54954990
Measurement of light charged particles in the decay channels of medium-mass excited compound nuclei
The 48 Ti on 40 Ca reactions have been studied at 300 and 600 MeV focusing on the fusion-evaporation (FE) and fusion-fission (FF) exit channels. Energy spectra and multiplicities of the emitted light charged particles have been compared to Monte Carlo simulations based on the statistical model.Indeed, in this mass region ( A ~ 100) models predict that shape transitions can occur at high spin values and relatively scarce data exist in the literature about coincidence measurements between evaporation residues and light charged particles. Signals of shape transitions can be found in the variations of the lineshape of high energy gamma rays emitted from the de-excitation of GDR states gated on different region of angular momenta. For this purpose it is important to keep under control the FE and FF processes, to regulate the statistical model parameters and to control the onset of possible pre-equilibrium emissions from 300 to 600 MeV bombarding energy.
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.
121651616
Reaction dynamics and nuclear structure studies via deep inelastic collisions with heavy-ions: spin and parity assignment in 49Ca
The population and gamma decay of neutron rich nuclei around 48Ca has been measured at Legnaro National Laboratory with the PRISMA-CLARA setup, using deep-inelastic collisions (DIC) on 64Ni, at an energy approximately twice the Coulomb barrier. The reaction properties of the main products are investigated, focusing on total cross sections and angular distributions both integrated in energy and associated to the population of specific excited states. Gamma spectroscopy studies are also performed, giving evidence, for the first time in transfer reactions with heavy ions, of a large spin alignment (~70%), perpendicular to the reaction plane. This makes possible the use of angular distributions and polarization measurements to firmly establish the spin and parity of excited states populated in nucleon transfer channels, as in the case of 49Ca, where candidates for particle-core coupling are investigated. Both reaction and gamma spectroscopy studies demonstrate the relevance of DIC with heavy ions for a detailed investigation of moderately neutron rich systems.
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)
117791829
Study of Solar and Geo-Neutrinos with the BOREXINO Detector
119259804
Lifetime measurements of 214Po and 212Po with the CTF liquid scintillator detector at LNGS
We have studied the α-decays of 214Po into 210Pb and of 212Po into 208Pb tagged by the coincidence with the preceding β-decays from 214Bi and 212Bi, respectively. The 222Rn, 232Th, and 220Rn sources used were sealed inside quartz vials and inserted in the Counting Test Facility at the underground Gran Sasso National Laboratory in Italy. We find that the mean lifetime of 214Po is (236.00 ± 0.42(stat) ± 0.15(syst)) μs and that of 212Po is (425.1 ± 0.9(stat) ± 1.2(syst)) ns. Our results, obtained from data with signal-to-background ratio larger than 1000, reduce the overall uncertainties and are compatible with previous measurements.
121625849
High precision Be-7 solar neutrinos measurement and day night effect obtained with Borexino
Abstract We report the direct measurement of the 7 Be solar neutrino signal rate performed with the Borexino detector at the Laboratori Nazionali del Gran Sasso and the search for a day–night asymmetry of this interaction rate. The interaction rate of the 0.862 MeV 7 Be neutrinos is 46 ± 1.6 ( stat ) − 1.6 + 1.5 ( syst ) counts/(day · 100 ton). The hypothesis of no oscillation for this solar neutrinos is inconsistent with our measurement at the 5.8 σ C.L. Our result is the first direct measurement of solar neutrinos with an accuracy better than 5%. We report the survival probability for solar ν e in the transition region between matter-enhanced and vacuum-driven oscillations. The measured day night asymmetry is A dn = 0.001 ± 0.012 (stat)±0.007 (syst), in agreement with the predicition of MSW–LMA neutrino [13] oscillations. This result discourages MSW oscillations with mixing parameters in the LOW region at more than 8.5 σ , meaning that this region is, for the first time, strongly rejected without the assumption of CPT symmetry. The result can also be used to constrain some neutrino oscillation scenarios involving new physics.
55022201
Artificial neutrino source experiment in Borexino
An experiment with an artificial neutrino source in Borexino is presented. The neutrino source can be located outside the detector or eventually, at the end of the solar neutrino phase, could be deployed inside. The physics case for the source experiment includes the search for short-baseline neutrino oscillations, neutrino-electron scattering at sub-MeV range, neutrino magnetic moment. Preliminary predictions of the sensitivity are reported for the sterile neutrino search.
116991669
Study of the Rare Processes with the BOREXINO Detector
The status of the search for rare processes with the Borexino detector is reviewed. The discussed experimental results include searches for violation of the Pauli exclusion principle in nuclei, 5.5 MeV axions from p+d → 3He+A reaction on the Sun and magnetic moments of solar neutrinos. New limits on the probability of non-Paulian transitions in 12C nuclei [3], on the axion-electron, axion-photon and axion-nucleon coupling constants [4] and on the neutrino magnetic moments [2] are presented. 1 The Borexino detector Borexino is a real-time detector for solar neutrino spectroscopy located at the Gran Sasso Underground Laboratory. Its main goalis to measure low energy solar neutrinos via (ν,e)-scattering in an ultra-pure liquid scintillator. The extremely high radiopurity of the detector and its large mass allow to simultaneously address other fundamental questions in particle physics and astrophysics. The main features of the Borexino detector have been thoroughly described in [1]. Borexino is a scintillator detector with an active mass of 278 tons of pseudocumene (PC, C9H12), doped with the light shifter (C15H11NO). The ae-mail: derbin@pnpi.spb.ru be-mail: fomenko@jinr.ru