3. Recent HRIBF Research - Online Computational Tool Processes HRIBF Results into Astrophysical Predictions and Aids Proposal Preparation
(M. S. Smith, Spokesperson)

The Computational Infrastructure for Nuclear Astrophysics is a suite of computer codes, online at nucastrodata.org, that was developed to streamline the incorporation of the most recent measurements at HRIBF and other facilities into astrophysical simulations. The suite, which has registered users in 42 institutions in 16 countries, enables researchers to upload and modify (e.g., renormalize, gain shift, extrapolate) a laboratory cross section [Fig. 3-1], convert this into a thermonuclear reaction rate [Fig. 3-2], combine with other rates into a library, run a simulation with this rate library, and visualize the results [Fig. 3-3]. A user-friendly interface with on-line help and an email-type commenting feature makes the suite ideal for students and for non-experts who wish to determine the astrophysical impact of their recent measurements or calculations. Customizable animations of the time-dependence of abundances [Fig. 3-4] and reaction fluxes [Fig. 3-5] in stellar explosions can be created, viewed, and exported for use in presentations and in research. The suite also has other features such as a Mass Model Evaluator where theoretical mass models can be uploaded, visualized, and compared to experimental values [Fig. 3-6].

The suite can also be used to investigate the sensitivity of astrophysical simulation predictions on the input nuclear reaction rates. Users can quickly modify (e.g., scale up and down) or replace a reaction rate, rerun a simulation, and examine the ratios of simulation predictions using the original and the new rate. Used in this way, the suite can be an invaluable tool for writing proposals for future experiments at HRIBF and elsewhere that have a relevance for astrophysics.

The suite has been recently used, for example, to determine that measurements of ¹⁸F + p reactions at HRIBF (RIB-020, RIB-044, and RIB-066) increased the amount of ¹⁸F synthesized in nova by up to a factor of 6 in the hottest zone of the explosion and up to a factor of 1.6 when the entire exploding envelope is considered - compared to estimates made with the previous "best", larger reaction rates. When compared to simulations using the older, lower, most widely-used ¹⁸F + p reaction reaction rates, our new rate decreases the ¹⁸F production by factors of 10 and 2 for the hot region and the entire envelope, respectively. Our calculations also change the predictions (by factors of ~2) of how many novae will be imaged by hundred million dollar satellites such as INTEGRAL which are presently searching for the decay of ¹⁸F produced in the outbursts. When the analysis of two additional experiments [¹⁸F(p,alpha)¹⁵O and ¹⁸F(d,n)¹⁹Ne, RIB-099 and RIB-145] are completed, the suite will be used to determine their impact on the problem of ¹⁸F production in nova outbursts.

Our online system is freely available to all at nucastrodata.org. By registering access to the suite via a short online form, users receive a disk allocation to save their work and share it with other researchers.