Search

Dipole transitions in the semi-magic nucleus 124Sn have been investigated by means of real photon scattering in order to complete a previous measurement. The experiment was performed at the superconducting Darmstadt electron linear accelerator S-DALINAC using an unpolarized, continuous spectrum of bremsstrahlung with an endpoint energy of approximately 7.8MeV. A concentration of dipole transitions in the energy range between 5 and 7MeV stemming from the pygmy dipole resonance (PDR) could be identified. Some of these states have been observed in an (α, α;γ) experiment for the first time and could now be confirmed in our measurement. [ABSTRACT FROM AUTHOR]

The 134Nd required for studies of the violation of the K selection rule for electromagnetic transitions in nuclei with mass numbers around 130 can be produced in the reaction of 122Te with 16O. The 122Te target was prepared by the evaporation in a high vacuum. The deposition of the Te isotope on the backing was performed from the very close distance to economize the usage of the isotopic material. The thickness distribution of the target material determined by measurements of the alpha particles energy loss was estimated as 32%. The first test of the target on the 16O beam with energy of 80 MeV and intensity of 40 enA proved that target prepared by the Te deposition on the Au backing in vacuum is stable in the in-beam conditions and in spite of its relatively high inhomogeneity is suitable for the planned studies. [ABSTRACT FROM AUTHOR]

Delayed conversion-electron and γ-ray spectroscopy of A = 151 nuclei has been performed at the Lohengrin mass spectrometer of the ILL Grenoble. A previously reported 35.1-keV isomer of 151Pr has been determined to decay by an E1 transition and its half-life of 50(8) μs measured for the first time. These data has been complemented by high-fold γ-ray coincidence data collected with the EUROGAM-II and GAMMASPHERE arrays of anti-Compton spectrometers to search for medium-spin excitations in these nuclei. The long half life of this isomer and the lack of intraband E1 transitions show an absence of strong octupole correlations in the observed states of 151Pr. [ABSTRACT FROM AUTHOR]

We have investigated nuclear fragmentation reactions of a relativistic 208Pb beam.Ten isomeric states for nuclei with A = 142-152 and Z = 62-67 were observed. Measured isomeric ratios were compared, together with values from other experiments, with prediction of theoretical models. The discrepancies between the experimental and theoretical values were discussed in terms of transitions by-passing the isomer that are not included in the models. [ABSTRACT FROM AUTHOR]

Studying the weak nuclear response, especially the Gamow-Teller (GT) transitions starting from stable as well as unstable nuclei is one of the key issues in nuclear and nuclear-astrophysics.We studied the GT transitions by means of hadronic (³He; t) charge-exchange reactions and complementary β decays. Owing to the simple δτ nature of the operator that causes GT transitions, information on the crucial and critical part of the nuclear structure can be studied. Under the assumption that isospin is a good quantum number, symmetry is expected for the structure of mirror nuclei and the GT transitions starting from them. The results from β-decay studies and the strength distribution of GT transitions from the (³He; t) reaction are compared and also combined for the understanding of nuclear structure of far-from-stability nuclei. [ABSTRACT FROM AUTHOR]

Modern standards of length and time are based on wavelength measurements of laser light sources, whose relative stability is limited by the temperature dependence of molecular or atomic transition frequencies and cannot be better than 10-15. The cardinal way of improvement is to find nuclear transitions coincident with any laser line. This short review is devoted to the present status of investigations and available projects of using the 7.6 eV transition in 229Th. Some new ideas are proposed and discussed. [ABSTRACT FROM AUTHOR]

The β decay of 112Ag has been used to populate spin 0+ and 2+ states in 112Cd to 3 MeV excitation energy. The statistical quality obtained allows the extraction of very weak γ-ray branching ratios that, combined with known level lifetimes, enables the determination of the B(E2) values or upper limits for transitions populating the proposed two-phonon states. While candidates for 3+, 4+, and 6+ three-phonon levels have been identified, there are no candidates for the 0+ and 2+ three phonon levels, and the upper limits of the B(E2) values indicate that phonon E2 strength is not fragmented, but absent below 5ħω2. [ABSTRACT FROM AUTHOR]

The poorly known B(E2; 0+ → 2+) values of 112Sn and 114Sn have been measured to high precision. Two Coulomb excitation experiments were performed to determine the reduced transition probabilities relative to 116Sn in order to minimize the systematic errors. The obtained B(E2 ↑) values of 0:242(8) e²b² for 112Sn and 0:232(8) e²b² for 114Sn confirm the tendency of large B(E2 ↑) values for the lighter tin isotopes below the midshell 116Sn that has been observed recently in various radioactive ion beam experiments. [ABSTRACT FROM AUTHOR]

Electromagnetic transition rates have been measured for decays from the ground state band in the transitional nucleus 100Pd using the Recoil Distance Doppler Shift Method in inverse kinematics via the 24Mg(80Se,4n) 100Pd reaction at a beam energy of 268 MeV. The nuclei produced were stopped using a Cu foil and data were recorded for 10 different target-stopper distances. The gamma-rays emitted were measured using the SPEEDY germanium detector array at WNSL Yale University and the target-to-stopper distances were determined and kept constant using the New Yale Plunger Device. The preliminary results of this study are presented. [ABSTRACT FROM AUTHOR]

We report on preliminary results from the experiment performed at Legnaro National Laboratories aiming at the investigation of the shape evolution of the 88Mo nucleus. The GDR spectra obtained for two data sets measured at 48Ti beam energy of 300 and 450 MeV corresponding to 3 and 3.8 MeV temperatures, respectively, are presented. The low energy component in GDR strength functions, similar to the theoretical predictions of LSD model, possibly indicates the presence of Jacobi shape transition. [ABSTRACT FROM AUTHOR]

We provide a brief review of our activities involving high energy gamma decay from hot-rotating nuclei. The two primary goals of this ongoing programme is to search for rare shape-phase transitions in heavy (A ~ 190) nuclei, from the analysis of the giant dipole resonance (GDR) gamma ray spectra and also to search for the Isovector Giant Quadrupole Resonance (IVGQR) based upon excited states. The efforts to carry out the exclusive measurements have resulted in the setting up of a sum-spin spectrometer in complete 4π configuration. The performance of this spin-spectrometer will be presented in brief. In addition, this paper also presents the results of our studies with lanthanum bromide detectors of different sizes and configurations using low energy sources and in-beam measurements. The finite temperature potential energy surface calculations, carried out to guide the measurements, will also be discussed. [ABSTRACT FROM AUTHOR]

We have measured the lifetime of the Due to image rights restrictions, multiple line equation(s) cannot be graphically displayed. state in 74Zn by the recoil distance Doppler-shift method at GANIL. It resulted to be of 27.6(43) ps and is consistent with previously measured values of transition rates from Coulomb excitation measurements. [ABSTRACT FROM AUTHOR]

Poincaré shape transitions in hot, fast rotating Barium nuclei have been investigated using a realistic, the so-called Lublin-Strasbourg Drop (LSD) model. In this contribution we present typical forms of the shape evolution the total energy landscapes in function of spin and isospin selecting for illustration 116Ba, 128Ba, 142Ba and 152Ba isotopes, as representative for the medium-mass A ~ 130 nuclei. [ABSTRACT FROM AUTHOR]

Using the radiative return allows for precision measurements of energy-dependent cross sections at particle factories. In the first part, the method of the measurement and its application at the KLOE experiment will be explained. In the second part, the status of the ongoing analyses based on the 2002 data set is presented. These analyses will improve the published result in many aspects and allow for important cross checks. [ABSTRACT FROM AUTHOR]