Cellulose Nitrate Detectors Research Articles

Accumulation rates of manganese nodules and sediments: An Alpha Track Method

Autoradiographs of the total alpha activity distribution in slices through manganese nodules can be used to determine growth rates and to investigate the mode of incorporation of alpha emitters into nodules. Total alpha vs. depth profiles, measured with high resolution by counting alpha tracks in cellulose nitrate detectors, are almost always exponential and apparently record nodule growth. Accumulation rates determined by 230Thex measurements are in approximate agreement with the alpha track measurements. Sediment accumulation rates may also be measured by this technique.

α-microdosimetry in bone sections by means of dielectric track detectors and electronic image analysis

The track diameter kinetics and variation of efficiency with etching time for 20°C and 30°C etching temperature were determined for cellulose nitrate detectors and explained theoretically. With planar 239Pu sources and bone slices of varying thickness the efficiency as function of source-detector distance was measured and allowed the computation of a factor converting track density to dose rate for tissue sections with arbitrary thickness. Moreover, the dependence of selfabsorption on the thickness of the bone section and of the absorber was evaluated. The scan of a bone section from the femur of a rat injected with 241Am demonstrates the application of the procedure for dose rate determinations with an image analysing system.

Microphotometry as a tool for automatic scanning of solid state nuclear track detectors.

By use of a scanning microphotometer the light transmission with both dark field and bright field illumination was determined as a function of the alpha-track density on cellulose nitrate detectors. The so obtained calibration curves allow a rapit measurement of the number of tracks per field and, thus, of the dose rate. To illustrate the application of the method, a scan of a detector exposed on a bone section of a rat injected with 241Am is presented.

Investigations on energy resolution in detecting alpha particles using a cellulose nitrate detector

The influence of the etching process and the error of the microscopic measurement on the energy resolution has been investigated. Energy resolution in the range from 3.5 to 6.0 MeV has been found to be about 48 keV. This method of energy determination can be used for alpha particles with energies greater than 2.7 MeV. The energy range which may be evaluated in a single etching process amounts to 800–1000 keV. The efficiency covers a span from 7.8% to 14.1% depending on the energy of the particles.

Energy spectrometry of protons by means of a dielectric track detector

The energy resolution of a cellulose nitrate detector has been investigated in a range from 500 to 1600 keV. The full width at half-maximum (fwhm) has been found to improve from 50 to 25 keV with increasing energy.

Diameter evolution of proton tracks in a cellulose nitrate detector

The diameter evolution of etch pits initiated by protons with energies in a span of 300 to 1000 keV is described. The registration threshold of the cellulose nitrate detector used is about 700 keV.

Influence of thermal effects on the track registration characteristics of plastics

Abstract Thermal effects can alter the physical and chemical parameters of the latent tracks and bulk material of dielectric track recorders, consequently those of the etched track pits too. A few characteristics of this thermal track-fading effect have been studied in various plastic track detectors irradiated with lightly and heavily ionizing nuclear particles. Experimental data are given for the influence of different annealing conditions on the diameter of etch pits and the bulk etch rate of plastics. The possibilities of the eradication of alpha-particle background and the selective thermal track discrimination in cellulose nitrate, cellulose acetate and polycarbonate detectors have been studied. Few practical applications of the thermal track fading are also presented.

Use of cellulose nitrate for alpha autoradiography

Plastic- and specimen-supported cellulose nitrate detector films were employed in the alpha autoradiography of metallographic specimens containing uranium and plutonium. For autoradiographs made with plastic-supported film, the film was removed from the specimen prior to developing in 6 N sodium hydroxide. For autoradiographs made with specimen-supported film, the film was developed directly on the polished surface of the specimen. The specimen-supported detector film was placed on the surface of the specimen by one of two methods: (1) dropping a 5.5% solution of pyroxylin (form of cellulose nitrate) in amyl acetate onto the surface, or (2) wetting or fixing onto the surface a film of cellulose nitrate which had been stripped from a glass plate. Finer alpha tracks were obtained by developing the exposed cellulose nitrate in 6 N sodium hydroxide at room temperature rather than at 50–60°C. Resolution of the cellulose nitrate detector film was improved by use of a 0.00045-in aluminum absorber between the specimen and the film.

Fission products in the atmospheric precipitation in debrecen, hungary, during 1968 and 1969

Observations concerning the beta activity of fission products in the atmospheric precipitation were continued during 1968 and 1969. The annual sum of beta activity in these two years was double and triple that in 1967, respectively. Some samples demonstrated exceedingly high specific activity in the summer of 1969. In these samples it was possible to localize alphaactive hot particles by means of cellulose nitrate detector foil.