Ionization of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Au</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mn>8</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and electron capture by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Au</mml:mi></mml:mrow><mml:mrow><mml:mn>7</mml:mn><mml:mn>9</mml:mn><mml:mo>+</

Claytor, N.; Belkacem, A.; Dinneen, T.; Feinberg, B.; Gould, Harvey

doi:10.1103/physreva.55.r842

Cited by 50 publications

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“…For g above ϳ100, the ln g scaling will be valid and s ECPP A ln g 1 B, where A and B are predicted to be [4] independent of 1͞g. Total electron capture and loss measurements were reported recently by Claytor et al [12] for g 12.6-Au ions, but the ECPP mechanism is not prominent at this low g, and ln g scaling is not expected to be valid.…”

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Electron Capture and Ionization of Pb Ions at 33 TeV

et al. 1998

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We have measured the total cross sections for electron capture by bare Pb 821 ions and ionization of hydrogenlike Pb 811 ions at 33 TeV (160 GeV͞A, g 168) in solid targets of Be, C, Al, Cu, Sn, and Au. The total capture cross sections are dominated by electron capture from pair production and are compared with theoretical calculations. The 1s ionization cross sections obtained are significantly smaller than those predicted by Anholt and Becker [Phys. Rev. A 36, 4628 (1987)]. The Pb radiative lifetimes extended by g 168 have a strong effect on the survival probability of excited states against ionization in high-Z solid targets. [S0031-9007(97) PACS numbers: 34.50. Fa, 34.80.Lx Interactions involving high-Z ions in the ultrarelativistic regime ͑.10 GeV͞amu͒, where the relevant physics is best described in terms of the Lorentz factor g, are currently a frontier in high-energy atomic collision physics [1]. A theoretical description of electron capture and ionization processes has been challenging in this regime because the interaction of high-Z projectile and target species (where Za ϳ 0.5) is strong enough at small impact parameters and large g to potentially invalidate perturbation treatments. Numerous methods for treating these processes using quantum electrodynamics (QED) in the ultrarelativistic regime now exist [1][2][3][4][5][6][7][8][9][10].An ultrarelativistic ion can capture an electron via three mechanisms: (i) radiative electron capture (REC), (ii) nonradiative capture (NRC), and (iii) electron capture via e 1 e 2 pair production (ECPP), in which the e 1 e 2 pair is produced by the intense electromagnetic pulse that arises when the projectile ion passes near a target nucleus. Capture cross sections s REC , s NRC , and s ECPP scale roughly as ϳZ t ͞g, ϳZ 5 t ͞g, and ϳZ 2 t ln g, respectively, where Z t is the target atomic number [2]. Each process has approximately the same dependence on the projectile atomic number, i.e., Z 5 p . The REC and NRC mechanisms, which dominate below the ultrarelativistic regime [11][12][13], become insignificant compared to ECPP when g . 100 even for high Z t . We report the first highenergy measurements ͑g 168͒ where s ECPP dominates the capture cross sections of competing mechanisms. Ionization cross sections are several orders of magnitude larger than capture, and our measurements test theory at the highest energy reported to date [2,10].The development of new relativistic ion colliders such as the Relativistic Heavy-Ion Collider at Brookhaven National Laboratory or the Large Hadron Collider at CERN [2,8,14] requires knowledge of the capture cross sections at high enough g so that beam lifetimes can be accurately predicted. The cross section for the ECPP process is of practical interest to collider designers because the lower charge-state projectiles produced are lost from the beam circulating in a ring. A significant loss rate of these ions by ECPP and also by nuclear loss processes decreases the ion storage time. These machines will operate at an effective g of 2.3 ...

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“…Each process has approximately the same dependence on the projectile atomic number, i.e., Z 5 p . The REC and NRC mechanisms, which dominate below the ultrarelativistic regime [11][12][13], become insignificant compared to ECPP when g . 100 even for high Z t .…”

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Electron Capture and Ionization of Pb Ions at 33 TeV

et al. 1998

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“…The resulting best fit of the K-REC cross section per target electron is shown in Fig. 4, where it is compared, and found to agree well, with extrapolation to lower energy measurements, especially those of Claytor et al [20], according to rigorous relativistic calculations by Eichler et al [15].…”

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“…Other ionization measurements for heavy ions near this energy regime were also performed by Claytor et al [20] at the brookhaven AGS for 10.8-GeV/nucleon Au ions. They observed good agreement with Anholt and Becker predictions.…”

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Atomic collisions at ultrarelativistic energies

Vane

Krause

2007

Nuclear Instruments and Methods in Physics Research Section B:

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“…At storage rings, of course, the ionization of the projectiles leads to a loss of the ions from the beam and, hence, has been explored in great detail, both by theory and experiment (Eichler andMeyerhof 1995, Voitkiv 2004). In the past, however, most experiments focused on the total ionization cross sections which have been measured not only for the intermediate energies of the projectiles (Rymuza et al 1993, Scheidenberger et al 1994, Stöhlker et al 1997 but also for the highrelativistic (Claytor et al 1997) and even the ultra-relativistic (Krause et al 1998, 2001, Vane et al 2000 ion-atom collisions. These experimental data are usually compared with the predictions from the first-order perturbation theory, based on the semi-classical (Pauli et al 1978, Amundsen and Aashamar 1981, Valluri et al 1984, Halabuka et al 1994 as well as the plane-wave Born (Anholt et al 1985, Voitkiv et al 2000, Voitkiv 2004 approximations.…”

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Effects of Ion-Beam-Irradiation on Morphology and Densification of CeO₂ Films Prepared by Ion-Beam-Assisted Deposition

Shimizu¹,

Setsuhara²,

Miyake³

et al. 2000

Jpn. J. Appl. Phys.

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The projectile ionization of highly charged, hydrogen-like ions is studied within the framework of first-order perturbation theory and Dirac's relativistic equation. Emphasis is placed, in particular, on the angular and energy distributions of the emitted electrons as observed in both the projectile and the laboratory frame. Detailed computations are carried out to investigate the effects from the excited states of the projectiles upon the energy-differential ionization cross sections. For relativistic U 91+ ions, for instance, a small partial population of the excited 2s 1/2 state results in a much narrower energy spectrum of the emitted electrons than obtained for the case of a pure K-shell ionization. This behaviour of the differential cross sections might help the understanding of a recent observation by Vane et al (2000 Proc. 21st Int. Conf. of the Physics of Electronic and Atomic Collisions (Sendai, Japan) (New York: AIP) pp 709-14) on the ionization of heavy, hydrogen-like projectiles in ultra-relativistic ionatom collisions.

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Ionization ofAu78+and electron capture byAu79+

Cited by 50 publications

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Electron Capture and Ionization of Pb Ions at 33 TeV

Electron Capture and Ionization of Pb Ions at 33 TeV

Atomic collisions at ultrarelativistic energies

Effects of Ion-Beam-Irradiation on Morphology and Densification of CeO₂ Films Prepared by Ion-Beam-Assisted Deposition

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Ionization ofAu78+and electron capture byAu79+

Cited by 50 publications

References 1 publication

Electron Capture and Ionization of Pb Ions at 33 TeV

Electron Capture and Ionization of Pb Ions at 33 TeV

Atomic collisions at ultrarelativistic energies

Effects of Ion-Beam-Irradiation on Morphology and Densification of CeO2 Films Prepared by Ion-Beam-Assisted Deposition

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Effects of Ion-Beam-Irradiation on Morphology and Densification of CeO₂ Films Prepared by Ion-Beam-Assisted Deposition