Dosimeter or radiometer: what is the difference and which radiation monitor to choose

A dosimeter shows dose and dose rate: whether you can stay in a place and how much radiation has been received. A radiometer shows contamination and activity: whether a surface, clothing or material is clean. Many NPP Doza instruments combine both modes, and some have a search mode that quickly shows where a source is. Below: units, three models and how to choose.

What each instrument measures

Type	Shows	Units	Question it answers
Dosimeter	dose rate and dose	µSv/h, µSv, mSv	how hazardous it is to stay here
Radiometer	particle flux density, contamination	particles per cm² per minute	is the surface clean
Search mode	count rate, audible signal	counts/s, sound	where is the source

Two quantities in a dosimeter datasheet:

• MAED: ambient dose equivalent rate H*(10), µSv/h. Shows how fast dose builds up.
• AED: ambient dose equivalent H*(10), accumulated dose in µSv.

1 mSv equals 1000 µSv. Natural background is usually fractions to a few microsieverts per hour and depends on the area, so measure the background in a clean place before checking an object.

Three NPP Doza instruments for typical tasks

	DKG-07D Drozd	DKG-09D Chizh	MKS-15D Snegir
Type	dosimeter	dosimeter, search mode	dosimeter-radiometer
Radiation	gamma	gamma and X-ray	gamma and beta
Detector	gas-discharge counter	scintillation CsI(Tl)	gas-discharge counter
MAED	0.1 µSv/h - 1.0 mSv/h	0.1 µSv/h - 50 mSv/h	0.1 µSv/h - 2 mSv/h
AED	1.0 µSv - 0.2 Sv	0.1 µSv - 10 Sv	1 µSv - 10 Sv
Beta flux	no	no	10 - 10⁵ cm⁻²·min⁻¹
Energy range	0.05-3.0 MeV	0.05-3 MeV	0.05-3.0 MeV (gamma)
Temperature	minus 20...+50 °C	minus 40...+50 °C	minus 20...+50 °C
Protection	plastic case	IP65	IP52
Power	2 AA cells	3 AAA cells	2 AA cells
Weight	0.25 kg	up to 0.2 kg	0.35 kg

Features per the manufacturer's documentation:

• Drozd is a simple gamma dosimeter. Continuous operation on one set of batteries is at least 200 hours.
• Chizh is highly sensitive: background measurement to 30 % error takes 5 seconds. Color OLED display, search mode with a reading-versus-time graph, archive of 9999 measurements, USB link.
• Snegir shows the statistical error during measurement, refines the result continuously and compensates the gamma contribution when measuring beta flux.

How to choose

1. You need to judge whether a place is safe. A dosimeter is enough: DKG-07D for routine control, DKG-09D when sensitivity and speed matter.
2. You need to check surfaces, clothing or materials for beta contamination. Take the MKS-15D dosimeter-radiometer.
3. You need to find a source. The search mode of the DKG-09D with a reading graph and audible alarm helps localize the point quickly.
4. Outdoor work in frost. The DKG-09D works to minus 40 °C and has IP65 protection.
5. You need data logging and transfer. The DKG-09D has a 9999-measurement archive and USB.

What this choice does not replace: the instrument must be type-approved and verified if results are used officially. The verification interval of the DKG-09D and MKS-15D is 2 years per the documentation. The Drozd and Chizh pages link to measuring-instrument certificates on the manufacturer's site. Check current Kazakhstan requirements with metrology and radiation safety specialists.

How to measure correctly

1. Switch the instrument on and let it reach working mode. For the MKS-15D this is 1 minute.
2. Measure the background in a clean place and record the value.
3. Measure the object without hurrying: the instrument has a statistical error and the result refines over time.
4. Compare the object with the background, not with an abstract number.
5. Record the point, time and result. An instrument with an archive saves this itself.

Common mistakes

• Measuring beta contamination with a gamma dosimeter. A gamma dosimeter will not show beta flux; you need a dosimeter-radiometer with a beta channel.
• Skipping the background. Without it there is nothing to compare a result with.
• Taking the reading right after power-on. The instrument needs time to stabilize and accumulate statistics.
• Ignoring temperature. In frost ordinary instruments stop working; check the rated range.

Where to look and order

The NPP Doza catalog on the site has over 600 items. KEG TRK is NPP Doza's partner in Kazakhstan: we will select an instrument for the task, price on request. Russian manuals and brochures are on the instrument pages.