Download or read book Comparison of the Target thickness Dependence of the Convoy Electron Yield and the Rydberg Electron Yield Measured in Coincidence with Exit Charge States in Fast Ion solid Collisions written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have simultaneously measured the yield of convoy electrons and the yield of electrons in high Rydberg states of the projectile (n /approx gt/ 70), produced by 2MeV/u C projectiles passing through C foils, whose thicknesses range from 4--10 ug/cm2, for incident charge states q/sub i/ = 4--6 and exit charge states q/sub e/ = 4--6. We have found that these yields exhibit similar trends as a function of foil thickness, but that, nevertheless, the ratio of the number of convoy electrons detected in coincidence with ions of exit charge state q/sub e/ to the number of electrons detected in high Rydberg states of ions with the same exit charge state is a function of foil thickness. This may be due to a broadening of the convoy electron energy spectrum with increasing foil thickness. 6 refs., 3 figs.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1990 with total page 620 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book ERDA Energy Research Abstracts written by and published by . This book was released on 1989 with total page 848 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1989 with total page 914 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Annual Index written by and published by . This book was released on 1989 with total page 1676 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1989-05 with total page 800 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comparison of Convoy Electron Production in Ion atom and Ion solid Collisions written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We begin with an overview for the benefit of participants lacking acquaintance with the subject of convoy-electron production, and continue with highlights of developments occurring since a review and a comprehensive article published in 1982. A sharp cusp in the velocity spectrum of electrons, ejected in ion-atom and ion-solid collisions, is observed when the ejected electron velocity vector v/sub e/ matches that of the emergent ion vector v in both speed and direction. In ion-atom collisions, the electrons primarily originate from capture to low-lying projectile-centered continuum states (ECC) for fast bare or nearly bare projectiles, and primarily from loss to low-lying continuum states (ELC) when loosely bound projectile electrons are available. Most investigators now agree that ECC cusps are strongly skewed toward lower velocities and exhibit full widths half maxima roughly proportional to v (neglecting sometimes strong shell effects). Convoy cusps produced in heavy ion-solid collisions at MeV/u energies are slightly skewed toward high electron velocities, but exhibit velocity-independent widths, very similar to ELC cusp widths. While the shape of the convoy peaks is approximately independent of projectile Z, velocity, and target, dependence on projectile Z as Z2 7 and energy as E−2 2. Attempts have been made to link convoy electron production to binary ECC or ELC processes, sometimes at the last layer, or alternatively to a solid-state wake-riding model, but our measured dependences of cusp shape and yield on heavy projectile charge state q and energy are inconsistent with available theories. These wake-riding theories seek to explain the origin of convoy electrons in terms of electrons trapped into an oscillatory electron density polarization potential trailing each projectile, which are then liberated at the surface.
Download or read book Exit Charge State Dependence of Convoy Electron Production in Heavy ion Solid Collisions written by and published by . This book was released on 1986 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dependence of the yield of convoy electrons emitted near the forward direction in collisions involving fast ions and thin solid targets on the emergent projectile charge state is presented and described in terms of primary electron loss events in the solid. The data include a large array of projectiles, projectile energies and charge states, as well as targets ranging in thickness from the non-equilibrium well into the equilibrium thickness region. The description presented is consistent with other experimental and theoretical results indicating that the convoy electron production is closely linked to the ELC process observed in binary ion-atom collisions, with the dominant contribution to the convoy yield stemming from excited states of the projectiles. 22 refs., 3 figs.
Download or read book Convoy Electrons in Coincidence with Outgoing Charge States of Ni 920 MeV written by and published by . This book was released on 1987 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have studied the target thickness (rho x) dependence of the convoy electron yield Y/sub e/(q/sub f/) for the incident projectiles of nickel ions (charge q/sub i/) (15.6 MeV/u) with q/sub i/ = 28 and 27 on carbon foils in coincidence with outgoing projectiles with charge q/sub f/ = 28 and 27. Simultaneously the charge state evolution F(q/sub f/, rho x) dependence on the incident charge q/sub i/ has been measured. For this collision system the charge state distribution equilibrates for target thicknesses> 650 .mu.g/cm2. In the framework of a model for convoy electron production the rho x dependence of the yield Y/sub e/ (q/sub i/, q/sub f/) can be explained if one introduces and electron transport length lambda/sub c/ which is much larger than the attenuation length lambda/sub e/ of free electrons.
Download or read book Convoy Electron Production in Polycrystalline and Monocrystalline Targets written by and published by . This book was released on 1980 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The velocity distribution of electrons ejected close to the forward direction by 0.8-2 MeV/A ions traversing various solid targets, including a Au monocrystal, is measured in coincidence with emerging charge-selected ions. The velocity spectrum is observed to be independent of outgoing projectile velocity and charge state for polycrystalline targets. Measurements on the Au crystal under channeling conditions show dependences on final charge state, and are tentatively explained by assuming that the main contribution to the production yield comes from the non-channeled fraction of the ions. A simple model for the creation of the forward-ejected electrons is proposed, which accounts for most of the experimental findings.
Download or read book Convoy Electron Production by Heavy Ions in Solids written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The term convoy electron refers to those electrons ejected in fast ion-atom and ion-solid collisions closely matched in vector velocity to that of the incident heavy particles responsible for their ejection. Similarities and differences among electrons ejected into such states through binary electron capture to continuum and electron loss to continuum processes in single ion-atom encounters are compared and contrasted to more complex ejection processes occurring in solid targets. Puzzles posed by the apparent strong projectile Z dependence but weak emergent ion charge dependence of the yield in the case of solid targets are reviewed. Very recent progress in resolving these puzzles has been made by recent observations that the apparent mean free path for electron scattering out of the forward direction within the target is observed to be an order of magnitude greater than that for free electrons of equal velocity provided the projectile charge is high. 13 references, 2 figures, 1 table.
Download or read book Multiple Electron Capture in Close Ion atom Collisions written by and published by . This book was released on 1989 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: Collisions in which a fast highly charged ion passes within the orbit of K electron of a target gas atom are selected by emission of a K x-ray from the projectile or target. Measurement of the projectile charge state after the collision, in coincidence with the K x-ray, allows measurement of the charge-transfer probability during these close collisions. When the projectile velocity is approximately the same as that of target electrons, a large number of electrons can be transferred to the projectile in a single collision. The electron-capture probability is found to be a linear function of the number of vacancies in the projectile L shell for 47-MeV calcium ions in an Ar target. 18 refs., 9 figs.
Download or read book Doubly Differential Cross Sections of Collision produced Forward Electron Emission written by and published by . This book was released on 1985 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The velocity space distribution of electrons emitted near the forward direction from collisions involving fast, highly stripped oxygen ions with gaseous and solid targets is presented and described in terms of multipole moments of the ejected charge distribution, which permits direct comparison with recent theory. The results are from a novel apparatus permitting rapid and efficient data acquisition by employing position-sensitive electron detection to combine angle definition with conventional electrostatic spectrometry. Excellent agreement is obtained between distribution observed for electron loss to projectile continuum processes and recent theory in the case of argon targets; less favorable results for simpler helium targets may indicate the need for theoretical study of higher order inelastic processes in that case. The multipole content observed with a solid target is consistent with a conceptual model of convoy electron production dominated by electron loss from the projectile within the bulk of the target and may signify the importance of steady-state production of excited states within the bulk solid. 26 refs., 4 figs., 2 tabs.
Download or read book Production and Transport of Convoy Electrons in Amorphous Carbon Foils written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The production of free convoy electrons, emitted with velocities near the ion velocity in ion-solid collisions, is not well understood. Experiments concerning thickness-dependent yields have suggested the dominant mechanism for convoy production is electron loss to the continuum (ELC) in the bulk of the solid. Free electrons created in the bulk are subject to multiple elastic and inelastic scattering during transport through remaining layers of the solid. We discuss doubly-differential measurements of convoy measurements of convoy electrons as a function of target thickness for fast O/sup 5 +/ ion projectiles incident on carbon foils of varied thicknesses. Angular distributions confirm the ELC model for convoy production. From the radial broadening of the convoy cusps we have determined energy and angular spreading parameters due to post-collisional multiple scattering. 8 refs., 2 figs., 1 tab.
Download or read book Anomalous Mean Free Paths for Scattering of Convoy Electrons Generated by Fast Highly Ionized Ions in Thin Solid Targets written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We have measured the yields of convoy electrons associated with 15.2-MeV/amu Ni/sup 24 +/ and Ni/sup 26 +/ ions transversing thin, poly-crystalline foils of C and Al. The thicknesses used were in the range 3 to 500 .mu.g/cm2. By observing how the yield saturates with increasing thickness, we obtained effective mean free paths (MFPs) for the scattering of convoy electrons out of the collector half angle (1.54°).
Download or read book Trapping Highly Charged Ions written by John Gillaspy and published by Nova Publishers. This book was released on 2001 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides and elementary introduction to the field of trapping highly charged ions. The first group of chapters is intended to describe the various sorts of highly charged ion traps: EBIT, EBIS, ECR, Storage Rings and various speciality traps. The authors focus on their own ion trap facilities in order to teach by example. The chapters range in scope from comprehensive reviews to brief introductions. The second group of chapters is intended to give a flavour of the various sorts of scientific research which are presently being carried out with traps for highly charged ions. These chapters not only inform, but also stimulate newcomers to think up fresh ideas. The articles in this second group generally fall into one of three broad categories: atomic structure experiments, ion-surface interactions and precision mass spectrometry. The third group of chapters is intended to deal with theory and spectroscopic analysis. It provides some of the background material necessary to make sense of observed phenomenology, to allow detailed explanation of experimental data, and to sensibly plan further experimentation. An appendix provides a complete keyword-annotated bibliography of pa
