V. Rizzi

Experimental Determination of In-Medium Cluster Binding Energies and Mott Points in Nuclear Matter

In-medium binding energies and Mott points for d, t, 3He and α clusters in low-density nuclear matter have been determined at specific combinations of temperature and density in low-density nuclear matter produced in collisions of 47A MeV 40Ar and 64Zn projectiles with 112Sn and 124Sn target nuclei. The experimentally derived values of the in-medium modified binding energies are in good agreement with recent theoretical predictions based upon the implementation of Pauli blocking effects in a quantum statistical approach.

A proton recoil telescope for neutron spectroscopy

The N2P research program funded by the INFN committee for Experimental Nuclear Physics (CSNIII) has among his goals the construction of a Proton Recoil Telescope (PRT), a detector to measure neutron energy spectra. The interest in such a detector is primarily related to the SPES project for rare beams production at the Laboratori Nazionali di Legnaro. For the SPES project it is, in fact, of fundamental importance to have reliable information about energy spectra and yield for neutrons produced by d or p projectiles on thick light targets to model the conversion target in which the p or d are converted in neutrons. These neutrons, in a second stage, will induce the Uranium fission in the production target. The fission products are subsequently extracted, selected and re-accelerated to produce the exotic beam. The neutron spectra and angular distribution are important parameters to define the final production of fission fragments. In addition, this detector can be used to measure neutron spectra in the field of cancer therapy (this topic is nowadays of particular interest to INFN, for the National Centre for Hadron therapy (CNAO) in Pavia) and space applications.

Soil biological and biochemical traits linked to nutritional status in grapevine

The purpose of this work was to study vineyards of NE Italy seeking for features associated to the soil or plant compartment that could serve as proxies to infer productivity of the grape. Soils were characterized for physicochemical properties, mineralization of organic matter by a novel patented device based on in-situ microbial degradation of buried fibers, bacterial intergenic spacer length diversity (ARISA), enzyme activities and the expression of genes involved in response to abiotic stresses. Significant differences (p<0.05) were observed among vineyards for the parameters evaluated. The groupings obtained by ARISA were coherent with those obtained by PCA of soil properties. Vineyards endowed with higher productivity had soils showing higher enzyme activities along with neutral pH, higher TOC content and appropriate C/N ratio. These soils also showed higher mineralization of organic matter determined the novel in-soil thread degradation method. Grapevines of less productive vineyards had suboptimal leaf nitrogen and sulfur contents and showed up-regulation of WRKY, SuSy, PAL and STS1 genes. Results put in evidence useful correlations with yield that can be obtained up to several months earlier than harvest time upon analyzing selected indicators. An interesting link arises unifying soil biological properties, nutritional status, molecular stress response of grapevine and its production level. Keyword: Soil biological properties, edaphic stresses, nutritional status, molecular stress response

A Proton Recoil Telescope for Neutron Spectroscopy

The N2P research program funded by the INFN committee for Experimental Nuclear Physics (CSNIII) has among his goals the construction of a Proton Recoil Telescope (PRT), a detector to measure neutron energy spectra. The interest in such a detector is primarily related to the SPES project for rare beams production at the Laboratori Nazionali di Legnaro. For the SPES project it is, in fact, of fundamental importance to have reliable information about energy spectra and yield for neutrons produced by d or p projectiles on thick light targets to model the conversion target in which the p or d are converted in neutrons. These neutrons, in a second stage, will induce the Uranium fission in the production target. The fission products are subsequently extracted, selected and re-accelerated to produce the exotic beam. The neutron spectra and angular distribution are important parameters to define the final production of fission fragments. In addition, this detector can be used to measure neutron spectra in the field of cancer therapy (this topic is nowadays of particular interest to INFN, for the National Centre for Hadron therapy (CNAO) in Pavia) and space applications.

Measurements of dynamical dipole in isospin asymmetric fusion reactions

In heavy ion nuclear reactions the process leading to complete fusion is expected to produce pre-equilibrium γ-ray emission, if particular conditions are met. Indeed, when there is an N/Z asymmetry between projectile and target, charge equilibration takes place with a collective dipole oscillation, called Dynamical Dipole (DD), associated to a γ-ray emission. The existing experimental data concerning this pre-equilibrium γ-ray emission are still rather scarce and manly concentrated in the A≊132 mass region. The very preliminary results concerning the measurement of the DD γ-ray emission in the fusion reaction 16O (Elab=192 MeV) + 116Sn at 12 MeV/u will be presented and compared with the γ yield measured for the same reaction at 8.1 and 15.6 MeV/u. The present experiment aims at the measurement of the total emission yield of the DD at 12 MeV/u where the predicted theoretical yield does not completely reproduce the experimental data. The experiment has been performed at the INFN Legnaro Laboratories using the GARFIELD-HECTOR array.

Statistics vs. dynamics: hints from systems of intermediate fissility

Systems of intermediate fissility are characterized by an evaporation residues cross section comparable or larger than the fission cross section, and by a relatively higher probability for charged particle emission in the pre-scission channel. In a theoretical framework in which time scale estimates of the fission process rely on statistical model calculations, the analysis of particle emission in the evaporation residues channel is the source of additional constraints on statistical and dynamical models. This contribution will focus on our statistical and dynamical analysis of a more complete set of data from the system 32S + 100Mo at ELab = 200 MeV. Statistical model fails in reproducing the whole set of data and no convincing estimate is possible of the fission time scale. In particular, while pre-scission multiplicities can be reproduced without delay, the model strongly overestimates proton and alpha particle multiplicities in the evaporation residues channel irrespective of the statistical model input parameters and prescriptions used for the level density and the transmission coefficients. The analysis of the same set of data with a dynamical model produces a very good agreement with the full set of data and indicates that one-body dissipation plays a dominant role in the fission process, implying a fission delay of 23–25×10−21s.