Nuclear responses of64,66Zn isotopes to supernova neutrinos

Abstract

Nuclear responses to energy spectra of supernova (SN) neutrinos are studied by folding original ν-nucleus cross sections calculated in the context of the quasiparticle random-phase approximation using realistic two-body forces. To this purpose, we employ two-parameter neutrino-energy distributions of Fermi-Dirac and power-law shapes for various SN neutrino scenarios. As concrete examples of promising neutrino detectors we have chosen the 64,66 Zn isotopes, contents of (i) the semiconductor CdZnTe (COBRA experiment) and (ii) the crystal scintillators ZnMoO 4 and ZnWO 4 . These materials are quite advantageous for measuring double-β-decay events and for potential use in studying current neutrino physics issues. We concentrate on the evaluation of folded differential cross sections, [dσ (ω)/dω] fold , and flux-averaged cumulative cross sections, [dσ (ω)/dω] cum fold , as well as total cross sections, σ tot , of the above Zn isotopes by adopting several realistic SN neutrino models parametrized by the neutrino temperature or the mean neutrino energy and the width of the aforementioned distributions.

Neutral-current neutrino-nucleus reactions and their impact to supernova physics

“…The maximum peak corresponds to a J π = 1 + (ground state) transition at ω= 9.482 MeV and a second one corresponds to a 1 − transition at ω= 13.311 MeV in agreement with the findings of Refs. [2,4].…”

“…In Table 1, we tabulate the values of the pairing parameters (g p,n pair ) and the energy gaps (∆ th p,n ) for protons (p) and neutrons (n) determined at the BCS level for this isotope. The first parameters renormalize the pairing force and adjust the gaps ∆ th p,n to the empirical ones, ∆ exp p,n , obtained through the application of the well known three point formulae [4]. [2].…”

“…However, the very low ν-interaction cross-section is simultaneously the biggest disadvantage for their detection that can be probed through measuring Cherenkov light from secondary particles or through the de-excitation products of ν-induced excitations of nuclear ν-detectors in extremely sensitive (mostly underground) experiments. Such probes, however, need significant event rates and, therefore, huge volume detectors have to be constructed [2,3,4]. On the other hand, from supernova (SN) physics it is known that, the death of massive (with mass M ≥ 8 − 10M ⊙ ) stars is marked through very energetic explosions known as core-collapse supernovae.…”

“…The relevant cross sections are by about an order of magnitude larger than the corresponding for NC ones. Third, we consider nuclear responses to SN-neutrinos focusing on the possibility of including in these estimations contributions coming from particle decays of ν-induced excited states lying above the separation energies for protons and neutrons [4]. In studying detector responses to SN neutrinos, particle decays cause extra signals which are important to be included in the study.…”

“…): (i) for measuring rare events (double-beta decay, etc. [5,6]) and (ii) for potential use in studying neutrino physics issues [2,3,4]. Second, we treat charged-current (CC) interactions of neutrinos with the above nuclei.…”