Post on 06-Feb-2016
description
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
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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