Merging Beams, A Different Approach to Collision Cross Section Measurements

Trujillo, S. M.; Neynaber, R. H.; Rothe, Erhard W.

doi:10.1063/1.1720077

Cited by 108 publications

(12 citation statements)

References 9 publications

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“…For merging beams experiments this information is contained in a quantity known as the overlap integral,l given by F = finteraction J 1 (X,y,Z)J 2 (x,y,z)dxdydz, volume (1) where J 1 and J 2 are the fluxes of the reactant beams in units of particles/cm2 sec. Reaction products in these experiments are formed by collision of fast particle beams which move along a common axis with a welldefined relative velocity.…”

Section: Introductionmentioning

confidence: 99%

Rapid determination of the overlap integral in a merging beams system

Nitz

Geis

Smith

et al. 1976

Review of Scientific Instruments

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A method for determining the beam overlap integral semiautomatically in a merging beams experiment is presented. The apparatus consists of a driven beam scanner and an analog circuit which computes two-dimensional overlap integrals from the sampled beam currents. Only a simple additional computation is required to obtain the three-dimensional overlap integral. Results of qualitative and quantitative tests demonstrate the validity of the technique. The capability for rapid measurement of beam overlap is employed to investigate the stability of the overlap integral.

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Section: Introductionmentioning

confidence: 99%

Rapid determination of the overlap integral in a merging beams system

Nitz

Geis

Smith

et al. 1976

Review of Scientific Instruments

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“…Ce sont ces considerations qui nous ont conduits à 6tudier les propri6t6s d'une nouvelle g6om6trie, inspiree de la g6om6trie a faisceaux superposes qui a deja ete utilis6e avec succ6s en physique des collisions [10].…”

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Pompage optique et absorption saturée d'un faisceau d'ions rapides superposé à un faisceau laser continu

et al. 1977

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“…This ensured that both beams occupied very nearly the same phase space independent of scattering angles at A. The overlap integral 6 for the merged beams was calculated with use of this assumption.…”

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confidence: 99%

Electron Loss in Low-EnergyH+-H(high n)Merged-Beam Collisi

Koch

Bayfield

1975

Phys. Rev. Lett.

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We have measured the electron-loss cross section for collisions between protons and highly excited hydrogen atoms having principal quantum numbers in the nominal n band 44%n% 50. The cm. collision energy range was 0.4 eV^ pp^ 61 eV. Theoretical ionization-cross-section results are compared with the data and are then used to unfold from the data the approximate electron-transfer cross section. Classical scaling calculations are found to be in reasonable agreement with the unfolded data while quantal predictions are not.The comparison of experiment and theory for H*-H(n) collisions leading to electron loss, the sum of electron transfer and ionization, has been limited to the one restricted case of principal quantum number n = l. 1 Although theory exists, the n dependence of the electron-loss cross section has never been measured in any collision energy range, either in this most fundamental ionatom system or in any other.The electron-transfer and ionization cross sections for low-energy (eV energy range) H + -H(high n) collisions are among those required for evaluation of the important role that electron-capture and -loss collisions involving excited states may have in affecting the transport properties of plasmas. 2 Astrophysically these collisions are believed to be important in the ionized-hydrogen (H II) regions in interstellar space. 3 It is the purpose of this Letter to report results of the first experimental study of H + -H(high n) collisions. The merged-beam electron-loss cross-section data cover the center-of-mass collision-energy range 0.4 eV< W^ 61 eV; the H(high n) target atoms had quantum numbers n in the nominal n band 44 % n % 50.The transition from "low"-to "high"-energy behavior of electron-transfer and ionization cross sections in ion-atom collisions occurs when the velocity v r of relative motion of the nuclei is comparable with the orbital velocity v" of the electron taking part in the collision. For H + -H(n) collisions, v r~v n when W^ 1.3x 10 4 n~2 eV. For n = l, this occurs at W^ 13 keV; forn = 47, at W ^6 eV. The cross-section data reported in this Letter cover both the low-and high-energy regions.The measurements were performed with a new, single-ion-source, merged-beam apparatus incorporating significant technological advances. The method is based on that introduced by Belyaev, Brezhnev, and Erastov. 4 Part of the apparatus is shown in Fig. 1. A pure H + beam with energy E B near 11 keV and energy spread measured to be % ± 20 eV around E B was generated with an rf ion source, accelerator, and mass analyzer system not shown in Fig.

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Merging Beams, A Different Approach to Collision Cross Section Measurements

Cited by 108 publications

References 9 publications

Rapid determination of the overlap integral in a merging beams system

Rapid determination of the overlap integral in a merging beams system

Pompage optique et absorption saturée d'un faisceau d'ions rapides superposé à un faisceau laser continu

Electron Loss in Low-EnergyH+-H(high n)Merged-Beam Collisi

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