Estimating Instrument Response
Type test, manufacturer’s data or calibration data can provide information on a particular instrument’s energy response.
This is usually established using high quality reference sources of a restricted range of radionuclides on ideal surfaces which do not mimic the types of surfaces that will be encountered in normal monitoring situations. Some typical energy response curves are shown in Figures 1, 2,and 3 for α, β and γ radiation respectively.
These curves can be used to estimate what the detector 2π efficiency will be for 'ideal' sources of different radionuclides.
Figure 1: 2π efficiency v. Alpha energy
Figure 2: 2π efficiency v. Beta energy
Figure 3: 2π efficiency v. Photon energy
- NaI detector 3 mm thick, Be window 47 mg cm-2
- NaI detector 2 mm thick, Al window 14 mg cm-2
- Xe gas detector 20 mm thick, Ti window 5 mg cm-2
3 of 7Good practice online modules
- Practical radiation monitoring
- Practical radiation monitoring units
- Radiation monitoring strategy
- Choice of radiation instrument
- Radiation monitoring techniques
- Estimating surface radioactivity
- Radiation instrument calibration
- Uncertainties in radiation measurement
- Troubleshooting in radiation monitoring