Luminosity (background) Generator

To add background coming from the beam the following quantities must be defined

• a time window: the total time of one event

• the number of beam particles for each event

• the number of beam bunches

These quantities are defined with the LUMI options. For example the clas12 10³⁵ luminosity on a 5cm LH₂ target is achieved with:

<option name="LUMI_EVENT"     value="124000, 250*ns, 2*ns" />
<option name="LUMI_P"         value="e-, 11*GeV, 0*deg, 0*deg" />
<option name="LUMI_V"         value="(0.,0.,-10.)cm" />
<option name="LUMI_SPREAD_V"  value="(0.01, 0.01)cm" />

The above directives add 124000 electrons in a 250 ns long event, grouped in 2 ns bunches. That means produce 125 bunches, with 992 particles each. The beam is 100 micron wide (LUMI_SPREAD_V) and starts 10 cm upstream the CLAS center (LUMI_V).