The 38K(p,γ)39Ca reaction is one of the key reactions that govern argon and calcium production in classical novae. Measuring the cross section of this reaction is difficult, though, because 38K is radioactive with a half-life of about 7 minutes. Instead, we can constrain the cross section by measuring the properties of the excited states in 39Ca that govern it. Previously, the energies in those excited states were poorly known. By performing a 40Ca(3He,α)39Ca neutron pick-up measurement led by postdoc Kiana Setoodehnia, we determined the energies and spin-parities of states in the astrophysically important energy region. This lead to a 40% increase in the reaction rate at 100 MK, and will lead to a decrease in the nucleosynthesis uncertainties associated with this reaction.
Our paper exploring the current experimental information on the 39K(p,γ)40Ca reaction cross section was just accepted in Physical Review C! This reaction is critical for explaining the peculiar elemental abundance patterns in the Globular Cluster NGC 2419, which can help us understand how the galaxy evolved. We found that inconsistencies in cross section measurements make the uncertainty in this rate larger than previously assumed, thus further exeperimental efforts should be aimed at investigating the 39K(p,γ)40Ca cross section.
Caleb Marshall's paper describing the design, construction, and testing of our focal plane detector was accepted into IEEE Transactions on Instrumentation and Measurement! This paper is the culmination of many years of hard work by Caleb and his co-authors. The detector is in use as I write this and will be the workhorse of many years of Enge split-pole spectrograph measurements. Congratulations, Caleb!
Dr. Richard Longland received the prestigious Department of Energy Early Career Award from the Office of Nuclear Physics. The Early Career Award program supports the development of individual research programs of outstanding scientists early in their careers and stimulates research careers in the disciplines supported by the DOE Office of Science.
The award will help Dr. Longland in his research to determine the rate of nuclear reaction in stars and stellar explosions. These experiments are challenging to perform, and the funds received will enable his group to build a world-class program using particle transfer reactions at the Facility for Experiments on Nuclear Reactions in Stars (FENRIS)
Out of about 700 proposals, just 59 were selected.
A flexible way to account for correlations in Monte Carlo reaction rate uncertainty calculations has been developed. The paper was just accepted to Astronomy and Astrophysics!
In December, Federico and María flew back to Venezuela to get married! In January, they were generous enough to invite our group to a celebration of their special bond in Durham, NC. The party was a great success! Many congratulations to Federico and María and we wish them the very best as they continue their journey together!
After 50 years of history, the Triangle Universities Nuclear Laboratory (TUNL) continues to push the limits of nuclear physics. As a Department of Energy "Center of Excellence", our lab is home to the world's most intense proton accelerator dedicated to nuclear astrophysics, the world's most luminous mono-energetic photon beam, and the only functioning Enge magnetic spectrograph in North America. Check out the video below!
Sean Hunt from the UNC astrophysics group did a fantastic job of carefully characterizing a boron-loaded neutron detector. His work was recently published in Nuclear Instruments and Methods A.
We recently collaborated with Alain Coc at the Centre de Sciences Nucléaires et de Sciences de la Matière (CSNSM) on an evaluation of big bang nucleosynthesis. Using theoretical ab initio models to predict the energy dependence of the cross section and carefully accounting for systematic uncertainties, we found a reduced deuterium abundance, in agreement with observations.
The NCSU experimental nuclear astrophysics group were featured in some UNC promotional material celebrating the 50th anniversary of the Triangle Universities Nuclear Laboratory.