Measurements of nuclearγ-ray line emission in interactions of protons andαparticles with N, O, Ne, and Si

Abstract

γ-ray production cross sections have been measured in proton irradiations of N, Ne and Si and α-particle irradiations of N and Ne. In the same experiment we extracted also line shapes for strong γ-ray lines of 16 O produced in proton and α-particle irradiations of O. For the measurements gas targets were used for N, O and Ne and a thick foil was used for Si. All targets were of natural isotopic composition. Beams in the energy range up to 26 MeV for protons and 39 MeV for α-particles have been delivered by the IPN-Orsay tandem accelerator. The γ rays have been detected with four HP-Ge detectors in the angular range 30 • to 135 • . We extracted 36 cross section excitation functions for proton reactions and 14 for α-particle reactions. For the majority of the excitation functions no other data exist to our knowledge. Where comparison with existing data was possible usually a very good agreement was found. It is shown that these data are very interesting for constraining nuclear reaction models. In particular the agreement of cross section calculations in the nuclear reaction code TALYS with the measured data could be improved by adjusting the coupling schemes of collective levels in the target nuclei 14 N, 20,22 Ne and 28 Si. The importance of these results for the modeling of nuclear γ-ray line emission in astrophysical sites is discussed.

Measurement and analysis of nuclear γ -ray production cross sections in proton interactions with Mg, Si, and Fe nuclei abundant in astrophysical sites over the incident energy range E=30–66 MeV

“…The experimental results are reported and discussed in Sec. IV, where the cross section excitation functions for known, main γ -ray lines are compared to previous counterparts measured at proton energies E p < 30 MeV [8,[11][12][13]18,19]. Results for new lines, measured for the first time in this work, are also reported in this section, where present and previous experimental cross section data are compared to the Murphy et al database [16], and to TALYS calculations in Sec.…”

“…More recently, measurements of γ -ray line cross sections have been carried out [18,19] at the Orsay tandem accelerator for reactions induced by swift protons and α particles on N, O, Ne, and Si targets over the incident energy range extending up to 26 and 39 MeV, respectively. The measured cross section data completed earlier data sets taken at the same facility [11,12,20,21] for lower particle energies.…”

“…However, the agreements between the calculated γ -ray line production cross sections and corresponding experimental data can be appreciably improved by using in TALYS modified nuclear level deformation parameters instead of the built-in default ones, as shown in Refs. [18,19], e.g., for the 14 N, 22 Ne, or 28 Si nuclei. Furthermore, these calculations revealed the presence of large structures at higher particle energies where no experimental data are available.…”

ERRATUM: “DEEXCITATION NUCLEAR GAMMA-RAY LINE EMISSION FROM LOW-ENERGY COSMIC RAYS IN THE INNER GALAXY” (2013, ApJ, 763, 98)

“…For all other γ-ray lines we relied entirely on calculations with the reaction code TALYS (Koning, Hilaire, & Duivestijn (2008)) as it was done in Murphy et al (2009), with some slight parameter changes for 14 N, 20,22 Ne and 28 Si which gave an improved reproduction of new experimental γ-ray data for proton and α-particle induced reactions with these nuclei (Benhabiles et al (2011)). This code works in the range up to 250 MeV for proton reactions and 62.5 MeV per nucleon for α-particle reactions.…”

“…In this paper, we calculate this total nuclear γ-ray line emission from the inner Galaxy by making use of the work of Indriolo, Fields, & McCall (2009), new developments in nuclear reaction cross sections (Murphy et al (2009), Benhabiles et al (2011) and recent observations of cosmic-ray induced high-energy γ-ray emission with Fermi-LAT (Abdo et al (2009);Strong (2011);Ackermann et al (2012)). Finally, the possibilities for a detection of this emission with existing and eventual future space-borne γ-ray instruments are discussed.…”