Reduction of deuterium content in carbon targets for 12C + 12C reaction studies of astrophysical interest

Abstract

Abstract. The12 C( 12 C, p) 23 Na and 12 C( 12 C, α) 20 Ne fusion reactions are among the most important in stellar evolution since they determine the destiny of massive (M 8-10 M ) stars. However, experimental low-energy investigations of such reactions are significantly hampered by ubiquitous natural hydrogen and deuterium contaminants in the carbon targets. The associated beam-induced background completely masks the reaction products of interest thus preventing cross-section measurements at the relevant energies of astrophysical interest, E cm < 2 MeV. In this work, we report about an investigation aimed at assessing possible deuterium reductions on both natural graphite and Highly Ordered Pyrolytic Graphite targets as a function of target temperature. Our results indicate that reductions up to about 80% can be attained on both targets in the temperature range investigated, T 200-1200 • C. A further reduction by a factor of 2.5 in absolute deuterium content is observed when the scattering chamber is surrounded by a dry nitrogen atmosphere so as to minimise light-particles uptake within the chamber rest gas (and thus on target) through air leaks. The results from this study will inform the choice of optimal experimental conditions and procedures for improved measurements of the 12 C + 12 C reactions cross-sections at the low energies of astrophysical interest.

New Measurement of C12+C12 Fusi

“…The advantage of using HOPG as target material is its superior purity compared to natural graphite. Impurity of hydrogen and deuterium in the target can cause background in charged particle spectra [41,42] while impurity of 23 Na can severely affect the gamma spectra as discussed later. The HOPG target with a dimension of 2 cm×2 cm×1 mm served also as a water-cooled beam stop.…”

Trends in particle and nuclei identification techniques in nuclear physics experiments

“…Using four modules of the GASTLY array and the SSD as a whole [133], it was possible to identify the 2 H contamination in the target allowing to perform a detailed study for beam-induced background reduction (see Ref. [134]). In addition, it was possible to test the optimum stability of the GASTLY system (2-week-long measurements), its great heat resistance (up to 40 µA on target and 1400 • C) and extremely low intrinsic background (10 −2 counts/h).…”

Recoil mass separators for nuclear astrophysics: The role of ERNA

“…As said, ERNA collaboration is involved not only in the RMS measurements. In the last years, studies of other nuclear reactions in direct kinematics, apparatuses developments and measurements of astrophysical interest have been performed [19,[26][27][28][29][30]. Recently, the 12 C+ 12 C reaction was studied using a partial configuration available in the first development phase of the GASTLY detector array, i.e., four GASTLY detectors with the SSD as an entire pad.…”