Isospin transport phenomena for the systems Kr80+Ca40,48 at 35 MeV/nucleon

Abstract

Experimental data concerning isospin transport phenomena for the systems 80 Kr + 40,48 Ca at 35 MeV/nucleon are presented. Data have been collected with four FAZIA blocks; this data set is the same analyzed in S. Piantelli et al., Phys. Rev. C 101, 034613 (2020). The isotopic composition of the QuasiProjectile residue (up to Z around 25) and of its decay products in the two reactions are compared, finding a neutron enrichment when the target is 48 Ca. The isotopic composition of the emitted light charged particles (LCP) and intermediate mass fragments (IMF) was also investigated in different windows of velocity. The obtained results have been compared with the prediction of the transport model AMD followed by the statistical code GEMINI (used as an afterburner), with different recipes for the density dependence of the symmetry energy term in the nuclear equation of state. A weak indication in favor of a stiff symmetry energy emerges when the fragments emitted at midvelocity are examined.

Trends in particle and nuclei identification techniques in nuclear physics experiments

“…The NUCLEX collaboration studies the behaviour of nuclear matter in a wide range of beam energies (5-100 MeV/nucleon) using different setups and particle identification techniques. This diversification is needed to better investigate phenomena typical of different energy regimes: compound nucleus formation and decay [62], α-clustering [63], charged particle spectroscopy [64], isospin transport mechanisms [65][66][67] and neck emissions [68]. Various setups have been developed and used at LNS, LNL and GANIL: FAZIA [69,70], GARFIELD [71], OSCAR [72] and the ACTAR demonstrator [73].…”

“…The enhancement at around 10 MeV comes from the contribution of the Pygmy Dipole Resonance decay of 68 Ni. The cross section of such Pygmy decay was evaluated from the difference between spectra measured in coincidence with 68 Ni and 66,67 Ni, as discussed in detail in Ref. [144].…”

“…The black dots represent the spectrum in coincidence with68 Ni, detected at forward angles. The blue dots represent the spectrum in coincidence with66,67 Ni. The bump at around 10 MeV is the contribution of the Pygmy Dipole Resonance decay (figure adapted from Ref [144]…”

First results from the INDRA-FAZIA apparatus on isospin diffusion in $^{58,64}$Ni+$^{58,64}$Ni systems at Fermi energies

“…Among these latter, a special focus has been put on the isospin transport phenomena [5]. Two main experimental observations in the field of isospin dynamics have been widely recognized by the scientific community: the process of isospin equilibration between reacting nuclei having different initial neutron-to-proton ratio N/Z [6][7][8][9][10][11][12][13][14][15][16][17], and the neutron enrichment of the midvelocity emissions [4,10,11,[14][15][16][18][19][20]. An interpretation of these two phenomena can be found in the framework of the Nuclear Equation of State (NEoS).…”

“…In this paper, we focus on the experimental observation of isospin diffusion in semi-peripheral and peripheral reactions by analyzing the isotopic composition of the QP. The isospin content of the QP can be probed either by inspecting the characteristics of its deexcitation emissions [10,12,16] or by the direct isotopic identification of its remnant [16,17]. Common experimental apparatuses generally access only QP evaporation or, less frequently, only the isotopic composition of the QP residue.…”