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| Geant 3.16 | GEANT User's Guide | PHYS410 ##
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Author(s) : M. Hansroul Submitted: 01.09.76
Origin : Geant 2 Revised: 19.12.92
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|CALL GLOREN (BETA,PA,PB) |
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GLOREN transforms the momentum and the energy from one Lorentz frame (A) to another (B). It uses the following input and output:
BETA(1)
Input: . BETA(2) } the velocity components of the frame B seen from the frame A
BETA(3)
2
BETA(4) 1/sqrt(1-beta )= gamma
PA(1)
. PA(2) } the momentum components in the frame A
PA(3)
PA(4) the total energy in the frame A
PB(1)
Output: . PB(2) } the quantities corresponding to PA in the frame B
PB(3)
PB(4)
GLOREN is called from the routine GDECAY.
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| CALL GDROT (P,COSTH,SINTH,COSPH,SINPH) |
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GDROT rotates a vector from one reference system to another. It uses the following input and output:
Input: P the three vector components of the initial system
COSTH costheta
SINTH sintheta where theta and phi are the angles between
COSPH . cosphi } the two coordinate systems
SINPH sinphi
Output: P the three vector components of the final system
GDROT is called from several routines to rotate a particle from the center-of-mass system to the GEANT (laboratory) system.
The momentum p and energy E of the Lorentz frame A are transformed to A A the momentum p and energy E of the Lorentz frame B which has a velocity B B beta seen from the frame A:
E = gamma(E - beta# p )
B A A
p = p +betagamma(((gammabeta #p )/ (gamma+ 1))-E )
B A A A
cos thetacosphi - sinphi sintheta cosphi cosphi - sinphi 0 costheta 0 sintheta
( cos thetasinphi cosphi sintheta sinphi )= ( sinphi cosphi 0 )( 0 1 0 )
-sin theta 0 cos theta ############## ############# ################0###############
|#############{z############}|###############{z##############}
R R
phi theta
R is a counterclockwise rotation about the axis 2 through angle theta theta, and R is a counterclockwise rotation about the new axis 3 phi (rotated by the angle theta from the initial position) through angle phi.