Method for the energy calibration of a spectrometry detector

A method for processing a calibration spectrum formed by a spectrometric measurement device, the device comprising:

• a detector configured to detect particles and to form, on each detection, a pulse whose amplitude depends on an energy of a particle having interacted in the detector;
• and
• a spectrometric measurement circuit configured to form a spectrum, the spectrum corresponding to a number of particles detected in channels, each channel being assigned a rank, a pulse amplitude corresponding to each rank,
• the method comprising:
• a) arranging the device facing a calibration object, the calibration object emitting, to the detector, particles of different known emission energies;
• b) detecting part of the particles by the detector and forming a calibration spectrum of the detected particles, the calibration spectrum comprising different peaks, each peak corresponding to one of the known emission energies;
• c) detecting some of the peaks of the calibration spectrum and assigning a channel rank to each detected peak;
• d) from the channel ranks assigned to different peaks in c) and the known emission energies, determining a calibration function, the calibration function determining an energy from the rank of each channel, the calibration function being a bijective function;
• wherein d) comprises:
• d-i) forming an analytical model of the calibration function, the analytical model being parameterized by a set of parameters;
• d-ii) for different values of each parameter of the set of parameters:
• applying the calibration function to the rank of each channel assigned to each detected peak, so as to obtain, for each rank, an energy determined by the calibration function, or
• applying a reciprocal function that is a reciprocal of the calibration function to each emission energy, so as to obtain, for each emission energy, a channel determined by the reciprocal function;
• and
• d-iii) determining the value of each parameter for which:
• the energies determined in d-ii) are closest to the emission energies of the calibration object, or
• the channels determined in d-ii) are closest to the channels assigned to each detected peak.