1 Ultracolod Photoelectron Beams for ion storage rings CSR E-Cooler TSR (magnetic) e-target e-cooler CSR (electrostatic) E lab : eV Current - 2 mA Lifetime - 24 h kT < 1.0 meV kT || = 0.02 meV Electron-ion collision spectroscopy D. A. Orlov, C. Krantz, A. Shornikov, A. Wolf E lab : 10-1eV Low e-energies: => low current (100-1A) => higher kT || e-transport by B => slow ions distorted Cooling at eV-energies - it is a challenge! Electron cooling TSR E-target Extremely high resolution is demonstrated! DR of Sc v e = v i 2 v e v i 6 meV Max-Planck-Institut fr Kernphysik, 69117, Heidelberg, Germany Dmitry Orlov, MPI-K, PESP-08 2 cold electrons OUTLINE 1 HOW TO: cold e-beams 2 E-cooling Collision resolution 6 Cooling of CF+ ions at TSR by 53 eV photoelectrons 7 Manipulation with eV e-beams at TSR target 4 Why? Electrostatic Cryogenic Storage Ring 3 electron collision TSR ( keV) 5 e-beams of eV energies, CSR cooler Dmitry Orlov, MPI-K, PESP-08 3 EFEF E vac Thermocathode vacuum T= K kT= meV Cold electrons. How to (A): Photocathode kT C = 10 meV Fully activated cathode: QY= 15-35% QY eff =1 % Laser: 800 nm9 (transmission) 532 nm (reflection) E-current: mA Lifetime : >24 h D.A. Orlov et al., APL, 78 (2001) 2721; Suppression Strong energy and impulse relaxations Energy spreads of about kT E vac E FE F E cE c (CsO) E vE v GaAs vacuum T= 80 K Suppression kT=10 meV Thermocathode kT C > 100 meV 4 Cold electrons. How to make them colder (B): 1. Magnetic expansion B 0 (high field) B guide (low field) 2. Acceleration Reduction of kT Reduction of kT || = 20 Thermocathode kT = 5-6 meV Photocathode kT = 0.5 meV kT || = meV Phase-space conservation vv E E v v' U0U0 5 Cold electrons. How o keep them cold (C): High magnetic field is required 1. To avoid beam divergence 2. To suppress TLR 3. To provide adiabatic transport e e e low current high current high current + magnetic field keeping dT || / dZ < 5 eV/m : e e B rcrc n e -1/3 r c meV Dmitry Orlov, MPI-K, PESP Dissociative recombination of HF + : 2D imaging Electron - Target ~ 12 m v beam (~MeV) ~cm detector surface Probability (normalized) d 2D [mm] Rotational resolution Particle distance, mm E KER E CM -kT, milli-eV PRELIMINARY HF + (X 2 , v=0,J ) + e - HF ** (V 1 + ) H(n=2) + F( 2 P 3/2,1/2 ) HF ** (V 1 + ) v=0 J=0,1,2,. H(n=2) + F( 2 P 3/2 ) Dmitry Orlov, MPI-K, PESP cold electrons 1 HOW TO: cold e-beams 6 Cooling of CF+ ions at TSR by 53 eV photoelectrons 7 Manipulation with eV e-beams at TSR target 5 e-beams of eV energies, CSR cooler 2 E-cooling Collision resolution 3 electron collision TSR ( keV) 4 Why? Electrostatic Cryogenic Storage Ring Dmitry Orlov, MPI-K, PESP Electrostatic Cryogenic Storage Ring at 2 K Reaction microscope Ion injection E-target Diagnostic section neutrals CSR Clusters, biomolecules (M up to few 1000 amu) ELECTROSTATIC Storage Rings (no mass limitation) Ring Circumference34m Straight Section Length2.5m Energy Range keV Maximum Beta h / v 12/6m Maximum Dispersion2.1m Tunes Q h /Q v 2.59/2.65 XHV (n