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Research activities of ATOMKI at former LSF IReS Strasbourg

This research activity at ATOMKI focuses on the investigation of high-spin states and the development of the DIAMANT charged-particle detector array. The main topics include octupole vibration, band termination, N~Z nuclei, chiral bands, and search for hyperdeformation. Collaboration with other labs has resulted in over 50 publications.

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Research activities of ATOMKI at former LSF IReS Strasbourg

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

  2. 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: CENBG (Bordeaux) – ATOMKI (Debrecen) – University of Napoli collaboration Prague 2007

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

  4. 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. 190Hg SD Experiment with Eurogam 2 Reaction: 160Gd + 34S at 153 MeV ~ 4x108quadruple- and higher-fold events Linking transitions were established Octupole vibration in the SD 190Hg (Eurogam) RPA calculations predicted octupole vibration in SD bands near 190Hg. Experimental signature: strong E1 transitions between the SD bands. A Wilson et al., Phys. Rev. C54 (1996) 559 Prague 2007

  5. Experiment with Euroball IV Reaction: 160Gd + 34S at 156 MeV ~ 2x109triple- and higher-fold events Multipolarity of linking transitions: E1 4 papers, 3 conference proceedings Octupole vibration in the SD 190Hg (Euroball) First example of SD bands built on collective vibration A Korichi et al., Phys. Rev. Lett. 86 (2001) 2746 Prague 2007

  6. 102Pd Z Pd Rh Ru N Band termination at A~100 Band termination was predicted also for nuclei around 100Ru at around spin 30 by CNS calcs. Experiment with Eurogam 2 Reaction: 70Zn + 36S at 130 MeV ~ 6x108 triple- and higher-fold events New high-spin bands for several Pd, Rh, and Ru nuclei J.Gizon et al., Phys. Lett. B410 (1997) 95 Prague 2007

  7. 8 papers, and 4 conference proceedings 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 102,103Pd, 101,102Rh, and 98,99,100Ru • 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 d5/2 and g7/2 orbitals Prague 2007

  8. N neutron h11/2 104Rh Fermi levels Vaman et al., Phys. Rev. Lett. 92 (2004) 032501. proton g9/2 Triaxial core + two valence quasiparticles One is a particle type, the other is a hole type Mutually perpendicular angular momenta Chiral bands in the A~100 mass region Z Ag Rh Tc S. Frauendorf, J. Meng, Nucl. Phys. A 617 (1997) 131. Prague 2007

  9. Chiral doublet band structures in 105,106Rh 3 papers + 3 conference proceedings Chiral bands in the A~100 mass region – results with EUROBALL Experiment: EUROBALL + DIAMANT at Vivitron IreS 96Zr(13C,p3n)105Rh fusion-evaporation reaction Beam energies of 51 MeV and 58 MeV ~ 2x109 triple- and higher-fold events ~ 5x107 belonged to 105Rh First composite chiral structure in this region J.Timár et al., Phys. Lett. B598 (2004) 178 Prague 2007

  10. Extreme deformations @ high spins No HD band is observed up to now Experiment with Euroball + Diamant Reaction: 64Ni + 64Ni at 255 and 261 MeV 2 x 2 weeks ~ 6x109 quadruple- and higher-fold events Search for hyperdeformation around 126Ba (HLHD experiment) LSD calcs. K. Pomorski, J. Dudek, Phys. Rev. C67, 044316 (2003). Prague 2007

  11. Rotational Plane (width = 3x2 keV) Data: 261 MeV – 255 MeV 4 x 52 keV FOLD 28+h 26+h 24+h 22+h ND: 2 papers, 2 conf. proc., HD: 4 conference proceedings -400 -200 0 200 400 Eγx – Eγy Search for hyperdeformation around 126Ba (HLHD experiment) Results from 'xn'-type data RPM analysis Preliminary results from 'particle xn'-type data: B. Herskind et al., Acta Phys. Pol. B 38, 1421 (2007) Cuts taken on 3D Rotational Plane:Eγx + Eγy - 2 Eγz = δ Prague 2007

  12. Participants MSI - ATOMKI(Stockholm) (Debrecen) 1989 – 1994 CENBG - Italian (Bordeaux) (Napoli) Late '80s – present 1992 – 1999: informal,2000 – 2004: MTA-CNRS Objectives of the Collaboration: Upgrading of DIAMANT --> Exploitation in experiments Contributions of the collaborating partners: Bordeaux Debrecen Napoli Design: Mechanics Detector+Preamps + VXI Electronics Financing: 8 VXI Cards 5 VXI CardsCsI Detectors +pin-diodesPreamps Total cost of upgrading: ~40 k€ The DIAMANT R&D collaboration Prague 2007

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

  14. EXOGAM experiments using DIAMANT @ GANIL Exp-# Physics Motivation; Stable-RadioactiveBeam/TargetDetectors (Spokesperson) EXOGAM + -------------------------------------------------------------------------------------------------------------------------------- E404S/E404aS Identification of γ-rays in nuclei around the drip-line nucleus 130Sm : DIAMAMT & (P.Nolan) probing the maximally deformed light rare-earth region DIAMANT 76Kr(60MeV)/1.1mg/cm2 58Ni; +VAMOS -------------------------------------------------------------------------------------------------------------------------------- E498S High Spin States in the Tz=-3/2 Nucleus 37Ca – Mirror Symmetry DIAMANT(S.Williams) at the Largest Values of Isospin; 18Ne(60MeV)/1mg/cm2 24Mg; +N-Wall E482 Mirror 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-Wall56Ni; 36Ar(85MeV)/0.5 mg/cm2 24Mg target on 90Zr backing, 4pnA E505 Electromagnetic 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 E514 Single-particle energies and proton-shell gap in 100Sn DIAMANT(M.Palacz) extracted from high-spin states in 103Sn; +N-Wall58Ni(240 MeV) 8 mg/cm2 54Fe target, 1.7 pnA E451 Search for T=0 pairing and a new coupling scheme in 92Pd and 88Ru DIAMANT(B.Cederwall) 36Ar(111 MeV) 6 mg/cm2 58Ni target, 5 pnA(Submitted to PRC)+N-Wall Prague 2007

  15. 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

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