A. M. Bizzeti-Sona

Description of nuclear octupole and quadrupole deformation close to the axial symmetry and phase transitions in the octupole mode

The dynamics of nuclear collective motion is investigated in the case of reflection-asymmetric shapes. The model is based on a new parametrization of the octupole and quadrupole degrees of freedom, valid for nuclei close to the axial symmetry. Amplitudes of oscillation in other degrees of freedom different from the axial ones are assumed to be small, but not frozen to zero. The case of nuclei which already possess a permanent quadrupole deformation is discussed in some more detail and a simple solution is obtained at the critical point of the phase transition between harmonic octupole oscillation and a permanent asymmetric shape. The results are compared with experimental data of the thorium isotopic chain. The isotope

Description of nuclear octupole and quadrupole deformation close to axial symmetry: Critical-point behavior of {sup 224}Ra and {sup 224}Th

^{226}\mathrm{Th}

Gamma-decay study of 21Na and 21Ne, octupole bands in 21Ne

is found to be close to the critical point.

Lifetimes of lower excited states in27Si

The model, introduced in a previous paper, for the description of the octupole and quadrupole degrees of freedom in conditions close to axial symmetry, is applied to situations of shape phase transitions where the quadrupole amplitude can reach zero. The transitional nuclei {sup 224,226}Ra and {sup 224}Th are discussed in the frame of this model. Their level schemes can be reasonably accounted for by assuming a square-well potential in two dimensions. Electromagnetic transition amplitudes are also evaluated and compared with existing experimental data.

The CLARA-PRISMA setup installed at LNL: first results

The reactions 16 O( 7 Li, 2n )a nd 16 O( 7 Li, np) populating 21 Na and 21 Ne have been studied at EL = 27 MeV using the GASP γ -detector array. The level scheme for 21 Na and 21 Ne has been extended to higher excitation energy. Spins and parities of the observed levels are assigned tentatively supporting th ei dentification of opposite parity structures connected by strong dipole transitions. The structure of these bands is interpreted as based on a reflection asymmetric cluster structure.

Transition rates and nuclear structure changes in mirror nuclei 47 Cr and 47 V

SummaryThe mean lives of some levels in27Si have been measured with the Doppler-shift attenuation method, by means of the28Si(3He, α)27Si reaction. The γ-rays were detected in coincidence with alphas at the angle ϑ=60°. The results for the mean lives are the following:τm=(1.8±0.6) ps, (65−35+40) fs, > 5 ps and < 63 fs for the 0.957, 2.162, 0.781 and 2.647 MeV levels, respectively.RiassuntoSi sono misurate le vite medie di alcuni livelli eccitati del27Si col metodo dello spostamento Doppler attenuato. La reazione usata per ottenere il27Si eccitato era28Si(3He, α)27Si all’energiaEτ=6.6 MeV. I raggi γ venivano rivelati in coincidenza con le particelle α emesse a (60 ± 5)° rispetto alla direzione del fascio incidente. I risultati per le vite medie sono i seguenti:τm=(1.8±0.6) ps,τm=(65−35+40) fs,τm > 5 ps eτm < 63 fs, rispettivamente, per i livelli a 0.957, 2.162, 0.781 e 2.647 MeV.РеэюмеИспольэуя реакцию28Si(3He, α)27Si, были иэмерены средние времена жиэни некоторых уровней в27Si с помошью метода, основанного на уменьщении допплеровского сдвига. γ-лучи детектировались по совпадению с альфа-частицами при угле ϑ=60°. Реэультаты для средних времен жиэни следуюшие: τm=(1.8±0.6) рs, (65−35+40) fs, > 5 рs и > 63 fs соответственно для уровней 0.957, 2.162, 0.781 и 2.647 МзВ.

T=0 Pairing Correlations and Band Crossing Phenomena in N=Z Nuclei

CLARA is an array of 25 Clover (EUROBALL type) Ge detectors, placed at the target position of the large acceptance magnetic spectrometer PRISMA. Due to the granularity of the CLARA Ge array (100 crystals), the photopeak efficiency (≈3%) and the PRISMA large acceptance (≈80 msr, and 20% Δp/p), the setup is an excellent tool to investigate the structure of neutron-rich nuclei, populated in multinucleon transfer reactions and deep inelastic collisions with stable beams. Since March 2004 the setup is fully operational, and since then several experiments have been performed, with beams delivered by the LNL XTU-Tandem and the ALPI linac. In this contribution the preliminary outcome of the first experiments is shown.

Sum-up and pile-up contribution to cross-over peaks in coincidence γ spectroscopy

Lifetime measurements in the mirror nuclei

Yrast states in the doubly-odd nucleus100Tc

{}^{47}\mathrm{Cr}

Electromagnetic decay of the 6+ isomer of102Rh

and