Spectrometer - Dosimeter
Development and Investigation of the Small-Scale Desk-Top Electronic Paramagnetic Resonance Spectrometer - Ionizing Emissions Dosimeter
Tech Area / Field
- INS-DET/Detection Devices/Instrumentation
- INS-MEA/Measuring Instruments/Instrumentation
- PHY-RAW/Radiofrequency Waves/Physics
3 Approved without Funding
VNIITF, Russia, Chelyabinsk reg., Snezhinsk
- Scientific and Research Institute of Physics and Applied Mathematics, Russia, Sverdlovsk reg., Ekaterinburg
- US Department of Commerce / National Institute of Standards and Technology, USA, MD, Gaithersburg\nUniversity of Denver/Department of Chemistry and Biochemistry, USA, CO, Denver
Краткое описание проектаThe purpose of this Project is development of desk-top electronic paramagnetic resonance spectrometer (EPR) of new generation and measurement methods using the specific peculiarities of the device and intended for dosimetry of ionizing irradiation, irradiation control of meal products, routine measurements in chemistry, physics and medicine, scientific researches and training. The spectrometer-dosimeter has to combine a high sensibility, spectral and temporary resolution, and also a multi-functionality of the expensive research spectrometers with cheapness, unpretentiousness and small sizes of simple spectrometers for routine measurements. A successful solution of such contradiction problem is possible only with the use of equipment, nonstandard for traditional EPR, of high-effective technological, system and engineering solutions accumulated by Russian science and defense branches.
Doctor D.Regull (Institute for Radiation Protection at the Research Environmental and Health Protection Center, Munich, Germany) and Doctor M.FDesrosiers (National Standards and Technologies Institute, USA).
During last years the perspective method in the area of high-dose dosimetry of hard electromagnetic irradiation has become a method based on the electron paramagnetic resonance effect. It is proved by the fact that the corresponding standards were accepted in 1994 in the USA, Canada, a number of European countries. Development of State Standard on retrospective (on the tooth enamel) EPR dosimetry has been begun in Russia.
EPR dosimetry of the ionizing irradiations is based on the fact that the quantity of radiation paramagnetic defects and, therefore, an integral intensity of their EPR signals, is exactly proportional to the ionizing irradiation dose absorbed by material of the dosimeter.
In 1980 the United Expert Committee of the International Atomic Energy Agency (IAEA), Committee of UNO on Food and Agriculture Issues and International Health Protection Organization (IHPO) approved treatment of food products with the aim of their decontamination and preparation for long storage with gamma irradiation up to 10 kGr. Correct technology of such treatment allows to store large amounts of food products and to make their use safe, however, at radiation sterilization of food products the radiation defects (free radicals), which have carcinogenic activity, are formed.
Limit irradiation doses stipulating concentrations of such defects are regulated by sanitary norms set by National Standards. Normatives in various countries are sufficiently different (doses of irradiation of vegetables according to Supplenebt to Food Irradiation Newslette, vol. 19, No 2 – October 1995: Argentine – 1 kGr, Canada – 10 kGr, Netherlands – 15 kGr, Russia – 4 kGr, the USA – 30 kGr). Control of presence in the food of free radicals is possible with methods of EPR, thermoluminescense and chromatography. The most operative one is electron paramagnetic resonance method.
A huge role is played by research methods based on EPR in organic chemistry, biochemistry and pharmacology.
In the world market there is an EPR analyzer EMS-104 produced by company BRUKER (Germany) with mass about 80 kg and proposed at the price of DM 60,000. There are data on developments of small-scaled spectrometers: ES-10 with mass 25 kg at the price of $80,000 (Sumitomo special metal America), PS 100X (Scientific-Production Firm "Adani", Minsk) $15,000 and EPR-10-MININ-D (Stock Company "SPIN", Saint-Peterburg) $15,000, which are theoretically applicable for use as devices for routine researches and reading devices of EPR dosimetry.
By now at NII FPM at UrGU the preliminary works connected with development of scientific-technical solutions allowing to create an EPR of new generation have been conducted. As a result, a prototype of desk-top EPR spectrometer has been developed. A coherent superheterodyne scheme not being used now in serial devices, but allowing to register the absorption spectrum with minimal apparatus consumption and without distortion (together with the first derivative of spectrum measured in serial spectrometers), that is very important when it is necessary to define an integral intensity of the EPR signal (just it is proportional to concentration of free radicals), is put into the base of the development. Microstrip performance of microwave dosimeter units on the base of solid-state microwave elements (for the first time in the civil device building) provides the depression of congenital sensibility of superheterodyne spectrometers to vibration and a high reliability.
The pointed solutions determined a structural-functional scheme of the spectrometer.
Preliminary researches of the spectrometer prototype have proved a life-ability and perspective of system and scheme-technical solutions and afford ground for expectation of appearance in the nearest future of a device which has no analogs on a set of parameters in the world.
The next step of the work is creation of automated lab sample of EPR spectrometer-dosimeter with the increased characteristics of sensibility and resolution giving rich possibilities of conduction of nonstandard for high-skilled researcher. At the same time, the operation of such spectrometer at dosimetry and other routine measurements should require a minimal skill of staff. Besides, the development of measurement methods of EPR spectrum parameters with the use of extended capabilities of the spectrometer and methods of restoration of the ionizing irradiation doses absorbed by the detector, should become a containment of this stage of the work. This stage may be fulfilled by NII FPM at UrGU together with RFNC-VNIITF which has methods and techniques of pilot-production design, of specifying and measuring of the ionizing irradiation doses.
The following results are supposed to be obtained during fulfillment of the Project:
· the development and approbation of scientific-technical principles of creation of small-scaled superheterodyne coherent spectrometer EPR;
· the development and manufacture of laboratory sample of desk-top EPR spectrometer;
· the development of methods of conduction of EPR measurements at such spectrometer;
· the development of methods of conduction of dosimetry measurements with the account of peculiarities of the spectrometer.
The conducted researches and developments should become a scientific-technical base for creation of EPR spectrometer of new generation and development on its base of approaches in the area of dosimetry control and diagnostics of the food products.
During the first year it is planned:
— to study the possibilities of perfection of laboratory prototype of the spectrometer-dosimeter;
— to perfect and manufacture the algorithm and software in the area of apparatus control of the spectrometer and processing of EPR-spectra;
— to develop and to manufacture the modified microwave and HF units of EPR spectrometer-dosimeter;
— to develop a specialized software for the use of the spectrometer as an automated spectrometer;
— to develop and to manufacture a perfected magnetic system with homogeneity of field 10-5;
— to develop and to manufacture the automated system of frequency adjustment and coordination of microwave resonator;
— to manufacture a pilot sample of EPR spectrometer-dosimeter.
During the second year it is planned:
— to conduct adjustment and testing of laboratory sample of EPR dosimeter;
— to study the possibility to develop a method of EPR measuremetns with the account of specifi capabilities of the developed spectrometer;
— to develop benchmark test-objects for calibration of EPR spectrometer-dosimeter;
— to conduct the gagging of EPR spectrometer-dosimeter;
— to research a possibility of development of method of retrospective dosimetry using the coherent and pulse capabilities of the spectrometer;
— to study a possibility of methods of restoration of the absorbed dose of food products at irradiation thereof.
This Project will allow specialists dealing with creation of nuclear and missile weapons to participate in conduction of the applied researches and development of technology for peaceful purpose, to promote the international integration of the scientists.