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Portuguese groups at ISOLDE - CERN

Portuguese groups at ISOLDE - CERN. Ulrich Wahl Instituto Tecnológico e Nuclear (ITN) Sacavém Centro de Física Nuclear da Universidade de Lisboa (CFNUL). ISOLDE and Nuclear Solid State Physics Portuguese experiments at ISOLDE: history, people, collaborations

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Portuguese groups at ISOLDE - CERN

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  1. Portuguese groups at ISOLDE - CERN Ulrich Wahl Instituto Tecnológico e Nuclear (ITN) Sacavém Centro de Física Nuclear da Universidade de Lisboa (CFNUL) • ISOLDE and Nuclear Solid State Physics • Portuguese experiments at ISOLDE: history, people, collaborations • Examples:- position-sensitive electron detector development - emission channeling lattice location of Fe in Si- PAC investigation of O and F in High-Tc Hg-1201 • Conclusions amd outlook

  2. The ISOLDE on-line isotope separator Available beams:~ 600 isotopes of~ 70 elements target andion source massseparation 60 keVacceleration 1 GeVprotons radioactive ion beams

  3. Experiments involving Portuguese groups:typically around 10-12 shifts per year i.e. ~3% of ISOLDE availability ISOLDE Experiments2003 Particle and Astro-Physics13% Solid State Physics22% Biology/Medicine5% Atomic Physics15% Weak Interaction andNuclear Physics46% 37 Experiments 300 Users 96 Institutes 22 Countries 375 8h-shifts of radioactive beams

  4. Experimental techniques used with radioactive isotopes at ISOLDE Portuguese groups:emission channeling (EC)perturbed angular correlation (PAC)

  5. History of e--g PAC and EC at ISOLDE-CERN e--g PAC 197mHg, 73Ge, 127Cs, 80Br 1986e-g PAC at ISOLDE IS01/13 spokesperson J.C.Soares 1994Test of new PAC probes IS-P66 spokesperson J.G. Correia 1997IS360 Studies of high-Tc superconductors with radioactive isotopes ~2006 spokesperson J.G. Correia (ITN & CFNUL) 1998IS368 Lattice location of transition metals and rare earths in semiconductors ~2006 spokesperson U. Wahl (ITN & CFNUL, then IKS Leuven) 2000IS390 Studies of colossal magnetoresistive oxides with radioactive isotopes ~2005spokesperson V. Amaral (U Aveiro) 2001New improved electron emission channeling paddetectors and development of self-triggering front-end electronics Cooperation agreement betweenITN, CFNUL and CERN EP-ATT Group (now: PH-TA1)

  6. KU Leuven(Belgium) ITN Sacavém CFNUL Lisbon Prof. José C. SoaresProf. Manuel. R. Silva2 PhD students:Elisabete RitaAna C. Marques1 Diploma student:Sonia Dias Dr. J. Guilherme CorreiaDr. Ulrich WahlDr. Heinz Haas (retired) Prof. André Vantomme2 PhD students:Bart De VriesStefan Decoster University of Porto Univ. of Kwazulu Natal(South Africa) University of Aveiro Prof. J. Pedro Araújo1 Masters student:Tania Mendonça Prof. Krish Bharuth-Ram Prof. Vitor AmaralDr. Mario S. Reis1 PhD student:Armandina Lopes1 Diploma student:João C. Amaral University of Göttingen(Germany) CERN Prof. Hans Hofsäss(future collaboration) Dr. Peter Weilhammer(detector development) LEUVEN Network of groups involved

  7. Funding: mainly from national sources KU Leuven(Belgium) ITN Sacavém CFNUL Lisbon Fund for Scientific Research - Flanders(dedicated project on emission channeling) Portuguese Foundation for Science & Technology(dedicated CERN project on PAC & emission channeling) University of Porto Univ. of Kwazulu Natal(South Africa) University of Aveiro University of Göttingen(Germany) CERN Portuguese Foundation for Science & Technology(dedicated CERN project on magnetic oxides) Federal Ministry of Education and Research (dedicated project on emission channeling)

  8. Position-sensitive Si pad detectors for Emission Channeling Collaboration: ITN, CFNUL & CERN PH-TA1 group Future detectors: pads self-triggering Þ 5 keV trigger Þ 10 kHz readout ¬ 73As in ZnO low electron energy [0001] [-1102] Cooled 2oC Arsenic occupies multiple sites in ZnO

  9. as-implanted: mainly displaced substitutional Fe annealedat T=300°C: mainly tetrahedral interstitial Fe annealed at T=800°C: mainly ideal substitutional Fe Lattice site changes of implanted 59Fe in Si Fe is gettered by at least two types of vacancy-like defects Following release to interstitial state re-gettering occurs at a different gettering center on ideal substitutional sites U. Wahl et al., accepted by Phys. Rev. B

  10. h ~ 0.20 EFG Simulations 100 50 Radioactive ions 0 0 2500 5000 100 w(Mrad/s) h ~ 0.0 50 0 0 0 0 2500 5000 w(Mrad/s) Oxygen & Fluorine Configurations in Hg1201 (High-Tc) Experiment O PAC PAC PAC F Electric Field Gradient  dopant configuration fingerprint HgBa2CuO4+d Tc > 92K J.G. Correia et al., submited to Phys. Rev. B

  11. Conclusions and outlook: Currently and near future (till ~2006): • IS368: Lattice location in semiconductors, e.g. Si, Ge, SiGe, diamond, III-V, nitrides, II-VI, ZnO… electrical doping, transition metals, rare earths, diluted magnetic semiconductors • IS360: PAC in High-Tc superconductors • IS390: Magnetism in manganites (CMR) After 2006: New emission channeling proposal(s) applying… • new position-sensitive detectors (self-triggering pad, CCD) - on-line experiments with short-lived isotopes - low energy electron emitters (Auger electrons?)Þ a new variety of elements (e.g. Mg, Co, Ni, Zn, Ge) will be available for emission channeling

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