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Frequently asked questions

Working with UMF-2000

1. What are different planchets intended for, which can be purchased along with UMF- 2000?

Historically, the UMF-2000 is the successor to the beta-radiometers UMF-1500 and UMF-3. For those radiometers planchets (plates) were used (sometimes referred to as "targets") with outside diameter 35 mm and working area of ​​2.5 and 4 cm2. These planchets were used for measurements of residues after radiochemical separation of Cs-137, Sr-90 and Pb-210. The new device was designed with the expectation that all procedures developed for UMF-1500 and UMF-3 will be applied for the UMF-2000 as well. However, UMF-2000 was able to solve additional measurement problem which was beyond capabilities of other radiometers. It is gross alpha and beta activity measurement in drinking water. It is this task (where planchet’s effective surface is an important factor) for which planchets with working area of 7 cm2 have been designed (for UMF-2000 with a ​​detector area of 4.5 cm2) and 14 cm2 (for UMF-2000 with a detector area of ​​10 cm2).

2. Why UMF-2000 is manufactured with different detectors?

Initially UMF -2000 was manufactured with only one type of detector (with an area of ​​4.5 cm2), but to measure the total activity of drinking water with high salinity (greater than 0.5 g/L) such area has been insufficient to achieve desired sensitivity in terms of alpha activity. For such cases a modification of UMF-2000 was developed with a detector with large area of ​​10 cm2. The sensitivity of such a device for the total activity measurements of alpha-emitters in the dry residues of water samples was twice of the sensitivity with a smaller detector. However, the sensitivity for beta radiation was not changed, because increased detector area has led to an increase in noise level.

In addition to measuring the total activity, a large area detector is used to measure the activity of AFA-RMP-20 or AFA-RSP-20 air filters. When measuring filters a metal clamp ring shall be used to hold the filter on sample drawer. More information about the measurement of activity on filters can be found in the relevant section.

3. How to handle UMF-2000, so as not to damage the detector?

The radiometer UMF-2000 includes an ion-doped silicon semiconductor detector. Detectors of this type have excellent characteristics for detection of alpha and beta radiation, but are very sensitive to the slightest damages to the work surface. In order to detect alpha radiation, the thickness of the aluminium protective layer on the working surface is less than 0.2 μm. This thin coating is easily destroyed by mechanical impact or chemical exposure. Penetrations in the detector are sources of noise resulting in sufficient degradation of radiometer’s characteristics. It may be manifested as chaotic uncontrolled counts in the beta channel, significantly higher than background values. Damaged detector should be replaced.

With the intent to protect the detector radiometer’s design does not provide user access to the detector.

Here are some simple rules that guarantee a long service life of the radiometer:

  • When performing measurements, use only original (supplied with the device) planchets, inserts, filters, etc.
  • Use only procedures (techniques) specifically designed for UMF-2000 to prepare samples, or consult with our experts about the possibility of using a specific method.
  • Avoid measuring the counting samples, which may generate vapours of chemically active compounds.
  • Do not place the radiometer for operation or storage in areas where relative humidity exceeds 95%.
  • Do not measure counting samples or reference sources with activity more than 1000 Bq. Such samples usually have loose contamination on their work surfaces. Even a minor activity (about 1 Bq), which got on the detector or its surrounding structures, can make the device unsuitable for measuring small activities. If there are a need to measure samples which significantly different activities, it is better to buy a separate radiometer for large activities.
  • When measuring particulate (loose) samples ensure that the counting sample does not rise above edges of the planchet. Always use alcohol or acetone to fix such samples.
  • Do not leave samples in the radiometer after the measurements.
When used properly the radiometer UMF- 2000 can be used for more than 10 years without replacement of the detector.

4. What is the UMF-2000 software intended for?

The UMF- 2000 software is designed to automate the processing of measurement results. It corresponds exactly to the recommendations outlined in the Operation Manual and the “Procedure for measurement of total radioactivity of water samples”.