Solar fusion cross sections II: the pp chain and CNO cycles

GammaPPeer ReviewedScienceStellar


The available data on nuclear fusion cross sections important to energy generation in the Sun and other hydrogen-burning stars and to solar neutrino production are summarized and critically evaluated. Recommended values and uncertainties are provided for key cross sections, and a recommended spectrum is given for 8B solar neutrinos. Opportunities for further increasing the precision of key rates are also discussed, including new facilities, new experimental techniques, and improvements in theory. This review, which summarizes the conclusions of a workshop held at the Institute for Nuclear Theory, Seattle, in January 2009, is intended as a 10-year update and supplement to 1998, Rev. Mod. Phys. 70, 1265.

Author: Adelberger, E. G.; GarcĂ­a, A.; Robertson, R. G. Hamish; Snover, K. A.; Balantekin, A. B.; Heeger, K.; Ramsey-Musolf, M. J.; Bemmerer, D.; Junghans, A.; Bertulani, C. A.; Chen, J.-W.; Costantini, H.; Prati, P.; Couder, M.; Uberseder, E.; Wiescher, M.; Cyburt, R.; Davids, B.; Freedman, S. J.; Gai, M.; Gazit, D.; Gialanella, L.; Imbriani, G.; Greife, U.; Hass, M.; Haxton, W. C.; Itahashi, T.; Kubodera, K.; Langanke, K.; Leitner, D.; Leitner, M.; Vetter, P.; Winslow, L.; Marcucci, L. E.; Motobayashi, T.; Mukhamedzhanov, A.; Tribble, R. E.; Nollett, Kenneth M.; Nunes, F. M.; Park, T.-S.; Parker, P. D.; Schiavilla, R.; Simpson, E. C.; Spitaleri, C.; Strieder, F.; Trautvetter, H.-P.; Suemmerer, K.; Typel, S.
Journal: Review of Modern Physics, vol. 83, Issue 1, pp. 195-246

A Gamma Ray Detector Array for DRAGON at ISAC


A prime justification for the accelerated beams facility (ISAC) at TRIUMF is the study of radiative capture reactions using radioactive  beams. Some key reactions for heavy-element synthesis during explosive burning in stars involve radioactive reactants of short half-lives. Table 1 lists some of these astrophysically-interesting reactions of the initial ISAC program. The limited intensity of radioactive beams  and the small cross sections for capture reactions require a detection system which has both high efficiency for detection of reaction products and highly effective suppression of beam background. The DRAGON system has been designed for radioactive beam capture studies at ISAC; with support from NSERC, TRIUMF and agencies outside Canada, construction is under way on a windowless gas target, electromagnetic mass separator (EMS) and recoil ion detector for DRAGON. This request is for an economical addition to DRAGON, a compact array of gamma-ray detectors, which will enhance its ability to suppress background and should provide additional information of significance both in performing the experiment and in interpreting the results.

Author: See Paper Document
Journal: Submitted to NSERC, Sept. 1999

Experimental developments for the study of explosive nucleosynthesis in stars

Aluminium 26Magnesium 23PStellar

For several years now, the -SNS collaboration has been working to place a small neutrino detector at the Spallation Neutron Source at Oak Ridge National Lab. If successful, the experiment may produce the needed neutrino-nucleus cross sections on solid targets such as iron and aluminum. These reaction probabilites are of great interest for a number of reasons, including: neutrino astronomy, explosive nucleosynthesis, and nuclear structure.

However, success for this project requires a very efficient cosmic ray detector to exclude backgrounds. The system would need to be 99% efficient while remaining affordable in a difficult financial climate for basic science. The first half of this thesis addresses a prototype cosmic ray veto based on extruded scintillator with embedded wave-length-shifting fibers. This approach has been successfully used before, and may provide the performance needed for this project. However, our results suggest some additional research and  development would be required to meet the requirements for the -SNS experiment.

The second half of this thesis relates to experimental work to study the resonance strength of the 23Mg(p,)24Al reaction. For this purpose a radioactive ion beam experiment has been conducted at TRIUMF using the DRAGON experiment. This reaction is thought to play an important role during explosive nucleosynthesis such as novae and X-ray bursts. If so, then accurate knowledge of this break-out reaction would help explain the isotopic abundances around that mass range in the universe.

Our results suggest the rate of this reaction at astrophysically relevant energies is lower than predicted and might further exclude explosive binary systems as the production site for such elements as 26Al.

Author: Luke E. Erickson