Shape determination in Coulomb excitation of 72Kr

B.S. Nara Singh

University of York

Oblate shape driving mechanismrp-processes in X-ray binaries

Shape co-existence in A=70 region; expected for Kr, Se isotopesW. Nazarewicz et al., NPA 435 (1985) 397

36

Present Scenario Moments of inertia, B(E2) values on 68Se,72Kr →oblate low-lying and prolate high-lying statesS. Fischer et al., PRC 67, 064318 (2003), PRL 84, 4064 (2000)A. Gade et al., PRL 95, 022502 (2005)

Coulomb energy differences, 70Se,70Br→ prolate (2=0.18) to prolate (0.33) shape changeB.S. Nara Singh et al., Submitted to PRC Rapid com.

Re-orientation effect in low energy Coulex on 70Se→ prolate 2+state for 70SeA.M. Hurst et al., PRL 98, 072501 (2007)

No excited 0+ state found in 68, 70Se

No direct evidence for oblate ground/low-lying states

E. Bouchez et al, PRL 90, 082502 (2003)

Y.Sun et al, NPA 758 (2005) 765

Electron and -spectroscopy

Intermediate energy Coulomb excitation

72Kr: All evidence points towards oblate ground/low-lying state

A. Gade et al., PRL 95, 022502 (2005)

E. Clément et al, to be published in PRC

Reproduced by triaxial HFB with Gogny DIS interaction

Coulomb excitation

~ 28 % reorientation effect

Population due to M

12 gives magnitude of β

M22

gives sign of β as well

~ 2% variation in the 2+ state population due to depletions

104Pd

72Kr

A. Gade et al., PRL 95, 022502 (2005)

70Se at 2.94 MeV/u on 104Pd

139 (13)

540 (40)

22 %

~ 11 % cross section measurement, relative to 104Pd→ 6 % accurate experimental B(E2) value for 104Pd

A.M. Hurst et al PRL 98, 072501 (2007)

B(E2: 0+→2+) = 0.4997(647) e2b2

A. Gade et al., PRL 95, 022502 (2005)

~ 26%

??

M02 < 0.70 eb

Rotational value for M22

72Kr at 3.0 MeV/u on 104Pd

Beam time request

AssumptionsCD coverage: 16.2 to 53.3ε

γ= 7% at 1.3 MeV

76kr at 3-3.1 MeV/u, ~106 pps at target position for 1+1 days

Condition Desirable Manageable

Energy (MeV/u) 3.1 2.9

Yield/uc 5000 2000

Transmission 8% 5%

Yield@target/2uc ~800 ~200

Beam time 4 + 4 days 4 + 4 days

Yield(710 KeV) ~1600 ~400

Accuracy in CS 7% 8%

72Kr at 200 MeV

104Pd 2mg/cm2

CD coverage: 16.2 to 53.3ε

γ= 7% at 1.3 MeV

B.S. Nara Singh, D. G. Jenkins, C. J. Barton, M. Bentley, M.J. Taylor, R. Wadsworth , Univ. of York, UK.

J. Cederkall, E. Clément, P. Delahaye, L. M. Fraile , J. Lettry, F. Wenander, ISOLDE

P. Van Duppen, K.U. Leuven, Belgium

R. Krücken, Technische Universität München, Germany

P. Reiter, University of Cologne, Germany

N. Pietralla, Technische Universität Darmstadt, Germany

A. Görgen, W. Korten, M. Zielinska, CEA-SACLAY, DSM/DAPNIA/SPhN, France

P.A. Butler, R.-D. Herzberg, R.D. Page, E.S. Paul and A. Petts, University of Liverpool, UK

J. Billowes, C.R. Fitzpatrick, S. J. Freeman, University of Manchester, UK

R. Chapman, X. Liang, J. Ollier, J. F. Smith, University of Paisley, UK

P.J. Woods, University of Edinburgh, UK

D. Bandyopadhyay, TRIUMF, Canada

K.Heyde, S. de Baerdemacker, V. Hellemans, Ghent University, Belgium

P.-H. Heenen, Université Libre de Bruxelles, Belgium

M. Bender, CNRS/IN2P3, Centre d'Etudes Nucléaires de Bordeaux Gradignan, France

and the Miniball collaboration and the REX-ISOLDE collaboration

Collaboration

Spokesperson: B.S. Nara Singh Contactperson: E. Clément

Thanks

B(E2) = 0.4997(647) e2b2 A. Gade et al., PRL 95, 022502 (2005)

> 26%

Intermediate energy Coulex; Isomeric ratio R unknown for 02

0+2

2+2

2+1

R * 1.61 b

R* 3.40 b + (1-R) * 1.94 b

2+2 is not observed

→ R <<1 and ~ 5%

B(E2) gets reduced by ~ 5%

No effect on sign determination

The case of 72kr

An over estimated coupling, 0.70 eb →~ 1 % uncertainty in the 2+ state population due to this depletion

Unlikely ?? M22

< < M02

M22 > 0.71 eb , M02 < 0.71 eb

Likely !!

Isotope M02 (eb) M02 (eb) M22 (eb) 2(E0) T(E2)/T(E0)

78Kr 0.80(4) 0.047 (13) 3360 (150)76Kr 0.849 (6) -0.490 (11) -0.9 (3) 0.079 (11) 490 (19)

74Kr 0.782 (7) 0.68 (4) -0.7 (3) 0.085 (19)

72Kr 0.71 (9) ?? ?? 0.072 (6) 0

M22

> M02

Unlikely

M22

< < M02

→ Second 2+ would be observed→ Re-orientation effect and the depletions at similar levels.→ More accurate B(E2) value

An independent B(E2) value +Angular distributions → determination of the shape

Interpretation may have to be done for two possible scenarios ??.

M02 ~ 0.70 eb

Rotational value for M22

Assumed