Isomer spectroscopy below 100Sn

Andrey BlazhevUniversity of Cologne

Shell Model as a Unified View of Nuclear Structure8-10 October 2012, Strasbourg

Introduction

RISING S352 Experiment

Isomers in 98Cd, 94Pd, 96Ag and 96Cd

Summary and Outlook

Outline

Introduction

Adapted from The NNDC Chart of The Nuclides

Adapted from The NNDC Chart of The Nuclides

N=Z line

Isomers in the 100Sn regionImportance 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)

Primary beam124Xe @ 0.85 GeV/u

RISING S352 Experimental SetupStopped RISING

Z

A/Q

cu

eB

Q

A

98Cd

Active stopper

96Ag

94Pd

98Cd

98Cd-gated Ge-spectrum

Gate 4157

98Cd (12+) isomer halflife (preliminary)

4157 keV: T1/2 = 230(80) ns4207 keV: T1/2 = 226(30) ns

Literature: T1/2 = 230 (+40−30 ) ns

(A. B. et al., Phys. Rev. C 69, 064304 (2004))

98Cd high-energy level scheme

A. B. et al., Phys. Rev. C 69, 064304(2004)

B(E4; 12+ → 8 +) = 3.0(10) W.u.B(E2; 12 + → 10 +) = 2.1(13) W.u.

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

ν g9/2d5/2g7/2d3/2s1/2

● SM-ph-pgds truncated to 1p1h in any orbit in the model spaces:

pgdg:

ν p3/2f5/2p1/2g9/2d5/2g7/2

pgndg:

ν p3/2f5/2p1/2g9/2 νd5/2g7/2

TBME from OXBASH (SNA+GF)*

SPE tuned to 100Sn

´´standard´´ d5/2 - g7/2 sequence

● LSSM-gds t=1,5

ν g9/2d5/2g7/2d3/2s1/2

● SM-ph-pgds truncated to 1p1h in any orbit in the model spaces:

pgdg:

ν p3/2f5/2p1/2g9/2d5/2g7/2

pgndg:

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

101Sn

MeV

7/2 +

1/2 +

5/2 +

3/2 +

11/2 -

´´reversed´´ g7/2 - d5/2 sequence

EXP: ΔE(d5/2 - g7/2 ) = 0,172 MeVD.Severyniak et al., PRL99 (2007) 022504

Code: Nushell@MSU[1] W.D.M. Rae, unpublished, (2007)[2] B. A. Brown and W. D. M. Rae, MSU-NSCL report (2007)

Interaction: SNET

Model space: SNEπν – f5/2pgds + vh11/2

Truncation:πν – f5/2p – fully occupiedxn-ph = νg9/2

-x (d5/2,g7/2)x

´´reversed´´ g7/2 - d5/2 sequence

EXP: ΔE(d5/2 - g7/2 ) = 0,172 MeVD.Severyniak et al., PRL99 (2007) 022504

Code: Nushell@MSU[1] W.D.M. Rae, unpublished, (2007)[2] B. A. Brown and W. D. M. Rae, MSU-NSCL report (2007)

Interaction: SNET

Model space: SNEπν – f5/2pgds + vh11/2

Truncation:πν – f5/2p – fully occupiedxn-ph = νg9/2

-x (d5/2,g7/2)x

98Cd

9 +

10 +14 +13 +12 +

11 +

Calculations: A.B.

98Cd EXP vs SM .

94Pd isomer spectrum96

324

660

814

905

995

1092

74534

7

T.S. Brock et al., PRC 82, 061309(R) (2010)

N. Mărginean et al., Phys.Rev C 67,

061301(R) (2003)

94Pd observed transitions

106

1545

1651

267

408

*

*

C. Plettner et al., Nucl. Phys. A 733, 20-36 (2004)

T.S. Brock et al., PRC 82, 061309(R) (2010)

1651

106

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.

1651

7211106

Calculations H.Grawe

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.

1651

7211106

Bexp(E3) = 0.28 W.u.+0.04-0.03

Btheo(E3) = 0.15 W.u.

Calculations H.Grawe

T.S. Brock et al., PRC 82, 061309(R) (2010)

Bexp (E1) = 0.3(1) μW.u.

Tf<1 s

0.16(3) s

1.56(3) s

100(10) s

P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)

B(E4; 19+ 15+) = 0.9(6) W.u.

B(E2; 19+ 17+) = 4.7(10) W.u.

B(E3; 13- 10+) = 0.145 (17) W.u.

E[keV]

Coun

ts

known: R. Grzywacz et al. PRC 55 (1997) 1126

new

4264

4168

SE

Isomers in 96Ag

E[MeV]

GF: model space: (g9/2, p1/2) 1p-1hinteraction: R.Gross and A.Frenkel,NPA 267(1976)85 → 13-, 15+ isomers

fpg: GF + SNA 1p-1h excitation from f5/2 and p3/2

Shell Model Calculations: H.Grawe

9647

Ag49

TBME from OXBASH package (SNA+GF) and SPE tuned to 100Sn

100(10)s

1.56(3)s

P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)

P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)

9647

Ag49

Calculations: GF, FPG – H.Grawe

LSSM GDS – F. Nowacki, K. Sieja

B(E4) = 0.9(6) W.u

B(E2) = 4.7(10) W.u B(E4) = 0.7 W.u

B(E2) = 3.6 W.u

B(E3) = 0.145(17) W.u B(E3) = 0.13 W.u

B(E2) = 2.5-6.6 W.u B(E2) = 4.3 W.uB(E2) = 4.3 W.u

0.16(3) s

4264

B(E2; 19+ 17+) = 4.7(10) W.u.

B(E4; 19+ 15+) = 0.9(6) W.u.

9647

Ag49

9848

Cd50

B(E2; 12+ 10+) = 2.1(13) W.u.

B(E4; 12+ 8+) = 3.0(10) W.u.

0.23(8) s

96Cd – beta decay96Cd, t = 0 – 0.2 s

96Cd, t = 0.2 – 4 s

96Cd, t = 0.2 – 4 s

T1/2 (421) = 0.67 0.15 sec, T1/2 (470, 1506, 667) = 0.29 + 0.11 sec

– 0.10 B.S. Nara Singh et al., PRL107, 172502 (2011)

0.16(3) s

1.56(3) s100(10) s

P. Boutachkov et al., Phys. Rev. C 84, 044311 (2011)

B(E4; 19+ 15+) = 0.4(3) W.u.

B(E2; 19+ 17+) = 4(3) W.u.

B(E3; 13- 10+) = 0.187 (20) W.u.

16+

0+

96Cd

96Ag2+

(1+)421?

β+

β +

0.67 s 1.03 s 20%,Bazin et al PRL 101, 252501 (2008)

0.29 s

Spin-gap isomer 96Cd

SM predictions: (p1/2,g9/2)

Int. J Ex (keV)GF 1+ 356 2+ 12SLGT0 1+ 382 2+ 0

B.S. Nara Singh et al., PRL107, 172502 (2011)

Isomers below 100Sn (summary)

H.Grawe

Summary and outlook• 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

o Exp. search for the 14+ in 98Cd and if possible reproduce level ordering by SM o Search for and clarify direct particle decays in the region, esp. from isomers o Direct mass measurements of “long lived” isomers without gamma decay o Possible Coulex experiments on gs. and isomeric beams of key isotopes

CollaborationAyse 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