Speaker
Mats Lindroos
(CERN)
Description
Rates of sub-barrier, radiative capture reactions involving radioactive reactants,
needed for understanding various astrophysics explosive scenarios, are often quite
difficult to measure directly at relevant stellar temperatures. In general
relatively intense radioactive beams (>1011/s) are needed for these inverse
kinematic studies, as cross sections are very low. A new production approach is
proposed herein that would supply such required intensities in a relatively
straightforward fashion. While this system may have many applications, one area
could be increasing our understanding of classical novae and X-ray bursts. 25Al
(p,g), 30P(p,g), and 15O(a,g)19Ne are key reactions in our understanding of nova
outbursts and/or X-ray bursts and their nucleosynthetic imprints in the Galactic
abundances. The first one is important for the synthesis of 26Al, since it
determines the amount of nuclear flow that bypasses 26Al synthesis through the
isomeric state, 25Al(p,g)26Si(b+)26mAl. Hence, reliable predictions of the
contribution of novae to the Galactic 26Al content depend critically on this rate.
In turn, 30P(p,g) determines the path through the Si-Ca region in nova outbursts,
and therefore, is crucial in the synthesis of these intermediate-mass elements, and
for the location of the nucleosynthesis endpoint in such explosions. Moreover,
competition between 30P(p,g) and 30P(b+) determines the final amount of 30Si, an
important signature that helps to identify presolar meteoritic grains of a likely
nova paternity. The 15O(a,g)19Ne reaction is believed to be the breakout path of the
hot CNO cycle in an X-ray burst leading to the rp process. It is important to our
understanding of ignition temperatures for the rp process to know the absolute value
of this rate, rather than an upper limit. In this presentation a new approach to the
production of required radioactive beam intensities is described which may lead to
measurements of the rates of these key reaction.
Author
John D'Auria
(Simon Fraser University)
Co-authors
Prof.
Jordi Jose
(Institut d'Estudis Espacialde Catalunya (IEEC)
Dr
Lothar Buchmann
(TRIUMF)
Mats Lindroos
(CERN)
