M. E. Howard

Extraction of weak transition strengths via the (He-3, t) reaction at 420 MeV

Differential cross sections for transitions of known weak strength were measured with the (3He, t) reaction at 420 MeV on targets of 12C, 13C, 18O, 26Mg, 58Ni, 60Ni, 90Zr, 118Sn, 120Sn, and 208Pb. Using these data, it is shown that the proportionalities between strengths and cross sections for this probe follow simple trends as a function of mass number. These trends can be used to confidently determine Gamow-Teller strength distributions in nuclei for which the proportionality cannot be calibrated via beta-decay strengths. Although theoretical calculations in the distorted-wave Born approximation overestimate the data, they allow one to understand the main experimental features and to predict deviations from the simple trends observed in some of the transitions.

Spectroscopy of 24 Al and extraction of Gamow-Teller strengths with the 24 Mg( 3 He,t) reaction at 420 MeV.

The {sup 24}Mg({sup 3}He,t){sup 24}Al reaction was studied at E({sup 3}He)=420 MeV. An energy resolution of 35 keV was achieved. Gamow-Teller strengths to discrete levels in {sup 24}Al were extracted by using a recently developed empirical relationship for the proportionality between Gamow-Teller strengths and differential cross sections at zero momentum transfer. Except for small discrepancies for a few weak excitations, good agreement with previous {sup 24}Mg(p,n) data and nuclear-structure calculations using the USDA/B interactions in the sd shell-model space was found. The excitation energy of several levels in {sup 24}Al of significance for determination of the {sup 23}Mg(p,{gamma}){sup 24}Al thermonuclear reaction rate were measured. Results are consistent with two of the three previous ({sup 3}He,t) measurements, performed at much lower beam energies. However, a new state at E{sub x}({sup 24}Al)=2.605(10) MeV was found and is the third state above the proton separation energy.

Nucleosynthesis of proton-rich nuclei. Experimental results on the rp-process

We report in this study the nuclear properties of proton-rich isotopes located along the rp-process path. The experiments have recently been performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The level properties above the proton separation energy of the nuclei 30S, 36K and 37Ca were measured with precision of < 10 keV. This will allow a reduction in the determination of the astrophysical (p,γ) reaction rate under rp-process conditions.

Gamow-Teller transitions to Cu 64 measured with the Zn 64 ( t , He 3 ) reaction

The

Decay studies at the end of the rp-process

^{64}\mathrm{Zn}

Gamow-Teller transitions to 64-Cu measured using the 64-Zn(t,3-He) reaction

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Gamow-Teller transitions toCu64measured with theZn64(t,He3) reaction

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Gamow-Teller strengths in 24 Na using the 24 Mg( t , 3 He) reaction at 115 A MeV

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Gamow-Teller strengths inNa24using the24Mg(t,3He)reaction at115AMeV

^{3}\mathrm{He}

Half-life measurement of neutron-rich nuclei relevant to astrophysical r-process at RIKEN

) reaction has been studied by using a secondary triton beam of 115 MeV/nucleon to extract the Gamow-Teller transition-strength distribution to