Search for: All records

The typical energy range for charge particle interactions in stellar plasmas corresponds to a few 10s or 100s of keV. At these low energies, the cross sections are so vanishingly small that they cannot be measured directly with accelerator based experimental techniques. Thus, indirect studies of the compound structure near the threshold are used in the framework of reaction models to complement the direct data in order to extrapolate the cross section into the low energy regime. However, at the extremely small cross sections of interest, there maybe other quantum effects that modify the such extracted cross section. These may result from additional nuclear interactions associated with the threshold itself or could be due to other processes, such as electron screening. Measurements in plasma environments like at the OMEGA or National Ignition Facility facilities offer an entirely new set of experimental conditions for studying these types of reactions, often directly at the energies of interest. In this paper, we examine three reaction, 10 B( p , α ) 7 Be, 12 C( p , γ ) 13 N and 14 N( p , γ ) 15 O, which have all been measured at very low energies using accelerator based methods. All three reactions produce relatively long-lived radioactive nuclei, which can be collected and analyzed at plasma facilities using a variety of collection and identification techniques. 

Abstract The resonant scattering of 10 B+ p reaction was measured at θ c.m. = 180°, 170°, 160°, 150° and 140° using a 35.93 MeV 10 B beam to investigate the spectroscopy of 11 C with the thick target inverse kinematic method at RIBRAS facility, IFUSP, São Paulo. Influence of the stopping power uncertainty on the resonant scattering cross section values for 11 C in the 10 B( p, p ) 10 B reaction is shown. The data measured for the reaction channels p ( 10 B, α ) and p ( 10 B, 3 He) is also presented. Interestingly, the cross sections for the 3 He channel are observed upto 2 MeV below the lowest energy measurement available in literature. 

The 19 F( p , αγ ) 16 O reaction is of crucial importance for Galactic 19 F abundances and CNO cycle loss in first generation Population III stars. Due to its extremely small cross sections, the 19 F( p , αγ ) 16 O reaction has not been measured in the low energy part of the Gamow window(70-200 keV). As a day-one campaign, the experiment was performed under the extremely low cosmicray-induced background environment of the China JinPing Underground Laboratory(CJPL), one of the deepest underground laboratories in the world. The γ -ray yields were measured over E c . m . =72.4–344 keV, covering the full Gamow window for the first time. The direct experimental data will help people to expound the fluorine over-abundances, energy generation, as well as heavy-element nuclosynthesis scenario in asymptotic giant branch (AGB) stars, with the astrophysical model on the firm ground.