Energy Calibration Menu

This menu initiates the energy-calibration of the multichannel spectra. The processing outputs are:

• a new database field called "base", which stores the energy (MeV) at the bottom of channel 1 for each spectrum in the database, and 
• a new database field called "gain", which stores the energy width of each spectrum channel (MeV). 

The input multi-channel spectra are not adjusted in any way. 

There are two options for energy calibration:

• Automatic (cross-correlation): No input parameters are required. The input spectra are cross-correlated with a typical "standard" airborne spectrum to estimate the required base and gain.
• Manual (photopeak identification): The user must specify the approximate position (channel number) of the Th photopeak maximum, and the energy of at least two photpeaks to estimate the base and gain.

For most processing applications where the K (1.460 MeV), U (1.76 MeV) and Th (2.614 MeV) photopeaks are well defined, the automatic method is usually effective. The method is convenient, in that no input parameters are required. However, the method is slower than the manual method, and not as accurate. For some applications, such as high altitude cosmic/aircraft calibration or over-water radon calibration flights, the manual method must be used to better target prominent photopeaks other than the K, U and Th peaks listed above.