1. Beta decay for neutron capture
Sean Liddick
ICNT, June 7th, 2016

2. r-process calculations
neutron star merger
hot wind
cold wind
Abundance pattern is different for the different astrophysical scenarios.
Does one of them reproduce the observed abundances best?
Why can’t we tell?
M. Mumpower, J. Cass, G. Passucci, R. Surman, A. Aprahamian, AIP Adv. 4, (2014)

3. Nuclear Physics Uncertainties: (n,γ)
(n,γ) uncertainties
1000
100 10 5
Monte-Carlo variations of (n,γ) rates within a factor 100 – 10 – 2 (light – darker – dark bands)
S.N. Liddick, A. Spyrou, et al., Phys. Rev. Lett. (in press)
R. Surman and J. Engel, Phys. Rev. C, 64, (2001)

4. Current (n,γ) measurements

5. Neutron Capture – Uncertainties
Hauser – Feshbach
Nuclear Level Density
Constant T+Fermi gas, back-shifted Fermi gas, superfluid, microscopic
γ-ray strength function
Generalized Lorentzian, Brink-Axel, various tables
Optical model potential
Phenomenological, Semi-microscopic
Level density
γ-strength function
ALL
95Sr(n,γ)96Sr
OMP
TALYS

6. Uncertain extrapolations: gamma-ray strengths and level densities
g-ray strength functions
Unexpected structural features.
Level densities
What is N,Z dependence of a?
Level density parameter, a, depends only on mass.
A.C. Larsen et al., Phys. Rev. C, 82, (2010)
Al-Quraishi et al., Phys. Rev. C 63, (2001)

7. One indirect technique: Oslo method
Reaction based
Populate the compound nucleus of interest through a transfer or inelastic scattering.
Extract level density and γ-ray strength function.
Calculate (n,γ) cross section.
Excellent agreement with measured (n,γ) reaction cross section.
Applicable close to stability.
T.G. Tornyi, M. Guttormsen,et al., Phys. Rev. C 2014

8. Beta decay and reactions
Measure beta decay of nucleus.
Extract level densities and gamma-ray strength function
Need total excitation energy of the daughter isotope.

9. Total Absorption Spectroscopy
Need to know initial excitation energy
Can’t use beta-decay electron (three body process).
Measure total g-ray energy.
Require high detection efficiency (low resolution detector).
Knowledge of multiplicities.

10. It Works A. Tonchev, et al. Photoscattering exeriment – HIγS
Talk at Oslo workshop 2015
A. Voinov, T. Renstrom, A.-C. Larsen, et al.
Preliminary Analysis - 70Zn(7Li,p)76Ge reaction
Experiment at Ohio University

11. It Works

12. 69Ni (n,g) 70Ni 64Ni 69Ni 70Ni (b) (n,g) 70Co Highlight 69ni
S.N. Liddick, A. Spyrou et al., Phys. Rev. Lett. (in press)
R. Surman et al., AIP Advances, 4, (2014)

13. 70Ni – Level Density and Gamma Strength
Note paucity of known excited states in 70Ni

14. 69Ni(n,g)70Ni

15. 69Ni(n,g)70Ni Impact

16. Uncertainties

17. Next Region Higher mass nuclei
Z = 50, N = 82
Compare statistical and direct neutron capture predictions.
For example: 130Sn
R. L. Kozub et al., Phys. Rev. Lett. 109, (2012).
M. Mumpower et al., Prog. Part. Nucl. Phys., 86, 86 (2016).
Y. Xu et al., Phys. Rev. C, 90, (2014).

18. Practical Aspects
10+1 (n,g)
10-2 Masses
10-4 Half-lives

19. Thanks Michigan State University Artemis Spyrou S.N. Liddick
B.P. Crider
K. Cooper
A.C. Dombos
D.J. Morrissey
R. Lewis
F. Naqvi
C.J. Prokop
S.J. Quinn
A. Rodriguez
C.S. Sumithrarachchi
R.G.T. Zegers
University of Oslo
A.C. Larsen
M. Guttormsen
L. Crespo Campo
S. Siem
T. Renstrøm
Central Michigan University
G. Perdikakis
S. Nikas
Notre Dame
M. Mumpower
A. Simon
R. Surman
LLNL
D.L. Bluel
LANL
A. Couture
S. Mosby
Universidad de Valencia
B. Rubio
This research was supported by Michigan State University and the Facility for Rare Isotope Beams and was funded in part by the NSF under Contract Nos. PHY (NSCL), (CAREER), (JINA-CEE), and (M.M. and R.S) and the U.S. Department of Energy under contract DE-SC (R.S.), DE-AC52-07NA27344 (LLNL), and the National Nuclear Security Administration under Award No. DE-NA Funding is also acknowledged from the European Research Council, ERC Starting Grant GA , the Research Council of Norway grant no and by the Spanish Ministry MINECO under contract FPA C2-1-P.