Measurement of non-linearity in the cathodoluminescence yield for non-doped scintillators.

We propose a method for studying nonlinearity in the cathodoluminescence (CL) characteristics of wide-bandgap materials based on the measurements of the CL energy dependence on the total energy of a pulsed electron beam E b using its bremsstrahlung. It is shown that the x-ray radiant energy produced by a high-power (∼ 10 MW / cm 2) electron beam with particle energies of 50–300 keV is proportional to E b in the case of weak variations in the electron energy distribution of the beam. This direct proportionality between E b and the x-ray radiant energy is experimentally confirmed in the current experiment by measuring the dependence of the molecular nitrogen emission radiant energy at 337 nm excited by a direct electron impact (the 0-0 vibrational transition of the second positive system of the emission bands of N 2 molecule) on the total electron beam energy E b. Using this result, the dependencies of the CL radiant energy on E b are studied for undoped Bi 4 Ge 3 O 12 , PbWO 4 , CeF 3 , and BaF 2 crystals with bright intrinsic luminescence. An interpretation of these dependencies is given using a simple theoretical model and photoluminescence nonlinearity data published in the literature. We estimate the average concentration of the electronic excitations (EE) provided by the electron beam (10 18 – 10 19 e.– h. p. / cm 3) and obtain the approximate dependencies of the CL yield on the EE density for the studied materials. For the CeF 3 crystal, different CL yield dependencies on the EE density are found for the bands at 300 and 350 nm. [ABSTRACT FROM AUTHOR]