Application of heavy charged particle spectrometry

1. Application of heavy charged particle spectrometry 1) Identification of superheavy elements by means of alpha decay sequence 2) Study of hot and dense nuclear matter by means of charged particle spectrometry Heavy ion collision with ultrarelativistic energy Table of isotopes in the range of superheavy elements

2. Production of superheavy elements Drop model: 1) stability decreases with increasing proton number 2) excess of neutrons increases with increasing proton number Competition of volume energy (strong nuclear interaction) and coulomb energy Existence of „more stable“ superheavy elements made possible by existence of magic numbers - shell structure ↔ shell model Stability island – Z = 114 and N = 184 – depends on potential form, significant uncertainty Problem: very small cross-sections production only single nuclei – necessary unambiguous identification Energy : 1) sufficient for overcoming of Coulomb barrier 2) as small as possible, to obtain “relatively stable“ compound nucleus Production possibilities: 1) Neutron capture – up to Z = 100 (earlier decay then neutron capture) 2) Reaction of light nucleus on heavy target 3) „Cold“ fusion of heavy nucleus – projectile A ~ 40, EEX ~ 10 MeV 4) „Hot“ fusion of heavy nucleus – usage of 48Ca (Z = 20) EEX ~ 40 MeV Decay of alpha decay sequence → alpha particles contain information about energy differences between following nuclei

3. TOF Stopping of beam dipole magnets rotatedtarget electric deflectors quadrupole magnets svazek Detection of superheavy elements at GSI Darmstadt Elements 107 – 112 device SHIP at GSI Darmstadt: fusion reaction on Pb, Bi nuclei: usage of separation, separation of compound nucleus, implantation to active volume of detector and identification by means of alpha decay sequences Identification of single cases of superheavy element production and decay: • Capture of all alpha from decay sequence and determination of their energy • Identification of fission Rotated target (Pb, Bi) low thaw point intensive beam – 1012 nuclei/s Choice of incurred compound nucleus: Velocity filter: Electric deflectors and dipole magnets: Fel = q·E Fmag = q·v·B SHIP device Right choice E a B  for vCMis FTOT = Fel – Fmag = 0

4. Suppression of residual background: TOF spectrometer: Start – transition detectors, thin carbon foils (electron production) and mikrochannel plates Efficiency 99,8%, resolution 700 ps Stop – 16 silicon strip detectors ΔE = 14 keV for alpha from 241Am transition detectory Coverage: 80% of 2π HPGe detectors – photons from deexcitation of excited nuclei Cross sections až ~ pb, single nucleus per tens days Very intensive beams during many months stop detector (silicon)

5. Fusion per low energies: • 107 Bh Bohrium • Hs Hassium • 109 Mt Meitnerium • Dm Darmstadtiumu • Rg Roentgenium • 112 Cp Copernicium First identified decays of named element with present second highest Z Further – fusion by means of higher energies: (112, 113, 114, 115, 116, 117, 118) Problem – sequence ends by unknown isotopes, rather long decay time (problem with identification by means of coincidences) Year 2006 – join – looks OK Results from GSI confirmed also by Japanese laboratory RIKEN Reaction:48Ca + 244Pu → Z = 114, A = 292 Excitation function for C+Pu reaction

6. Cold fusion Proton number Stability island Hot fusion Neutron number Map of superheavy elements

7. Nucleon Decay number halftime only elements in this column can be octavalent Element density [g/cm3] melting point [oC] boiling point [oC] stiffness [Mohs] Chemical analysis of single atoms Nucleus decays early than new is produced 108 Hassium – one from last element chemically studied Known isotopes of hassium First produced hassium nucleus Oxid of ruthenium RuO4 Oxid of osmium OsO4 Oxid of hassium HsO4 Study of volatility → oxides of VIII group are very volatile Production of more stable Hs isotopes Narrow channel with decreasing temperature from -20oC up to -170oC → the more volatile the further molecules will flight before adsorption Hs with A ~ 288 will be maybe very stable

8. Study of hot and dense nuclear matter by means of charged particles production Relativistic heavy ion collisions→ Big number of produced charged particles Effort to build 4π detectors of charged particles Example of FOPI spectrometer at GSI Darmstadt Determination of nuclear matter temperature – spectrum Determination of pressure – particle collective flow Scheme of FOPI spectrometer Determination of nuclear matter equation of state Display of event detected by FOPI spectrometer Spectrometer of charged particles FOPI

9. Introduction of transfer mass mT: and rapidity y: and then: Relative rapidity:YREL = (Y - YPRO/2)/(YPRO/2) YPROJ – projectile rapidity Projectile region YREL +1 Target region YREL -1 Collision region YREL 0 Spectra of charged particles (Ni+Ni a Au+Au experiments with beam energy 1 GeV/A) Identificationof charged particles

10. Two Arm Photon Spectrometer Detection of gamma, neutrons and charged particles 384 BaF2 detectors with plastic veto – distinguishing of neutral and charged particles cooperation with TOF plastic wall - collisioncharacteristic: Beam energy: 10 MeV - 200 GeV (GSI Darmstadt, KVI Groningen GANIL Caen, CERN)

11. Collective flow of nucleons N = N0( 1 + A·cosφ + B·cos(2·φ)) A – magnitude of asymmetry in the collision plane B – magnitude of asymmetry perpendicular to it (eliptical flow) Relative rapidity:YREL = (Y - YPRO/2)/(YPRO/2) YPROJ – projectile rapidity A < 0, B = 0 A = 0, B < 0 A > 0, B = 0 Target region YREL -1 Collision region YREL 0 Projectile region YREL +1

12. Dependence of collective flows on rapidity (origin of nukleons) Experimental data – dependency of collective flow on nucleons number – agreement of hydrodynamical models Squeeze out of particles perpendicular to reaction plane Bounce off particles to the Reaction plane: Target region Collision region Target region Projectile region

13. Application at material research - scattering, channeling, ion reaction ... Usage ions for modification and studies of structure of surface layers of solid materials Usage of ion accelerators for relatively low energies in the range from keV up to MeV Spectrometers of charged nuclei – often semiconductor silicon detectors Different types of silicon semiconductor detectors of charged particles Tandetrom 4130 MC at NPI ASCR is used for material research – from H up to Au, energies from hundreds keV up to tens MeV

14. detector reflected ion incident ion scattered ion incident ion detector Elastic scattering ions: RBS (Rutheford Backscattering Spectroscopy) - spectrometry of charged pasrticles back scattered by Rutheford scattering – layers from nm up to μm – spectrometry of scattered ions by semiconductor detectors. Change of energy given by momentum change and ionisation losses – profiles of impurities distribution materials are determined – mainly heavy nuclei RBS channeling– channeling of charged particles – crystal structures – determination of distinctive directions of crystal axes and impurities – slight turning of crystal sample ERDA (Elastic Recoil Detection Analysis) – detection of atoms knocked on by ions – mostly lighter nuclei, from hydrogen up to nitrogen – possibility of control changes of surface properties – study of hydrogen amount at polymers – connection with measurement of ion time of flight ERDA RBS

15. Ion reaction with nuclei PIGE (Particle Induced Gamma ray Emission) PIXE – (Particle Induced Gamma ray Emission) see gamma spectroscopy Material modification and working Ion microprobe – very narrow and intensive ion beam – usage – scanning of object surface with micrometer accuracy Ion implantation – modification of surface material layers Ion litography and ion beam machining – preparing of microelectronical a optoelectronical components and microscopic mechanical devices. AMS – accelerator mass spectroscopy – impurity of elements with concentration 10-15 – often for carbon dating Sprockets produced by ion litography method at photoresistive material