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Spectroscopic insight into the shape coexistence in 76,78 Sr, (78),80 Zr

Spectroscopic insight into the shape coexistence in 76,78 Sr, (78),80 Zr. Letter of Intent for AGATA@GSI. P. Boutachkov, C. Domingo-Pardo , H. Geissel, J. Gerl, M. Gorska, E. Merchan, S. Pietri, T.R. Rodriguez , C. Scheidengerger, H.J. Wollersheim

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Spectroscopic insight into the shape coexistence in 76,78 Sr, (78),80 Zr

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  1. Spectroscopic insight into the shape coexistence in 76,78Sr, (78),80Zr Letter of Intent for AGATA@GSI P. Boutachkov, C. Domingo-Pardo, H. Geissel, J. Gerl, M. Gorska, E. Merchan, S. Pietri, T.R. Rodriguez, C. Scheidengerger, H.J. Wollersheim GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany G. de Angelis, D.R. Napoli, E. Sahin, J.J. Valiente-Dobon INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo, D. Mengoni, F. Recchia, C. Ur Dipartimento di Fisica and INFN, Sezione di Padova, Padova, Italy A. Dewald, C. Fransen, M. Hackstein, T. Pisulla, W. Rother Institut fuer Kernphysik der Universitaet zu Köln, Köln, Germany A. Algora, A. Gadea, B. Rubio, J.L. Tain IFIC Instituto de Fisica Corpuscular, Valencia, Spain

  2. Spectroscopic insight into the shape coexistence in 76,78Sr, (78),80Zr Scientific Motivation

  3. Beyond Mean Field calculations show shape coexistence and evolution in p-rich Strontium isotopes: Shape coexistence along Z=38 and Z=40

  4. Beyond Mean Field calculations show shape coexistence and evolution in p-rich Strontium isotopes: Shape coexistence along Z=38 and Z=40

  5. A=78 N=38 • Beyond Mean Field calculations show shape coexistence and evolution in p-rich Strontium isotopes: Shape coexistence along Z=38 and Z=40 and Zirconium isotopes: A=80 N=40

  6. Beyond Mean Field calculations predict shape coexistence in 78Sr and strong triaxial effects Scientific Motivation • One observes shape-coexistence in 78Sr with the appearance of a rotational yrast band (build on top of the prolate minimum) and a vibrational band (build on the spherical minimum). The energy difference between both band heads is of about 0.7 MeV. • These two bands do not mix, the transition probabilities between states of the two different bands are neglibible, as it is reflected by the collective wave-functions. • The appearance of the rotational band as the Ground State happens after including the beyond mean field correlations (Projection in good angular momentum), which energetically favors the deformed (prolate) minimum rather than the spherical one. • Axial calculations (K=0) yield a rather rotational spectrum compared to the experiment. Including triaxial effects in the BMF calculation should bring the energy of J>0 states lower, thus giving a better agreement with the experiment.

  7. Beyond Mean Field calculations predict shape coexistence in 78Sr and strong triaxial effects Scientific Motivation (*) (*) L.Gaudefroy et al. Phys. Rev. C 80, 2009

  8. A=78 N=38 Shape coexistence along Z=40 A=80 N=40

  9. Shape coexistence along Z=40 A=80 N=40 • One observes shape-coexistence in 80Zr, with one spherical minimum and one prolate minimum separated by a barrier of more than 5 MeV. • After doing the projection in good angular momentum J, (at variance with 78Sr!) the deformed minimum drops in energy but not enough to become the absolute minimum. • The deformed state is practically at the same energy as the spherical one. Theoretically, here one can speak of shape coexistence better than anywhere else!

  10. A=78 N=38 Shape coexistence along Z=40 A=80 N=40

  11. B(E2;J J-2)/B(E2;2 0) • Study the possibleX(5) character of these N=Z=38,40 Sr and Zr isotopes Scientific Motivation X(5) 152Sm Casten et al.,Phys.Rev.Lett. 85 (2000) E.A. McCutchan et al. Phys.Rev.C 71 (2005) Iachello,Phys.Rev.Lett. 85 (2000), 87 (2001)

  12. X(5) 78Sr • Search for the possible empirical realization of X(5) Critical Point Symmetry in 78Sr Scientific Motivation 10+ Rudolph et al. Phys. Rev. C, 1997 Gross et al. Phys. Rev. C, 1994 U(5) X(5) X(5) SU(3) 78Sr Lister et al., Phys. Rev. Lett. 49 (1982)

  13. Spectroscopic insight into the shape coexistence in 78Sr What can we measure?

  14. lifetime values of yrast levels up to 10+ with high accuracy (5%/20%) Measurables t = ? t = ? t = ? t = ? t = ? t = ? t = ? t = ? t = ? t = 5.1(5) ps t = ? t = ? t = ? t = ? t = 155(19) ps 78Sr 76Sr 80Zr • yrast band livetime measurements at LNL via fusion evaporation • yrare band (2+,4+) measurements at GSI via n-knockout/Coulex

  15. lifetime values of yrast levels up to 10+ with high accuracy (5%/20%) Measurables LNL GSI • yrast band livetime measurements at LNL via fusion-evaporation reactions • low-spin yrast and yrare band (2+,4+) measurements at GSI via n-knockout/Coulex

  16. Spectroscopic insight into the shape coexistence in 78Sr How can we measure it?

  17. J • Livetime measurements via line-shape analysis (?) Experiment AGATA S2’ FRS Sec. beams: 100 MeV/u 81Zr 81Sr, 79Sr SIS-18 Primary beam: 1 GeV/u 107Ag 4x109 pps 79Sr 78Sr + n E’g 79Sr (to LYCCA) bR=0.43 9Be-Target

  18. AGATA RISING Comparison vs. Pieter’s MC of 36K 37Ca @ 150MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 23.5 cm cut qg [15,25] deg Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  19. Summary & Outlook • We plan to study deformation, shape coexistence and evolution effects in the 78,80Zr and 76,78Sr isotopes. • Both AGATA@LNL and AGATA@GSI offer complementary possibilities in order to approach this problem in a concomitant way. This means, high-spin yrast states at LNL via Fusion-Evaporation reactions, and low-spin yrast and yrare states at GSI-FRS. • The experiment proposal for AGATA@LNL concentrates on the high-spin yrast states of the 76,78Sr isotopes. Here we plan to measure the livetimes of the yrast levels up to 10+ by combining Plunger (RDDS) with Thick target (DSAM) techniques. • The experiment proposal for AGATA@GSI will concentrate on the measurment of the 0+,2+(4+) yrare states in the 78,80Zr and 76,78Sr isotopes.

  20. END

  21. d = 23.5 cm Be (1g/cm2) • AGATA S2’ Experiment (a) <t = 0.1 ps> 2+ t x 0.5 4+ <t = 0.12 ps> 6+ 8+ 10+ <t = 1 ps> t = 5.1 ps t = 155 ps 278 keV 78Sr (t x 0.5)

  22. d = 23.5 cm Be (1g/cm2) • AGATA S2’ Experiment (a) <t = 0.1 ps> 2+ t = 155 ps t x 0.5 <t = 0.12 ps> <t = 1 ps> t = 5.1 ps t = 155 ps 278 keV (t x 0.5)

  23. d = 23.5 cm Be (1g/cm2) • AGATA S2’ Experiment (a) <t = 0.1 ps> 4+ t = 5.1 ps t x 0.5 <t = 0.12 ps> <t = 1 ps> t = 5.1 ps t = 155 ps 278 keV (t x 0.5)

  24. d = 23.5 cm Be (1g/cm2) • AGATA S2’ Experiment (a) <t = 0.1 ps> 6+ t = 1 ps t x 0.5 <t = 0.12 ps> <t = 1 ps> t = 5.1 ps t = 155 ps 278 keV (t x 0.5)

  25. Comparison vs. Pieter’s MC of 36K 37Ca @ 150 MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 23.5 cm Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  26. Comparison vs. Pieter’s MC of 36K 37Ca @ 150 MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 23.5 cm Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  27. Comparison vs. Pieter’s MC of 36K 37Ca @ 150 MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 73.5 cm Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  28. Comparison vs. Pieter’s MC of 36K 37Ca @ 150 MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 73.5 cm Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  29. Comparison vs. Pieter’s MC of 36K 37Ca @ 150 MeV/u bRecoil at de-excitation time: 36K+n 810 keV (3+) d = 73.5 cm Be (1g/cm2) t = 15 ps GS 2+ t = 0 ps t = 15 ps t = 0 ps

  30. Comparison vs. Pieter’s MC of 36K 37Ca @ 200 MeV/u bRecoil at de-excitation time: 36K+n 810 keV t = 15 ps (3+) d = 73.5 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps t = 0 ps

  31. Comparison vs. Pieter’s MC of 36K 37Ca @ 200 MeV/u 37Ca @ 150 MeV/u 36K+n 810 keV (3+) d = 73.5 cm Be (1g/cm2) d = 70-140 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps

  32. 810 keV (3+) GS 2+ Comparison vs. Pieter’s MC of 36K 37Ca @ 200 MeV/u 37Ca @ 200 MeV/u 36K+n 36K+n 810 keV (3+) d = 73.5 cm Be (1g/cm2) d = 23.5 cm Be (1g/cm2) GS 2+ t = 0 ps t = 15 ps t = 0 ps t = 15 ps

  33. 37Ca @ 200 MeV/u 37Ca @ 200 MeV/u t = 0 ps t = 15 ps d = 73.5 cm Be (1g/cm2) d = 23.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u 37Ca @ 150 MeV/u t = 0 ps t = 15 ps t = 0 ps t = 15 ps Summary of 36K lifetime studies with AGATA S2’ (no angular cut!) d = 23.5 cm Be (1g/cm2) d = 73.5 cm Be (1g/cm2) t = 0 ps t = 15 ps

  34. AGATA S2’:Efficiency vs. Theta for several distances

  35. AGATA S2’:Efficiency vs. Theta for several distances

  36. 810 keV (3+) GS 2+ AGATA S2’: lineshape effect with and w/o angular cut 36K+n d = 23.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u q in [15,25] deg 37Ca @ 200 MeV/u All q‘s t = 0 ps t = 15 ps t = 0 ps t = 15 ps

  37. AGATA S2’: angular differential lineshape effect study

  38. q in [25,35] deg AGATA S2’: angular differential lineshape effect study d = 23.5 cm Be (1g/cm2) q in [15,25] deg t = 0 ps t = 15 ps q in [35,45] deg q in [45,55] deg

  39. Level Scheme of 78Sr D.Rudolph et al. Phys. Rev. C, 1997

  40. Previous Experimental Work on 78Sr

  41. lifetime values of yrast levels up to 10+ with high accuracy (5%/20%) Measurables t = ? t = ? t = ? Expected lifetimes (ps): t = 5.1(5) ps t = 155(19) ps 78Sr

  42. Spectroscopic insight into the shape coexistence in 78Sr (LNL Proposal 10.25) C. Domingo-Pardo, T.R. Rodriguez, P. Boutachkov, J. Gerl, M. Gorska, E. Merchan, S. Pietri, H.J. Wollersheim GSI Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany J.J.Valiente-Dobon, G. de Angelis, D.R. Napoli, E. Sahin INFN, Laboratori Nazionali di Legnaro, Legnaro, Italy S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo, D. Mengoni, F. Recchia, C. Ur Dipartimento di Fisica and INFN, Sezione di Padova, Padova, Italy T. Pisulla, A. Dewald, C. Fransen, M. Hackstein, W. Rother Institut für Kernphysik der Universität zu Köln, Köln, Germany A.Gadea, A. Algora, B. Rubio, J.L. Tain IFIC Instituto de Fisica Corpuscular, Valencia, Spain

  43. Spectroscopic insight into the shape coexistence in 78Sr Scientific Motivation

  44. B(E2;J J-2)/B(E2;2 0) • Search for the possible empirical realization of X(5) Critical Point Symmetry in 78Sr Scientific Motivation X(5) 152Sm Casten et al.,Phys.Rev.Lett. 85 (2000) McCutchan et al. Phys.Rev.C 71 (2005) 2 4 6 8 10 Iachello,Phys.Rev.Lett. 85 (2000), 87 (2001)

  45. X(5) 78Sr • Search for the possible empirical realization of X(5) Critical Point Symmetry in 78Sr Scientific Motivation 10+ Rudolph et al. Phys. Rev. C, 1997 Gross et al. Phys. Rev. C, 1994 U(5) X(5) X(5) SU(3) Lister et al., Phys. Rev. Lett. 49 (1982)

  46. (*) • Quantum Phase Transitions can be also studied from a microscopic perspective e.g. as shown by T.Niksic et al., Phys. Rev. Lett. 99 (2007) • Beyond Mean Field calculations predict shape coexistence in 78Sr and strong triaxial effects, and can provide quantitative predictions of E(J) or BE2 values. Scientific Motivation BMF Calculation by T.R. Rodriguez (*) L.Gaudefroy et al. Phys. Rev. C 80, 2009

  47. Spectroscopic insight into the shape coexistence in 78Sr What can we measure?

  48. lifetime values of yrast levels up to 10+ with high accuracy (5%/20%) Measurables t = ? t = ? Expected lifetimes (ps): t = ? t = 5.1(5) ps t = 155(19) ps 78Sr

  49. Spectroscopic insight into the shape coexistence in 78Sr How can we measure it?

  50. E’g Eg 40Ca J bR=0.04 Ca-Target Au-Degrader • AGATA Demonstrator (5 triple cluster) + Köln Plunger Experiment AGATA Demonstrator 40Ca XTU-TANDEM 120 MeV 40Ca-Beam 1 pnA Recoil Distance Doppler Shift Method (RDDS) Köln Plunger 40Ca(40Ca, 2p)78Sr 78Sr Ca-target 400 mg/cm2 Au-Degrader 10.5 mg/cm2

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