Physics Letters B 751 (2015) 311–315
Contents lists available at ScienceDirect
Physics Letters B
www.elsevier.com/locate/physletb
The first science result with the JENSA gas-jet target: Confirmation and
study of a strong subthreshold
18
F(p, α)
15
O resonance
D.W. Bardayan
a,b,∗
, K.A. Chipps
b,c,d
, S. Ahn
c,e
, J.C. Blackmon
f
, R.J. deBoer
a
, U. Greife
d
,
K.L. Jones
c
, A. Kontos
e
, R.L. Kozub
g
, L. Linhardt
f
, B. Manning
h
, M. Matoš
b,c
,
P.D. O’Malley
a
, S. Ota
h
, S.D. Pain
b
, W.A. Peters
b,c
, S.T. Pittman
b,c
, A. Sachs
c
,
K.T. Schmitt
b,c
, M.S. Smith
b
, P. Thompson
c
a
Dept. of Physics, University of Notre Dame, Notre Dame, IN 46556, USA
b
Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
c
Dept. of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA
d
Physics Dept., Colorado School of Mines, Golden, CO 80401, USA
e
National Superconducting Cyclotron Laboratory, East Lansing, MI 48824, USA
f
Dept. of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803, USA
g
Physics Dept., Tennessee Technological University, Cookeville, TN 38505, USA
h
Dept. of Physics and Astronomy, Rutgers University, Piscataway, NJ 08854, USA
a r t i c l e i n f o a b s t r a c t
Article history:
Received
15 July 2015
Received
in revised form 9 October 2015
Accepted
26 October 2015
Available
online 28 October 2015
Editor:
D.F. Geesaman
Keywords:
Novae
Nucleosynthesis
Nuclear
Reactions
The astrophysical
18
F(p, α)
15
Orate determines, in large part, the extent to which the observable
radioisotope
18
F is produced in novae. This rate, however, has been extremely uncertain owing to the
unknown properties of a strong subthreshold resonance and its possible interference with higher-lying
resonances. The new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has
been used for the first time to determine the spin of this important resonance and significantly reduce
uncertainties in the
18
F(p, α)
15
Orate.
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license
(http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP
3
.
Novae are some of the most energetic and frequent astrophys-
ical
explosions in the Universe. Approximately 30 occur each year
in the Milky Way galaxy with each releasing ∼ 10
45
ergs of en-
ergy
[1]. Novae occur in binary systems of stars when accretion
of hydrogen-rich material from one leads to a thermonuclear run-
away
on a white-dwarf companion. Despite years of study, many
open questions remain [2–4]: How much mass do novae eject? Do
novae form grains that can be captured and analyzed on Earth?
Is there a link between recurrent novae and type Ia supernovae?
Additional observational constraints are needed to resolve these
open issues.
A
rather direct constraint on nova models could come from the
observation of discrete-line γ rays from the decay of radioisotopes
produced by the nucleosynthesis in novae. The most promising
*
Corresponding author at: Dept. of Physics, University of Notre Dame, Notre
Dame, IN 46556, USA.
E-mail
address: danbardayan@nd.edu (D.W. Bardayan).
targets for observation are those radioactive isotopes produced in
large amounts and with half-lives long enough to survive until
the atmosphere is transparent to radiation. This γ -ray emission is
thought to be dominated by the decay of
18
F during the first day
or so after the initial outburst [5,6], and thus understanding the
nuclear reactions affecting
18
F nucleosynthesis in novae is critical
to interpretation of this γ -ray signature.
After production the largest loss of
18
F occurs via the
18
F(p, α)
15
Oreaction, and several studies have identified this re-
action
as one of the 3 most important for novae for further
experimental investigations [7,8]. Avariety of direct [9–13] and
indirect measurements with both stable [14–16] and radioac-
tive
beams [17–19] have been used to characterize the reaction
rate [20]. The primary temperature range for novae nucleosynthe-
sis
is 0.05–0.40 GK, and the rate is dominated towards the higher
end of this range by contributions through a
3
2
+
resonance at
E
c.m.
= 665 keV [10] and a
3
2
−
resonance at E
c.m.
= 330 keV [11]
above
the proton threshold at 6.4100(5) MeV in
19
Ne. At the lower
http://dx.doi.org/10.1016/j.physletb.2015.10.073
0370-2693/
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by
SCOAP
3
.