Intersection of a Track with a Cylinder or a Plane

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| Geant 3.10  |               GEANT User's Guide              | HITS400  ##
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Author(s) : R.Brun                                     Submitted: 01.10.81
Origin    : GEANT2,H. Boerner                            Revised: 21.05.86
                                  

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|CALL GICYL (R,X1,X2,S1,S2,IC,XINT*,SINT*,PZINT*,IFLAG*) |
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Calculates intersection of track (x1,x2) with cylindrical detector of radius R. The track is approximated by a cubic in the track length. To improve stability, the coordinate system is shifted.

R

radius of cylinder in cm

X1

x,y,z,xp,yp,zp of 1st point

X2

x,y,z,xp,yp,zp of 2nd point

S1(2)

S at 1st (2nd) point

IC

=1 straight line defined by x+xp

IC

=2 straight line defined by x1+x2

IC

=3 cubic model

XINT

x,y,z,xp,yp,zp at intersection point

SINT

S at intersection point

PZINT

phi,z,dphi/dr,dz/dr

IFLAG

=1 if track intersects cylinder, =0 if not

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|CALL GIPLAN (YC,X1,X2,S1,S2,IC,XINT*,SINT*,PZINT*,IFLAG*) |
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Calculates intersection of track (x1,x2) with plane parallel to (X-Z). The track is approximated by a cubic in the track length. To improve stability, the coordinate system is shifted.

YC

Y coordinate of plane

X1,...

as for GICYL

IFLAG

=1 if track intersects plane, =0 if not

Warning: the default accuracy is 10 microns. The value of EPSI (internal variable) must be changed for a better precision.