Linking Transitions (and Search for Superintruders) in the A80 Region of

Superdeformation

Nilsson Conf.Lund, Sweden17 June 2005

C. J. Chiara, D. G. Sarantites, M. Montero, J. O’Brien, O. L. Pechenaya, and W. Reviol, Washington University

R. M. Clark, P. Fallon, A. Görgen, A. O. Macchiavelli, and D. Ward, Lawrence Berkeley National Laboratory

W. Satuła, University of Warsaw

Y. R. Shimizu, Kyushu University

SD regions

A40 (linked)

A60(linked)

A190(linked)

A80(not linked!)

B. Singh, R. Zywina, R.B. Firestone, Nucl. Data Sheets 97,

241 (2002)

F. Lerma et al., PRC 67, 044310 (2003)84Zr

(linked)A130

TSD(linked)

A150(linked)

• 140-MeV 32S + 0.5-mg/cm2 58Ni 84Zr + 2p

• Gammasphere [102 Ge detectors]

• Microball [95 CsI(Tl) detectors] for charged particle detection; p80%, 70%

• Total of 2.2109 events of fold 5 or higher over 6 days.

Experimental details

0

1 0

2 0

3 0

coun

ts

S D 1 /4 0 5 2

1246

1527

1663

1808

1958

2113

2272

184516

46

1433

0

5

1 0

1 5

2 0

coun

ts

S D 1 /3 7 4 31563

135812

65

1527

1663

1808

1958

2113

2272

1402

181015

68

2 7 0 0 3 0 0 0 3 3 0 0 3 6 0 0 3 9 0 0 4 2 0 0E [k e V ]

0

1 0

2 0

3 0

4 0

5 0

coun

ts

S D 1 /S D 1

2780

3102

3464

*

3743

*

4052

*

2598

1 2 0 0 1 4 0 0 1 6 0 0 1 8 0 0 2 0 0 0 2 2 0 0 2 4 0 0E [k e V ]

0

5

1 0

1 5

2 0

coun

ts

S D 1 /3 4 6 4

1225

1363

1996

1808

1813

1555

1527

1663

1958

2113

Double-gated spectra of 84Zr

links

spectra

IS D 1 ~ 3 % I(2 +0 +)

IS D 2 ~ 1 % I(2 +0 +)

I(4 0 5 2 ) ~ 0 .9 % IS D 1

I(3 7 4 3 ) ~ 0 .7 % IS D 1

I(3 4 6 4 ) ~ 0 .4 % IS D 1

84Zr lev.sch

.

I0 = 25-

E1 M1/E2 E1

Compare with calculations using Cranked Strutinsky + Lipkin-Nogami pairing

5251 configuration previously assigned to SD1 based on Qt—now compare Ex, I as well:

0 .0 0 .5 1 .0 1 .5 2 .0 [M e V / ]

0

1 0

2 0

3 0

4 0

5 0

I x []

N D 1S D 1v acu u m5

251

(b )

0 1 0 2 0 3 0 4 0 5 0I [ ]

-2

0

2

4

6

8

E-0

.02I

(I+

1) [

MeV

]

N D 1S D 1v acu u m5

251

(a )

CSLN

Ex (near ND-SD crossing)

spin (except at alignments)

parity

Depopulation of the SD wellSD1 in 84Zr has weak decays to ND states, similar to the A=150,190 SD bands.

84Zr 152Dy* 192Pb†

* T.Lauritsen, PRL88, 042501 (2002)† A.N.Wilson, PRL90, 142501 (2003)

B(E1) ~10-6 W.u. ~10-6 W.u. ~10-7-10-8 W.u.

Weak decay-out explored with several statistical models, e.g.:• E.Vigezzi et al., PLB249,163 (1990)

• J.-z.Gu and H.A.Weidenmüller, NPA660, 197 (1999)

• D.M.Cardamone et al., PRL91, 102502 (2003)

Each relates S, N, d, FS with spreading width .

Compare 84Zr with results in A.N.Wilson, Prog. Theor. Phys. (Kyoto), Suppl.

154, 138 (2004):

nuclide I FS / S [eV]

192Pb 10+ 0.12 1.1107 511

12+ 0.66 9.8104 13194Pb 8+ 0.65 2.0104 0.28

10+ 0.9 3.3103 0.15194Hg 12+ 0.58 2.6102 0.025152Dy 28+ 0.6 6.0102 684Zr 25- < 0.2 > 1.1105 > 3700

27- 0.65 4.5 103 273

B(E1) [W.u.]

510-7

210-7

210-8

510-8

710-9

210-6

510-6

—

stat’l

Tunneling paths and barriers

• Calculate potential energy surfaces for fixed spins.

• Determine least-action path from SD min to ND well.

• Get barrier height in direction of path.

[K.Yoshida et al., NPA696, 85 (2001) and refs. therein.]

Compare 152Dy and 84Zr surfaces….

152Dy PES

Below the decay-out spin in 152Dy!

84Zr PES

Below the decay-out spin in 84Zr!

Barrier heights calculated along least-action paths from fixed-spin potential surfaces, as in K.Yoshida et al., NPA696, 85 (2001).

barriers

0 1 0 2 0 3 0 4 0I [ ]

0

1

2

3

4

barr

ier

heig

ht [

MeV

]

8 4Z r

1 5 2D y

1 9 2H g

Summary• “Full” characterization of an A80 SD band: Ex, I, Qt, B() [several neighbors studied too, but no luck linking!]

• Results are consistent with CS-LN calculations for 5251

configuration [esp. Ex(I) in crossing region]

• 84Zr SD1 has eclectic properties; similar to:

152Dy [spin, energy, B(E1)]

192Pb [strength of SD-ND coupling]

A60,130 regions [potential barriers]

• HF+SLy4 calcs at I=25 reveal many configs at different deformations with similar energies supports PES picture

C. J. Chiara, D. G. Sarantites, M. Montero, J. O’Brien, O. L. Pechenaya, and W. Reviol,

Washington U.

R. M. Clark, P. Fallon, A. Görgen, A. O. Macchiavelli, and D. Ward, LBNL

Theoretical support from

W.Satuła, U. of Warsaw

and

Y.R.Shimizu, Kyushu U.

C. J. Chiara, D. G. Sarantites, M. Montero, J. O’Brien, O. L. Pechenaya, and W. Reviol,

Washington U.

R. M. Clark, P. Fallon, A. Görgen, A. O. Macchiavelli, and D. Ward, LBNL

Theoretical support from

W.Satuła, U. of Warsaw

and

Y.R.Shimizu, Kyushu U.

The End