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Nuclear Experiment

Nuclear Experiment. 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.

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Nuclear Experiment

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  1. Nuclear Experiment Nuclear Experiment

  2. 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

  3. 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

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

  5. Electrostatic Accelerators Cascade Van de GraaffV.d.G. Single &Tandem generator Accelerator 2-3 stages steady (DC) beam, high quality focusing, energy, currents; but low energies Electrodynamic Accelerators Cyclotrons SynchrotonsLinacs conventional, Wideröe, Alvarez sector-focusing pulsed (AC) beam, high energies but lower quality focusing, energy definition, lower currents Advanced Technology Accelerators New principles: Collective acceleration, wake-field acceleration conceptual stage Overview Accelerator Types 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. + - E Electrodynamic Accelerators: Cyclotron Principle of operation of electrodynamic (cyclic) accelerators:Short pulses of low accelerating voltage, apply many times. Cyclotrons at MIT, Berkeley, MSU, Texas A&M, …., many around the world (Catania, GANIL). Linacs mostly for electrons or protons. Synchrotons and variations for high energy particle physics. Cyclotron technique: Magnetic holding field, contain particles on circular orbits, apply RF voltage across gaps of 2 half Faraday cages (“D”) shielding most of the orbits. Radio Frequencywfield Nuclear Experiment

  9. 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

  10. 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) R Radio Frequencywfield Nuclear Experiment Relativistic effects: m  W = e + moc2Q: Is there technical compensation ?

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

  12. + + - q+ RF Power Supply Linear Accelerators Wideröe 1928, Alvarez 1946 Linear trajectory, no deflection magnet, no radiative losses Ln-1 Ln Ln+1 Hollow drift tubes, E-field-free interior, contain magn. focusing elements. Accelerating gap between 2 drift tubes on different el. potential U(t) = U0.sin (wt) 10MHz-3GHz on all gaps  alternating E field switch polarity while particle is hidden. Nuclear Experiment Phase conditions may change during acceleration, particle speed.Q: Is continuous operation possible without loss of particles?

  13. Phase Stability Passage time (at gaps): t=f/w,encountering U(t) ~ U0sin(wt) U(t) DE ideally synchronous particle passes gaps at tn=ts+nT t Nominalts=fs/w Phase angle of particle: f = fs+ w·(t-ts), force F=qU0/(gap length L) Stability analysis: Stable oscillations about synchronous phase occur for cosfs> 0,  fs< 900 inject during first quarter cycle! Nuclear Experiment

  14. CERN PS Proton Linac Nuclear Experiment

  15. 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

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

  17. 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

  18. RIA: A New Secondary-Beam Facility One of 2 draft designs : MSU/NSCL proposal Superconducting-RF driver linear accelerator ( 400 kW) All beams up to uranium 200 MeV/nucleon, lighter ions with increasing energy (protons at 600 MeV/nucleon) Nuclear Experiment

  19. 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

  20. ISOLDE Mass Separators General Purpose Separator calculated Nuclear Experiment

  21. 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

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