A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to... more A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to the high resolution gamma measurement and accurate DCO's or angular distributions, the information concerning the Electric or Magnetic character of the transition. This information for transitions in nuclei far from stability valley is now reachable in the new generation of Ge-arrays based in composite detectors. EUROBALL III is a good example with the high polarization sensitivity of the 90° ring of Clovers. The Polarization correlations PCO's measured in coincidence with the Cluster detectors permits to investigate transitions in weakly populated nuclei. In this contribution we present results on medium mass N=Z nuclei measured with EUROBALL III coupled with light particle ancillary detectors.
ABSTRACT Excited states of the N=Z=33 nucleus 66As have been populated in a fusion-evaporation re... more ABSTRACT Excited states of the N=Z=33 nucleus 66As have been populated in a fusion-evaporation reaction and studied using γ-ray spectroscopic techniques. Special emphasis was put into the search for candidates for the T=1 states. A new 3+ isomer has been observed with a lifetime of 1.1(3) ns. This is believed to be the predicted oblate shape isomer. The excited levels are discussed in terms of the shell model and of the complex excited Vampir approaches. Coulomb energy differences are determined from the comparison of the T=1 states with their analog partners. The unusual behavior of the Coulomb energy differences in the A=70 mass region is explained through different shape components (oblate and prolate) within the members of the same isospin multiplets. This breaking of the isospin symmetry is attributed to the correlations induced by the Coulomb interaction.
Very exotic shapes can be assumed for the nuclei at high angular momenta. Their study has become ... more Very exotic shapes can be assumed for the nuclei at high angular momenta. Their study has become possible with the advent of the last generation high-resolution γ-ray spectrometers. In this talk results are presented on superdeformed nuclei of theA=140 mass region where a detailed spectroscopy in the second minimum is now possible. Hyperdeformed rotational bands, expected in the third minimum, lie at even higher spins where their observation is very difficult from the experimental point of view. We have up to now only weak signals of their presence. The status of the search for hyperdeformation in152Dy is reported.
The recent availability of high precision data of heavy-ion fusion and quasi-elastic reactions at... more The recent availability of high precision data of heavy-ion fusion and quasi-elastic reactions at energies close to the Coulomb barrier allows detailed comparisons with microscopic nuclear theories. Two experiments have been recently performed in Legnaro: A) the detailed measurement of the fusion excitation function for the system 58Ni+60Ni and B) the measurement of the elastic scattering and transfer cross sections for 32S+208Pb. Both experiments have the common aim of enlightening the role of nucleon correlations, in the fusion process (A) and in the multinucleon transfer (B). In the following a very short preliminary report is given.
The status of the MARS project to build a gamma-ray tracking array is presented. It comprises the... more The status of the MARS project to build a gamma-ray tracking array is presented. It comprises the development of tracking algorithms, the simulation of 4pi arrays and the calculation and analysis of pulse shapes from highly segmented detectors.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
a b s t r a c t A large set of data on long term performance of n-type HPGe detectors used in GAS... more a b s t r a c t A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA g spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode, repair frequency, repair outcome and its influence in the energy efficiency and energy resolution. A remarkable result is that the life span distribution is exponential. A detector's failure is a memory-less process, where a previous failure does not influence the upcoming one. Repaired spectrometers result in high reliability with deep implications in the management of large scale high-resolution gamma spectrometry related projects. Findings show that on average, detectors initial counting efficiency is slightly lower ($ 2%) than that reported by the manufacturers and the repair process (including...
The comparison of analogue E1 transitions of mirror nuclei offers a valuable tool in the investig... more The comparison of analogue E1 transitions of mirror nuclei offers a valuable tool in the investigation of isospin symmetry breaking. Differences in the measured B(E1) reduced strengths in fact can be interpreted as the signature of isospin mixing. In this work, the isospin Tz = 1/2 nuclei 67As and 67Se were investigated. The nuclei were produced via the fusion evaporation
A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to... more A complete study of the nuclear structure by means of gamma spectroscopy requires, in addition to the high resolution gamma measurement and accurate DCO's or angular distributions, the information concerning the Electric or Magnetic character of the transition. This information for transitions in nuclei far from stability valley is now reachable in the new generation of Ge-arrays based in composite detectors. EUROBALL III is a good example with the high polarization sensitivity of the 90° ring of Clovers. The Polarization correlations PCO's measured in coincidence with the Cluster detectors permits to investigate transitions in weakly populated nuclei. In this contribution we present results on medium mass N=Z nuclei measured with EUROBALL III coupled with light particle ancillary detectors.
ABSTRACT Excited states of the N=Z=33 nucleus 66As have been populated in a fusion-evaporation re... more ABSTRACT Excited states of the N=Z=33 nucleus 66As have been populated in a fusion-evaporation reaction and studied using γ-ray spectroscopic techniques. Special emphasis was put into the search for candidates for the T=1 states. A new 3+ isomer has been observed with a lifetime of 1.1(3) ns. This is believed to be the predicted oblate shape isomer. The excited levels are discussed in terms of the shell model and of the complex excited Vampir approaches. Coulomb energy differences are determined from the comparison of the T=1 states with their analog partners. The unusual behavior of the Coulomb energy differences in the A=70 mass region is explained through different shape components (oblate and prolate) within the members of the same isospin multiplets. This breaking of the isospin symmetry is attributed to the correlations induced by the Coulomb interaction.
Very exotic shapes can be assumed for the nuclei at high angular momenta. Their study has become ... more Very exotic shapes can be assumed for the nuclei at high angular momenta. Their study has become possible with the advent of the last generation high-resolution γ-ray spectrometers. In this talk results are presented on superdeformed nuclei of theA=140 mass region where a detailed spectroscopy in the second minimum is now possible. Hyperdeformed rotational bands, expected in the third minimum, lie at even higher spins where their observation is very difficult from the experimental point of view. We have up to now only weak signals of their presence. The status of the search for hyperdeformation in152Dy is reported.
The recent availability of high precision data of heavy-ion fusion and quasi-elastic reactions at... more The recent availability of high precision data of heavy-ion fusion and quasi-elastic reactions at energies close to the Coulomb barrier allows detailed comparisons with microscopic nuclear theories. Two experiments have been recently performed in Legnaro: A) the detailed measurement of the fusion excitation function for the system 58Ni+60Ni and B) the measurement of the elastic scattering and transfer cross sections for 32S+208Pb. Both experiments have the common aim of enlightening the role of nucleon correlations, in the fusion process (A) and in the multinucleon transfer (B). In the following a very short preliminary report is given.
The status of the MARS project to build a gamma-ray tracking array is presented. It comprises the... more The status of the MARS project to build a gamma-ray tracking array is presented. It comprises the development of tracking algorithms, the simulation of 4pi arrays and the calculation and analysis of pulse shapes from highly segmented detectors.
Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment
a b s t r a c t A large set of data on long term performance of n-type HPGe detectors used in GAS... more a b s t r a c t A large set of data on long term performance of n-type HPGe detectors used in GASP, EUROBALL and CLARA g spectrometers, as well as environmental measurements have been collected over two decades. In this paper a detailed statistical analysis of this data is given and detector long term behaviour is provided to the scientific community. We include failure, failure mode, repair frequency, repair outcome and its influence in the energy efficiency and energy resolution. A remarkable result is that the life span distribution is exponential. A detector's failure is a memory-less process, where a previous failure does not influence the upcoming one. Repaired spectrometers result in high reliability with deep implications in the management of large scale high-resolution gamma spectrometry related projects. Findings show that on average, detectors initial counting efficiency is slightly lower ($ 2%) than that reported by the manufacturers and the repair process (including...
The comparison of analogue E1 transitions of mirror nuclei offers a valuable tool in the investig... more The comparison of analogue E1 transitions of mirror nuclei offers a valuable tool in the investigation of isospin symmetry breaking. Differences in the measured B(E1) reduced strengths in fact can be interpreted as the signature of isospin mixing. In this work, the isospin Tz = 1/2 nuclei 67As and 67Se were investigated. The nuclei were produced via the fusion evaporation
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