Spectroscopic insight into the shape coexistence in 76,78Sr, (78),80ZrP. Boutachkov, C. Domingo-Pardo, H. Geissel, J. Gerl, M. Gorska, E. Merchan, S. Pietri, T.R. Rodriguez, C. Scheidengerger, H.J. WollersheimGSI Helmholtzzentrum fr Schwerionenforschung GmbH, Darmstadt, Germany

G. de Angelis, D.R. Napoli, E. Sahin, J.J. Valiente-DobonINFN, Laboratori Nazionali di Legnaro, Legnaro, Italy

S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo, D. Mengoni, F. Recchia, C. UrDipartimento di Fisica and INFN, Sezione di Padova, Padova, Italy

A. Dewald, C. Fransen, M. Hackstein, T. Pisulla, W. RotherInstitut fuer Kernphysik der Universitaet zu Kln, Kln, Germany

A. Algora, A. Gadea, B. Rubio, J.L. TainIFIC Instituto de Fisica Corpuscular, Valencia, SpainLetter of Intent for AGATA@GSI

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

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

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

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

Scientific Motivation Beyond Mean Field calculations predict shape coexistence in 78Sr and strong triaxial effects 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.

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

Shape coexistence along Z=40A=80N=40

Shape coexistence along Z=40A=80N=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!

Shape coexistence along Z=40A=80N=40

Scientific Motivation Study the possible X(5) character of these N=Z=38,40 Sr and Zr isotopesE.A. McCutchan et al. Phys.Rev.C 71 (2005)Casten et al.,Phys.Rev.Lett. 85 (2000) X(5) 152SmIachello,Phys.Rev.Lett. 85 (2000), 87 (2001)

Scientific Motivation Search for the possible empirical realization of X(5) Critical Point Symmetry in 78SrX(5)X(5)U(5)SU(3)78Sr10+Lister et al., Phys. Rev. Lett. 49 (1982)Rudolph et al. Phys. Rev. C, 1997Gross et al. Phys. Rev. C, 1994

Spectroscopic insight into the shape coexistence in 78SrWhat can we measure?

Measurables lifetime values of yrast levels up to 10+ with high accuracy (5%/20%)t = 155(19) pst = 5.1(5) pst = ?t = ?t = ?78Sr80Zrt = ?t = ?t = ?t = ?t = ?76Srt = ?t = ?t = ?t = ?t = ? yrast band livetime measurements at LNL via fusion evaporationyrare band (2+,4+) measurements at GSI via n-knockout/Coulex

Measurables lifetime values of yrast levels up to 10+ with high accuracy (5%/20%) 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 LNL GSI

Spectroscopic insight into the shape coexistence in 78SrHow can we measure it?

Experiment Livetime measurements via line-shape analysis (?)SIS-18 Primary beam: 1 GeV/u 107Ag4x109 pps79SrAGATA S2 9Be-TargetbR=0.43 Eg79Sr78Sr + nFRS Sec. beams: 100 MeV/u 81Zr 81Sr, 79Sr(to LYCCA)

Sec. Frag.I@S4 (pps)81Zr for (80Zr+n) 45077Sr for (76Sr+n)1.5E379Sr for (78Sr+n)1.4E5

Comparison vs. Pieters MC of 36Kd = 23.5 cmcut qg [15,25] deg Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSt = 0 pst = 15 psd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/uAGATARISING

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.

END

Experiment (a) AGATA S2t = 155 psd = 23.5 cm Be (1g/cm2) (t x 0.5)t = 5.1 pst x 0.5278 keV2+4+6+8+10+

78Sr

Experiment (a) AGATA S2t = 155 psd = 23.5 cm Be (1g/cm2) (t x 0.5)t = 5.1 pst x 0.5278 keV2+

t = 155 ps

Experiment (a) AGATA S2t = 155 psd = 23.5 cm Be (1g/cm2) (t x 0.5)t = 5.1 pst x 0.5278 keV4+

t = 5.1 ps

Experiment (a) AGATA S2t = 155 psd = 23.5 cm Be (1g/cm2) (t x 0.5)t = 5.1 pst x 0.5278 keV6+

t = 1 ps

Comparison vs. Pieters MC of 36Kd = 23.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/ut = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 23.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/ut = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/ut = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/ut = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 150 MeV/u36K+n2+(3+)810 keVGSbRecoil at de-excitation time:t = 15 pst = 0 pst = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u36K+n2+(3+)810 keVGSbRecoil at de-excitation time:t = 15 pst = 0 pst = 0 pst = 15 ps

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u36K+n2+(3+)810 keVGSt = 0 pst = 15 psd = 70-140 cm Be (1g/cm2) 37Ca @ 150 MeV/u

Comparison vs. Pieters MC of 36Kd = 73.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u36K+nt = 0 pst = 15 psd = 23.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u36K+n2+(3+)810 keVGSt = 0 pst = 15 ps

Summary of 36K lifetime studies with AGATA S2 (no angular cut!)t = 0 pst = 15 psd = 73.5 cm Be (1g/cm2) 37Ca @ 150 MeV/ud = 23.5 cm Be (1g/cm2) 37Ca @ 150 MeV/ut = 0 pst = 15 pst = 0 pst = 15 ps

AGATA S2:Efficiency vs. Theta for several distances

AGATA S2:Efficiency vs. Theta for several distances

AGATA S2: lineshape effect with and w/o angular cut36K+nd = 23.5 cm Be (1g/cm2) 37Ca @ 200 MeV/u37Ca @ 200 MeV/ut = 0 pst = 15 pst = 0 pst = 15 psq in [15,25] degAll qs

AGATA S2: angular differential lineshape effect study

AGATA S2: angular differential lineshape effect studyq in [35,45] degt = 0 pst = 15 psq in [15,25] degq in [45,55] degd = 23.5 cm Be (1g/cm2)

Level Scheme of 78SrD.Rudolph et al. Phys. Rev. C, 1997

Previous Experimental Work on 78Sr

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

SU(3)X(5)U(5)BMF2+ 155 (19) (exp. value)4+ 5.1(0.5) (exp. value)6+1.00.760.501.278+0.190.120.070.3910+0.200.110.050.16

Spectroscopic insight into the shape coexistence in 78SrC. Domingo-Pardo, T.R. Rodriguez, P. Boutachkov, J. Gerl, M. Gorska, E. Merchan, S. Pietri, H.J. WollersheimGSI Helmholtzzentrum fr Schwerionenforschung GmbH, Darmstadt, Germany

J.J.Valiente-Dobon, G. de Angelis, D.R. Napoli, E. SahinINFN, Laboratori Nazionali di Legnaro, Legnaro, Italy

S. Aydin, D. Bazzacco, E. Farnea, S. Lenzi, S. Lunardi, R. Menegazzo, D. Mengoni, F. Recchia, C. UrDipartimento di Fisica and INFN, Sezione di Padova, Padova, Italy

T. Pisulla, A. Dewald, C. Fransen, M. Hackstein, W. RotherInstitut fr Kernphysik der Universitt zu Kln, Kln, Germany

A.Gadea, A. Algora, B. Rubio, J.L. TainIFIC Instituto de Fisica Corpuscular, Valencia, Spain(LNL Proposal 10.25)

Spectroscopic insight into the shape coexistence in 78SrScientific Motivation

Scientific Motivation Search for the possible empirical realization of X(5) Critical Point Symmetry in 78SrMcCutchan et al. Phys.Rev.C 71 (2005)Casten et al.,Phys.Rev.Lett. 85 (2000) X(5) 152SmIachello,Phys.Rev.Lett. 85 (2000), 87 (2001)2 4 6 8 10

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

Scientific Motivation 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.(*) L.Gaudefroy et al. Phys. Rev. C 80, 2009BMF Calculation by T.R. Rodriguez

Spectroscopic insight into the shape coexistence in 78SrWhat can we measure?

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

SU(3)X(5)U(5)BMF2+ 155 (19) (exp. value)4+ 5.1(0.5) (exp. value)6+1.00.760.501.278+0.190.120.070.3910+0.200.110.050.16

Spectroscopic insight into the shape coexistence in 78SrHow can we measure it?

Experiment AGATA Demonstrator (5 triple cluster) + Kln PlungerXTU-TANDEM 120 MeV 40Ca-Beam 1 pnA40Ca40Ca(40Ca, 2p)78SrCa-target 400 mg/cm2Au-Degrader 10.5 mg/cm2AGATA DemonstratorKln Plunger78SrRecoil Distance Doppler Shift Method (RDDS)

Experiment (a) AGATA Demonstrator (5 triple cluster) + Kln Plungert = 155(19) psd = 0.2 mm 2 mm 4 mm(t x 0.95)t = 155(19) pst x 0.95MC Code by E. Farnea and C. Michelagnoli278 keV

Experiment (a) AGATA Demonstrator (5 triple cluster) + Kln Plungert = 5.1(5) psd = 0.03 mm 0.06 mm 0.10 mm(t x 0.95)t = 5.1(5) ps(t x 0.95)503 keVMC Code by E. Farnea and C. Michelagnoli

Experiment (a) AGATA Demonstrator (5 triple cluster) + Kln Plungerd = 0.008 mm 0.01 mm 0.02 mm+ Information from thick-target measurementt ~ 1 ps(t x 0.8)t ~ 1 ps(t x 0.8)712 keV

Experiment (a) AGATA Demonstrator (5 triple cluster) + Kln Plunger712 keV503 keV278 keVDifferential Decay Curve (DDC) Analysis Methoddistance target-degrader (mm)rel. gated peak intensity (a.u.)

Experiment (b) AGATA Demonstrator (5 triple cluster) + Thick Targett ~ 0.12 ps(t x 0.8)t ~ 0.12 ps(t x 0.8)895 keVt ~ 0.1 ps(t x0.8)1058 keVt ~ 0.1 ps(t x0.8)MC Code by E. Farnea and C. Michelagnoli

Spectroscopic insight into the shape coexistence in 78SrHow much beam-time is needed?

Beam-Time estimateTotal Beam-Time Request = 5 daysPLUNGERThick Target

JpEg (keV) t (ps) d (mm)gg-Countstime (h)2+277.61550.214325.3214525.4415095.64+503.25.10.0311788.70.0612149.00.1011828.76+7121.00.00810377.70.01010367.60.0209927.38+8950.120544953534010+10580.1

OutlookThe proposed lifetime measurements may provide the first strong evidence of X(5) quantum phase transition in 78Sr.

These results will be complemented with further yrare band measurements on 78Sr with AGATA at GSI in 2011/2012.

Measured lifetimes or B(E2) values will allow us to study shape coexistence in 78Sr from a microscopic point of view and they will provide an stringent test for BMF calculations, the predicted triaxiality effect in this nucleus and how the triaxial degree of freedom is included in the calculation.

Backup Slides

Level Scheme of 78SrD.Rudolph et al. Phys. Rev. C, 1997yrast band

Previous Experimental Work on 78Sr

Shape coexistence along Z=38 Beyond Mean Field calculations do predict shape coexistence in 78Sr and strong triaxial effects

Beam-Time estimateTotal Beam-Time = 5.6 daysPLUNGERThick Target

JpEg (keV) t (ps) d (mm)Countstime (h)2+277.61550.214325.3214525.4415095.64+503.25.10.0311788.70.0612149.00.1011828.76+7121.00.00810377.70.01010367.60.0209927.38+8950.120953593687010+10580.1

Theoretical Framework BMF(from T.R. Rodriguez)

Theoretical Framework BMF(from T.R. Rodriguez)

Theoretical Framework BMF(from T.R. Rodriguez)

Theoretical Framework BMF(from T.R. Rodriguez)