Setting VELO HV for run 3 verse integrated luminosity
The HV for the Velo pixel sensors will be kept as low as possible in the data taking to reduce the heat and so rate of radiation damage. As such the default HV is the starting value for 2022 data taking is 105V set in SIMCOND, giving the full 200 microns depletion depth. As the detector takes damage the HV will be increased module by module as required, so is set from SIMCOND as it will be different for each module after some running time. At 5fb^-1 integrated lumi that means below ~7mm the detector has no sensitivity at 105V, a voltage of 250V for all sensors gives at least 80 microns depletion at 5mm which gives full efficiency.
There are a number of methods to simulate different luminosities:
- Set 1000V in SIMCOND and always have full sensitivity
- Make a SIMCOND for each luminosity so Velo and other detectors with radiation damage have consistent parameters
- Set a SIMCOND overlay in python in the same file that sets the luminosity to simulate [current solution]
from Configurables import UpdateManagerSvc
VPSensorHV = 250.0 # Volts
UpdateManagerSvc().ConditionsOverride += \
["Conditions/HardwareProperties/VP/Sensors/VP-Sensor{:03d}-HV := double HV = {}"\
.format(s,VPSensorHV) for s in range(208)]
print("Set VP HV to {} V".format(VPSensorHV))
Added to Boole options (from v43r0 onwards) or for earlier Boole versions (set from an option):
from Configurables import VPDepositCreator
VPDepositCreator().BiasVoltage = 250.0