Isomer spectroscopy below
100Sn
Andrey Blazhev
University of Cologne
Shell Model as a Unified View of Nuclear Structure
8-10 October 2012, Strasbourg
Outline
Introduction
RISING S352 Experiment
Isomers in 98Cd, 94Pd, 96Ag and 96Cd
Summary and Outlook
Introduction
Adapted from The NNDC Chart
of The Nuclides
Adapted from The NNDC
Chart of The Nuclides
Isomers in the
100Sn
region
Importance of isomers
 Test of the shell model
 Single-particle structure
 Residual interaction
 Astrophysics
Properties of isomers
 Existence
 Excitation energy
 Halflife (transition strength)
 Spin and parity
 γ-decay cascades
 Particle decays
Main goals of the RISING
S352 experiment
K. Ogawa, Phys. Rev. C 28, 958, (1983)
A. B. et al., PRC 69 064304 (2004)
RISING S352 ExperimentalStopped
Setup
RISING
Primary beam
124Xe @ 0.85
GeV/u
98Cd
98Cd
96Ag
Z
94Pd
A Be

Q cu
A/Q
Active stopper
98Cd-gated
Ge-spectrum
Gate 4157
98Cd
(12+) isomer halflife
(preliminary)
4207 keV: T1/2 = 226(30) ns
Literature: T1/2 = 230 (+40−30 ) ns
(A. B. et al., Phys. Rev. C 69, 064304 (2004))
4157 keV: T1/2 = 230(80) ns
98Cd
high-energy level scheme
B(E4; 12+ → 8 +) = 3.0(10) W.u.
B(E2; 12 + → 10 +) = 2.1(13) W.u.
A. B. et al., Phys. Rev. C 69, 064304(2004)
A. B. et al., J. Phys.:
Conf. Ser. 205 (2010) 012035.
56Ni
- 100Sn similarities
H. Grawe, M. Lewitowicz, Nucl. Phys. A693, 116 (2001)
98Cd
Shell Model
´´standard´´ d5/2 - g7/2 sequence
● LSSM-gds
t=1,5
 p ν g9/2d5/2g7/2d3/2s1/2
● SM-ph-pgds truncated to 1p1h
in any orbit in the model spaces:
 pgdg:
p ν p3/2f5/2p1/2g9/2d5/2g7/2
pgndg:
p ν p3/2f5/2p1/2g9/2 νd5/2g7/2
TBME from OXBASH (SNA+GF)*
SPE tuned to 100Sn
Calculations:
F. Nowacki
H. Grawe
98Cd
SM Calculations 2
´´reversed´´ g7/2 - d5/2 sequence
3.000
EXP: ΔE(d5/2 - g7/2 ) = 0,172 MeV
9.400
2.500
D.Severyniak et al., PRL99 (2007) 022504
[1] W.D.M. Rae, unpublished, (2007)
[2] B. A. Brown and W. D. M. Rae,
MSU-NSCL report (2007)
2.000
Interaction: SNET
1.500
8.800
Truncation:
πν – f5/2p – fully occupied
xn-ph = νg9/2-x (d5/2,g7/2)x
11/2 -
9.200
Code: Nushell@MSU
3/2 +11 +
12 +
+
1/2 13 +
14 +
10 +
9.000
MeV
Model space: SNE
πν – f5/2pgds + vh11/2
98Cd
101Sn
1.000
8.600
0.500
8.400
5/2 +
0.000
8.200
0.000
0.049
0-ph
1n-ph1n-ph
0.105
2n-ph
2n-ph
0.110
7/2 9+ +
0.112
3n-ph3n-ph
4n-ph
Calculations: A.B.
98Cd
EXP vs SM
.
isomer spectrum
1092
995
905
814
745
347
660
324
96
94Pd
T.S. Brock et al., PRC 82, 061309(R) (2010)
N. Mărginean et al.,
Phys.Rev C 67,
061301(R) (2003)
observed transitions
*
1545
1651
94Pd
106
T.S. Brock et al., PRC 82, 061309(R) (2010)
408
106
*
267
1651
C. Plettner et al.,
Nucl. Phys. A 733,
20-36 (2004)
94Pd
new isomer halflife
t1/2 = 197(22) ns
T.S. Brock et al., PRC 82, 061309(R) (2010)
94Pd
•
•
Shell Model Calculations
SM-GF: shell model
calculation using the
empirical interaction of
Gross & Frenkel for
πν(p1/2,g9/2).
SM-FPG: also includes
πν(f5/2,p3/2) using SNA
interaction from
OXBASH. Excitations
from fp space restricted
to 1p1h.
Calculations H.Grawe
T.S. Brock et al., PRC 82,
061309(R) (2010)
106
1651
7211
94Pd
•
•
Shell Model Calculations
SM-GF: shell model
calculation using the
empirical interaction of
Gross & Frenkel for
πν(p1/2,g9/2).
SM-FPG: also includes
πν(f5/2,p3/2) using SNA
interaction from
OXBASH. Excitations
from fp space restricted
to 1p1h.
Calculations H.Grawe
106
7211
1651
Bexp (E1) = 0.3(1) μW.u.
Bexp(E3) = 0.28
T.S. Brock et al., PRC 82, 061309(R) (2010)
+0.04
-0.03
W.u.
Btheo(E3) = 0.15 W.u.
Isomers in 96Ag
0.16(3) s
new
Tf<1 s
known: R. Grzywacz et al. PRC 55 (1997) 1126
E[keV]
B(E4; 19+ 15+)
= 0.9(6) W.u.
4264
SE
Counts
4168
B(E2; 19+  17+)
= 4.7(10) W.u.
1.56(3) s
100(10) s
B(E3; 13-  10+)
= 0.145 (17) W.u.
P. Boutachkov et al.,
Phys. Rev. C 84, 044311 (2011)
E[MeV]
96
Ag
47 49
1.56(3)s
100(10)s
Shell Model Calculations:
H.Grawe
GF: model space: pn(g9/2, p1/2)
1p-1h
interaction: R.Gross and
A.Frenkel,NPA 267(1976)85
→ 13-, 15+ isomers
fpg: GF + SNA
pn 1p-1h excitation
from f5/2 and p3/2
TBME from OXBASH package
(SNA+GF) and SPE tuned to 100Sn
P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)
96
Ag
47 49
B(E4) = 0.9(6) W.u
B(E4) = 0.7 W.u
B(E2) = 4.7(10) W.u
B(E2) = 3.6 W.u
B(E2) = 4.3 W.u B(E2) = 2.5-6.6 W.u
Calculations:
GF, FPG –
H.Grawe
B(E2) = 4.3 W.u
B(E3) = 0.145(17) W.u B(E3) = 0.13 W.u
LSSM GDS –
F. Nowacki,
K. Sieja
P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)
96
Ag
47 49
0.16(3) s
0.23(8) s
B(E2; 19+  17+) = 4.7(10) W.u.
98
Cd
48 50
B(E2; 12+  10+) = 2.1(13) W.u.
B(E4; 19+  15+) = 0.9(6) W.u.
B(E4; 12+  8+) = 3.0(10) W.u.
4264
96Cd
96Cd,
96Cd,
– beta decay
t = 0 – 0.2 s
t = 0.2 – 4 s
96Cd,
T1/2 (421) = 0.67  0.15 sec,
t = 0.2 – 4 s
T1/2 (470, 1506, 667) = 0.29 + 0.11 sec
B.S. Nara Singh et al., PRL107, 172502 (2011)
– 0.10
Spin-gap isomer 96Cd
0.16(3) s
16+ 0.29 s
B.S. Nara Singh et al.,
PRL107, 172502 (2011)
B(E4; 19+ 15+)
= 0.4(3) W.u.
β+
0+
96Cd
0.67 s
1.03 s  20%,Bazin et al
PRL 101, 252501 (2008)
β+
B(E2; 19+  17+)
= 4(3) W.u.
1.56(3) s
100(10) s
B(E3; 13-  10+)
= 0.187 (20) W.u.
SM predictions: (p1/2,g9/2)
Int.
Jp
Ex (keV)
GF
1+
356
+
2
12
+
SLGT0
1
382
+
2
0
(1+)
421?
2+
P. Boutachkov et al.,
Phys. Rev. C 84, 044311 (2011)
96Ag
Isomers below 100Sn
(summary)
H.Grawe
Summary and outlook
•
•
•
•
•
o
o
o
o
98Cd
new level (10+ ) and Exp. B(E4) and B(E2) estimates of the (12+ )
depopulating transitions
94Pd a new high-spin (19- ) E3 isomer
96Ag – 3 isomeric states (E4, E3, E2) incl. core excited, extended level scheme
96Cd – 16+ Spin-gap isomer confirmed in beta decay
LSSM-GDS, FPG and GF calculations complement to describe isomerism in the
region
Exp. search for the 14+ in 98Cd and if possible reproduce level ordering by SM
Search for and clarify direct particle decays in the region, esp. from isomers
Direct mass measurements of “long lived” isomers without gamma decay
Possible Coulex experiments on gs. and isomeric beams of key isotopes
Collaboration
Ayse Atac, Linus Bettermann, Andrey Blazhev, Plamen Boutachkov,
Norbert Braun, Tim Brock, Lucia Caceres, Cesar Domingo, Tobias Engert,
Katrin Eppinger, Thomas Faestermann, Fabio Farinon, Florian Finke,
Kerstin Geibel, Jurgen Gerl, Namita Goel, Magda Gorska, Andrea Gottardo,
Hubert Grawe, Jerzy Grebosz, Christoph Hinke, Robert Hoischen, Gabriela Ilie,
Hironori Iwasaki, Jan Jolie, Ivan Kojouharov, Reiner Krucken, Nikolaus Kurz,
Zhong Liu, Edana Merchant, B. S. Nara Singh, Chiara Nociforo,
Frederic Nowacki, Johan Nyberg, Marek Pfutzner, Stephane Pietri,
Zsolt Podolyak, Andrej Prochazka, Patrick Regan, Peter Reiter, Sami Rinta-Antila,
Dirk Rudolph, Clemens Scholl, Kamila Sieja, Par-Anders Soderstrom, Steve
Steer, Robert Wadsworth, Nigel Warr, Hans-Jurgen Wollersheim, Philip Woods
Thank you