Recent Results from Ridge Analysis- Evidence for Hyperdeformation?

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1 Recent Results from Ridge Analysis- Evidence for Hyperdeformation? B. Herskind, G.B. Hagemann, G. Sletten, Th. Døssing, C. Rønn Hansen, N. Schunck, S. Ødegård 1), H. Hübel, P. Bringel, A. Bürger, A. Neusser, A. K. Singh, A. Al-Khatib, S.B. Patel 2), A. Bracco, S. Leoni, F. Camera, G. Benzoni, P. Mason, A. Paleni, B Million, O. Wieland 3), P. Bednarczyk, F. Azaiez, Th. Byrski, D. Curien, O. Dakov, G. Duchene, F. Khalfallah, B. Gall, L.Piqeras, J. Robin, J. Dudek, N. Rowley 4), N. Redon 5), F. Hannachi, J.N. Scheurer, J.N. Wilson 6), A. Lopez-Martens, A. Korichi, K. Hauschild, J. Roccaz, S. Siem 7), P. Fallon,, I. Y. Lee, A. Görgen 8), B.M. Nyakó, A. Algora, Z. Dombradi, J. Gal, G. Kalinka, D. Sohler, J. Molnár, J. Timár, L. Zolnai 9), K. Juhász 10), A. Maj, M. Kmiecik, M. Brekiesz, J. Styczen, K. Zuber 11), J.C. Lisle 12), B. Cederwall, K. Lagergren 13), A.O. Evans, G. Ranovski 14), G. De Angelis 15), G. La Rana, R. Moro 16), W. Gast, R.M. Lieder, E. Podsvirova, H. Jäger 17), C.M. Petrache and D. Petrache 18). Data-Base Producing Teams from Bonn and Debrechen. Theoretical Support. 1. A Short Overview of the HyperLong-HyperDeformation (HLHD) Experiment made by the use of EUROBALL-IV at the Vivitron, Strasbourg with: 2 x 2 weeks of beamtime: 64 Ni + 64 Ni 128 Ba*, at Ebeam = 255 and 261 MeV. 2. Recent Results after Charged Particle Emission with emphasis on the cases with: J(2) 100 h 2 /MeV HD The Gudrun Symposium, December , 2005.

2 Lublin-Strasbourg liq.drop (LSD) model by K. Pomorski and J. Dudek, Phys.Rev. C67, (2003)

3 ND HD ND HD Most Recent Microscopic Calculations (including LSD) by Nicolas Schunck: private communication

4 ND SD HD ND SD HD (2p,2n) channel (2n) - channel (α,2n) channel (2p,2n) channel Most Recent Microscopic Calculations (including LSD) by Nicolas Schunck: private communication

5 J (2) in Second Potenial Minimum (SD) J (2) in Third Potenial Minimum (HD) Most Recent Microscopic Calculations (including LSD) by Nicolas Schunck: private communication

6 Ex 82 Population and Decay in the (α, 2n) channel 122 Xe from the highest spin reached by 261 MeV 64 Ni + 64 Ni in Complete fusion. T=1.5 MeV 30 MeV above Yrast 70 Neutron Decay in the Jacobi transition region E λ To ND T 1.0 MeV 6-10 MeV over Yrast γ- Decay to Normal States α Decay to HD states and ND states: δl - 6 to 8 h) T 0.5 MeV 2-6 MeV over yrast γ-decay between HD Continuum states Linking Transition to Normal states T ~ 0 yrast IN-COMPLETE FUSION will improve the loss of L in part.-decay and may be needed in eg. the 2-α channels Angular Momentum Potentials(β,I,T I,T) calculated by Nicolas Schunck

7 European collaboration Denmark, France, Germany, Italy, Sweden and the UK Euroball 7 encapsulated detectors INFN, Legnaro, Italy, 1997 IReS, Strasbourg, France, Ge crystals + supp. shields Total peak eff. => 7.44%, Mγ=30) per Cluster Ge detector 30 Large single crystal Ge detectors 64 Ni + 64 Ni => 128 Ba (xp,xα,xn) 261 MeV (2 weeks)+255 MeV (2 weeks) using the DIAMANT For Multi Particle Combinations in 84 CsI 26 Clover Ge detectors 4 crystals per cryostat 15 Cluster Ge detectors A closer Look Mount of DIAMANT Inner BGO ball

8 Results of the First Experiment at Gammasphere in Berkeley using 64 Ni + 64 Ni => 128 Ba* - 2n Cut J energy (2) ~ (E Eh 2 2 )/2=/ MeV 1440 => ± 142SD kev Rotational Plane Mapping (RPM) N=1, and after 2n filtering and note: => 265MeV 64 Ni beam ND SD/ HD Eγ 2 Extracted by Filtering and Rotational Plane Mapping Eγ 1 (kev) The RPM technique

9 EB-IV: FOLD Selection only and COR95 Background treatment 3D Rotational Plane (width = 3 x 2 kev) 261 MeV 64 Ni + 64 Ni 2 n => 126 Ba From xn Data-Base veto for charged particles 4 x 52 kev THE FIRST BIG SURPRISE FOLD 28+h Rotational Plane (width = 3x2 kev) Data: 261 MeV 255 MeV Perpendicular Cuts (PCut) = 1440 ± 102 kev Counts= x 52 kev 26+h Counts= h 22+h E γx E γy E γx E γy Confirm the Berkeley results => J(2) ~ 77 h2/ MeV => SD, and show a strong beam dependent effect

10 spectra for 1α - channel Gates on 123 Xe ( α,n) NOTE SCALE 7000 Gates on 121 Xe ( α,3n) Gates on 122 Xe ( α,2n) GATES Select 122 Xe Total Projection Spectrum Bg in coincidence with 1α

11 α,2n channel, selected spectra Pcut = 1400 and Plane thickness = 5x4 kev; Cutting Width: 88, 238, 488 kev; Fold 22 Transition Energy Dependence of 4 x 52 kev Ridge Structure vs. Fold Cutting Width Fold 22, 24, 26, 28, 30, 32 NOTE Scales!

12 N=3: x+3y-4z = ±δ (α,2n) => 122 Xe N=2: x+2y-3z = ±δ y z z x N=1: x+y-2z = ±δ y z x J (2) ~ 77 h 2 / MeV

13 1p channel Gates on 124 Cs (p,3n) Gates on 123 Cs (p,4n) Gates on 125 Cs (p,2n) Total Projection Spectrum in coincidence with 1 proton Gates selecting 125 Cs

14 Compare RPM Ridges for (p,2n) 125 Cs 261 MeV 64 Ni + 64 Ni or 255 MeV 64 Ni + 64 Ni at Fold 20 Pcut = 1440 ± 164 kev J (2) = 100 h 2 /MeV 4 x 40 kev Plane Thickness = 5 x 4 kev Pcut = 1280 ± 164 kev J (2) = 100 h 2 /MeV Pcut = 1360 ± 164 kev J (2) = 100 h 2 /MeV 4 x 40 kev 4 x 40 kev Ex Ey (kev) Ex Ey (kev)

15 p,2n channel 125 Cs Sequencial Series of Perpendiculat Cuts (PCuts) of width: 8 kev PCut = kev PCut = PCut = (PCut = ) / 2 4 x 40 kev 4 x 40 kev 4 x 40 kev 4 x 40 kev SUM SUM SUM Ex Ey (kev) Ex Ey (kev) Ex Ey (kev)

16 NPC for (p2n) => 125 Cs Statistical Analysis of HD Ridge Structures by extracting the Number of Positive Channels which are higher than a smoothed average in the 2D spectra along different paths parrallel to the E γx = E γy Diagonal. Example of Paths along the E γx = E γy Diagonal around the HD Ridge structure as 1 or 0, displaced by 2 in increasing order from the diagonal. Goodness = ((Ridge Height)-Mean) / σ E γy (kev) E γx (kev) SUM Mean=25.67 σ = 3.99 µ2 = Goodness: 12.3/4.0 = 3.1 σ

17 Mean=25.67 σ = 3.99 µ2 = Goodness: 12.3/4.0= 3.07 COMPARE COMPARE Ridges Ridges for (p,2n) for (p,2n) 125 Cs 125 Cs 261 MeV Ni MeV + 64 Ni 64 Ni + 64 Ni or or 255 MeV Ni MeV + 64 Ni 64 Ni + 64 Ni at Fold at 20Fold 20 Mean=24.07 σ = 3.39 µ2 = Goodness: Plane Thickness Plane = Thickness 5 x 4 kev = 58.1/3.4 x 4 kev = MeV Data Pcut = 1440 ± 164 kev 4 x 40 kev Statistiacal Analysis of Number of Positive channels (NPC) in the HD Ridge Structure Pcut = 1280 ± 164 kev J (2) = 100 h 2 /MeV Pcut = 1360 ± 164 kev J (2) = 100 h 2 /MeV 4 x 40 kev 4 x 40 kev Ex Ey (kev) Ex Ey (kev)

18 2-proton channel Further Gated by gs-band of (2p,2n) => 124 Xe ; plane = 3x4 kev RAW-DATA: Pcut = 1280 kev; Fold 12 NPC Statistical Analysis, (2p gate only) 4 x 36 kev 111 ħ 2 / MeV Width Intensity Significance δeγ (kev) (counts) (in σ) (kev) 328 => 270 ± 60 => x => 250 ± 58 => x => 138 ± 45 => x 36 J (2) = 111 h 2 /MeV RPM: δ = 0 COR-TREATED: Pcut = 1280 kev; Fold 12 Pcut Intensity Significance δeγ (kev) (counts) (in σ) (kev) 328 = > 239 ± 43 => x => 236 ± 41 => x Ex Ey (kev) 168 => 151 ± 32 => x 36

19 Statistics Too Poor to make a NPC Analysis 1440 kev 1360 kev

20 RPM-Analysis after sort with 2α gate only NPC Statistical Analysis, (2α gate only) Pcut = 1440 Pcut ± 82,122,162,202; = kev δ = 5 x 4 kev 4 x 36 kev 4 x 32keV 111 PCuts = ; Pcut = ± 82, -1440; 122, 162; 1440 δ = x 4 kev kev 4 x 36 kev 4 x 32 kev Ex Ex Ey Ey (kev) (kev)

21 α,p channel Further Gated by gs-band of (α,p,2n) => 121 I Pcut = 1440 ± 84, 124, 164, 204 kev NPC Statistical Analysis Pcut = 1280, 1360, 1440 ± 164 kev 4 x 52 kev 4 x 52 kev Eγx Eγy (kev)

22 α,2n 122 Xe Ridge-Structure: 4 ħ 2 /J (2) 52 kev Intensity: Pcut = 1520 kev Intensity Relations vs. (Fold + higher) Plane = ± 10 kev Normalized(fold) Intensity: Pcut = 1520 kev ND-Ridge Plane thickness = 5 x 4 kev ND-Ridge Plane thickness = 5 x 4 kev ND-Ridge HD-Ridge Norm. δ = 5x4 kev δ = 5x4 kev HD Ridge in (2p,2n) HD Ridge HD-Ridge HD-Ridge reaction HD-ridge in (2α,2n) 124 Xe reaction (p,2n) 118 Te HD HD Ridge in (2α,2n) (2p,2n) reaction HD-Ridge (p,2n) Xe Te Ex=Ey=1520 kev

23 Part. γ- δeγ Most probable J (2) exp gate gate (kev) Nucleus h 2 /MeV x n (2n) Ba 77 1 α (α,1n) Xe 71 1 α (α,2n) Xe 77 1 α (α,3n) Xe 63 2 α (2α,0n) Te 71 2 α (2α,2n) Te p (p,2n) Cs p (p,3n) 36 (48) 124 Cs p (2p,2n) Xe 111 p α (α,p,1n) I 71 p α (α,p,2n) I 77 1 p (p,xn) 40 (64) p (2p,xn) 32 wide α (2α,xn) 32 (48) 125 p α (α,p,xn) 44 wide 91 J (2) theory *) h 2 /MeV 118 SD? SD? 108 SD? SD? SD? SD? 102 SD? 48 Ca+ 82 Se (- 4n) Xe SD? * ) Theoretical Calculations by Nicolas Schunck, private communication

24 Incomplete Fusion => α Escape? α α α 64 Ni 64 Ni 60 Fe α 64 Ni 124 Xe or perhaps 120 Te

25 Summary:. No discrete HD bands has been firmly identified yet, but Continuum HD and SD Ridge Structures identified in 12 nuclei. 118 Te, 124 Xe and 125 Cs strong candidates for Hyperdeformation. For 121 I, 122 Xe, 126 Xe and 126 Ba, Superdeformation are more likely. The length of the ridges indicates 6-10 transitions in many bands. Fluctuation Analysis on the best cases shows 10 bands. No sign of delayed α-emission after the HD or SD cascades. A strong beam energy dependence is observed close to the L max. Incomplete Fusion may explain the beam energy dependence and the high-angular momentum feeding in the α and 2α channels.

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