Spallation reactions: A successful interplay between modeling and applications

Abstract

The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.

Coherent elastic neutrino-nucleus scattering at the European Spallation Source

“…This agreement is preserved at 2 GeV for most MC-NPX 2.7.0 intranuclear cascade and evaporation model combinations, but not for the GEANT4 options tested. A large dispersion in GEANT4 pion yield predictions has been noticed before, during benchmarks using the most recent hadroproduction measurements by the HARP [46] and HARP-CDP [47] collaborations: experimental pion production cross-sections for 2.2 GeV protons striking Ta and Pb targets are over-or under-estimated by different GEANT4 physics lists [48][49][50], following a pattern similar to that in Fig. 3.…”

Benchmark study of the recent version of the PHITS code

“…The results from PHITS are generally in acceptable agreement with the experimental data [22], except for a peak spectrum at 24°. This is because INCL4.6 cannot appropriately reproduce the quasi-elastic scattering [23]. The benchmark calculations for charged particle production shown in the other parts of Figure 4 are discussed in the next subsection.…”

Improvement of one-nucleon removal and total reaction cross sections in the Liège intranuclear-cascade model using Hartree-Fock-Bogoliubov calculations

“…During recent decades, it has been demonstrated that INC models coupled to de-excitation ones are able to describe many experimental observables [22]. Recently, some works have pointed that this kind of model describes reasonably inclusive measurements of one-nucleon-removal reactions on light nuclei, such as carbon or oxygen, at projectile energies below 120 MeV [23][24][25] where, basically, one-nucleon removal reactions must fulfill two conditions simultaneously: Only one nucleon must be knocked out in the intranuclear-cascade process and the residual excitation energy of the remnant must be below the neutron and proton separation energies.…”