Advantages of scintillator-photodiode (SPD) detectors and devices based on them are described in the pioneer papers of U.S. (Wandpend et al.) and Soviet (Stolyarova E.L. et al) researchers back in the 1960s. These are a wide energy and dynamic range (over 10 orders of magnitude), pocket size, reliability, low power consumption, high energy resolution (5.5 to 7% for line 622 keV).

According to our data, the first attempt of practically using an SPD detector device was made in 1988 by the author and colleagues to measure radiation levels inside the destroyed reactor of ChNPP Unit 4. In the follow-up, emergency dosimeter DKS-DZ with a companion detector (attached with a 50 m cable) was developed in cooperation with the Monolit Production Association, Kharkiv. To date, the first pilot batch of it (about 200 items) has been manufactured by the Metrologhiya State Research & Industrial Association, Kharkiv. According to our information the device outperforms similar instruments of foreign make offering performance such as dynamic range of 50 mR/h to 10,000 R/h, detector radiation margin up to 10⁸ rad, good operator safety features and durability of electronics owing to the companion detector used. A radiation-proof scintillator is used in the device.

We are now further improving the underlying idea of the device by developing a multi-purpose dosimeter with a measurement range extended down to the background level as well as a survey gamma-radiation meter allowing real-time measurements in the range of 10 mR/h through 200 R/h.

A portable spectrometer is being developed for commercial production at RTC RIE based on a 586 Notebook computer and using the SPD detector. The spectrometer offers a ¹³⁷Cs 622 keV line energy resolution of 6.5 to 7 % for a 1 cm³ detector and 13 to 14 % for a 20 cm ³ one, the scintillator being CsJ (Tl). The device uses a special ADC unit built in the Notebook accumulator module and a spectrometric amplifier developed at RTC RIE and brought through to commercial level in hybrid design by the Microelectronics Workshop of the Kommunar Production Association. The one-board spectrometer and preamplifier are powered with the Notebook power supply module using 5 % of the unit power consumption at the most. In a field option for mobile laboratories the device is additionally equipped with a satellite-based system of field reference. Special software has been implemented under the Windows system.

Amongst oxide scintillator devices, alpha-gamma radiometer RK-AG is currently conditioned for quantity production offering a superior performance to foreign analogs. In this device, use of the unique GSO (gadolinium silicate) scintillator with a K-jump of gamma absorption around 60 keV combined with a dedicated mathematical method of gamma spectrum processing and specialized software allowed to improve the sensitivity threshold of ²⁴¹Am detection up to units of Bqs per sample with a measurement time of 20 to 30 min. Earlier similar sensitivities could only be after preliminary samples enrichment or using a radiochemical method. The fact that the said sensitivity is provided while there is an accompanying contamination by ¹³⁷Cs up to 10,000 Bq is a critical point for use in real conditions.

Digital and computing modules of the device are implemented based on a Palmtop microcomputer, software being implemented under the Windows system.

Ph.D., Professor

Director of the Research & Technology Center for Radiation Instrument Engineering

STC Institute of Single Crystals, NASU

Address: 310001, Kharkiv, Lenina Prospekt, 60

Telephone: (0572) 32 13 79

Fax: (0572) 32 13 91

E-mail: rizhikov@stcri.kharkov.ua