From nuclear reactions to astrophysics
Jeudi 18 Mars 2010, à 14h15
par- 8 mars 2010
Nuclear processes driving the energy production and nuclear synthesis in stars often cannot be studied directly in the laboratory. This is because the reactions in many cases involve short-lived nuclei, and are furthermore hindered by the Coulomb repulsion of the nuclei, making direct observation of the reactions difficult or even impossible. The triple-alpha reaction where three helium nuclei fuse to carbon through the so-called Hoyle state is in this category as are many reactions related to the breakout from the Hot-CNO cycle in for example X-ray bursts, a nuclear run-away on the surface of neutron stars. Instead of direct measurements, the reactions must be studied indirectly in beta-decay or in reaction studies both of which can probe the nuclear structure that determine the astrophysical processes.
The Silicon Highly-segmented Array for Reactions and Coulex (SHARC) is a new multipurpose array for charged-particle detection designed to address such questions, and is used in conjunction with the TIGRESS γ-ray spectrometer  at TRIUMF/ISAC, Canada . Upcoming experiments include indirect studies of astrophysical reactions such as the Hot-CNO breakout reaction 18Ne + alpha → 21Na + proton.
 C. E. Svensson, et al., J. Phys. G 31, S1663 (2005).  R. Laxdal, et al., in Proceedings of LINAC08, Victoria, BC, Canada (2008), p. 97.