I M P A UNIVERSITT GIESSEN www.uni-giessen.de/cms/iamp Stefan - PowerPoint PPT Presentation

Electron-Ion Collisions in Heavy-Ion Storage-Rings Stefan Schippers Institut für Atom- und Molekülphysik JUSTUS-LIEBIG- I M P A UNIVERSITÄT GIESSEN www.uni-giessen.de/cms/iamp Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 1

Overview • Electron-ion collisions at storage rings • Atomic structure • Electron-ion collision spectroscopy • Nuclear and QED effects on atomic structure • Lifetimes of atomic levels (exotic decay modes) • Atomic collisions • Absolute cross sections (important for applications in astrophysics and plasma physics) • Electron-ion recombination • Electron-impact ionization of ions Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 2

Ion-Storage Rings from accelerator Schottky beam profile pick-up ion current monitor monitor (hor./vert.) collision product detectors TSR @ ISOLDE Electron target section injection CSR @ MPIK and extraction ion beam direction 5m collision product electron cooler detectors CRYRING ESR @ GSI/FAIR @ GSI/FAIR Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 3

Decay of Excited States Be-like 47 Ti 18+ 500 2s2p 3 P 0 HFI decay -1 ) 400 Count rate (s Simply wait until metastable ions 300 have relaxed to their ground state. S. Schippers et al. PRL 98 (2007) 033001 0 2 4 6 8 Storage time (s) Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 4

Reactions e - beam charge-changing collisions Reaction products • beams of high directionality • high particle energies in lab frame 100% detection efficiency collision experiments with dilute ensembles of particles tunable relative energy: sub meV to sub MeV cross sections on an absolute scale electron-ion recombination electron-impact ionization of ions Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 5

Recombination of Ions in the CSR electrostatic single-particle storage rings detector reaction provide access products to low-charged T =10 K heavy ions p = 10 -13 mbar electron cooler 1 m ion injection Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 6

Single-Particle Detector ~100% detection efficiency adapted to cryogenic environment secondary electrons incident particle converter plate Kaija Spruck, Claude Krantz et al. Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 7

Dielectronic Recombination (DR) recombination of a q-fold charged ion with a free electron (time-inverse of photoionization)  A** (q-1)+  A q+ + e - A (q-1)+ + photons  intermediate resonance state n=16 19 2p 3/2 25+ 150 Ni 8 2p 1/2 series series -1 ) 6 3 s -10 cm 2p 3/2 11l 4 n=30 100 2p 1/2 13l Rate coefficient (10 2 0 40 50 60 70 n=12 13 14 15 50 n=14 15 16 17 18 0 0 10 20 30 Electron-ion collision energy (eV) S. Schippers et al., PRA 62 (2000) 022708 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 8

Strong Astrophysical Relevance absolute rate coeffcients D.W. Savin, JPCS 88 (2007) 012071 S. Schippers, JPCS 388 (2012) 012010 A. Müller and S. Schippers, in Atomic Processes in Basic and Applied Physics , V. Shevelko and H. Tawara (eds.), Springer Series on Atomic, Optical, and Plasma Physics 68 (2012) Chapter 2 Also many papers from CRYRING, e.g. Ali et al., A&A 557 (2013) A2 Orban et al., ApJ 721 (2010) 1603 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 9

Electron-Ion Collision Spectroscopy DR of Li-like Sc 18+ TSR electron target with LN 2 -cooled photocathode hyperfine splitting M. Lestinsky et al., PRL 100 (2008) 033001 uncertainty of resonance energies: 0.1 meV Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 10

Sensitivity to Nuclear Size recombination of Li-like Nd 57+ - two different isotopes Rate coefficient ( arb. units ) A=142 <r> = 4.914 fm A=150 <r> = 5.047 fm 56+ (1 s 2 2 p 1/2 18 l j ) 4 Nd n =  3 n = 18 ... 2 p 1/2 2 s 1/2 2 1 j=3/2 j=5/2 j>5/2 j=1/2 1.0 1.5 2.0 2.5 C. Brandau, et al., Electron-ion collision energy ( eV ) PRL 100 (2008) 073201; see also R. Schuch et al. PRL 95 (2005) 183003 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 11

ESR – CRYRING Comparison higher resolving power  higher energy-precision courtesy of C. Brandau Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 12

Electron-Ion Recombination with In-Flight Produced Nuclei T 1/2 = 6.7 h C. Brandau, et al., HFI 196 (2010) 115 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 13

DR of Stochastically Cooled Ions @ ESR KLL-DR of H-like Xe 53+ ESR storage ring, GSI Darmstadt experiment theory 8 natural line width electron cooler Rate coefficient (arb. units) theory convoluted 6 long. kicker KL 1/2 L 3/2 transv. pick-up 4 combiner- station transv. kicker KL 1/2 L 1/2 2 long. pick-up KL 3/2 L 3/2 0 20.6 20.8 21.0 21.2 21.4 21.6 Electron-ion collision energy (keV) The ion beam is cooled stochastically, the electron cooler is exclusively C. Kozhuharov, C. Brandau et al., ICPEAC 2003 used as an electron target. Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 14

KLL-DR of Hydrogen-like U 91+ 4.0 KL 1 L 1 KL 1 L 2/3 KL 2/3 L 2/3 MCDF-calculations by Z. Harman, T. Steih, W. Scheid et al. 3.0 Recombination rate coefficient [10 -12 cm 3 s -1 ] Coulomb only Coulomb + Breit 2.0 1.0 up to 44% Breit 0.0 experiment and theory independently 8.0 on absolute scales 6.0 experimental resolution 4.0 close to natural linewidths 2.0 0.0 63.8 64.0 68.4 68.6 72.8 73.0 73.2 Electron-ion collision energy [keV] Electron-ion collision energy [keV] D. Bernhardt et al., PRA 83 (2011) 020701 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 15

Exotic Atomic Decay Modes hyperfine induced 2s2p 3 P 0  2s 2 1 S 0 transition in 47 Ti 18+ A=48 A=48 A=48 -1 ) 2 1000 Recombination count rate (Hz) 3 s -9 cm 800 1 Recomb. rate coeff. (10 600 0 A=47 A=47 A=47 2 400 1 0 0.70 0.75 0.80 0.85 0.90 200 Electron-ion collision energy (eV) 0 2 4 6 8 Storage time (s) 𝝊 𝐈𝐆𝐉 = 1.8(1) s S. Schippers et al., PRL 98 (2007) 033001 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 16

E1M1 Two-Photon 2s2p 3 P 0  2s 2 1 S 0 Decay theoretical predictions 11 10 E1M1 nonrelativistic theory millennium 10 10 century [Laughlin, PLA 75, 199 (1980)] 9 10 decade 8 10 year 7 10 relativistic theory month 6 Lifetime (s) 10 F. Fratini, A. Surzhykov, 5 10 S. Fritzsche (preliminary) day 4 10 hour 3 10 2 10 minute 1 10 0 10 second -1 10 10 20 30 40 50 60 70 80 90 Nuclear charge Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 17

Exotic Recombination Pathways Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 18

Recombination of W 18+ ([Kr] 4d 10 4f 10 ) 100 statistical theory -1 ) 3 s -8 cm TSR experiment 10 Rate coefficient (10 factor of 300 1 difference DR theory (autostructure) 0.1 radiative recombination 0.01 0.1 1 10 Electron-ion collision energy (eV) K. Spruck, N. R. Badnell, C. Krantz et al., in preparation Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 19

Many-Electron Systems with High Level Densities first 491 levels of Ce + 6 5 Level energy (eV) In principle, a Rydberg series of DR 4 resonances is associated with the excitation of each level. 3 2 1 4f ( 2 F) 5d 2 ( 3 F) 4 H 7/2 ground state 0 energies taken from the NIST atomic spectra data base Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 20

Giant Atomic Resonances Photoionization of Xe(4d) shell Time inverse process: Recombination via collective excitation of 10 4d electrons free Xe atom [exp, West & Morton 60 ADNDT 22 (1978) 103] Cross section ( Mb ) 40 20 0 80 90 100 110 120 130 140 150 160 Photon energy ( eV ) Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 21

+ Plasmon Excitations in C 60 Photoionization of ions at the ALS (Gießen-Reno-Berkeley-Dresden collaboration) 600 500 + + h   C 60 2+ + e - + 2+ - C 60 60 + h   C C 60 + e Photoionization cross section ( Mb ) 400 Photoionization cross section ( Mb ) Experiment Theory (LDA) 300 Theory (TDLDA) 400 density 200 experiment functional theory surface 200 fit curve plasmon 100 90 80 70 volume 60 plasmon 0 50 10 20 30 40 50 60 70 80 20 30 40 50 60 70 Photon Energy ( eV ) Photon energy ( eV ) S. Scully et al., PRL 94 (2005) 065503 Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 22

Access to Super-Atom States Feng et al., Science 320 (2008) 359 0 1 2 3 4 5 eV Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 23

Beam lifetime of stored C 60+ ions stored in ASTRID at room temperature 58 keV C 60+ P. Hvelplund, Proceedings Yield of neutral particles XVIII ICPEAC, Aarhus1993 AIP CP 295 (1993) p. 709 t = 10.8 s will be two orders of magnitude longer in CSR Stefan Schippers, FLAIR workshop, Heidelberg, 15-16 May 2014 24