GDR Decay Feeding of Low-Energy Structures with Different Deformations Using nuBall + PARIS

1. Feeding of low-energy structures with different deformations by the GDR decay: the nuBall array coupled to PARIS M. Kmiecik, A. Maj, B. Fornal, P. Bednarczyk et al. IFJ PAN Kraków for the PARIS collaboration ALTO nu-ball hybrid spectrometer workshop 2016 Orsay, May 19-20, 2016

2. Plan • Motivation • Studying nuclear shapes by GDR measurements – examples of the method • Jacobi shape transitions • GDR feeding of superdeformed states • Nuclear deformation at highest spin studied using isomer gated GDR • Idea to apply described methods in experiments using nuBall + PARIS in regions of shape coexistence and shape isomer • link between deformation of hot compound nucleus and evaporation residues • population of states of different deformation by high-energy γ–rays from GDR decay • Outlook

3. n GDR g a n n GDR g n n Motivation link betweendeformation of hot compoundnucleus and deformation of coldevaporationresidue GDR • GDR high energy gamma rays • - hot nucleusshape • lowenergytransitions - deformation of excitedresidue Excitation energy [MeV] Angular momentum [h]

4. G G G GDR goodprobe for shapeinformation G oblate prolate triaxial

5. GDR strengths for hot, rotating nucleiismorecomplicated • thermalshapefluctuations • Coriolissplitting K. Mazurek – LSD calculations potential energy calculated with LSD (Lublin-Strasbourg Drop) model:Dudek & Pomorski Phys. Rev. C67 (2003) 044316 oblate oblate triaxial triaxial prolate Jacobi shapes Low energy component in GDR strength function

6. Examples of using the GDR to studynuclearshapes

7. a) Search for Jacobi shapetransition in lightnuclei:46Ti* decay to 42Ca Experiment @ IRES: 105MeV18O+28Si 46Ti* Lmax 35 , E* = 88 MeV, v/c  4.3% Setup: • Euroball IV(26 clovers + 15 clusters) • HECTOR(8 big BaF2) • EUCLIDES(40 Si telscopes)

8. MC Cascade fit – 5-L M. Lach et al., EurPhys J. A12, 381 (2001) GDR gatedon discrete transitions in 42Ca A. Maj et al., Nucl. Phys. A731, 319c (2004) Jacobi shape transition and seen for the firsttimeCoriolis effect

9. sd / spher nd / spher sd / nd nd sd spher b) GDR feeding of SD states M. Kmiecik et al., Acta Phys. Pol. B36 (2005) 1169 feeding of the highly deformed states by the low energy GDR component M. Lach et al., EurPhys J. A12, 381 (2001)

10. GDR feeding of SD states in 143Eu Experiment @ LNL: 165MeV37Cl+110Pd  147Eu* G. Benzoni et al., Phys. Lett. 540B, 199 (2002) • Setup: • Euroball • HECTOR SD feeding of the SD states in 143Euby the low energy GDR component spher ND

11. 96 MeV 18O + 198Pt→ 216Rn* E*=56MeV, Lmax=39h isomer c) GDR decay to high-spinisomericstates gating on isomers choosing nuclei at highest spins surviving fission • Setup: • Hector + Helena • Catcher • Ge • BGO

12. Isomergated GDR high-energy γ-rays gated on isomer gate on time GDR width for 216Rn small increase of deformation for highestspin - nucleusremainsalmostsphericalup to the fission limit M. Kmiecik et al. PR C70, 064317 (2005)

13. Idea – to apply described methods in experiments using nuBall + PARIS • Study: • GDR decay to states of differentdeformation in evaporationresidues • Obtaininformation on: • feeding of thesestates by GDR • corelationbetweenshape of hot nucleus and deformation of evaporationresidues

14. Example 1 - shapecoexistence P. Mölleret al., Phys. Rev. Lett. 103, 212501 (2009) 72-78Kr oblate prolate 38 ns 18.8 ns E. Bouchez et al., Phys. Rev. Lett. 90, 082502 (2003) oblate 11 ps β=0.3-0.4 oblate 61 ps oblate prolate prolate prolate

15. Possiblereactions 16O @ 90 MeV on 66Zn,64Zn → 80Sr*,82Sr* → 76Kr, 78Kr 32S @ 144 MeV on 46Ti → 78Sr* → 74Kr 32S

16. GDR gated on transitionsbetweenstates of differentdeformation E. Clement et al., Phys. Rev. C 75, 054313 (2007) gating on low-energy γ-transitions 76Kr oblate prolate result: GDR strength → nuclear shape

17. γ-transitions yield gated on GDR energy E. Clement et al., Phys. Rev. C 75, 054313 (2007) 76Kr gating on high-energy γ-rays oblate result: transitions yield as a function of GDR energy → GDR feeding of low energy structures prolate

18. 74,78Kr isotopes E. Clement et al., Phys. Rev. C 75, 054313 (2007) 74Kr F. Becker et al., Nucl. Phys. A 770, 107 (2006) 78Kr oblate prolate oblate prolate

19. Example2 - shape isomer – 188Pt S. Mukhopadhyayet al., Phys. Lett. B 739, 462 (2014) 188Pt near prolate triaxial β =0.18and γ=−6° β=0.16and γ=−40°

20. Availablereaction 176Yb(18O @ 82 MeV, 4n)188Pt

21. GDR decay to differentdeformationstructures GDR in CN (192Pt) triaxial β=0.16γ=−40° how the states of differentdeformationarepopulated by high energygammas from GDR decay near prolate β =0.18and γ=−6°

22. gating on time Example of time spectrum measured by FATIMA gate on triaxial deformation gate on (mostly) prolate deformation result: GDR strengthfunctiondeliveringinformation on shapeof hot nucleidecaying to givenfinaldeformation oblate triaxial prolate

23. Experimental set-up measured: • low energy discrete transitions: • energy • time • multiplicity • high energy γ-rays • nu-ball array: • 24 clover Ge detectors at 90 degrees ~4.5% efficiency at 1MeV • 36 LaBr3 detectors from Fatima - 5% efficiency • PARIS clusters - 2% (at 23 cm) efficiencyfor 15 MeV gamma rays

24. The PARIS PHOSWICH 10 ns risetime Single pulses HAMAMATSU Mixed signal

25. First PARIS cluster – alreadyusedin the experimentat IPN Orsay

26. Conclusions • nuBall array together with PARIS clusters can be used for measurement of GDR high-energy gamma decay from compound nucleus in coincidence with low energy gamma transitions or/and with isomers • Possible regions of interest are: a) shape coexistence in Kr isotopes; and b) shape isomers around A≈190 • Such experiments will allow us to: • trace shape evolution from hot nuclear system to specific cold nuclear structures • and study the feeding of states of different deformation by high-energy γ–rays from GDR decay

27. Deadlines: Abstractsubmission: May 27, 2016 Registrationcloses: July 10, 2016 http://zakopane2016.ifj.edu.pl