5029078
Study of shape transition in the neutron-rich Os isotopes
The neutron-rich isotopes of tungsten, osmium and platinum have different shapes in their ground states and present also shape transitions phenomena. Spectroscopic information for these nuclei is scarce and often limited to the gamma rays from the decay of isomeric states. For the neutron-rich even-even osmium isotopes 194 Os and 198 Os, a shape transition between a slightly prolate deformed to an oblate deformed ground state was deduced from the observed level schemes. For the even-even nucleus lying in between, 196 Os, no gamma ray transition is known. In order to elucidate the shape transition and to test the nuclear models describing it, this region was investigated through gamma-ray spectroscopy using the AGATA demonstrator and the large acceptance heavy-ion spectrometer PRISMA at LNL, Italy. A two-nucleon transfer from a 198 Pt target to a stable 82 Se beam was utilized to populate medium-high spin states of 196 Os. The analysis method and preliminary results, including the first life-time measurement of isomeric states with AGATA, are presented.
5034444
Study of the multi-nucleon transfer reactions of 136Xe + 198Pt for producing exotic heavy nuclei
The feasibility of the multi-nucleon transfer (MNT) reaction in the 136 Xe + 198 Pt system was investigated for synthesizing neutron-rich heavy nuclei around mass number A 200 of astrophysical interest. Identification of the projectile-like fragments (PLF's) was successfully performed by using VAMOS++ spectrometer. The isotopic distributions of the PLF's produced by two-proton stripping and pickup reactions were compared with each other, demonstrating the properties of the MNT reactions observed in the present system. The two-proton pickup channels strongly populated than the two- proton stripping channels were observed. The isotopic distributions for di erent total kinetic energy loss (TKEL) ranges are also discussed. The overall enhancement of the strength of the two-proton pickup compared with the two-proton stripping appears to be related to the MNT reactions with relatively moderate energy dissipation.
121575889
Lifetime Measurements of the Neutron-Rich N=30 Isotones Ca-50 and Sc-51: Orbital Dependence of Effective Charges in the fp Shell
The lifetimes of the first excited states of the N=30 isotones Ca-50 and Sc-51 have been determined using the Recoil Distance Doppler Shift method in combination with the CLARA-PRISMA spectrometers. This is the first time such a method is applied to measure lifetimes of neutron-rich nuclei populated via a multinucleon transfer reaction. This extends the lifetime knowledge beyond the f(7/2) shell closure and allows us to derive the effective proton and neutron charges in the fp shell near the doubly magic nucleus Ca-48, using large-scale, shell-model calculations. These results indicate an orbital dependence of the core polarization along the fp shell.
54660865
Dynamical Dipole and Equation of State in N/Z Asymmetric Fusion Reactions
In heavy ion reactions, in the case of N/Z asymmetry between projectile and target, the process leading to complete fusion is expected to produce pre-equilibrium dipole γ -ray emission. It is generated during the charge equilibration process and it is known as Dynamical Dipole. A new measurement of the dynamical dipole emission was performed by studying 16 O + 116 Sn at 12 MeV/u. These data, together with those measured at 8.1 MeV/u and 15.6 MeV/u for the same reaction, provide the dependence on the Dynamical Dipole total emission yield with beam energy and they can be compared with theoretical expectations. The experimental results show a weak increase of the Dynamical Dipole total yield with beam energies and are in agreement with the prediction of a theoretical model based on the Boltzmann–Nordheim–Vlasov (BNV) approach. The measured trend with beam energy does not confirm the rise and fall behavior previously reported for the same fused compound but with a much higher dipole moment.
56152487
Rotation and shape changes in 151Tb and 196Pb: Probes of nuclear structure and tunneling process in warm nuclei. I. Experimental analysis
The {gamma} decay associated with the warm rotation of the superdeformed nuclei {sup 151}Tb and {sup 196}Pb has been measured with the Euroball IV array. Several experimental quantities are presented, putting strong constraints on the decay dynamics in the superdeformed well. The data are successfully reproduced using a Monte Carlo simulation of the {gamma} decay based on microscopically calculated energy levels, E2 decay probabilities, collective mass parameters, and potential energy barriers between the wells associated with normal and super deformation. This allows one to test the basic ingredients of the physical process, such as the strength of the two-body residual interaction and the potential barriers as a function of spin and excitation energy. We also show that the data probe the E1 strength function, indicating an enhancement around 1-2 MeV {gamma} rays, which might be related to octupole vibrations.
120912280
Measurement of isospin mixing at a finite temperature in Zr-80 via giant dipole resonance decay
A. Corsi,1,2,* O. Wieland,2 S. Barlini,3,4 A. Bracco,1,2 F. Camera,1,2 V. L. Kravchuk,5 G. Baiocco,7 L. Bardelli,4 G. Benzoni,2 M. Bini,3 N. Blasi,2 S. Brambilla,2 M. Bruno,7 G. Casini,4 M. Ciemala,8 M. Cinausero,5 F. C. L. Crespi,1,2 M. D’Agostino,7 M. Degerlier,5 A. Giaz,1,2 F. Gramegna,5 M. Kmiecik,8 S. Leoni,1,2 A. Maj,8 T. Marchi,5,6 K. Mazurek,8 W. Meczynski,8 B. Million,2 D. Montanari,6 L. Morelli,7 S. Myalski,8 A. Nannini,4 R. Nicolini,1,2 G. Pasquali,3 G. Poggi,3 V. Vandone,1,2 and G. Vannini7 1Dipartimento di Fisica, Università di Milano and INFN Sezione di Milano, Italy 2INFN, Sezione di Milano, Milano, Italy 3Dipartimento di Fisica, Università di Firenze and INFN Sezione di Firenze, Italy 4INFN Sezione di Firenze, Italy 5INFN Laboratori Nazionali di Legnaro, Padova, Italy 6Dipartimento di Fisica, Università di Padova and INFN Sezione di Padova, Italy 7Dipartimento di Fisica, Università di Bologna and INFN Sezione di Bologna, Italy 8The Henryk Niewodniczaǹski Institute of Nuclear Physics PAN, Krakow, Poland (Received 20 March 2011; published 20 October 2011)
121396997
Measurement of CNGS muon neutrino speed with Borexino
Abstract We have measured the speed of muon neutrinos with the Borexino detector using short-bunch CNGS beams. The final result for the difference in time-of-flight between an 〈 E 〉 = 17 GeV muon neutrino and a particle moving at the speed of light in vacuum is δ t = 0.8 ± 0.7 stat ± 2.9 sys ns , well consistent with zero.