High-resolution in-beam spectroscopy coupled with neutron transfer reactions enabled access to the single-particle structure of 131Sn.

1. High-Resolution In-Beam Spectroscopy of 131Sn81
Precise location of the neutron single-particle states &
First measurement of neutron transfer on an isomer
Anissa Bey
University of Tennessee, Knoxville
JIHIR, ORNL
XXXIII Mazurian Lakes Conference on Physics - Frontier in Nuclear Physics
Piaski, Poland, 1-7 September, 2013
Piaski|03/09/2013

2. R-process in the vicinity of 132Sn
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 2/13
from J.J. Cowan et al., Physics Today 47 (2004)
Z=50
N=82
Limit of laboratory
experiments
r-process path
 R-process
 Nucleosynthesis mechanism responsible for
production of approx. half of heavy elements
beyond iron (A=70) peak
 Interplay between rapid neutron captures (n,),
photo-dissociation (,n), and -decay
 Crucial inputs
 Masses,  half-lives, and -n ratios

3. R-process in the vicinity of 132Sn
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 2/13
from J.J. Cowan et al., Physics Today 47 (2004)
Z=50
N=82
Limit of laboratory
experiments
r-process path
 R-process
 Nucleosynthesis mechanism responsible for
production of approx. half of heavy elements
beyond iron (A=70) peak
 Interplay between rapid neutron captures (n,),
photo-dissociation (,n), and -decay
 Crucial inputs
 Masses,  half-lives, and -n ratios
Late times, freeze-out stage, (n,) captures on
some “seed” nuclei can be decisive in defining
the final isotopic abundance pattern
 Case with 130Sn
However!
R. Surman et al., PRC 64, 035801 (2001)
& PRC 79, 045809 (2009)

4. Freeze-out direct (n,) captures on 130Sn
N=82
Z=50
130Sn
3.72 m
131Sn
-56 s
132Sn
39.7 s
130In
0.29 s
131In
0.28 s
130Cd
162 ms
131Cd 132Cd
(n,)
-
(,n)
Adapted from:
R. Surman et al., PRC 79, 045809 (2009) ------------
J. Beun et al., JPG-NPP 36, 025201 (2009)
At R-process late times
 Path nucleus 130Cd is highly populated
 Significant amount of material is collected in 130Sn
 Flow of material along Z=50 is sensitive to DC(n,) on 130Sn
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 3/13

5. Isotopic abundance sensitivity to (n,) captures on 130Sn
 Abundance changes under increase of 130Sn(n,)131Sn rate by x100
 12% overall on average
 34% around A~195
 191% near A~131
J. Beun et al., JPG-NPP 36 (2009)
130Sn Rate x 10 132Sn Rate x 10
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 4/13

6. DC(n,) sensitivities
 FRDM
 RMFT
 HFB
Mass number A
Crosssection[barn]
(n,) cross-sections at 30 keV
 In Sn isotopes, DC(n,) dominated by
captures to p-shell orbitals (3p1/2,3p3/2)
 Largest dependencies of DC(n,)
on spin-parities J & energies Ex of
given individual shell model states
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 5/13
T. Rauscher et al., PRC 57, 4 (1998)

7. 2h-1p excitations or single-particle states in 131Sn81 ?
 130Sn(d,p)131Sn - R.L. Kozub et al.
 Population of 4 lowest shell model states
 S.F.s support a single-particle nature
131Sn Spectroscopic Factors (S.F.s)
DWBA calculations ( 30% uncertainty)
Neutron-rich beams transfer studies at HRIBF - ORNL
0.7
0.71.0
0.75
R.L. Kozub et al., PRL 109 (2012)
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 6/13

8. 2h-1p excitations or single-particle states in 131Sn81 ?
 130Sn(d,p)131Sn - R.L. Kozub et al.
 Population of 4 lowest shell model states
 S.F.s support a single-particle nature
 Limited resolution; no GS population
 Particle (d/d) insensitive to spin
 (d,p) not well-matched to populate higher -----
----spin shell model states (1h9/2, 1i13/2)
131Sn Spectroscopic Factors (S.F.s)
DWBA calculations ( 30% uncertainty)
Neutron-rich beams transfer studies at HRIBF - ORNL
0.7
0.71.0
0.75
R.L. Kozub et al., PRL 109 (2012)
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 6/13

9. 2h-1p excitations or single-particle states in 131Sn81 ?
 130Sn(d,p)131Sn - R.L. Kozub et al.
 Population of 4 lowest shell model states
 S.F.s support a single-particle nature
 Limited resolution; no GS population
 Particle (d/d) insensitive to spin
 (d,p) not well-matched to populate higher -----
----spin shell model states (1h9/2, 1i13/2)
131Sn Spectroscopic Factors (S.F.s)
DWBA calculations ( 30% uncertainty)
 130Sn(9Be,8Be-) & (13C,12C-) - This work
 In-beam -ray spectroscopy
 precise energy location
 infer spin from  angular correlations
Neutron-rich beams transfer studies at HRIBF - ORNL
0.7
0.71.0
0.75
R.L. Kozub et al., PRL 109 (2012) 2 targets (13C, |1p1/2) and (9Be, |1p3/2)
different transfer matching conditions
probe spin selectivity
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 6/13

10. High-resolution heavy-ion transfer experiments at HRIBF
HYBALL
CLARION
 Monitoring and diagnostics
 40 CsI(Tl) + photodiodes for particle-tagging
 11 HPGe segmented Clovers + Compton suppression BGOs
0 deg. Bragg detector
Beam
 Highly-purified 130SnS @ 4 MeV/u
 7-12x105 part./s for this run
 4 days of data taking
Targets
9Be (2.005 mg/cm2)
13C (1.975 mg/cm2)
Particle- coincidence setup @ HRIBF
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 7/13

11. -ray emission: single-particle states
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 8/13

12. -ray emission: single-particle states
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 8/13

13. -ray emission: single-particle states
A. Bey et al., to be published (2014)
single-neutron states partial level scheme
3p1/2
3p3/2
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 8/13

14. -ray emission: 1h11/2 orbital position
 Previously
Decay spectroscopy measurements
 Fogelberg et al., PRC 70, 034312 (2004)
- 69 (14) keV / Q
- 65.1 keV / M2 -transition
 Fogelberg et al., PLB 137, 20 (1984)
- 160 (100) keV / Q
- 242 keV / another M2 -transition
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 9/13

15. -ray emission: 1h11/2 orbital position
 This work
X (7/2-  5/2+) = 68(1) keV
 Previously
Decay spectroscopy measurements
 Fogelberg et al., PRC 70, 034312 (2004)
- 69 (14) keV / Q
- 65.1 keV / M2 -transition
 Fogelberg et al., PLB 137, 20 (1984)
- 160 (100) keV / Q
- 242 keV / another M2 -transition
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 9/13

16. -ray emission: high-spin states
 Energies known from Cm source fission
fragments studies @ Gammasphere
--Bhattacharyya et al., PRL 87,6 (2001)
 But assigned to high-spin states (very
high spin ~ 19/2+!!)
 How to explain present population??
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 10/13

17. 130Sn 7- (1.7 min) isomer: nuclear structure point
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 11/13
Single-neutron hole & particle
states at Z=50/N=81

18. 130Sn 7- (1.7 min) isomer: nuclear structure point
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 11/13
Single-neutron hole & particle
states at Z=50/N=81

19. 130Sn 7- (1.7 min) isomer: nuclear structure point
 Theory
 QMSSM, Insolia et al., NPA 550, 34 (1992)
 Oxbash Shell Model - G-matrix + SN100PN interaction
A. Brown et al., PRC 71, 044317 (2005) & D.S. Judson, Ph.D. thesis (2007)
7- : ~98% |d3/2|h11/2
shell model state!
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 11/13
Single-neutron hole & particle
states at Z=50/N=81

20. 131Sn81: the yrast band via single-neutron transfer
Seniority 2 -configurations
 Level assignments and structure interpretation
Bhattacharyya et al., PRL 87,6 (2001)
 f7/2 d3/2
-1 h11/2
-1

1h11/2
2d3/2
10
2f7/2
1h11/2
2d3/2
10
2f7/2


7-
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 12/13

21. Summary & Outlook
 Precise location of the astrophysically relevant
shell-model states in 131Sn
 Population of select members in 131Sn ~5.0
MeV yrast band via direct single-neutron transfer
 Measured -p  -h -ray cross transition
yields 68  1 keVstat. for 1h11/2 orbital in 131Sn
 Further evidence supporting the robustness of
the 132Sn doubly-magic core
 Updated DC(n,) calculations and R-process
simulations
 Nuclear shell structure theory to interpret our
new data (core excitations, fragmentation & level
density, EM properties & lifetimes...)
Single-neutron states across 132Sn82
…and more if
133Sn: K.L. Jones et al., Nature 465, 454 (2010)
131Sn: A. Bey et al., to be published (2014)
Sn: ISOLTRAP (2008), JYFLTRAP (2012), CPTRAP
(2013) mass measurements
A. Bey High-Resolution In-Beam Spectroscopy of 131Sn81 Piaski|03/09/2013 13/13