Paper on constraining the 25Al(p,γ) reaction accepted for publication!

Our research group and collaborators at the University of Edinburgh, UK, have recently had their paper on constraining the 25Al+p reaction rate in classical nova explosions. By studying the 25Mg(d,p)26Mg, excited states in the mirror nucleus were populated and neutron spectroscopic factors were extracted. We measured the spectroscopic factor of the key 0+ resonance and set a stringent upper limit on the 1+ resonance. The result of these findings is a dramatic decrease of the reaction rate below 200 MK.

Get the article here!

Sulphur isotopic ratios in novae paper published!

Presolar grains from oxygen-neon novae can be identified using their sulphur isotopic ratios. However, these ratios depend on detailed knowledge of the sulphur destruction reactions: 33S(p,γ)34Cl and 34S(p,γ)35Cl. We performed an experiment using the high-resolution TUNL Enge split-pole spectrograph to identify states in 35Cl, which are important for the latter of these two reactions. We were also able to constrain the spins and parities of those states, improving our understanding of the reaction cross section. We found that previous studies did not fully account for the uncertainties in the cross section and prove recommendations for future study.

Get the article here!

Parallel Computing in Hydrodynamics Paper Published!

With the advent of high-precision astronomy, high precision hydrodynamics models of stars and stellar events are more important than ever. These models, however, are computationally expensive so methods must be employed to speed them up. In this paper we investigated a number of methods for speeding up the implicit hydrodynamics code, SHIVA, using parallelization methods. In particular, we found that parallelization of the hydrodynamics part of the calculation is beneficial, speeding up the calculations on the order of the number of CPUs used in the calculation. On the other hand, parallelizing the nucleosynthesis part of the calculations adversely affected the computation because of the communication overhead required.

Get the article here!

39Ca nova nucleosynthesis paper accepted for publication!

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.

Get the preprint here!

39K(p,γ)40Ca paper accepted for publication!

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.

arXiv paper can be found here!

Focal plane detector paper published!

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!

Journal article can be found here!


Keilah Davis wins first place in the the McCormick Symposium poster session

Our very own Keilah Davis won first prize in the 2018 McCormick Symposium poster session! Her poster highlighted her work analyzing theoretical particle transfer reaction cross sections using statistical techniques. She has applied her methods to the 22Ne(p,γ)23Na reaction, which is key in understanding sodium production in stars. Congratulations, Keilah!

Keilah wins!

Dr. Longland receives DOE Early Career Award!

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.

See the full announcement here!

NCSU Announcement!

Correlated Uncertainty paper published!

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!

See the article here!

Congratulations, Federico!

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!

Federico and María

The Triangle Universities Nuclear Laboratory

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!

Boron-loaded detector paper published!

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.

See the article here!

Big Bang Nucleosynthesis Paper Accepted!

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.

See the arXiv preprint here!

November 2015

Federico's famous!

The NCSU experimental nuclear astrophysics group were featured in some UNC promotional material celebrating the 50th anniversary of the Triangle Universities Nuclear Laboratory.

See it here!