Nuclear isotope production by ordinary muon capture reaction

Abstract

Muon capture isotope production (MuCIP) using negative ordinary muon (µ) capture reactions (OMC) is used to efficiently produce various kinds of nuclear isotopes for both fundamental and applied science studies. The large capture probability of µ into a nucleus, together with the high intensity µ beam, make it possible to produce nuclear isotopes in the order of 10 9−10 per second depending on the muon beam intensity. Radioactive isotopes (RIs) produced by MuCIP are complementary to those produced by photon and neutron capture reactions and are used for various science and technology applications. MuCIP on Nat Mo by using the RCNP MuSIC µ beam is presented to demonstrate the feasibility of MuCIP. Nuclear isotopes produced by MuCIP are evaluated by using a pre-equilibrium (PEQ) and equilibrium (EQ) proton neutron emission model. Radioactive 99 Mo isotopes and the metastable 99m Tc isotopes, which are used extensively in medical science, are produced by MuCIP on Nat Mo and $

Ordinary Muon Capture for Double Beta Decay and Anti-Neutrino Nuclear Responses

“…The OMC strength distribution as a function of the excitation energy E is derived from the mass-number (A−x) distribution (x distribution) through the particle cascade model (Hashim et al, 2018;Hashim et al, 2020). The excited states in Nb isotopes decay by emitting mostly neutrons since the Coulomb barrier much suppresses proton emission.…”

“…The strength distribution is fitted by the sum of the μ-GR strengths of B 1 (μ,E 1 ) and B 2 (μ,E 2 ) given by 4) where E Gi and Γ i with i 1,2 are the resonance energy and the width for the ith GR, and the constant B i (μ) is given by σ i Γ i /(2π) with σ i being the total strength integrated over the excitation (Hashim et al, 2020). (A) When OMC on 100 Mo occurs, 100 Nb is excited to some energy up to around 50 MeV, with B n (B p ) 5.68 MeV (9.46 MeV), 6.87 MeV (8.34 MeV), 5.99 MeV (7.87 MeV) and 8.07 MeV (7.46 MeV) for Nb A with A 100, 99, 98, and 97, respectively.…”

“…Recently a proton-neutron emission model (PNEM) has been developed by considering the probability of proton emission as well (Hashim et al, 2020). The proton energy spectrum is given by S(E p ) m × exp(−n×Ep), where m and n are the density parameter constant with the value of 0.832 MeV and 0.163 MeV −1 .…”

“…Since then, various calculations have been made for understanding the formation of the GR populated by muon capture reactions in 98, < A < 209 (Hashim et al, 2020). These calculations have been compared with previous experimental works by OMC on the nuclei reported in references (Measday, 2001;Measday et al, 2007b;Measday et al, 2007a).…”

“…The parameters of E G1 and E G2 as a function of A are given as E G1 30A −1/5 and E G2 75A −1/5 for OMC on nat Mo, 100 Mo, 107 Pd, 108 Pd, 127 I and 209 Bi. They FIGURE 2 | Radioactive isotope (RIs) mass-number distribution from the ratio of number of isotopes N (X′) where X being the atomic mass number of the daughter nucleus in experimental observations over the total isotopes ΣN(X′) observed for the experiment, and calculations for neutron and proton emission events after muon capture reactions (Hashim et al, 2020). The black bar represents the experimental observation while the gray bar represents calculated value by Proton neutron emission model (PNEM).…”