The pair-production channel in atomic processes

Belkacem, A.; Sørensen, Allan

doi:10.1016/j.radphyschem.2005.03.003

Cited by 7 publications

(5 citation statements)

References 79 publications

(167 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For some recent developments in pair production research, attention is here called to a special topical issue of Radiation Physics and Chemistry edited by Bergstrom (2006) including an over-all historical pair production review by Hubbell (2006), an update by Pratt (2006) on Tseng's low-energy calculations, intermediate-energy distorted wave Born approximation calculations by Sud and Sharma (2006), internal-source absolute pair production cross section measurements by Avignone (2006), the pair production channel in atomic processes by Belkacem and Sørensen (2006), extreme high energy pair production (10 GeV to 10 ZeV) by Klein (2006), relativistic positronium physics by Olsen (2006), and pair production of arbitrary spin particles by electromagnetic fields, by Kruglov (2006).…”

Section: Electron-positron Pair Productionmentioning

confidence: 99%

Review and history of photon cross section calculations

Hubbell

2006

Phys. Med. Biol.

128

View full text Add to dashboard Cite

Photon (x-ray, gamma-ray, bremsstrahlung) mass attenuation coefficients, mu/rho, are among the most widely used physical parameters employed in medical diagnostic and therapy computations, as well as in diverse applications in other fields such as nuclear power plant shielding, health physics and industrial irradiation and monitoring, and in x-ray crystallography. This review traces the evolution of this data base from its empirical beginnings totally derived from measurements beginning in 1907 by Barkla and Sadler and continuing up through the 1935 Allen compilation (published virtually unchanged in all editions up through 1971-1972 of the Chemical Rubber Handbook), to the 1949 semi-empirical compilation of Victoreen, as our theoretical understanding of the constituent Compton scattering, photoabsorption and pair production interactions of photons with atoms became more quantitative. The 1950s saw the advent of completely theoretical (guided by available measured data) systematic compilations such as in the works of Davisson and Evans, and by White-Grodstein under the direction of Fano, using mostly theory developed in the 1930s (pre-World War II) by Sauter, Bethe, Heitler and others. Post-World War II new theoretical activity, and the introduction of the electronic automatic computer, led to the more extensive and more accurate compilations in the 1960s and 1970s by Storm and Israel, and by Berger and Hubbell. Today's mu/rho compilations by Cullen et al, by Seltzer, Berger and Hubbell, and by others, collectively spanning the ten decades of photon energy from 10 eV to 100 GeV, for all elements Z= 1 to 100, draw heavily on the 1970s shell-by-shell photoabsorption computations of Scofield, the 1960s coherent and incoherent scattering computations of Cromer et al, and the 1980 computations of electron-positron pair and triplet computations of Hubbell, Gimm and Øverbø, these names being representative of the vast legions of other researchers whose work fed into these computations.

show abstract

Section: Electron-positron Pair Productionmentioning

confidence: 99%

Review and history of photon cross section calculations

Hubbell

2006

Phys. Med. Biol.

128

View full text Add to dashboard Cite

show abstract

“…neutrino-induced showers will be detected by Cherenkov emission in the unusually transparent ice present at large depths. A similar reduction may apply in the case of vacuum-assisted photo-ionization [10], where the created pair that knocks out the electron may suffer internal screening, leading to a reduced photo-ionization cross section compared to the case where internal screening is neglected. Finally, the radiation emission from relativistic positronium may be influenced by similar screening effects, depending on emission frequency [11].…”

Section: Introductionmentioning

confidence: 97%

Measurements and theories of the King–Perkins–Chudakov effect

Thomsen

Uggerhøj

2011

Nuclear Instruments and Methods in Physics Research Section B:

View full text Add to dashboard Cite

“…This internal screening effect may affect decisively the behavior of the Cherenkov emission in neutrino-induced electromagnetic showers. A similar reduction may apply in the case of vacuum-assisted photoionization [7], where the created pair that knocks out the electron may suffer internal screening, leading to a lower photoionization cross section. Finally, the radiation emission from relativistic positronium may be influenced by similar screening effects, depending on emission frequency [8].…”

mentioning

confidence: 95%

Direct Measurement of the Chudakov Effect

Virkus

Thomsen²,

Uggerhøj³

et al. 2008

Phys. Rev. Lett.

View full text Add to dashboard Cite

Experimental results for the restricted energy loss of pairs created from 1-178 GeV photons in a thin Au target and subsequently passing a CCD detector are presented. It is shown that pairs-when detected close to the creation vertex-suffer a reduced energy loss due to the internal screening of the charges constituting the pair. Furthermore, the ability to measure directly the energy of the pair by calorimetry enables a comparison with theory as a function of energy. The observed phenomenon is in good qualitative agreement with general expectations from the Chudakov effect but indicates a quantitative disagreement with either of two mutually disagreeing theories. DOI: 10.1103/PhysRevLett.100.164802 PACS numbers: 41.60.ÿm, 07.85.Fv, 29.40.Vj, 95.30.Gv In the preparatory phase of the CERN NA63 experiment, we have investigated the reduced energy deposition from a positron-electron pair in the vicinity of their creation point. This reduction is due to the internal screening of charges, the so-called Chudakov (or King-Perkins-Chudakov) effect [1,2].By taking into account the density effect, a considerable contribution to the ionization energy loss originates from transverse distances b q ' v=! p , where v is the particle speed through the medium with plasma frequency ! p . If a penetrating assembly of separate charges is internally spaced less than this distance, the ionization is influenced by interference terms. This can be the case, e.g., for an energetic hydrogen molecule that is stripped upon entry to the substance, but it can also be an effect present for an electron-positron pair where each participating charge screens the charge of the other as seen from the relevant distance b q in the medium. Because of the Lorentz transformation of angles to the laboratory system, the electron and positron emitted in the pair creation process from a photon of energy @! appear with an approximate angle of 1= mc 2 =E e ' 2mc 2 =@! to the photon momentum @k in the frame of the laboratory. Thus, by defining E e =@! and p @!=mc 2 , we get an opening angle of the pairthe so-called Borsellino angle [3]. The energy loss thus diminishes close to the creation point if the created pair is sufficiently energetic and therefore forward directed. This is the so-called Chudakov effect. In a sense, the Chudakov effect is the pair production analogue of the more familiar density effect in radiation emission.A closely related effect -to both the density effect ([4], Chap. 13.5) and the Chudakov effect-has recently been calculated for Cherenkov radiation emission from e e ÿ pairs in the vicinity of the creation point [5,6]. This internal screening effect may affect decisively the behavior of the Cherenkov emission in neutrino-induced electromagnetic showers. A similar reduction may apply in the case of vacuum-assisted photoionization [7], where the created pair that knocks out the electron may suffer internal screening, leading to a lower photoionization cross section. Finally, the radiation emission from relativistic positronium may be in...

show abstract

The pair-production channel in atomic processes

Cited by 7 publications

References 79 publications

Review and history of photon cross section calculations

Review and history of photon cross section calculations

Measurements and theories of the King–Perkins–Chudakov effect

Direct Measurement of the Chudakov Effect

Contact Info

Product

Resources

About