End-window Geiger-Muller Counter Research Articles

Absorption method for determination of pure beta-emitters in samples containing more than one beta-emitter

Absorption method is shown to be suitable for direct determination of pure β-emitting, isotopes in samples containing more than one β-emitter. This method consists of (1) measurement of the β-counting rate as a function of the thickness of the absorber placed in between the sample and the β-detector and (2) decomposition of the complex absorption curve by computation in order to obtain the contributions of the nuclides to the total counting rate one by one. The method is presented through two examples of its practical application in the field of environmental radioanalysis:90Sr and147Pm isotopes were determined in aerosol samples contaminated by Chernobyl radioactivity and in hot particles of Chernobyl origin using a simple end-window Geiger-Muller counter as a β-detector.

Measurement of radon decay products and thoron decay products in air by beta counting using end-window Geiger-Muller counter.

A new grab sampling method has been developed for the simultaneous measurement of radon decay products and thoron decay products in air. It is based on direct beta counting of filtered aerosol sample over successive time intervals by end-window Geiger-Muller counter. Defined solid angle absolute counting was used to evaluate the efficiencies for the decay products one by one. Absolute activity concentrations can be determined with less than 10% systematic error. Glass-fiber filter, high sampling flow rate, and long duration of sampling can be used, as a result of which the detection limits are about 0.1, 0.2, and 0.01 Bq m(-3) for 214Pb, 214Bi, and 212Pb, respectively. Indoor saturated activity concentrations were measured in 86 buildings in Ajka town, Hungary, where industrial wastes rich in uranium had been used as building materials. Elevated radon decay product levels were found in houses built before 1960. Radon gas concentration was also measured simultaneously in 26 cases and the minimum, maximum, and average values of the equilibrium factor were 0.17, 0.73, and 0.40, respectively.

Use of Defined Solid Angle Absolute β Counting for Environmental Radioanalytical Purposes Part II. Applications

Abstract Three practical applications of the defined solid angle absolute β counting (DSAABC) method using end-window Geiger-Muller counter are presented. 90Sr and 147Pm nuclides were determined in filtered aerosol samples collected in Debrecen, Hungary, immediately after the Chernobyl accident. Development of an active method is in progress in order to determine radon and thoron daughters attached to airborne aerosols. Indoor concentrations were measured by this method in Ajka, Hungary, where radioactive industrial wastes were used as building materials. Determination of 90Sr and 147Pm in hot particles of Chernobyl origin, collected in Kiev, Ukraine, is in progress. The relation to the application of the DSAABC method is treated in detail and some results are presented.

<sup>114</sup>In<sup>m</sup> as a Long Half-Life Exposure Indicator for Criticality Accident Dosimetry

Indium is activated, principally by epithermal neutrons, to give 114Inm with a half-life of about 50 d. Indium foils exposed in the UK criticality dosemeter, at an International Intercomparison Experiment at the SILENE reactor, were measured three months later both by gamma ray spectrometry and beta ray counting. The specific activity measured was in good agreement with that estimated independently from gold foil measurements of the thermal and intermediate energy neutron fluences. Beta ray counting with a low background end window Geiger-Muller counter was the more sensitive method of measurement, giving a detection efficiency of about 0.14 count.disintegration-1. This gave a practical lower limit of measurement for 114Inm of 0.5 Bq.g-1, which corresponded to total neutron doses of about 16mGy and 21mGy for the lead shielded and bare SILENE neutron spectra respectively. Such measurements demonstrate the value of indium as a long-term exposure indicator, in addition to its usually accepted uses as a short-term exposure indicator (116Inm) and a fast neutron detector (115Inm).

Metabolism of C(14)-glucose by Ascaridia galli

The fowl nematode Ascaridia galli employed in this experiment was obtained from the intestine of domestic fowls at the local market. The worms selected and washed several times in normal sterilized saline solution. Each about thirty of intact worms were incubated in 50 cc volume of special incubation flasks with incubation mixture consisting of 10 cc of Krebs-Ringer phosphate buffer (pH 7.4) to which were added universally labeled C14-glucose and non-radioactive carrier glucose so as to contain concentration of 200 mg per cent. The worms were allowed to incubation for 3 hours in Dubnoff metabolic shaking incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central well of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. Glycogen samples isolated from worms were analysed for uptake rate was determined by analyzing the difference of the glucose concentration in a medium before and after incubation period. Radioactivities of these series of experiments were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantitative analysis of C(14)-glucose utilized by Ascaridia galli was summarized as the following. 1. The glucose uptake rate by A. galli was a mean value of 1.73 +/- 0.32 micro M/hr/g of wet wt. and total CO2 production rate by the worms averaged 8.44 +/- 1.11 micro M/hr/g of wet wt. The relative specific activity of respiratory CO2 (R.S.A CO2) averaged 2.68 +/- 0.38 per cent. Thus, a man of 2.68 per cent of total CO2 production rate was originated from the glucose in the medium, therefore the rate of CO2 production derived from medium glucose was a mean of 0.23 +/- 0.03 micro M/hr/g of wet wt. Thus, the average value of 2.58 +/- 0.55 percent (R.G.D CO2)of glucose utilized by the worms from the medium glucose was oxidized to respiratory CO2. 2. The tissue concentration of glycogen in A. galli was a mean of 22.59 +/- 1.18 mg per gram of wet wt or 2.26 +/- 0.123 percent per gram, and the turnover rate of glycogen pool yielded with a mean of 0.17 +/- 0.04 percent per hour or 0.037 +/- 0.006 miligram per hour per gram of wet wt. Therefore, a mean value of 16.37 +/- 4.04 per cent (R.G.D gly) of glucose was incorporated to the glycogen. 3. These data account for that at least 18.95 per cent of the utilized glucose by the worms participated in furnishing the oxidation into respiratory CO2 and the synthetic process into glycogen. According to the above data of the experiment, it is suggested in the metabolic process of glucose by Ascaridia galli that the synthetic process into the glycogen is more active than the oxidative process into the respiratory CO2.

Metabolism of C(14)-acetate by some trematodes

The adult trematodes, Fasciola hepatica, Eurytrema pancreaticum and Paramphistomum cervi, employed in this experiment were obtained from the cattle slaughtered at the local abbatoir. The worms selected and washed several times in normal sterilized saline solution. Each about ten of intact F. hepatica, fourty of E. pancreaticum, and twenty of P. cervi were incubated in 50 cc volume of special incubation flasks with incubation medium consisting of 10 cc. of Krebs-Ringer phosphate buffer(pH 7.4) The incubation medium was added C(14)-1-acetate and non-radioactive carrier Na-acetate so as to contain acetate concentration of 50 mg per cent. The worms were allowed to incubate for 5 hours in the Dubnoff metabolic shaking incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central well of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. The lactate and pyruvate appearance rates were determined by analyzing the lactate and pyruvate concentration in a medium after incubation. The glycogen samples isolated from worms were analyzed for the tissue concentration and their radioactivities in order to determine the turnover rate of glycogen pool. Radioactivities of these series of experiments were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantitative analysis of C(14)-acetate utilized by F. hepatica, E. pancreaticum and P. cervi were compared and discussed in this report. According to these data of the experiment, it is suggested that the fatty acid such as acetate may play a part of their oxidative process into the respiratory CO2 and the synthetic process into glycogen in the above species of trematodes.

Metabolism of C(14)-glucose by Paramphistomum cervi

The trematode Paramphistomum cervi empolyed in this experiment was obtained from the reticulum of cattle slaughtered at the local abbatoir. The worms were selected and washed several times in normal sterilized saline solution. Each about ten of intact worms were incubated in 50 cc volume of special incubation flasks with incubation mixture consisting of 50 cc of Krebs-Ringer phosohate buffer (pH 7.4) to which were added universally labeled C(14)-glucose and non-radioactive carrier glucose concentration of 200 mg per cent. The worms were allowed to incubate for 3 hours in the incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central wall of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. Glycogen samples isolated from worms were analysed for the tissue concentration and their radioactivities in order to determine the turnover rate of glycogen pool. 1. The glucose uptake rate was determined by analysing the difference of the glucose concentration in a medium before and after incubation period. Radioactivities of these series of experiments were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantitative analysis of C(14)-glucose utilized by Paramphistomum cervi was summerized as the following. The glucose uptake rate by Paramphistomum was a mean value of 2.32 +/- 0.27 micro M/hr/g of wet wt. and total CO2 production rate by the worms averaged 10.85 +/- 0.41 micro M/hr/g of wet wt. The relative specific activities of respiratory CO2 averaged 49.72 +/- 13.20 per cent. Thus, a mean of 49.72 per cent of total CO2 production rate was originated from the glucose in the medium, therefore the rate of CO2 production derived from medium glucose was mean of 5.24 +/- 2.16 micro M/hr/g of wet wt. Thus, the average value of 37.46 +/- 5.28 per cent of glucose utilized by the worms from the medium glucose was oxidized to respiratory CO2. 2. The tissue concentration of Paraphismum was a mean of 41.56 +/- 5.82 micro M/hr/g of wet wt or 4.16 +/- 0.72 %/g, and the turnover rate of glycogen pool yielded with a mean of 0.12 +/- 0.014 %/hr or 0.06 +/- 0.04 mg/hr/g of wet wt. Therefore, a mean value of 16.75 +/- 4.84 per cent of glucose was incorporated to the glycogen. 3. These data account for that at least 54.21 per cent of the utilized glucose by the worms participated in furnishing the oxidation into respiratory CO2 and the synthetic process into glycogen. According to the above data of the experiment, it is suggested in the metabolic process of glucose by the Paramphistomum that the synthetic process into the glycogen is less active than the oxidative process into the resppiratory CO2.

Metabolism Of C(14)-Lactate By Fasciola Hepatica And Eurytrema Pancreaticum

The adult trematode, Fasciola hepatica and Eurytrema pancreaticum, employed in this experiment were obtained from the cattle slaughtered at the local abbatoir. The worms were selected and washed several times in normal sterilized saline solution. Each ten of intact F. hepatica and about thirty to fifty of E. pancreaticum were incubated in 50 cc volume of special incubation flasks with incubation medium consisting of 50 cc of Krebs-Ringer phosohate buffer (pH 7.4). The incubation medium was added C(14)-lactate and non-radioactive carrier Na-lactate so as to contain lactate concentration of 32 mg per cent. The worms were allowed to incubate for 3 hours in the Dubnoff metabolic shaking incubator at 38 degrees C. After incubation period, respiratory CO2 samples from central wall of incubation flask were analysed for total CO2 production rate and their specific activity of respiratory CO2. The lactate uptake rate was determined by analyzing the the difference between lactate concentration in a medium before and after the incubation period, and the pyruvate appearance rate was dertermined by analyzing the pyruvate concentration in a medium after incubation. The glycogen samples isolated from worms were analyzed for the tissue concentration and their radioactivities in order to determine the turnover rate of glycogen pool. Radioactivities of these serise of experiment were counted by an endwindow Geiger-Muller counter as an infinitely thin samples. The quantative analysis of C(14)-lactate utilized by F. hepatica and E. pancreaticum were summerized and compared as following. In F. hepatica the lactate uptake rate was a mean value of 1.04 +/- 0.15 micro M/hr/g of wet wt. and pyruvate apperance rate was a mean value of 0.132 +/- 0.005 micro M/hr/g of wet wt. The total CO2 production rate by the flukes averaged 13.82 +/- 0.75 micro M/hr/g of wet wt. The relative specific activities of respiratory CO2 R.S.A(CO2) showed a mean value of 9.93 +/- 0.62 per cent. The rate of CO2 production derived from medium C(14)-lactate was a mean of 1.38 +/- 0.13 micro M/hr/g of wet wt. Therefore the averge value of 55.27 +/- 5.78 per cent (R.L.D(CO2)) and 15.35 +/- 1.90 per cent (R.L.D(pyr)) of lactate was oxidized into respiratory CO2 and pyruvate respectively. On the other hand, in E. pancreaticum the lactate uptake rate was a mean value of 0.61 +/- 0.18 micro M/hr/g of wet wt, and pyruvate appearance rate was a mean of 0.023 +/- 0.001 micro M/hr/g of wet wt. The total CO2 production rate by the E. pancreaticum averaged 4.29 +/- 0.85 micro M/hr/g of wet wt. The relative specific activity of respiratory CO2 (R.S.A(CO2)) showed a mean value of 9.20 +/- 0.34 per cent. Thus, a mean value of 9.20 per cent of total CO2 production rates was originated from C14-lactate in a medium, therefore the rate of CO2 production derived from medium C(14)-lactate was a mean value of 0.40 +/- 0.10 micro M/hr/g of wet wt. The average value of 23.93 +/- 7.11 per cent(R.L.D(CO2)) and 3.86 +/- 0.45 per cent(R.L.D(pyr)) of lactate was oxidized into respiratory CO2 and pyruvate respectively. The tissue concentration of glycogen in F. hepatica was a mean of 2.63 per cent/g of wet wt, while in E. pancreaticum was a mean of 4.06 per cent/g of wet wt. The turnover rate of glycogen pool in F. hepatica yielded a value of 0.073 +/- 0.008 micro M/hr/g of wet wt whereas in E. pancreaticum yielded only a mean of 0.006 +/- 0.002 mg/hr/g of wet wt. Therefore, the half time (t(2/1)) of glycogen turnover, which is the time interval required to replace the half of glycogen pool with medium C(14)-lactate, gave value of a mean of 10.73+/-0.76 days in F. hepatica. However, incorporation of C(14)-lactate into glycogen was negligible in the E. pancreaticum. Theses data impressed that the carbohydrate such as lactate may play a role of major part of their oxidative metabolism in F. hepatica, whereas minor part of lactate participates in the oxidative metabolism in E. pancreaticum.

Backscattering of Carbon-14 Beta Radiation

The backscattering of C14 beta particles by various substrates was investigated in connection with studies of radiostearic acid monolayers. Comparisons were made for backscattering from C14 and Tl204 (0.76 Mev) with a mica end-window Geiger-Muller counter under conditions of similar geometry, and the absorption (in aluminum) of the backscattered radiation was measured. Slight variations in the geometry of the source or counting arrangement may lead to significant differences in the observed backscattering, especially at low-energy radiation.