[Triumf-seminars] TRIUMF Special Seminar today at 14:00

[TRIUMF Seminars]

Date/Time: Tue 2012-07-24 at 14:00

Location:  Auditorium          

Speaker:   Christian Diget (University of York, UK)

Title:     From nuclear reactions to astrophysics: Stellar explosions studied through nuclear spectroscopy

Abstract: 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 hindered by the Coulomb repulsion of the nuclei, making direct observation of the reactions difficult or even impossible. In this category are the 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, typically in reaction studies which probe the nuclear structure that determine the astrophysical processes. Similarly, electron capture on medium-mass radioactive nuclei is critical in the collapse of the pre-supernova stellar core. This type of reaction can, however, not be measured directly, and is therefore also best studied through a combination of nuclear reactions on beams of the radioactive nuclei.

The Silicon Highly-segmented Array for Reactions and Coulex (SHARC) [1] is a new multi-purpose array for charged-particle detection designed to address a diverse set of outstanding nuclear-physics questions. This includes indirect studies of astrophysical reactions through a combination of charged-particle and gamma-ray spectroscopy. The array is utilized in radioactive-ion-beam studies at the ISAC-II accelerator at TRIUMF [2] in conjunction with the TIGRESS-ray spectrometer [3]. Experiments utilising the array include a range of different reactions such as transfer of neutrons, a deuteron, or an  particle.

Recent examples of such indirect studies of Hot-CNO breakout and electron capture in core-collapse supernovae will be given, with particular emphasis on the potential for future use of SHARC, TIGRESS, and EMMA [4] in the furthering of this field of research.

[1] C. Aa. Diget, et al., J. Inst. 6, P02005 (2011).
[2] R. Laxdal, et al., in Proceedings of LINAC08, Victoria, BC, Canada (2008), p. 97.
[3] C. E. Svensson, et al., J. Phys. G 31, S1663 (2005).
[4] B. Davids and C. N. Davids, Nucl. Instrum. Methods A 544, 565 (2005).

Stimulants available 15 minutes before the talk.

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