W. Udo Schröder, 2007 Nuclear Experiment 1

W. Udo Schröder, 2007 Nuclear Experiment 2 Probes for Nuclei and Nuclear Processes To “see” an object, the wavelength of the light used must be shorter than the dimensions d of the object. (DeBroglie: p=ħk=ħ2  /  Rutherford’s scattering experiments d Nucleus ~ few m ~ fm Need light of wave length  1 fm, or photon energy Photons not easily available in nature Can be made with charged particle accelerators

W. Udo Schröder, 2007 Nuclear Experiment 3 Elements of a Generic Nuclear Experiment A: Studying natural radioactivity (cosmic rays, terrestrial active samples) B: Inducing nuclear reactions in accelerator experiments 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 Ion Source Accelerator Target Detectors Vacuum Chamber Vacuum Beam Transport

W. Udo Schröder, 2007 Nuclear Experiment 4 Ionization Process 1. e - impact (gaseous ionization) hot cathode arc discharge in axial magnetic field (duo- plasmatron) electron oscillation discharge (Penning ion source) (PIG) radio-frequency electrode-less discharge (ECR) electron beam induced discharge (EBIS) 2. ion impact charge exchange sputtering e - /ion beam - + q-q- discharge - + q+q+ Acceleration possible for charged particles  ionize neutral atoms

W. Udo Schröder, 2007 Nuclear Experiment 5 Electron Cyclotron Resonance (ECR) Source “Venus” Making an e - /ion plasma

W. Udo Schröder, 2007 Nuclear Experiment 6 Principle of Electrostatic Accelerators Van de Graaff, 1929 Operating limitations: 2 MV terminal voltage in air, MV in pressure tank with insulating gas (SF 6 or gas mixture N 2, CO 2 ) Acceleration tube has equipotential plates connected by resistor chain (R), ramping field down. Typical for a CN: 7-8 MV terminal voltage + - R R R R R R R q+q+ Charger C/m 2 Corona Points 20kV + HV Terminal Ion Source Acceler- ation Tube insulating Charging Belt/ Pelletron - Ground Plate Conducting Sphere +

W. Udo Schröder, 2007 Nuclear Experiment 7 “Emperor” (MP) Tandem MP Tandem 15 MV 90 o Deflection/ Analyzing Magnet Vacuum Beam Line Ion BNL, TUNL, FSU, Seattle,…, SUNY Geneseo,… many around the world. Munich University Tandem Quadrupole Magnet Pumping Station

W. Udo Schröder, 2007 Nuclear Experiment 8 Charged Particles in Electromagnetic Fields B: Magnetic guiding field v r Charged particles in electromagnetic fields follow curvilinear trajectories  used to guide particles “optically” with magnetic beam transport system q B

W. Udo Schröder, 2007 Nuclear Experiment 9 Electrodynamic Accelerators: Cyclotron  field Relativistic effects: m  W =  + m o c 2 shape B field to compensate. Defocusing corrected with sectors and fringe field. +- E Electrodynamic linear (LINAC) or cyclic accelerators (cyclotrons, synchrotons) Cyclotrons at BNL, LBL Berkeley, MSU, Texas A&M, …., many around the world (Catania, GANIL) Acceleration, if  field  =  0 Equilibrium orbit r: p = qBr  maximum p max = qBR

W. Udo Schröder, 2007 Nuclear Experiment 10 CERN Proton Linac

W. Udo Schröder, 2007 Nuclear Experiment 11 Experimental Setup: Neutron Time-of-Flight Measurement Experiment at GANIL 29 A MeV 208 Pb  197 Au Scatter Chamber Beam Line    Electronics Rack Neutron Detector

W. Udo Schröder, 2007 Nuclear Experiment 12 Particle ID: Resolution in Z, A, E Nuclear Radiation Detectors Si Telescope Massive Reaction Products SiSiCsI Telescope (Light Particles) He Li Be Na Ne F O N C B 20 Ne MeV/u -  lab = 12°

W. Udo Schröder, 2007 Nuclear Experiment 13 THE CHIMERA DETECTOR Chimera mechanical structure 1m 1° 30° REVERSE EXPERIMENTAL APPARATUS TARGET BEAM Experimental Method  E-E  Charge  E-E E-TOF  Velocity, Mass Pulse shape Method  LCP Basic elementSi (300  m) + CsI(Tl) telescope Primary experimental observables TOF  t  1 ns Kinetic energy, velocity  E/E Light charged particles  2% Heavy ions  1% Total solid angle  /4  94% Granularity1192 modules Angular range1°<  < 176° Detection threshold <0.5 MeV/A for H.I.  1 MeV/A for LCP CHIMERA characteristic features 688 telescopes Laboratori del Sud, Catania/Italy

W. Udo Schröder, 2007 Nuclear Experiment 14 Secondary-Beam Facilities 2 principles: A) Isotope Separator On Line Dump intense beam into very thick production target, extract volatile reaction products, study radiochemistry or reaccelerate to induce reactions in 2 nd target (requires long life times: ms) GANIL-SPIRAL, EURISOL, RIA, TAMU,…. B) Fragmentation in Flight Induce fragmentation/spallation reactions in thick production target, select reaction products for experimentation: reactions in 2 nd target GSI, RIKEN, MSU, Catania, (RIA) G. Raciti, 2005 Primary Accelerator

W. Udo Schröder, 2007 Nuclear Experiment 15 Secondary Beam Production Bombard a Be target with 1.6-GeV 58 Ni projectiles from SCC LNS Catania Particle Identification Matrix  E x E EE EE E Particle Target

W. Udo Schröder, 2007 Nuclear Experiment 16 RIA: A New Secondary-Beam Facility One of 2 draft designs : MSU/NSCL proposal

W. Udo Schröder, 2007 Nuclear Experiment 17 ISOLDE Facility at CERN Primary proton beam CERN-PS Project in the 1960s

W. Udo Schröder, 2007 Nuclear Experiment 18 Secondary-Beam Accelerator Radiochemical goal (high-T chemistry, surface physics, metallurgy): produce ion beam with isotopes of only one element Ion Source Low-energy LINAC Mass Separator X 1+ High Charge Primary target: oven at C – C, bombarded with beams from 2 CERN accelerators (SC, PS).

W. Udo Schröder, 2007 Nuclear Experiment 19 ISOLDE Mass Separators General Purpose Separator calculated

W. Udo Schröder, 2007 Nuclear Experiment 20 Secondary ISOLDE Beams Yellow: produced by ISOLDE n-rich, n-rich Sn: A = low energy O: A = low energy Source: CERN/ISOLDE ISOLDE accepts beams from several CERN accelerators (SC, PS)

W. Udo Schröder, 2007 Nuclear Experiment 21 Mass Measurement with Penning Trap ISOLTRAP Ion motion in superposition of B and E Q fields has 3 cyclic components with frequencies  C,  +,  - Electric quadrupole field Cyclotron frequency Oscillating quadrupole field E Q can excite at  =  0  determine m

W. Udo Schröder, 2007 Nuclear Experiment 22

W. Udo Schröder, 2007 Nuclear Experiment 23 Injection and Acceleration Transfer to accelerator Acceleration Injection (axial) Ion trajectory (cyclic)

W. Udo Schröder, 2007 Nuclear Experiment 24