IEC 62372:2021 pdf free download – Nuclear insFor each value of energy, the position of a maximum of a peak of full absorption is defined.
The values of the nonlinearity and the initial point of assembly conversion response shall bedefined using a housed scintillator based on thallium-activated sodium iodide single crystalduring irradiation by gamma-radiation.
Pulse height spectra are measured using monoenergetic gamma radiation with at least fiveenergy values in the range from 300 keV to 1 500 kev.
For each energy value the total absorption peak maximum position should be defined.
The light output of a housed scintillator may be used to determine the nonlinearity and theinitial point of assembly conversion response in cases where it is necessary to measure theparameters of housed scintillators with low light output.For that,light flux from housedscintillator is attenuated by a neutral light filter.The pulse heights obtained after attenuationshould correspond to the working range of pulse heights of the tested scintillator.
Neutral light absorbers are added after the PMT power supply is turned off and the lightprotection chamber is opened.After setting the light absorber,the chamber is closed,thePMT power supply is turned on and measurements are taken after not less than half an hour’sirradiation.
The values of nonlinearity and V。 are measured at the same gain factor which is used formeasuring the parameters of tested housed scintillator. The nonlinearity and Vshould bemeasured once per month or more frequently, after PMT replacement or assembly ‘repair.
4.2.1.2 Measurements
The test conditions and the order of measurements are in accordance with 4.1.
The value of pulse heights (V) corresponding to total absorption peak maximum isdetermined. The measurements are repeated three times and the average value V iscalculated.
All above-mentioned procedures are repeated for each value of energy (E).
The pulse height spectra may be accumulated simultaneously from all the gamma-emittingsources during irradiation of the housed scintillator.trumentation-Housed scintillators – Test methods of light outputand intrinsic resolution.
During measurement of the light output of the housed scintillators, the instability is determinedby the change of pulse height over time.
During measurement of the intrinsic resolution of the housed scintillators,the instability isdetermined by the change of pulse height and energy resolution of the scintillation detectorover time.
The instability of the assembly may be determined by using a housed scintillator based on thesame scintillator material type and during irradiation by the same radiation type as for thetested housed scintillator.
The test conditions and the order of measurements are in accordance with 4.1.
Three measurements should be carried out before the start and at the end of themeasurement.
4.3.1 Equipment
The test conditions and the order of measurements are in accordance with 4.1.
A PMT with the known spectral characteristic S(l.) and quantum sensitivity Q is used.
The nonlinearity and the initial point of assembly conversion response is measured asspecified in 4.2.1.
The assembly is qualified for making measurements if its nonlinearity does not exceed 3 %.
The instability of the assembly is assessed as specified in 4.2.2.The assembly is qualified formaking measurements if its instability does not exceed 2 %.
4.3.2 Measurements
The tested housed scintillator is mounted on the PMT photocathode by optical contact and thepulse height spectrum is measured as specified in 4.1.1.
The number of channels (V) corresponding to total absorption peak maximum is determinedtaking into account the initial point of assembly conversion response.