A. Bacher

Resonance states in 22Mg for reaction rates in the rp-process

Abstract Motivated by the need of spectroscopic data to better understand the astrophysical rp-process, we developed a new experimental method using the Grand Raiden magnet spectrometer to study protin rich nuclei with α and 3 He induced reactions. First results of the 24 Mg( 4 He, 6 He) 22 Mg reaction at 206 MeV and 0° are presented, showing states relevant for resonant reaction rate calculations of the proton capture 21 Na(p,γ) 22 Mg and the 18 Ne(α,p) 21 Na reaction which controls the break-out of the hot CNO cycles at X-ray burst conditions.

Possible observation of the 12+[880] orbital in 96249Cm

Abstract The position of the K 17 2 shell orbital plays a significant role in determining the shell correction energy and hence the stability of the superheavy elements. A deformed component of this orbital, 1 2 + [880] , comes down in energy with increasing prolate deformation, and is expected to have an excitation energy of less than 2 MeV in nuclei with N = 153. We have performed the reaction 248Cm(4He,3He) using 98.5-MeV alpha particles from the IUCF cyclotron to populate high-l states in 249Cm. this reaction preferentially excites high-l states because of the angular momentum mismatch. The emerging 3He ions were momentum analyzed with the K600 magnetic spectrometer. Spectra were measured at θcm = 4.1°, 6.1°, 10.2°, 12.2°, and 16.2° The spectrometer was calibrated with the 208Pb(4He,3He) and 232Th(4He,3He) reactions at the same incident energy. Three strong peaks were identified in the 248Cm(4He,3He) spectrum and these have been given tentative assignments: 593 keV, 15 2 11 2 − [725] ; 1560 keV and 1898 keV, 17 2 1 2 + [880] , 15 2 13 2 − [716] . Our data do not distinguish between the 17 2 + and 15 2 − assignments.

Spectroscopy of 14C from the 11B(α,p)14C reaction at 118 MeV

Abstract Proton angular distributions have been measured for the 11 B(α, p) 14 C reaction at 118.1 MeV. DWBA calculations employing three-nucleon semi-microscopic form factors were made for states of excitation energies ranging from 6 MeV to 21.5 MeV. The weak coupling shell model wavefunctions of Lie were used in the DWBA calculations for states of 14 C below 12 MeV excitation energy. For states above 14.8 MeV 3p-5h components in the 14 C wavefunctions are shown to play a dominant role.

Tz = −1 nuclei in the rp-process — astrophysical implications and a new experimental approach

The ( α , 8 He) reaction is used to measure level energies in very proton rich nuclei. The results allow a more reliable calculation of the reaction flow in the rp and αp processes in Novae, X-ray pulsars and X-ray bursts.

Isospin identification for highly-excited Gamow—Teller and M1 states in mirror nuclei

Under the assumption that nuclear interaction is charge symmetry, isospin T is a good quantum number. Exotic nuclei have large |T z | values, where T z is defined by (N — Z)/2. Assuming isospin is a good quantum number, the analog states of the low-lying states in the T z = ±(T 0+ 1) nuclei can be found as the highly excited T 0+ 1 states in T z = ±T 0 nuclei. Therefore, if T 0 + 1 states are identified in highly excited region of T z = ±T 0 nuclei, the structure of the exotic nuclei with T z = ±(T 0 + 1) can be deduced.

Isospin identification for A = 25A=25 mirror nuclei by high resolution (p,p′)(p,p′) and (3He,t)(3He,t) experiments

Gamow-Teller and M1 states excited in 25Mg(3He,t)25Al and 25Mg(p,p′) reactions at 0° and 450 MeV incident energy, respectively, have been measured and compared. Good symmetry structure in the mirror nuclei 25Al and 25Mg has been identified up to the highest measured excitation energy of Ex∼16 MeV.

Looking for the isoscalar giant dipole resonance in 208Pd using inelastic a scattering at and near O

Abstract The isoscalar giant dipole resonance (ISGDR) in 208 Pb has been investigated using inelastic scattering of 200 MeV α particles at and near 0° where the angular distribution of the ISGDR can be clearly differentiated from other modes. The “difference of spectra” technique was employed to separate the contribution from the high-energy octupole resonance (HEOR). Results from a preliminary analysis of the data are consistent with the expected positions of the ISGOR and HEOR, as well as their expected angular distributions near 0°.