ISO 4037-2:2019 pdf free.Radiological protection——X and gamma reference radiation for calibrating dosemeters and doserate meters and for determining their response as a function of photon energy——Dosimetry for radiation protection over the energy ranges from 8keVto 1,3 MeVand4MeVto9 MeV.
4 Standard instrument
41 General
The instrument to be used for the measurement of the reference radiation shall be a primary or secondary standard or other appropriate instrument, whose calibration is traceable to a primary standard. Generally, this comprises an ionization chamber assembly and a measuring assembly. The instrument shall be operated as described in Annex A and be specific for the dosimetric quantity to be measured. Therefore, several different types of instruments for the measuring quantities, Ka, H*(10), H(10), H’(3), H(3), H’(007) and H(O,O7) and the appropriate phantoms are required for characterized reference fields. This means, for the example of a H(10) chamber, that it is put into the reference field without any further phantom and the indication is the H(10) value at the reference point of the H(10) chamber. If conversion coefficients from the measured quantity to the required quantity according to Clause 5 are used, then only one type of instrument for the measuring quantity air kerma free-in-air, Ka, is routinely required. For matched reference fields a second instrument, preferably for the definition depth 10 mm, is required for the verification.
4.2 Calibration of the standard instrument
The standard instrument shall be either a primary standard or a secondary standard traceably calibrated for the ranges of energies, air kerma rates and quantity values for which it is intended to be used. The expanded overall uncertainty (k = 2) of the calibration factor(s) of this instrument shall not exceed 4 % in the energy range from above 30 keV to 1,5 MeV and shall not exceed 6 % in the energy range above and below this energy range.
4.3 Energy dependence of the response of the standard instrument
The standard instrument shall fulfil two requirements. First, the ratio of the maximum value to the minimum value of the response of the instrument, Rmax/Rmin, shall not exceed the limit values, (Rmax/Rniin)iim, given in Tablel over the energy range for which the standard instrument is to be used.
This is valid for the mean energy values, E(P), see ISO 4037-1:2019, 3.8. The requirements depend on the measuring quantity, as given in Table 1. Second, if determined for two different radiation qualities of a given series, which are adjacent to each other with respect to mean energy, this response ratio shall not exceed 1 + 0,4 x L(Rmax/Rinin)iirn — 1]. If both requirements cannot be met for the whole range, at least the second requirement shall be met.
The calibration factor and the correction factors for the standard instrument refer to specific spectra. If the energy dependence of the response of the standard instrument cannot be neglected and if the spectral distribution of the radiation for which the dosimetry shall be performed differs significantly from that used for the calibration, a correction factor may have to be applied. This may be the case if the radiation series for the calibration of the standard instrument and the radiation series for which the dosimetry shall be performed are different. The aim shall be that the expanded overall uncertainty (k = 2) of the calibration factor used shall not exceed 5 %.
Whenever practicable, the reference radiations used to calibrate the secondary standard instrument should be the same as those used for the calibration of radiation protection instruments.ISO 4037-2 pdf download.