bhabha deflection treatment

guineapig++ can apply beam-beam effect on Bhabha event input file bhabha.ini ( and eventually bhabha_photon.ini)

internally, bhabhas are considered as being pairs. For activating the bhabha treatment use in acc.dat the keywords : do_bhabhas, track_secondaries, store_secondaries. If do_bhabhas = 1 : reads bhabha.ini only. If do_bhabha = 2 reads bhabha_photon.ini in addition.

• bhabha.ini and bhabha_photon.ini can be produced with a dedicated bhabha study tool (e.g. ​BHLUMI). A bhabha event input is a couple of 4-momenta (in GeV). The format of the file is then :

px1 py1 pz1 E1 px2 py2 pz2 E2 

( index 1 : electrons; index 2 : positrons )

output files are:

• bhabha_prod.dat : bhabhas from file bhabha.ini with additionnal information : a identifier label and 'mother energy'

The format of the file is :

label1 motherEnergy1 E1(GeV) px1/E1 py1/E1 pz1/E1
label2 motherEnergy2 E2(GeV) px2/E2 py2/E2 pz2/E2
............................................

( index 1 : electrons; index 2 : positrons )

• secondaries0.dat : 4-momenta of bhabhas before tracking :

 E(GeV) px/E py/E pz/E x y z process id. label 

(In case of bhabhas, process is always -1 )

• secondaries.dat : same as bhabhas0.dat, but after tracking

Note : for versions before guineapig++-0.4.0-b the keywords track_bhabhas and store_bhabhas are to be used in place of track_secondaries and store_secondaries. In a similar way, the output files are not secondaries0.dat and secondaries.dat but : bhabhas0.dat and bhabhas.dat .