D. Nicolosi

Carbon fragmentation measurements and validation of the Geant4 nuclear reaction models for hadrontherapy

Nuclear fragmentation measurements are necessary when using heavy-ion beams in hadrontherapy to predict the effects of the ion nuclear interactions within the human body. Moreover, they are also fundamental to validate and improve the Monte Carlo codes for their use in planning tumor treatments. Nowadays, a very limited set of carbon fragmentation cross sections are being measured, and in particular, to our knowledge, no double-differential fragmentation cross sections at intermediate energies are available in the literature. In this work, we have measured the double-differential cross sections and the angular distributions of the secondary fragments produced in the (12)C fragmentation at 62 A MeV on a thin carbon target. The experimental data have been used to benchmark the prediction capability of the Geant4 Monte Carlo code at intermediate energies, where it was never tested before. In particular, we have compared the experimental data with the predictions of two Geant4 nuclear reaction models: the Binary Light Ions Cascade and the Quantum Molecular Dynamic. From the comparison, it has been observed that the Binary Light Ions Cascade approximates the angular distributions of the fragment production cross sections better than the Quantum Molecular Dynamic model. However, the discrepancies observed between the experimental data and the Monte Carlo simulations lead to the conclusion that the prediction capability of both models needs to be improved at intermediate energies.

FIRST experiment: Fragmentation of Ions Relevant for Space and Therapy

Nuclear fragmentation processes are relevant in different fields of basic research and applied physics and are of particular interest for tumor therapy and for space radiation protection applications. The FIRST (Fragmentation of Ions Relevant for Space and Therapy) experiment at SIS accelerator of GSI laboratory in Darmstadt, has been designed for the measurement of different ions fragmentation cross sections at different energies between 100 and 1000 MeV/nucleon. The experiment is performed by an international collaboration made of institutions from Germany, France, Italy and Spain. The experimental apparatus is partly based on an already existing setup made of the ALADIN magnet, the MUSIC IV TPC, the LAND2 neutron detector and the TOFWALL scintillator TOF system, integrated with newly designed detectors in the interaction Region (IR) around the carbon removable target: a scintillator Start Counter, a Beam Monitor drift chamber, a silicon Vertex Detector and a Proton Tagger for detection of light fragments emitted at large angles (KENTROS). The scientific program of the FIRST experiment started on summer 2011 with the study of the 400 MeV/nucleon 12C beam fragmentation on thin (8mm) carbon target.

(18O,18Ne) double charge-exchange with MAGNEX

An experimental study concerning Double Gamow-Teller (DGT) modes in (18O,18Ne) Double Charge-Exchange reactions has been very recently performed at INFN-LNS laboratory in Catania. The experiment was performed using a 40Ca solid target and a 18O Cyclotron beam at 270 MeV incident energy. Charged ejectiles produced in the reaction were momentum analyzed and identified by MAGNEX spectrometer at very forward angles. Preliminary results are presented in the present paper.

Elastic scattering for the system 6Li+p at near barrier energies with MAGNEX

Elastic scattering measurements have been performed for the {sup 6}Li+p system in inverse kinematics at the energies of 16, 20, 25 and 29 MeV. The heavy ejectile was detected by the large acceptance MAGNEX spectrometer at the Laboratori Nazionali del Sud (LNS) in Catania, in the angular range between ∼2{sup 0} and 12{sup 0} in the laboratory system, giving us the possibility to span almost a full angular range in the center of mass system. Results will be presented and discussed for one of the energies.

The (18O, 16O) reaction as a probe for nuclear spectroscopy

The response of nuclei to the (18O, 16O) two-neutron transfer reaction at 84 MeV incident energy has been systematically studied at the Catania INFN-LNS laboratory. The experiments were performed using several solid targets from light (9Be, 11B, 12,13C, 16O, 28Si) to heavy ones (58,64Ni, 120Sn, 208Pb). The 16O ejectiles were detected at forward angles by the MAGNEX magnetic spectrometer. Exploiting the large momentum acceptance (−10%, +14%) and solid angle (50 msr) of the spectrometer, energy spectra were obtained with a relevant yield up to about 20 MeV excitation energy. The application of the powerful trajectory reconstruction technique did allow to get energy spectra with energy resolution of about 150 keV and angular distributions with angular resolution better than 0.3°. A common feature observed with light nuclei is the appearance of unknown resonant structures at high excitation energy. The strong population of these latter together with the measured width can reveal the excitation of a collective...

Two-neutron stripping in (18O, 16O) and (t,p) reactions

The 12C(18O,16O)14C reactions has been investigated at 84 MeV incident energy. The charged ejectiles produced in the reaction have been momentum analyzed and identified by the MAGNEX magnetic spectrometer. Q-value spectra have been extracted with an energy resolution of 160 keV (Full Width at Half Maximum) and several known bound and resonant states of 14C have been identified up to 15 MeV. In particular, excited states with dominant 2p - 4h configuration are the most populated. The absolute values of the cross sections have been extracted showing a striking similarity with those measured for the same transitions by (t,p) reactions. This indicates that the effect of the 16O core is negligible in the reaction mechanism.

The role of couplings in nuclear rainbow formation at energies far above the barrier

A study of the 16O+28Si elastic and inelastic scattering is presented in the framework of Coupled Channel theory. The Sao Paulo Potential is used in the angular distribution calculations and compared with the existing data at 75 MeV bombarding energy. A nuclear rainbow pattern is predicted and becomes more clear above 100 MeV.

Study of new resonances at high excitation energy by the 120Sn(p,t)118Sn reaction at 35 MeV

The 120Sn(p,t)118Sn reaction was investigated at 35 MeV incident energy. The 118Sn excitation energy spectrum was reconstructed up to about 16 MeV. Preliminary results show the presence of a broad resonance at high excitation energy, compatible with the predicted population of the Giant Pairing Vibration (GPV).

Experiment FIRST: Fragmentation of 12 C beam at 400 MeV/u

The knowledge about fragmentation processes in ion-ion interactions is fundamental in hadrontherapy and radiation protection in space missions. Hadrontherapy, based on 12C, features many advantages with respect to conventional radiation therapy with photons due to the possibility to shape the dose delivery region in tissues but side effects of the projectile fragmentation in healthy tissues are not negligible. NASA recently pointed out that measurements for some light ions and kinetic energies are missing in nuclear fragmentation databases. FIRST experiment aims to measure the fragmentation double differential cross section of 12C in the energy range 1001000 MeV/u on several elements, constituents of organic tissues and electronic devices, in order to fill some of the mentioned lack of information on light ions. A first set of data has been taken in 2011 at GSI (Darmstadt), using 12C beam at 400 MeV/u on C and Au targets. About 3·107 events with C target and 5 · 106 with Au target were recorded. Together with these data other sets of runs have been collected to calibrate the forward part of the whole experimental setup, the ToF-Wall. The calibration procedure and the detector performances, which fit the experiment requirements for what concerns efficiency, resolution and stability, will be illustrated. Moreover, some preliminary results concerning the 12C-12C elastic scattering, in agreement with the Rutherford model, will be presented.

Effects of the polarization potential on the classical elastic scattering trajectories of 16O + 27Al at 100 MeV

The 16O + 27Al elastic scattering is studied in the framework of Coupled Channel theory with Sao Paulo parameter free optical potential. The deflection function and the complex polarization potential are extracted. A surprising reduction of the overall absorption is found near the surface of the colliding systems. The semi-classical trajectories reveal a strong Ldependent behavior.