Defining Occupancy

The occupancy measures the number of particles per a detector cell for an event. For the CLAS12 drift chamber, there are 112 wires on each layer, with 12 layers within a region, giving 1344 cells. The registering of a "hit" takes a finite time in which the detector and its associated electronics are not able to register an additional signal if it occurs. This time window is known as the "dead time" during which only limited events are registered.

DC occupancy [math]\equiv \frac{N_{hits}}{N_{evt}}\frac{\Delta t}{t_{sim}}\frac{1}{112}\frac{1}{12}[/math]

where

[math]N_{hits}\equiv [/math]The number of DC wires intersected by primary and secondary events throughout the drift chamber in Region 1

[math]N_{evt} \equiv \phi \times P(interacting)[/math]

[math]\phi \equiv [/math] Number of incident particles on the face of drift chamber per cm^2

[math]\Delta t \equiv [/math] 250 ns: The time needed for events to be read by the electronics within Region 1

[math]t_{sim} \equiv [/math] Time of simulation = [math]\frac{N_{incident}}{I}[/math]