Portable alpha, beta, gamma, x and neutron radiation monitor

Full text: Here below there is short information about new instrument developed in SPE ATOMTEX, which will be produced at the close of the year. The instrument consists of the main unit, including built-in detector Nal (Tl) of diameter 25x40 mm and photomultiplier tube, analog devices (amplifier, multichannel pulse-height analyzer of 256 channels, high-voltage power supply, LED stabilization scheme of measuring path) and digital devices (microprocessor for data processing, control and storage, liquid crystal display, interface). The main unit operates also as processing and indication device of connected external detection units: α, β-radiation contamination scintillator detection unit; x, γ-radiation detection unit with silicon detector to measure equivalent dose and equivalent dose rate and n-radiation detection unit with proportional 3He-counters. Because of scintillator detector Nal (Tl), the main unit, operating in counting mode, searches and detects effectively x- and gamma-radiation sources with the energy from 30 keV to 3 MeV. The point source of 137Cs of 50 kBq is detected at the distance of 10 cm for 2s. Ambient equivalent dose and equivalent dose rate are measured with this detector using the method of instrumental spectrum transformation into dose. In this case the energy range is from 40 keV to 3 meV. Energy relationship of readings do not exceed ± 15% with respect to the energy of 0,662 MeV. The range of ambient equivalent dose rate measurement is from 0,05 μSv/h to 0,05 mSv/h, with response time of 20 s at background change from 0,05 μSv/h to 0,1 μSv/h. The main unit operates also as selective express-radiometer, which could evaluate sample activity by single gamma-line. Measurement geometry is Marinelly's vessel of 0,5 l. The lower limit of measuring activity is 300 Bq/l without lead shield and 20 Bq/l with it with measurement time of 10 min. The unit weighs not more than 0,9 kg. External detection units connect to interface socket by turns with unit identification. They also provide for searching, detection and measuring. α, β-radiation detection unit is phoswich-detector with combined detector ZnS (Ag)+plastic, which provides simultaneous detection and measurement of α- and β-radiation. Diameter of sensitive detector surface is diameter 60 mm. The range of surface contamination measurement of α-radiation is 0,004-4000 Bq/cm2 for the energy of 4-7 MeV, β-radiation is 0,05-10,000 Bq/cm2 for the energy of 0,25-3,5 MeV. α, β-radiation detection unit uses the method of LED stabilization of measuring path. Detection unit weighs not more than 0,5 kg. Instrument complete set could include another α, β-radiation detection unit with front Geiger counter of diameter 40 mm, which has lower sensitivity with proper background compensation. To extend main unit possibilities at measuring ambient equivalent dose rate, instrument complete set includes small detection unit with silicon detector, which operates with x- and γ-radiation of 0,01 mSv/h - 1 Sv/h with the energy of 30 keV - 3 MeV. Energy relationship is ± 30% with respect to the energy of 0,662 MeV. The unit weighs not more than 0,2 kg. To detect neutron flux density there is detection unit with proportional 3He-counters (3 items, diameter 19x150), placed into cylinder-shaped polyethylene inhibitor with wall thickness of 1,5 cm. The range of neutron flux density measurement (against Pu-Be source) is from 1 to 104 cm-2 s-1. Detection unit weighs not more than 1 kg. Large liquid crystal display with backlighting in the main unit displays necessary information from internal and external detectors. It is user-friendly. The instrument feeds from built-in accumulator (6 V), AC mains (220 V, 50 Hz) or DC mains (12V). Continuous operation time without accumulator charge is 16 h. It is possible to set thresholds for visual and audible alarm. Results are saved into non-voltative memory (up to 1000 values) within measuring. Then data could be transferred to PC by interface cable. Calibration error of dose rate does not exceed ±5 %, of activity - ±10%, of flux density - ±12 %. The present instrument meets IP 54 standard requirements, have reference temperature range from -30 to +50 deg. C. Instrument complete set includes also 2 m telescopic extension bar and AC adapter. (author)