Speaker
Christof Vockenhuber
(TRIUMF, Vancouver, BC, Canada)
Description
44Ti (60.0 yr half-life) is one of the few short-lived radionuclides which has been
detected in space by gamma-ray astronomy and thus confirm ongoing nucleosynthesis.
Since it is produced predominantly in supernovae during the alpha-rich freezeout, its
measured abundance can be used to constrain supernova models. The
40Ca(alpha,gamma)44Ti reaction plays a key role in 44Ti production. It has been
studied partly in the past by prompt gamma-ray measurements. A recent integral
measurement over a larger temperature regime by off-line counting of 44Ti nuclei with
AMS showed a significantly larger 44Ti yield compared to previous results from prompt
gamma-ray measurements.
We have measured this reaction in inverse kinematics at the recoil mass spectrometer
DRAGON, located at the ISAC facility at TRIUMF (Vancouver, Canada). High-purity 40Ca
beam (less than 0.5% 40Ar contamination) was accelerated to energies of 0.8 – 1.2
MeV/amu impinging on a windowless He gas target surrounded by a high-efficiency BGO
gamma-ray detector array. 44Ti recoils are then separated from the 40Ca beam by the
recoil mass spectrometer and identified in an ionization chamber. The advantage of
direct detection of 44Ti recoils and prompt gamma rays allows a detailed study of
this reaction over a large energy range with sufficient resolution to resolve
individual resonances.
In this presentation, we report on the status of our investigations, which begins at
the strong isospin triplet around E_x = 9.2 MeV and continues from here to lower
energies covering a temperature regime of T_9 ~ 1.5 – 2.5 relevant for supernova
nucleosynthesis.
Author
Christof Vockenhuber
(TRIUMF, Vancouver, BC, Canada)
Co-authors
A. A. Chen
(McMaster University, Hamilton, ON, Canada)
A. Hussein
(University of Northern British Columbia, Prince George, BC, Canada)
A. Wallner
(VERA, Institut für Isotopenforschung und Kernphysik, Universität Wien, Austria)
B. Davids
(TRIUMF, Vancouver, BC, Canada)
C. O. Ouellet
(McMaster University, Hamilton, ON, Canada)
C. Ruiz
(TRIUMF, Vancouver, BC, Canada)
D. A. Hutcheon
(TRIUMF, Vancouver, BC, Canada)
D. Frekers
(Institut für Kernphysik, Universität Münster, Germany)
D. Ottewell
(TRIUMF, Vancouver, BC, Canada)
G. Ruprecht
(TRIUMF, Vancouver, BC, Canada)
J. Caggiano
(TRIUMF, Vancouver, BC, Canada)
J. M. D'Auria
(Simon Fraser University, Burnaby, BC, Canada)
J. Pearson
(McMaster University, Hamilton, ON, Canada)
L. Buchmann
(TRIUMF, Vancouver, BC, Canada)
L. Fogarty
(TRIUMF, Vancouver, BC, Canada)
M. Paul
(Racah Institute of Physics, Hebrew University, Jerusalem, Israel)
M. Trinczek
(TRIUMF, Vancouver, BC, Canada)
W. Kutschera
(VERA, Institut für Isotopenforschung und Kernphysik, Universität Wien, Austria)
