Offset Correction; Charge And Energy Calibration - Pyramid CR10 User Manual

PSI System Controls and Diagnostics
amplifier, and generally should not require further adjustment. However, if the amplifier
configuration is changed, or if the shape of the charge pulse from the detector changes
significantly, it may be necessary to adjust the setting. Simply adjust the control until the output
pulse has a good symmetric shape.
Figure 9. Incorrect pole-zero setting (top), correct pole-zero setting (bottom)

11.3 Offset correction

The offset trimpot should be adjusted as necessary to remove any residual DC offset on the
output.

11.4 Charge and energy calibration

The amplitude of the output shaped signal will be linear with the charge in the input pulse. If the
amount of charge from the detector is also linear with the energy of the radiation, then the system
can be calibrated as an energy analyser. You will need to know at least one point to establish the
calibration.
As an example, you can calibrate a system comprising a silicon diode detector and the CR10
using a suitable monochromatic X-ray source. A convenient source is the Am-241 isotope which
generates a 59.5 keV gamma ray which will create a measurable peak in a pulse height spectrum.
Because the average energy to create an electron-hole pair in silicon is known (3.6 eV) this
gamma ray corresponds a known amount of measured charge, namely (59500/3.6) = 16500
electrons, or 2.6 fC.
CR10 User Manual CR10_UM_180115 Page 24 of 40