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CERN Program Library Long Writeup W5013 - CERNLIB ...

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GEANT 3.16 GEANT User’s Guide PHYS231<br />

Origin : L.Urbán Submitted: 26.10.84<br />

Revision : J. Chwastowski Revised: 16.12.93<br />

Documentation :<br />

1 Subroutines<br />

Simulation of photoelectric Effect<br />

CALL GPHOT<br />

GPHOT<br />

simulates the photoelectric effect. It uses the following input and output:<br />

Input<br />

Output<br />

via common GCTRAK<br />

via common GCKING<br />

It calls the functions GPHSG1, GPHSGP, GAVRL2 and GAVRL3 for the cross-section and the functions GHPHAK,<br />

GHPHAL1, GHPHAL2, GPHAL3 for the cosine distribution of the photoelectron. GPHOT is called by the tracking<br />

routine GTGAMA, if, and when, the photon reaches its interaction point.<br />

VALUE = GAVRL2 (GAMAL2,BETAL2,X)<br />

GAVRL2 calculates approximation of the cross-section for the photoelectric effect from L II shell. GAMAL2,<br />

BETAL2 are the Lorentz gamma and beta factors of the emitted photoelectron and X = m e /E γ where m e is<br />

the electron mass and E γ is the incident radiation energy. GAVRL2 is called by GHPOT.<br />

VALUE = GAVRL3 (GAMAL3,BETAL3,X)<br />

GAVRL3 calculates approximation of the cross-section for the photoelectric effect from L III shell. GAMAL3,<br />

BETAL3 are the Lorentz gamma and beta factors of the emitted photoelectron and X = m e /E γ where m e is<br />

the electron mass and E γ is the incident radiation energy. GAVRL3 is called by GPHOT.<br />

VALUE = GPHAK (BETAK)<br />

VALUE = GPHAL1 (BETAL1)<br />

GPHAK and its entry point GPHAL1 poll the cosine distribution (w.r.t. the incident photon direction) of the<br />

photoelectron emitted from K or L I shell, respectively. They are called by GPHOT.<br />

VALUE = GPHAL2 (BETAL2)<br />

GPHAL2 polls the cosine distribution (w.r.t. the incident photon direction) of the photoelectron emitted from<br />

L II shell.<br />

VALUE = GPHAL3 (BETAL3)<br />

GPHAL3 polls the cosine distribution (w.r.t. the incident photon direction) of the photoelectron emitted from<br />

L III shell. It is called by GPHOT.<br />

VALUE = GPHSGP (EGAM)<br />

GPHSGP calculates the photoelectric effect total cross-section for a particular atom of a mixture taking into<br />

account weights. It is called by GPHOT for Z ≤ 100.<br />

224 PHYS231 – 1

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