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Nuclear Experiment

Nuclear Experiment. Probes for Nuclear Processes. To “see” an object, the wavelength l of the light used must be shorter than the dimensions d of the object. ( DeBroglie : p= ħk =ħ2 p / l) Rutherford’s scattering experiments d Nucleus ~ few 10 -15 m

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Nuclear Experiment

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  1. Nuclear Experiment Nuclear Experiment

  2. Probes for Nuclear Processes To “see” an object, the wavelength l of the light used must be shorter than the dimensions d of the object. (DeBroglie: p=ħk=ħ2p/l) Rutherford’s scattering experiments dNucleus~ few 10-15 m Need light of wave length l 1 fm, or an energy E Not easily available as light Nuclear Experiment Can be made with charged particle accelerators

  3. A: Study natural radioactivity (cosmic rays, terrestrial active samples) B: Induce nuclear reactions in accelerator experiments Vacuum Chamber Vacuum Beam Transport Ion Source Target Accelerator Detectors Elements of a Generic Nuclear Experiment Particle Accelerator  produces fast projectile nuclei Projectile nuclei interact with target nuclei Reaction products are a) collected and measured off line, b) measured on line with radiation detectors Detector signals are electronically processed Nuclear Experiment

  4. 1.e-impact (gaseous ionization) hot cathode arc discharge in axial magnetic field (duo-plasmatron) electron oscillation discharge (PIG) radio-frequency electrode-less discharge (ECR) electron beam induced discharge (EBIS) 2. ion impact charge exchange sputtering + - q+ discharge - + q- Ionization Process Acceleration possible for charged particles  ionize neutral atoms Nuclear Experiment e-/ion beam

  5. Electron Cyclotron Resonance (ECR) Source Making an e-/ion plasma “Venus” Nuclear Experiment

  6. Conducting Sphere + + + + Ion Source +HV Terminal + + + + + + + R Charging Belt/ Pelletron + R + InsulatingAcceleration Tube/wEP plates R + Corona Points 20kV R + R Ground Plate - R Charger 10-4C/m2 R - q+ Principle of Electrostatic Accelerators Van de Graaff, 1929 Operating limitations: 2 MV terminal voltage in air, 18-20 MV in pressure tank with insulating gas (SF6 or gas mixture N2, CO2) q+ Acceleration tube has equipotential plates connected by resistor chain (R), ramping field down. Typical for a CN: 7-8 MV terminal voltage Nuclear Experiment

  7. “Emperor” (MP) Tandem Munich University Tandem @Yale, BNL, TUNL, Florida, Seattle,…, Geneseo (small),…many around the world. Ion Source MP Tandem15 MV Pumping Station Quadrupole Magnet Vacuum Beam Line 90o Deflection/Analyzing Magnet Nuclear Experiment

  8. B q Charged Particles in Electromagnetic Fields Charged particles in electromagnetic fields follow curvilinear trajectories  used to guide particles “optically” with magnetic beam transport system r v Nuclear Experiment B: Magnetic guiding field Independent of velocity or energy

  9. Acceleration, if wfield= w0 Equilibrium orbit r: p = qBr  maximum pmax = qBR - + E Electrodynamic Accelerators: Cyclotron Electrodynamic linear (LINAC) or cyclic accelerators(cyclotrons,synchrotons) Cyclotrons at MIT, Berkeley, MSU, Texas A&M, …., many around the world (Catania, GANIL) wfield Nuclear Experiment Relativistic effects: m  W = e + moc2 shape B field to compensate. Defocusing corrected with sectors and fringe field.

  10. CERN Proton Linac Nuclear Experiment

  11. Experimental Setup: Neutron Time-of-Flight Measurement Experiment at GANIL 29 A MeV 208Pb  197Au Scatter Chamber Beam Line   Electronics Rack NeutronDetector Nuclear Experiment

  12. Nuclear Radiation Detectors 20Ne + 12C @ 20.5 MeV/u - qlab = 12° Na Ne F O N C B Be Li He Particle ID (Z , A, E) Specific energy loss, spatial ionization density, TOF SiSiCsI Telescope (Light Particles) Si TelescopeMassive Reaction Products DE-E Telescope DE E-DE Nuclear Experiment

  13. THE CHIMERA DETECTOR Laboratori del Sud, Catania/Italy CHIMERA characteristic features REVERSE EXPERIMENTAL APPARATUS BEAM 688 telescopes TARGET 30° 1° Nuclear Experiment 1m Chimeramechanical structure

  14. Secondary-Beam Facilities • 2 principles: • Isotope Separator On Line Dump intense beam into very thick production target, extract volatile reaction products, study radiochemistry or reaccelerate to induce reactions in 2nd target (requires long life times: ms)GANIL-SPIRAL, EURISOL, RIA, TAMU,…. • Fragmentation in Flight Induce fragmentation/spallation reactions in thick production target, select reaction products for experimentation: reactions in 2nd target • GSI, RIKEN, MSU, Catania, (RIA) Nuclear Experiment G. Raciti, 2005

  15. Particle Target DE DE E Secondary Beam Production Particle Identification Matrix DE x E Bombard a Be target with 1.6-GeV 58Ni projectiles from SCC LNS Catania Nuclear Experiment

  16. RIA: A New Secondary-Beam Facility One of 2 draft designs : MSU/NSCL proposal Nuclear Experiment

  17. ISOLDE Facility at CERN Primary proton beam CERN-SPS Nuclear Experiment

  18. High Charge Ion Source X1+ Mass Separator Low-energy LINAC Secondary-Beam Accelerator Radiochemical goal (high-T chemistry, surface physics, metallurgy): produce ion beam with isotopes of only one element Primary target: oven at 7000C – 20000C, bombarded with beams from 2 CERN accelerators (SC, PS). Nuclear Experiment

  19. ISOLDE Mass Separators General Purpose Separator calculated Nuclear Experiment

  20. Secondary ISOLDE Beams Sn: A = 108 -142 low energy Yellow: produced by ISOLDEn-rich, n-rich O: A = 19 -22 low energy ISOLDE accepts beams from several CERN accelerators (SC, PS) Nuclear Experiment Source: CERN/ISOLDE

  21. Mass Measurement with Penning Trap ISOLTRAP Ion motion in superposition of B and EQ fields has 3 cyclic components with frequencies wC, w+, w- Electric quadrupole field Cyclotron frequency Nuclear Experiment Oscillating quadrupole field EQ can excite at w = w0 determine m

  22. Injection and Acceleration Ion trajectory (cyclic) Acceleration Injection (axial) Transfer to accelerator Nuclear Experiment

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