Smear Test Analysis
The Laboratory of Radiation Metrology has a shielded portable instrument for the smear test measurement.
The instrument is based on two proportional counter detectors: one for the sample and one for the environmental background. An anti-incidence circuit between the two detectors allows to minimize the background contribution.
It is possible to select one of the different measurement modes:
- beta radiation
- alpha and beta radiation
- beta radiation with automatic detection of alpha radiation presence
Then, it is possible with only one instrument to evaluate the contamination both by alpha and beta emitters.
The instrument efficiency for different radionuclides is verified periodically, using certificated reference sources. The following table shows the instrument efficiency and the minimum detectable activity (MDA) for the available radionuclides.
| Radionuclide | Maximum Energy (keV) | Instrument Efficiency (%) | MDA (Bq) | |
| a | b | |||
| Am-241 | 5480 | 49.2±3.5 | 0.08 | |
| Ni-63 | 66 | 2.6±0.4 | 8.0 | |
| C-14 | 154 | 19.2±1.7 | 0.9 | |
| Cs-137 | 1173 | 45.5±3.4 | 0.2 | |
| Sr-90/Y-90 | 2260 | 41.9±3.0 | 0.2 | |
Information and contacts
For information about the smear test and our activities, please do not hesitate to contact us by email under the following address: metrologia-radiazioni@polimi.it