Showing papers by "Lutz Spielberger published in 1997"

Recoil-ion momentum spectroscopy

Abstract: High-resolution recoil-ion momentum spectroscopy (RIMS) is a novel technique to determine the charge state and the complete final momentum vector of a recoiling target ion emerging from an ionizing collision of an atom with any kind of radiation. It offers a unique combination of superior momentum resolution in all three spatial directions of with a large detection solid angle of . Recently, low-energy electron analysers based on rigorously new concepts and reaching similar specifications were successfully integrated into RIM spectrometers yielding so-called `reaction microscopes'. Exploiting these techniques, a large variety of atomic reactions for ion, electron, photon and antiproton impact have been explored in unprecedented detail and completeness. Among them kinematically complete experiments on electron capture, single and double ionization in ion - atom collisions at projectile energies between 5 keV and 1.4 GeV have been carried out. Double photoionization of He has been investigated at energies close to the threshold up to . At the contributions to double ionization after photoabsorption and Compton scattering were separated kinematically for the first time. These and many other results will be reviewed in this paper. In addition, the experimental technique is described in some detail and emphasis is given to envisaging the rich future potential of the method in various fields of atomic collision physics with atoms, molecules and clusters.

Ionization of Helium in the Attosecond Equivalent Light Pulse of 1 GeV/Nucleon U{sup 92+} Projectiles

Abstract: Single and double ionization of helium by 1GeV/nucleon U{sup 92+} impact was explored in a kinematically complete experiment. The relativistic ion generates a subattosecond (10{sup {minus}18} s ) superintense (I{gt}10{sup 19} W/cm {sup 2} ) electromagnetic pulse, which is interpreted as a field of equivalent photons (Weizs{umlt a}cker-Williams method). Cross sections, the emission characteristics of ions and electrons as well as momentum balances, are quantitatively discussed in terms of photoionization of the atom in this broadband, ultrashort virtual photon field. {copyright} {ital 1997} {ital The American Physical Society}

Intra-atomic Electron-Electron Scattering in p-He Collisions (Thomas Process) Investigated by Cold Target Recoil Ion Momentum Spectroscopy

Abstract: We have performed a kinematically complete experiment for the transfer ionization reaction 0.15{endash}1.4 MeV p+He{r_arrow}H{sup 0}+He{sup 2+} +e{sup {minus}} by measuring the three-dimensional momentum vector of the He{sup 2+} ion in coincidence with the scattering angle and the plane of the H{sup 0} . In the measured fourfold differential cross section we can clearly distinguish between the independent two-step process of capture plus ionization and the correlated e -e Thomas scattering. We find a v{sup {minus}7.4{plus_minus}1}{sub P} scaling for the total cross section of the e -e Thomas process. {copyright} {ital 1997} {ital The American Physical Society}

Kinematically complete experiments using cold target recoil ion momentum spectroscopy

Abstract: Cold Target Recoil Ion Momentum Spectroscopy allows the detection of the three-dimensional momentum vector of the recoiling product ion from ion, electron or photon atom collisions with 4π solid angle and high resolution. It can be combined with large area position-sensitive detectors for electron detection or measurement of the projectile charge-state and scattering angle. Such ‘reaction microscopes’ cover the full correlated momentum space of all fragments of an atomic reaction yielding kinematically complete information for each reaction event. For the first time in atomic collision physics fully differential data became available in the sense that not only the momenta of all fragments, but also the complete momentum space is observed in one experiment. Recent results achieved with this new technique for slow p-He collisions and threshold photo ionization of He will be discussed.

A design study for an internal gas-jet target for the heavy-ion storage ring CRYRING

Abstract: This paper presents the design of the internal gas-jet target, CRYJET, which is being constructed for investigations of, e.g., fast ion--atom collisions in the heavy-ion storage and cooler ring CRYRING at the Manne Siegbahn Laboratory, Stockholm University. The goal for the design work was to create an ultra-cold He target (< = 10 mK in the longitudinal direction and 0.5 mK transverse temperature) with a density of ∼ 1012 atoms/cm3. Care was taken in order to minimize the influence from the jet on the very low background pressure in the storage ring (∼ 10-11 mbar). The low temperature is essential for the resolution in the experiments. The high density will enable us to get sufficient luminosities for investigations of processes with cross sections down to the 10-27 cm2 range. The gas-jet target will be equipped with two recoil-ion-momentum spectrometers in order to extract detailed information about the collision dynamics.

Fully Differential Cross Sections for Double Photoionization of He Measured by Recoil Ion Momentum Spectroscopy [Phys. Rev. Lett. 77, 1024 (1996)]

Abstract: ravis, Fully Differential Cross Sections for Double Photoionization of He Measured by Recoil Ion Momentum Spectroscopy [Phys. Rev. Lett. 77, 1024 (1996)] R. Dörner, J. M. Feagin, C. L. Cocke, H. Bräuning, O. Jagutzki, M. Jung, E. P. Kanter, H. Khemliche, S. K V. Mergel, M. H. Prior, H. Schmidt-Böcking, L. Spielberger, J. Ullrich, M. Unversagt, and T. Vogt [S0031-9007(97)02684-7] On page 1026, the last sentence of the second paragraph should read, “However, Lablanquie et al. [5] could show from their sg, 2ed data that atEexc ­ 4 eV the ratioK ­ 0 (which is proportional to theau term in their notation) to K ­ 1 is small, typically down to1y19.”

Particle and UV-Imaging with Position Sensitive MCP-Detectors-Three-Dimensional Momentum Space Imaging

Abstract: Various position sensitive microchannel-plate (MCP) detector systems for ion, electron and photon detection are presented. We have also developed a complete set of electronics to operate the detectors and software to analyze the incoming data. The detectors provide two-dimensional position as well as excellent timing information, e.g. for time-of-flight measurements. All data can be stored in single event mode. These MCP-detectors were used for electron and ion analyzers, which provide a three-dimensional imaging of the momentum space of all detected particles.

From (γ,2e) to (γ,eR): Kinematically Complete Experiments with Coltrims

Abstract: The technique of Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS) has been developed to study the reaction dynamics in atomic collisions1,2. Recently, this method has been applied to collisions of electrons and photons with helium3,4,5,6 Combining this technique with position sensitive large solid angle electron time-of-flight detectors it became possible to perform experiments of the type (γ,2e)7 and (e,2e) 8, with the recoil-ion momentum measurement replacing the spectroscopy of one of the electrons.