Bug in BBKICK
Dear CAIN colleagues
Last week Tohru reported a result of comparison between
CAIN1.1 and CAIN2.0 on the NLC gamma-gamma. He says
(1) The agreement on the e-gamma conversion is
execellent.
(2) Gamma-gamma differential luminosity dL(gg)/dW
agrees well.
(3) CAIN2.0 gives the e-e luminosity smaller by factor
of two than CAIN1.1, although the shape of dL(ee)/dW
looks the same.
I have been thinking of the disagreement (3) and found a bug
in "source/physics/bb/bbmain/bbkick.f".
The line 89
EP1(I)=EP1(I)+DEP
is wrong. EP1(I) on the right-hand-side must be the initial
value of EP. This will cause an over estimation of the
beam-beam effect, although the field evaluation is correct
(so that the beamstrahlung spectrum is essentially correct).
I changed the file and mailed to you. Please replace
bbkick.f. Sorry for many bugs.
Thank you, Tohru.
Kaoru