Electromagnetic pair production with capture

Aste, Andreas; Hencken, Kai; Trautmann, D.; Baur, G.

doi:10.1103/physreva.50.3980

Cited by 29 publications

(40 citation statements)

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“…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].…”

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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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Electron Capture and Ionization of Pb Ions at 33 TeV

et al. 1998

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“…The numerical result for Z t = 1 agrees well with eq. (8). However, at high energies, the cross section for hydrogen is smaller by a factor of 0.971 than the Sauter cross section.…”

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“…Calculations of the single-photon bound-free pair production cross section σ K e + e − with simultaneous capture of the electron into the K-shell of a target nucleus with nuclear charge number Z t have been presented in [8]. In the meantime, the program used in [8] has been refined to higher precision, leading to small corrections of the originally calculated K-shell cross sections of some few percent.…”

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“…In the meantime, the program used in [8] has been refined to higher precision, leading to small corrections of the originally calculated K-shell cross sections of some few percent. In [9], it has been shown that the higher shells contribute about 20% of the K-shell capture to the total bound-free pair production cross section σ e + e − , i.e., σ e + e − = ζ(3)σ K e + e − provides a good approximation for σ e + e − , where ζ is the Riemann zeta function defined by…”

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Bound-free pair production cross-section in heavy-ion colliders from the equivalent photon approach

Aste¹

2008

Europhys. Lett.

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Abstract. -Exact calculations of the electron-positron pair production by a single photon in the Coulomb field of a nucleus with simultaneous capture of the electron into the K-shell are discussed for different nuclear charges. Using the equivalent photon method of Weizsäcker and Williams, a simple expression for the bound-free production of e + e − pairs by colliding very-high-energy fully stripped heavy ions is derived for nuclei of arbitrary charge.

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“…In this process, the charge of the ion decreases and it is depleted out of the beam. For this reason, calculation of the exact bound-free electron-positron pair production cross section is important for deciding the stability of the beam [1][2][3][4][5][6][7][8][9][10].…”

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Bound-free pair production with a correction term in relativistic heavy-ion collisions

Şengül¹

2017

Turk J Phys

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Abstract:In our previous work, we calculated bound-free electron-positron pair production cross section without a correction term. In this work, bound-free electron-positron pair production with a correction term is considered to calculate the cross section for peripheral relativistic heavy ion collisions. The Dirac wave functions have been used for the leptons and first order corrections are included. It is seen that the results for the production cross sections are considerably smaller than those of the previous calculations. We applied the same method for the calculations of the antihydrogen production cross sections as well.

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Electromagnetic pair production with capture

Cited by 29 publications

References 12 publications

Electron Capture and Ionization of Pb Ions at 33 TeV

Electron Capture and Ionization of Pb Ions at 33 TeV

Bound-free pair production cross-section in heavy-ion colliders from the equivalent photon approach

Bound-free pair production with a correction term in relativistic heavy-ion collisions

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