Role of breakup processes in deuteron-induced spallation reactions at 100–200 MeV/nucleon

Abstract

Background: Use of deuteron-induced spallation reactions at intermediate energies has recently been proposed for transmutation of several long-lived fission products (LLFPs). In the design study of a transmutation system using a deuteron primary beam, accurate cross section data of deuteron-induced reactions on the LLFPs are indispensable. Reliable model predictions play an important role in completing the necessary cross section data since currently available experimental data are very limited. Under the circumstances, we have been developing a code system dedicated for deuteron-induced reactions, which is called DEURACS.Purpose: Aiming to predict the production cross sections of residual nuclei, the purpose of the present work is to clarify a role of deuteron breakup processes in deuteron-induced spallation reactions at intermediate energies.Methods: Isotopic production cross sections of residual nuclei in the deuteron-induced reactions on 93 Zr and 107 Pd at 100-200 MeV/nucleon are analyzed using DEURACS, in which the breakup processes are explicitly taken into account. The calculated cross sections are decomposed into individual components corresponding to the absorption of either neutron or proton in the incident deuteron, or the deuteron itself.Results: The calculated cross sections reproduced the experimental data well over a wide mass number range of residual nuclei. From a component-by-component analysis, it was found that the components of nucleon absorption have the significant contributions to the production of residual nuclei.Conclusions: Consideration of the breakup processes is essential to predict the production cross sections of residual nuclei in deuteron-induced reactions. The framework of DEURACS is applicable to deuteron-induced spallation reactions at intermediate energies.

Enhancement of element production by incomplete fusion reaction with weakly bound deuteron

“…In (c), the colliding nucleus remains unexcited and thus has no contribution to the production of other nuclei highlighted by our 104 Ag data compared to the linear extrapolation at high energy, revealing the characteristic of absorption of nucleon(s). As discussed before, the absorption of breakup protons can produce ΔZ = +1 isotopes and lead to a second compound process in addition to CF [6][7][8] . Thus, the enhancement of σ d (E) in the 104 Ag results of the present work provides direct experimental evidence for ICF of breakup proton.…”

“…Thus, the enhancement of σ d (E) in the 104 Ag results of the present work provides direct experimental evidence for ICF of breakup proton. Theoretical calculations of cross sections for 103,104,105 Ag using a newly developed deuteron-induced reaction analysis code system (DEURACS) 8,24 are presented in Fig. 4.…”

“…Nucleon optical potentials (OPs) of Koning and Delaroche 27 are applied for breakup proton and neutron in ICF; OPs of An and Cai 28 are used for deuteron in CF. As described by Nakayama et al 8 , in order to obtain a reliable value with a wide energy range up to 200 MeV/u, the calculated isotopic-distribution cross sections are renormalized using the deuteron-induced total reaction cross sections given by the Minomo-Washiyama-Ogata formula 29 , which is based on a microscopic three-body reaction model. Details on the definition of CF and ICF in DEURACS are provided in the section "Methods".…”

“…For these isotopes, DEURACS indicates that contributions from CF and ICF are comparable to each other as discussed in ref. 8 . When more nucleons are removed from the projectile, it is found that σ d becomes larger than σ p and the difference increases towards the neutron-deficient side within one isotopic chain as displayed in Fig.…”

“…An alternative reaction for producing proton-rich nuclei via incomplete fusion (ICF) induced by loosely bound nuclei has been proposed, and this possibility has been recently demonstrated for deuteron by theoretical studies [6][7][8] . To produce isotopes with increased charge (ΔZ = +1), the breakup of deuteron allows ICF; namely, absorption of the proton released during the breakup in addition to complete fusion (CF) of deuterons, as displayed in Fig.…”