UNIVERSITÄT DES SAARLANDES 1 Introduction to solid state physics at ISOLDE Th. Wichert (Universität des Saarlandes) Nuclear Physics & Astrophysics at CERN - NuPAC Applications: material science, life sciences and nuclear technologies

UNIVERSITÄT DES SAARLANDES 2 Radioactive ion beams for getting information on  the chemical identity of a specific defect or impurity atom in a solid  the lattice site of an impurity atom  the interaction between impurity atoms and other defects  thermal properties of defects (diffusion, binding between defects)  optical and electrical properties  magnetic properties

UNIVERSITÄT DES SAARLANDES 3 1. Advantage of radioactive isotopes  Background free (10 23 atoms) detection due to nuclear radiation.  Very high sensitivity to very low concentrations of impurity atoms in materials, on surfaces, at interfaces.  Several problems can only be solved by the use of radioactive isotopes. 2. Required are Facilities like ISOLDE providing a large variety of isotopically cleanradioactive ion beams. Facilities like ISOLDE providing a large variety of isotopically clean radioactive ion beams.

UNIVERSITÄT DES SAARLANDES 4 ANL -- ATLAS Exotic Beam FacilityANL -- ATLAS Exotic Beam Facility (Argonne, IL, USA) ANL -- ATLAS Exotic Beam Facility CERN -- ISOLDECERN -- ISOLDE (Genéve, Switzerland) CERN -- ISOLDE Flerov Lab, JINR U400/U200 + In-Flight Separators (Dubna, Russia) U400/U200 + In-Flight SeparatorsU400/U200 + In-Flight Separators GANIL -- SPIRAL (ISOL) and SISSI/LISE (In-flight) (Caen, France) SPIRALSISSI/LISESPIRALSISSI/LISE GSI -- FRS Fragment SeparatorGSI -- FRS Fragment Separator -- ISOL (Darmstadt, Germany) ISOL GSI -- FRS Fragment SeparatorISOL IMP LanzhouIMP Lanzhou -- RIBLL fragment Separator (Lanzhou, China) IMP Lanzhou INFN/LNS -- EXCYTINFN/LNS -- EXCYT (Catania, Italy) INFN/LNS -- EXCYT IRISIRIS (Gatchina, Russia) IRIS JYFL -- IGISOLJYFL -- IGISOL (Jyväskylä, Finland) JYFL -- IGISOL Radioactive Ion Beams in CYCLONERadioactive Ion Beams in CYCLONE (Louvain-la-Neuve, Belgium) Radioactive Ion Beams in CYCLONE LBL Berkeley BEARS ISOL facility (Berkeley, CA, USA) BEARS LBL Berkeley IRIS facility (Berkeley, CA, USA) IRIS Nuclear Science CentreNuclear Science Centre, (New Delhi, India) Nuclear Science Centre NSCL - K1200 Cyclotron/A1900 Fragment SeparatorNSCL - K1200 Cyclotron/A1900 Fragment Separator (East Lansing, MI, USA) NSCL - K1200 Cyclotron/A1900 Fragment Separator ORNL -- Holifield Radioactive Ion Beam FacilityORNL -- Holifield Radioactive Ion Beam Facility (Oak Ridge, TN, USA) ORNL -- Holifield Radioactive Ion Beam Facility OSIRISOSIRIS (Studsvik, Sweden) OSIRIS RIKEN RI Beam Factory - RRC and RIPSRIKEN RI Beam Factory - RRC and RIPS (Saitama, Japan) RIKEN RI Beam Factory - RRC and RIPS TRIUMFTRIUMF - ISAC (Vancouver, Canada) ISAC TRIUMFISAC TWINSOLTWINSOL at the University of Notre Dame (Notre Dame, IN, USA) TWINSOL Existing Radioactive Nuclear Beam Facilities: CERN – ISOLDE (Géneve, Switzerland) unique facility for the next 5 – 7 years

UNIVERSITÄT DES SAARLANDES 5 3. Introduction of these isotopes into solids  by ion implantation  by diffusion  during crystal growth  soft landing on surfaces 2. Required are Facilities like ISOLDE providing a large variety of isotopically cleanradioactive ion beams. Facilities like ISOLDE providing a large variety of isotopically clean radioactive ion beams.  well defined, clean conditions  Background free (10 23 atoms) detection due to nuclear radiation.  Very high sensitivity to very low concentrations of impurity atoms in materials, on surfaces, at interfaces.  Several problems can only be solved by the use of radioactive isotopes. 1. Advantage of radioactive isotopes

UNIVERSITÄT DES SAARLANDES 6 SSP topics at ISOLDE  Semiconductors  Magnetic semiconductors  High-T C superconductors  Oxides  Ceramics  Metals  Surfaces and interfaces

UNIVERSITÄT DES SAARLANDES 7 Experimental methods used Take advantage of the emitted radiation:  Radiotracer diffusion  Emission channeling (EC) some decay radiation charged particles REQUIREMENTS

UNIVERSITÄT DES SAARLANDES 8 History (1920): Tracer diffusion Using “natural” radioactive isotopes from U or Th decay series to study diffusion in solids (v. Hevesy, 1920): x 2 = D(T) · t x T, t

UNIVERSITÄT DES SAARLANDES 9 Today (2005): Tracer diffusion of 111 Ag in CdTe “Normal” diffusion profile (i.e. monotonous decrease of concentration)

UNIVERSITÄT DES SAARLANDES 10 Today (2005): Tracer diffusion of 111 Ag in CdTe “Normal” diffusion profile (i.e. monotonous decrease of concentration) Symmetrical diffusion profile (here: depletion of surface regions)

UNIVERSITÄT DES SAARLANDES 11 Emission channeling (EC) (charged particles)

UNIVERSITÄT DES SAARLANDES 12 Experimental methods used Take advantage of the emitted radiation:  Radiotracer diffusion  Emission channeling (EC) Interaction of nuclear moments with fields in solids:  Perturbed  -  (e-  ) angular correlation (PAC)  Mössbauer effect (ME)   -NMR  NMR on oriented nuclei (NMR-ON) particular nuclear properties } REQUIREMENTS

UNIVERSITÄT DES SAARLANDES 13 local electric and magnetic hyperfine fields

UNIVERSITÄT DES SAARLANDES 14 Surfaces, interfaces, ultra-thin layers ASPIC (Apparatus for Surface Physics and Interfaces at CERN) Observes local hyperfine fields via PAC

UNIVERSITÄT DES SAARLANDES 15 Mössbauer effect

UNIVERSITÄT DES SAARLANDES 16 Implantation of 57 Mn  57 Fe into Si Implantation of 57 Mn into Si

UNIVERSITÄT DES SAARLANDES Fe atoms in different local environments Implantation of 57 Mn  57 Fe into Si

UNIVERSITÄT DES SAARLANDES 18 Experimental methods used Take advantage of the emitted radiation:  Radiotracer diffusion  Emission channeling (EC) Interaction of nuclear moments with fields in solids:  Perturbed  -  (e-  ) angular correlation (PAC)  Mössbauer effect (ME)   -NMR  NMR on oriented nuclei (NMR-ON) Label chemically blind techniques with radioactive isotopes:  Photoluminescence spectroscopy (PL)  Deep level transient spectroscopy (DLTS)  Hall effect measurements nuclear lifetime } REQUIREMENTS

UNIVERSITÄT DES SAARLANDES 19 ISOLDE isotopes as analytical tool e / cm 3 1 ohm ∙ cm

UNIVERSITÄT DES SAARLANDES 20 Optical properties of impurity atoms ‘Classical’ spectroscopical techniques used in semiconductor physics are very sensitive to optical/electrical properties of dopants (i.e. their band gap states), but: they do not directly reveal information about their microscopic origin. (1) (2) (3)(4)

UNIVERSITÄT DES SAARLANDES 21 PL spectrum of GaN after 71 As implantation Related to 71 Ge creation and decay Related to 71 As decay

UNIVERSITÄT DES SAARLANDES 22 Publications181 PhD thesis27 Invited talks and schools94 Conference contributions113 Investments at CERN1900 k€ at home institutes2700 k€ Maintenance and Operation at CERN150 k€/year at home institutes650 k€/year Positions (100%) at CERN1 at home institutes53 21 acccepted experiments 4 accepted proposals 2 letters of intent Participating institutes63 Participating countries16 AUDIT of ‘Solid State Physics at ISOLDE’ CERN, February 27, 2002 Conclusion of AUDIT REPORT (2002) “It is the general opinion of the Audit Commission that the ISOLDE-SSP community is reaching a scientific level and scientific output that is far above average.”

UNIVERSITÄT DES SAARLANDES 23 Running SSP experiments at ISOLDE

UNIVERSITÄT DES SAARLANDES 24 Introduction to solid state physics at ISOLDE Th. Wichert (Universität des Saarlandes) Nuclear Physics & Astrophysics at CERN - NuPAC Applications: material science, life sciences and nuclear technologies