I've just received a very nice and compact russian dosimeter, the Terra-P, purchased from Ebay.

IMG_8938 IMG_8943

It came with a nice leather case, manual and good quality batteries. It is easy to use, and quite sensitive. The background radiation in my location is 0.11uSv/h .
This dosimeter can measure gamma radiation from 0.1uSv/h up to 999.9uSv/h . Besides this dose rate, it also features a dose measurement, a clock and alarm triggered by unsafely high levels of radiation.
It can measure Beta rays if the Geiger Muller cover is removed, but also x-rays (tested with a DY86 rectifier tube, more on this later).
Scanbox1

  • The main control keys are the MODE and THRESHOLD buttons.
    Press shortly the MODE button to switch the dosimeter on.
  • The Terra-P includes four operational modes: measurement of gamma radiation equivalent dose rate, measurement of gamma radiation equivalent dose !(TERRA-P is unique among pocket dosimeters. Only TERRA-P able to measure this parameter. It very important parameter which show how many of radiation energy absorbed body and how long time man can stay in zone with high radiation), clock, and alarm clock. Press the MODE button to switch the operational modes of the dosimeter.
  • By default, the dosimeter is switched in the mode of measurement of gamma radiation equivalent dose rate, which is indicated by the "µSv/h" symbol.
    Use the THRESHOLD button to run the programmed threshold level and change its value. At excessive threshold level the dosimeter will alarm about hazard (by default, the preset threshold value is 0.30 µSv/h, an average permissible radiation level for premises). Zero the previous measurement results by the THRESHOLD button.
  • To enter the mode of measurement of gamma radiation equivalent dose, press shortly the MODE button. Four digits and "mSv" symbol appear on the display.
    Note. In case of natural (c 0.1 µSv/h) gamma radiation background, an ED change by one low-order digit occurs on the display in 10 hours, and the "0.001 mSv" result, equal to 1.0 µSv, is shown on the digital indicator.
  • The clock mode of the dosimeter operation follows and two periods start blinking with one-second interval.
  • The alarm clock mode of the dosimeter follows and two steady periods appear on the display. Program the alarm clock with the help of the MODE and THRESHOLD buttons. The alarm clock signal symbol is indicated on the display at that. Note. The alarm clock operates even if the dosimeter is off.
  • Download the English manual here.

    To read more on radiation measurements, you can also see this Wikipedia article on the Sievert.

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