Analysis of pairing correlations in neutron transfer reactions and comparison to the constrained molecular dynamics model

The transfer yields mass spectra were measured in B11,C12,13,Si28(O18,O17) and B11,C12,13,Si28(O18,O16) reactions at 84 MeV. The two-neutron transfer (2NT) and the one-neutron transfer (1NT) cross sections were extracted for all the systems. The 2NT cross section is found comparable to the 1NT one and remarkably larger than that predicted assuming no correlations among the two transferred nucleons and only natural parity states are populated via the (O18,O16) two-neutron transfer reaction. Calculations based on the constrained molecular dynamics model show that such behavior is uniquely a consequence of neutron pairing correlations in the O18 ground state

Virtualit\ue0 al quadrato: proposta di sperimentazione di un ambiente didattico universitario in Second Life

Il presente lavoro intende esplorare le possibilit\ue0 offerte da Second Life in ambito online-learning, sperimentando un percorso di allestimento di ambienti di apprendimento in ambito universitario attraverso metodologie didattiche e strumenti che si avvalgono della sinergia fra due tecnologie: da una parte, la ricostruzione tridimensionale di un contesto formativo accademico utilizzando la piattaforma Second Life valorizzata dall'introduzione di nuovi tool, dall'altra l'interfacciamento con Moodle, nella delineazione di un possibile utilizzo a livello didattico

First lattice evidence for a non-trivial renormalization of the Higgs condensate

General arguments related to ``triviality'' predict that, in the broken phase of $(\lambda\Phi^4)_4$ theory, the condensate re-scales by a factor $Z_{\phi}$ different from the conventional wavefunction-renormalization factor, $Z_{prop}$. Using a lattice simulation in the Ising limit we measure $Z_{\phi}=m^2 \chi$ from the physical mass and susceptibility and $Z_{prop}$ from the residue of the shifted-field propagator. We find that the two $Z$'s differ, with the difference increasing rapidly as the continuum limit is approached. Since $Z_{\phi}$ affects the relation of to the Fermi constant it can sizeably affect the present bounds on the Higgs mass.Comment: 10 pages, 3 figures, 1 table, Latex2

The MAGNEX spectrometer: results and perspectives

This article discusses the main achievements and future perspectives of theMAGNEX spectrometer at the INFN-LNS laboratory in Catania (Italy). MAGNEX is alarge acceptance magnetic spectrometer for the detection of the ions emitted innuclear collisions below Fermi energy. In the first part of the paper anoverview of the MAGNEX features is presented. The successful application to theprecise reconstruction of the momentum vector, to the identification of the ionmasses and to the determination of the transport efficiency is demonstrated byin-beam tests. In the second part, an overview of the most relevant scientificachievements is given. Results from nuclear elastic and inelastic scattering aswell as from transfer and charge exchange reactions in a wide range of massesof the colliding systems and incident energies are shown. The role of MAGNEX insolving old and new puzzles in nuclear structure and direct reaction mechanismsis emphasized. One example is the recently observed signature of the longsearched Giant Pairing Vibration. Finally, the new challenging opportunities touse MAGNEX for future experiments are briefly reported. In particular, the useof double charge exchange reactions toward the determination of the nuclearmatrix elements entering in the expression of the half-life of neutrinolessdouble beta decay is discussed. The new NUMEN project of INFN, aiming at theseinvestigations, is introduced. The challenges connected to the major technicalupgrade required by the project in order to investigate rare processes underhigh fluxes of detected heavy ions are outlined

A view of recent results and perspectives on nuclear structure with MAGNEX at the INFN-LNS laboratory

An intense activity in the field of experimental, as well as theoretical, nuclear structure is ongoing at the INFN-LNS laboratory in Catania. A short overview of the main recent results is reported

Microscopic cluster model for the description of (18O,16O) two-neutron transfer reactions

Excitation energy spectra and absolute cross-section angular distributions were measured for the 13C(18O,16O)15C two-neutron transfer reaction at 84 MeV incident energy. Exact finite-range coupled reaction channel calculations are used to analyse the data considering both the direct two-neutron transfer and the two-step sequential mechanism. For the direct calculations, two approaches are discussed: The extreme cluster and the newly introduced microscopic cluster. The latter makes use of spectroscopic amplitudes in the centre-of-mass reference frame, derived from shell-model calculations. The results describe well the experimental cross sections

Microscopic cluster model for the description of new experimental results on the C 13 (O 18, O 16) C 15 two-neutron transfer at 84 MeV incident energy

The C13(O18,O16)C15 reaction is studied at 84 MeV incident energy. Excitation energy spectra and absolute cross-section angular distributions for the strongest transitions are measured with good energy and angular resolutions. Strong selectivity for two-neutron configurations in the states of the residual nucleus is found. The measured cross-section angular distributions are analyzed by exact finite-range coupled reaction channel calculations. The two-particle wave functions are extracted using the extreme cluster and the independent coordinate scheme with shell-model derived coupling strengths. A new approach also is introduced, the microscopic cluster, in which the spectroscopic amplitudes in the center-of-mass reference frame are derived from shell-model calculations using the Moshinsky transformation brackets. This new model is able to describe well the experimental cross section and to highlight cluster configurations in the involved wave functions

A mini-phoswich scintillator as a possible stop detector for the NUMEN project

AbstractIn the framework of the NUMEN project, aimed at the investigation of the nuclear matrix elements connected to the neutrinoless double beta decay by means of the Double Charge Exchange nuclear reactions (Cappuzzello et al., 2015), a high granularity stop detector for heavy ions is needed. It has to allow the identification of ions up to Z≈10 while maintaining a total energy resolution around 2%. As the use of silicon detectors is not possible, due to their poor radiation hardness, scintillators are being investigated as possible candidates. In this paper we show a promising result obtained using a plastic+inorganic phoswich scintillator readout by means of a Silicon Photo Multiplier

Performance of the reconstruction algorithms of the FIRST experiment pixel sensors vertex detector

Hadrontherapy treatments use charged particles (e.g. protons and carbon ions) to treat tumors. During a therapeutic treatment with carbon ions, the beam undergoes nuclear fragmentation processes giving rise to significant yields of secondary charged particles. An accurate prediction of these production rates is necessary to estimate precisely the dose deposited into the tumours and the surrounding healthy tissues. Nowadays, a limited set of double differential carbon fragmentation cross-section is available. Experimental data are necessary to benchmark Monte Carlo simulations for their use in hadrontherapy. The purpose of the FIRST experiment is to study nuclear fragmentation processes of ions with kinetic energy in the range from 100 to 1000 MeV/u. Tracks are reconstructed using information from a pixel silicon detector based on the CMOS technology. The performances achieved using this device for hadrontherapy purpose are discussed. For each reconstruction step (clustering, tracking and vertexing), different methods are implemented. The algorithm performances and the accuracy on reconstructed observables are evaluated on the basis of simulated and experimental data