Research activities of ATOMKI at former LSF IReS Strasbourg High-spin states J Timár, ATOMKI, Debrecen Prague 2007

Roots of the ATOMKI high-spin group – IReS collaboration Personal links with labs building EG and EB A Algora, BM Nyakó, D Sohler, J Timár, L Zolnai: PhD, postdoc or other positions in Liverpool, Grenoble, Stockholm, and Legnaro for periods from a few months to a few years Developement of the DIAMANT charged-particle detector array for use with EB J Gál, Gy Hegyesi, K Juhász, G Kalinka, J Molnár, BM Nyakó: Prague 2007 CENBG (Bordeaux) – ATOMKI (Debrecen) – University of Napoli collaboration

Main topics and results of our research activity at IReS Octupole vibration in a SD nucleus (2 experiments, EG +EB) 190 Hg Band termination at A~100 (1 experiment, EG) 102,103 Pd, 100,101,102 Rh, 98,99,100 Ru, Band termination at A~130 (2 experiments, EB) 132 Ce, 128 La, 132 La N~Z nuclei at A~100 (5 experiments, EB) 93 Pd, 95 Ag, 98 Cd Chiral bands at A~100 (1 experiment, EB+DIAM) 105,106 Rh, 102 Ru Search for hyperdeformation (2 experiments, EB+DIAM) 126 Ba, 118 Te, 124 Cs, 125 Cs, 124 Xe Prague 2007 In collaboration with other EWON and non-EWON labs >50 pulications

Octupole vibration is expected in nuclei where sp orbitals with Δl=3 and ΔJ=3 are close to the Fermi surface Rotational bands built on octupole vibration were known for several nuclei. However, no SD rotational bands built on any kind of vibration was known. Octupole vibration in the SD 190 Hg (Eurogam) 190 Hg SD A Wilson et al., Phys. Rev. C54 (1996) 559 RPA calculations predicted octupole vibration in SD bands near 190 Hg. Experimental signature: strong E1 transitions between the SD bands. Experiment with Eurogam 2 Reaction: 160 Gd + 34 S at 153 MeV ~ 4x10 8 quadruple- and higher-fold events Linking transitions were established Prague 2007

Octupole vibration in the SD 190 Hg (Euroball) Experiment with Euroball IV Reaction: 160 Gd + 34 S at 156 MeV ~ 2x10 9 triple- and higher-fold events Multipolarity of linking transitions: E1 First example of SD bands built on collective vibration 4 papers, 3 conference proceedings A Korichi et al., Phys. Rev. Lett. 86 (2001) 2746 Prague 2007

Band termination at A~100 Z N Pd Rh Ru Band termination was predicted also for nuclei around 100 Ru at around spin 30 by CNS calcs. Experiment with Eurogam 2 Reaction: 70 Zn + 36 S at 130 MeV ~ 6x10 8 triple- and higher-fold events New high-spin bands for several Pd, Rh, and Ru nuclei 102 Pd J.Gizon et al., Phys. Lett. B410 (1997) 95 Prague 2007

Band termination at A~100 – results First observation of band termination in the A~100 mass region Termination of several bands based on valence-particle and core excited intrinsic configurations in 102,103 Pd, 101,102 Rh, and 98,99,100 Ru The observed band terminations correspond to a new type: rigid rotation-like band termination On the basis of the properties of the observed terminating states we proposed a larger value for the energy spacing between the neutron d 5/2 and g 7/2 orbitals 8 papers, and 4 conference proceedings Prague 2007

Chiral bands in the A~100 mass region Ag RhRh Tc N Z Fermi levels proton g 9/2 neutron h 11/2 Vaman et al., Phys. Rev. Lett. 92 (2004) Rh Triaxial core + two valence quasiparticles One is a particle type, the other is a hole type Mutually perpendicular angular momenta Prague 2007 S. Frauendorf, J. Meng, Nucl. Phys. A 617 (1997) 131.

Chiral doublet band structures in 105,106 Rh 3 papers + 3 conference proceedings Chiral bands in the A~100 mass region – results with EUROBALL J.Timár et al., Phys. Lett. B598 (2004) 178 Experiment: EUROBALL + DIAMANT at Vivitron IreS 96 Zr( 13 C,p3n) 105 Rh fusion-evaporation reaction Beam energies of 51 MeV and 58 MeV ~ 2x10 9 triple- and higher-fold events ~ 5x10 7 belonged to 105 Rh First composite chiral structure in this region Prague 2007

Search for hyperdeformation around 126 Ba (HLHD experiment) Prague 2007 Experiment with Euroball + Diamant Reaction: 64 Ni + 64 Ni at 255 and 261 MeV 2 x 2 weeks ~ 6x10 9 quadruple- and higher-fold events Extreme high spins No HD band is observed up to now K. Pomorski, J. Dudek, Phys. Rev. C67, (2003). LSD calcs.

ND: 2 papers, 2 conf. proc., HD: 4 conference proceedings Search for hyperdeformation around 126 Ba (HLHD experiment) FOLD 28+h 26+h 24+h 22+h Eγx – Eγy 4 x 52 keV Rotational Plane (width = 3x2 keV) Data: 261 MeV – 255 MeV Cuts taken on 3D Rotational Plane: Eγx + Eγy - 2 Eγz = δ Results from 'xn'-type data RPM analysis Preliminary results from 'particle xn'-type data: Prague 2007 B. Herskind et al., Acta Phys. Pol. B 38, 1421 (2007)

The DIAMANT R&D collaboration Objectives of the Collaboration: Upgrading of DIAMANT --> Exploitation in experiments Contributions of the collaborating partners: BordeauxDebrecenNapoli Design:Mechanics Detector+Preamps + VXI Electronics Financing:8 VXI Cards5 VXI Cards CsI Detectors +pin-diodes Preamps Total cost of upgrading:~40 k€ MSI - ATOMKI (Stockholm) (Debrecen) 1989 – 1994 CENBG - Italian (Bordeaux) (Napoli) Late '80s – present 1992 – 1999: informal, 2000 – 2004: MTA-CNRS Participants Prague 2007

The DIAMANT ancillary detector DIAMANT: a high-granularity, 4π detector array of CsI(Tl) scint., used in large  -ray spectrometers for light charged-particles The octal Part. Discr. Card in VXI standard  particles Protons Deuterons  Rays (CsI)  Rays (PIN- diode) Example spectrum of a CsI crystal Efficiency: [% of 4  geometrical:  90 det. protons:  70 det. alphas:  50 Prague 2007

EXOGAM experiments using GANIL Exp-#Physics Motivation; Stable-RadioactiveBeam/Target Detectors (Spokesperson) EXOGAM Identification of γ-rays in nuclei around the drip-line nucleus 130 Sm : (P.Nolan)probing the maximally deformed light rare-earth region E404S/E404aSIdentification of γ-rays in nuclei around the drip-line nucleus 130 Sm : DIAMAMT & (P.Nolan)probing the maximally deformed light rare-earth region DIAMANT 76 Kr(60MeV)/1.1mg/cm2 58 Ni; +VAMOS E498SHigh Spin States in the Tz=-3/2 Nucleus 37 Ca – Mirror Symmetry DIAMANT (S.Williams)at the Largest Values of Isospin; 18 Ne(60MeV)/1mg/cm2 24 Mg; +N-Wall E482Mirror Energy Differences in the A=58, T=1 mass triplet and Charge DIAMANT (A.Gadea)Symmetry Breaking terms in the nuclear effective interaction above +N-Wall 56 Ni; 36 Ar(85MeV)/0.5 mg/cm2 24 Mg target on 90Zr backing, 4pnA E505Electromagnetic decay properties of the Tz=±1/2, A=67 and 71 DIAMANT (G.deAngelis)mirror pairs: A test for isospin mixing and for pn pairing; +N-Wall E514Single-particle energies and proton-shell gap in 100 Sn DIAMANT (M.Palacz)extracted from high-spin states in 103 Sn; +N-Wall 58 Ni(240 MeV) 8 mg/cm2 54 Fe target, 1.7 pnA E451Search for T=0 pairing and a new coupling scheme in 92 Pd and 88 Ru DIAMANT (B.Cederwall) 36 Ar(111 MeV) 6 mg/cm2 58 Ni target, 5 pnA (Submitted to PRC) +N-Wall Prague 2007

Future plans with LSF-s in Europe We plan to continue high-spin studies at LSF-s in Europe with special emphasis on: SPIRAL 2, EXOGAM (Ganil) GASP, CLARA, AGATA (Legnaro) Diamant needs to be upgraded to fit to the new arrays It is very much suitable for studying proton drip line nuclei because of its high granularity Every groups are welcome to performe experiments with it! Prague 2007