Glass dosimeter

Radiation ecologists have attached various types of dosimeters to small animals in an attempt to estimate the radiation dose. Kaye (1965) studied the use of silver-activated metaphosphate-glass dosimeters, which measure dose by radiophotoluminescence, in ecological research at Oak Ridge National Laboratory. These solid-state dosimeters, measuring 1x6 mm, were injected subcutaneously into cotton rats (Sigmodon hispidus) (Figure 19a). The rats were... 

Bochvar, I. A., I. B. Keirim-Markos, and A. A. Moiseyev. 1971. Using thermoluminescent alu-mophosphatic glass dosimeters in experimental investigations, pp. 223-230. In Methods of Radioecological Investigations (I. N. Verkhovskaya, ed.). Atom Press, Moscow (in Russian). 

Impinger preceded by filter Glass fibre filter Impinger or fritted bubbler Miscellaneous sampler (dosimeter etc.)... 

For most quantitative work in TLC the sample is applied to the layer using a fixed-volume dosimeter comprising a platinua-iridium capillary of 100 or 200 nl volume, sealed into a glass. . support capillary of larger bore [6]. The capillary tip is... 

Cellophane dosimeter strips from beneath the treated samples were then compared with the control piece from the same section of a roll. In all tests, there was clear evidence that penetration had occurred. At the higher energies, there was evidence of secondary effects—backscattering and possibly, secondary emission. The discoloration of the glass slides showing fairly sharp delineation between the uncovered and covered portions gave useful visual evidence of what had occurred. 

To calibrate the cobalt source, three systems are most often used ferrous sulfate, ferrous sulfate-cupric sulfate, and ceric sulfate. Dosimeters of these solutions are prepared by filling 5-ml. chemical-resistant glass ampoules with approximately 5 ml. of solution and flame-sealing the ampoules. The ampoules are then arranged in phantoms of Masonite or similar materials (Figure 13) to simulate the food items. These phantoms are placed in containers similar to those used for food products, and arranged in the conveyor carrier in which they are transported into the irradiation cell. Because of the upper dose limit of the ferrous sulfate and ferrous sulfate-cupric sulfate dosimeters (40,000 and 800,000 rads, respectively), these systems can be used only to establish the dose rate in the facility and not to monitor the total dose during food irradiation. The ceric dosimeter which... 

For metal, dielectric and semiconductor films fabrication, optical and silica glass are popular substrate materials because of their availability, cost-effectiveness, and inert character, i.e., they are stable in the required temperature range for common photonic, optoelectronic and photovoltaic applications, they do not chemically react with the prepared films, and the hard plane surface makes the formation of optically smooth thin films fairly easy. Generally, it is preferable to form films by a simple, low-temperature, inexpensive and environment friendly method. Sol-gel technique and thermal evaporation is found suitable for the preparation of film parts of efficient solar cells [1], emitters, transformers [2], detectors and modulators of light [3], as well as optically stimulated luminescence dosimeters [4]. Here, we present the experimental data on the resistance to high-power optical and ionizing irradiations of the undoped components of film compositions with nanociystais. 

C. Description and Use. Each individual will be issued a DT236/PDR-75 dosimeter. This device, worn on the wrist, contains a neutron diode and a phosphate glass gamma detector. When a determination of exposure is required, the dosimeter is inserted into a CP-696/PDR-75 reader, which then displays the cumulative neutron and gamma dose. 

Radiolysis and Photolysis Techniques. The source of ionizing radiation was a 50-Kev. x-ray unit, operated at peak energy and 50-ma. current. The radiolysis vessels were spherical borosilicate glass flasks (1000 cc.) into which thin bubble windows were blown of thickness on the order of 20 mg./sq. cm. These vessels were fitted with calibrated volumes to facilitate determination of absolute yields. The majority of irradiations were conducted at a gas pressure of 357 mm. Hg, although several experiments at a pressure of 40 mm. Hg are also reported. Using a nitrous oxide dosimeter (15, 38) the dose rate for ethyl chloride at 357 mm. Hg pressure was determined to be 1.2 X 1018 e.v./min. 

Dosimetry is the measurement of absorbed dose. The unit of absorbed dose is the gray (Gy). Because dose is a measure of absorbed energy, calorime-try is the fundamental method of measurement. However, calorimetry suffers from being insensitive, complex, slow and highly demanding in technical skills and experience. Primary dose measurement is usually done with substances that are chemically changed quantitatively in response to the amount of radiation absorbed. For most purposes the standard primary system is the Fricke or ferrous sulfate dosimeter. In this system, which consists of a solution of ferrous sulfate in dilute sulfuric acid, ferrous ions Fe are oxidized by absorbtion of radiation to ferric ions Fricke dosimeters are usually presented in glass... 

Irradiation Procedure. Irradiation was carried out with a Siemens x-ray set operated at 220 kv. and 20 ma., with 2 mm. Al filtration. The sample solutions in irradiation vessels of borosilicate glass (23) were flushed with appropriate gases before and during irradiation. The dose rate for each irradiation vessel was determined with the Fricke dosimeter (36), assuming 15.5 molecules of Fe3+ (36) formed per 100 e.v. absorbed energy. The dose rate was 1.94 krad min."1. 

The dosimeter is rather insensitive to impurities and standard sealed glass-ampules can be used as irradiation cells. 

The neutron bubble detector (trade name BD-IOOR) is a reusable, passive integrating dosimeter that allows instant, visible detection of neutron dose. The bubble detector consists of a glass tube filled with thousands of superheated liquid drops in a stabilizing matrix. When exposed to neutrons, these droplets vaporize, forming visible permanent bubbles in an elastic polymer. The total number of bubbles formed is proportional to the neutron dose equivalent H. The bubbles can be counted manually or by a machine. Figure 16.15 shows the response of the bubble detector as a function of neutron energy. 

The amount of radiation energy absorbed in a substance is measured with dose meters (or dosimeters). These may react via a variety of processes involving (a) the heat evolved in a calorimeter, (b) the number of ions formed in a gas, (c) the chemical changes in a liquid or in a photographic emulsion, and (d) the excitation of atoms in a glass or crystal. The first two ones are primary meters in the sense that they can be used to accurately calculate the exposure or dose absorbed from a radiation source. They can be used to calibrate the secondary meters. 

Hold the dosimeter up to a light source with the glass end or top of the dosimeter near the eye and read the dosimeter. The dosimeter should have a line against the scale showing either roentgens or milliroentgens. The dosimeter should read near zero but may have had some drift. 

A personal NO dosimeter employs trapping of the gases on a glass filter impregnated with sodium dichromate and sulfuric acid (NO is oxidized to NO2), followed by passage of the NO2 through a silicone rubber membrane into an acidic solution of hydrogen peroxide in which nitrate is formed and measured by a nitrate ISE. 

Silver/aluminium phosphate glasses of this kind have an important application in dosimeters for y-rays, since the intensity of induced fluorescence can be related to the amount of radiation received. 

The dosimeter containers are usually sealed glass ampoules of 2-5 cm capacities. Fe ion concentration is measured in a spectrophotometer at the absorption maximum of these ions, at 304 nm. The dose is determined from the increase of optical absorbance, AA ... 

Figure 19. Glass-roddosimeter insertion in cottonratsfSig/mM/on/rfjpiJujjandresults. (a) Subcutaneous insertion of glass-rod dosimeter in the field. The glass rod is in a nylon capsule held in the orifice of the implantation needle, (b) Average absorbed dose rate for 38 cotton rats on the radioactive White Oak Lake bed. (c) Exposure rate above the radioactive White Oak Lake bed. Toshiba low-Z rods were tied at 1-ft intervals to a nylon cord affixed normal to the soil surface. Each rod was contained in a small nylon capsule (wall thickness 0.047-inch). From Kaye (1%5). Copyright 1%5 by The Ecological Society of America.

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