75As ont été réexaminés. Un faible embranchement supplémentaire (0,04 %) a été observé vers le niveau de 575 keV

Radium, Marie Curie and modern science

NESTE