Study of the 4He(4He,4He)4He* inelastic scattering at the MAGNEX facility

V Soukeras,M Cicerchia,C Ciampi,M Cavallaro,O Sgouros,I Ciraldo,F Cappuzzello,L La Fauci,C Frosin,G A Brischetto,T Marchi,S Firat,M Hilcker,M Fisichella,C Agodi,M Vigilante,I Lombardo,A Spatafora,D Carbone,D Torresi,M Cinausero,A Hacisalihoglu,M D ́ Andrea ,H.w Becker ,Salvatore Calabrese ,Daniele Dell' Aquila ,Aydın Yıldırım

doi:10.1051/epjconf/202125204007

Abstract

The 4He(4He,4He)4He* inelastic scattering was revisited in a new coincidence measurement at the MAGNEX facility of Istituto Nazionale di Fisica Nucleare – Laboratori Nazionali del Sud. The 4He + 4He → 4He + 4He* → 4He + 3H + 1H and 4He + 4He → 4He + 4He* → 4He + 3He + n reactions were measured simultaneously by detecting the 4He particles at the MAGNEX magnetic spectrometer in coincidence with the 3H and 3He at the OSCAR silicon telescope. The main concept of the experiment is described and the data reduction strategy is reported.

Highlights

The 4He is a well bound nucleus with a breakup threshold of 19.8 MeV for the 3H – 1H mode and 20.7 MeV for the 3He – n one
The different ions were detected by the Focal Plane Detector (FPD) [10,11] of MAGNEX, which consists of a gas tracker followed by a wall of 60 silicon pad detectors
The two different decay modes 4He + 4He → 4He + 4He* → 4He + 3H + 1H and 4He + 4He → 4He + 4He* → 4He + 3He + n were reconstructed by two coincidence measurements. In both modes 4He nuclei were detected by the MAGNEX FPD [11], while the 3H and 3He fragments were detected by OSCAR telescope [13]

Summary

Introduction

The 4He is a well bound nucleus with a breakup threshold of 19.8 MeV for the 3H – 1H mode and 20.7 MeV for the 3He – n one. A recent ab-initio calculation of the monopole transition form factor of 4He with realistic nuclear forces pointed to a strong dependence on the different realistic potential used and revealed a significant disagreement with respect to all existing electron scattering data when a method based on modern Hamiltonians from chiral perturbation theory was adopted [7]. The inconsistencies met between the recent ab-initio form factor and all existing data from 4He(e,e)4He* studies call for further investigation. From both the experimental and theoretical point of view the 4He(e,e)4He* and 4He(4He,4He)4He* studies are challenging. The 4He induced scattering is governed by the nuclear force, making the extraction of the electric monopole form factor less direct. A global interpretation together with the elastic scattering channel, which was measured, ensures a precise optical model analysis, allowing the extraction of the form factors

The experiment

Elastic scattering measurement

Inelastic scattering measurement

Data Reduction

Summary