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CERN Program Library Long Writeup W5013 - CERNLIB ...

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Geant 3.16 GEANT User’s Guide PHYS340<br />

Origin : L. Urbán Submitted: 28.05.86<br />

Revision : Revised: 16.12.93<br />

Documentation :<br />

1 Subroutines<br />

Total cross-section and energy loss for bremsstrahlung by e-e+<br />

CALL GBRELA<br />

GBRELA fills the tables for the energy loss of electrons, positrons and muons due to bremsstrahlung at initialisation<br />

time for different materials. The energy binning is set within the array ELOW (common /CGMULO/)in<br />

the routine GPHYSI. In the tables, the dE/dx due to bremsstrahlung is summed with that due to the ionisation.<br />

For energy loss of electrons and positrons, GBRELA calls the function GBRELE. Following pointers are used:<br />

JMA = LQ(JMATE-I) pointer to the I th material;<br />

JEL1 = LQ(JMA-1) pointer to dE/dx for e − ;<br />

JEL1+NEK1 pointer to dE/dx for e + .<br />

GBRELA is called at initialisation time by GPHYSI.<br />

VALUE = GBRELE (ZZ,T,BCUT)<br />

GBRELE calculates the energy loss due to bremsstrahlung of an electron with kinetic energy T in material<br />

with atomic number ZZ. It is called by GBRELA and for energies below the cut BCUT it adds the contribution<br />

of bremsstrahlung to. Above this cut, the bremsstrahlung process is simulated explicitly (see [PHYS341])<br />

and tabulation of these continuous losses is not needed. GBRELE is called by GBRELA.<br />

VALUE = GBFLOS (T,C)<br />

GBFLOS calculates a weight factor for the positron continuous bremsstrahlung energy loss. T is the kinetic<br />

energy in GeV of the positron and C is the energy cut for bremsstrahlung (BCUTE). The value is the ratio<br />

of the energy loss due to bremsstrahlung of the positron to that of the electron so that: =<br />

GBFLOS × . GBFLOS is called by GBRELA.<br />

CALL GBRSGA<br />

GBRSGA calculates the total cross-section for bremsstrahlung in all materials. It tabulates the mean free<br />

path, λ = 1 Σ<br />

(in cm) as a function of medium and energy. The energy binning is set within the array ELOW<br />

(common /CGMULO/) in the routine GPHYSI. The following pointers are used:<br />

JMA = LQ(JMATE-I)<br />

JBREM = LQ(JMA-9)<br />

JBREM<br />

pointer to the I th material<br />

pointer to bremsstrahlung cross-sections<br />

pointer for e −<br />

JBREM+NEK1 pointer for e +<br />

JBREM+2*NEK1<br />

pointer for µ + /µ −<br />

GBRSGA is called at initialisation time by GPHYSI.<br />

VALUE = GBRSGE (ZZ,T,BCUT)<br />

GBRSGE calculates the total cross-section of bremsstrahlung of an electron with kinetic energy T in material<br />

with atomic number ZZ. It is called by GBRSGA. For kinetic energies which are below the cut BCUT or for<br />

which bremsstrahlung process is not simulated explicitly (see [PHYS341]) it returns 0.<br />

276 PHYS340 – 1

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