Speaker
Description
PANDORA (Plasmas for Astrophysics, Nuclear Decay Observations and Radiation for Archaeometry) is an upcoming facility at INFN - LNS aiming to use an electron cyclotron resonance ion source (ECRIS) as a magnetoplasma trap to measure $\beta$-decay rates of radioisotopes in certain electron density and temperature ranges [1]. Decay rates $\lambda$ are susceptible to changes in atomic configuration of the parent and daughter systems and are modified inside plasmas due to the ionic charge state distribution (CSD) and level population distribution (LPD). Measuring $\lambda$ in energetic plasmas is crucial, for instance, for providing accurate inputs to nucleosynthesis models – s-process models in particular – where competition between $\beta$-decay and neutron capture dictates the elemental abundance.
Since the CSD and LPD are strongly non-uniform in ECRIS, so are the decay rates, and calculating them is a complex process involving sequential simulations of plasma electrons, ions and nuclei in order. Taking as example the test-case of $^{7}$Be, we present here a detailed analysis of how its electron capture rates are modified in a realistic ECRIS, by starting from the Takahashi-Yokoi model and calculating plasma-induced $\lambda$ variation for a grid of plasma density and temperatures [2]. The analysis is then extended to a realistic laboratory magnetoplasma, where, using a Particle-in-Cell Monte Carlo (PIC-MC) code [3, 4] to model ECR dynamics, we predict the expected spatial gradients of 7Be decay rates in the plasma chamber. The stepwise analysis results in a general model that covers both low-density plasmas in non-local thermodynamic equilibrium (NLTE) and high-density LTE plasmas as in the stellar interior. It also underlines the role of the plasma-decay model for extracting meaningful information from experimental data and the inherent technological challenges. These points offer useful perspectives for PANDORA which is expected to be operational by the end of 2024.
[1] D. Mascali, D. Santonocito et al, Universe 8, 80 (2022)
[2] K. Takahashi and K. Yokoi, Nuclear Physics A 404 (1983)
[3] A. Galatà et al, Frontiers in Physics 10:947194 (2022)
[4] B. Mishra et al, Frontiers in Physics 10:932448 (2022)
