Radiation dosimetry with acetylene

1971 ◽  
Vol 24 (10) ◽  
pp. 2053
Author(s):  
KG McLaren
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
No Value ◽  
Free Radical Scavengers ◽  
Lower Yield ◽  
Γ Irradiation ◽  
Dose Rates ◽  
Wide Range ◽  
Absolute Basis ◽  
Dose Rate Effect

The suitability of acetylene as a gas-phase radiation dosimeter has been studied. Yields were obtained on an absolute basis, using ionization current dosimetry. Radiolysis of acetylene produces two products, benzene and polymer. The yield of benzene is dependent on dose, dose rate, presence of hydrogen or free radical scavengers, and temperature, and is of no value for estimating dose. ��� For 60Co γ irradiation at a dose rate of 4.1 x 1013 eV cm-3 mmHg-1 hr-1 and acetylene pressure 500 mmHg (6.6x104 N m-2) at 30�C, G(-C2H2) = 82.1�0.5. ��� 1-MeV electron irradiation at a dose rate of 3.9 x 1016 eV cm-3 mmHg-1 hr-1 gave a much lower yield, G(-C2H2) = 55.0�1.9, believed to be due to a dose rate effect. G(-C2H2) increased by about 67% when the temperature was increased from 25�C to 125-250�C. ��� Comparison with ethylene indicates the latter is the more useful dosimeter, as the yields do not vary significantly over a wide range of dose rates and temperatures.

scholarly journals Serum Metabolomic Alterations Associated with Cesium-137 Internal Emitter Delivered in Various Dose Rates

Metabolites ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 270
Author(s):  
Heng-Hong Li ◽  
Yun-Tien Lin ◽  
Evagelia C. Laiakis ◽  
Maryam Goudarzi ◽  
Waylon Weber ◽  
...  
Keyword(s):  
Dose Rate ◽  
Cumulative Dose ◽  
Low Dose ◽  
Biological Effects ◽  
Serum Samples ◽  
Dose Rates ◽  
Sphingosine 1 Phosphate ◽  
Cesium 137 ◽  
Dose Rate Effect ◽  
Medium Dose

Our laboratory and others have use radiation metabolomics to assess responses in order to develop biomarkers reflecting exposure and level of injury. To expand the types of exposure and compare to previously published results, metabolomic analysis has been carried out using serum samples from mice exposed to 137Cs internal emitters. Animals were injected intraperitoneally with 137CsCl solutions of varying radioactivity, and the absorbed doses were calculated. To determine the dose rate effect, serum samples were collected at 2, 3, 5, 7, and 14 days after injection. Based on the time for each group receiving the cumulative dose of 4 Gy, the dose rate for each group was determined. The dose rates analyzed were 0.16 Gy/day (low), 0.69 Gy/day (medium), and 1.25 Gy/day (high). The results indicated that at a cumulative dose of 4 Gy, the low dose rate group had the least number of statistically significantly differential spectral features. Some identified metabolites showed common changes for different dose rates. For example, significantly altered levels of oleamide and sphingosine 1-phosphate were seen in all three groups. On the other hand, the intensity of three amino acids, Isoleucine, Phenylalanine and Arginine, significantly decreased only in the medium dose rate group. These findings have the potential to be used in assessing the exposure and the biological effects of internal emitters.

Ion lifetimes in irradiated gaseous HCl

1967 ◽  
Vol 45 (24) ◽  
pp. 3079-3082 ◽  
Author(s):  
D. A. Armstrong ◽  
R. A. Back
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Gamma Rays ◽  
Half Life ◽  
Field Method ◽  
Dose Rates ◽  
Phase Combination

An intermittent-field method has been used to measure ion lifetimes in gaseous HCl during irradiation by gamma rays under conditions of pressure, dose rate, and vessel geometry similar to those employed in radiolysis studies. At 23 °C, with HCl pressures from 119 to 660 Torr and dose rates from 5.5 to 86 × 1010 eV cc−1 s−1, the ion half-life ranged from 6 to 30 ms. The dependence on dose rate and pressure strongly indicated that ion neutralization occurred almost entirely in the gas phase. Values of α, the gas-phase combination coefficient, were calculated; at pressures above 246 Torr the value was constant and equal to 3.1 ± 0.3 × 10−6 cc ions−1 s−1. The addition of SF6 had little effect on α, while reducing the temperature to −79 °C increased α to 5.1 × 10−6.

Radiation protection in irradiated dimethylsiloxane polymers

1963 ◽  
Vol 273 (1352) ◽  
pp. 117-132 ◽  
Keyword(s):  
Protective Effect ◽  
Dose Rate ◽  
Reaction Mechanisms ◽  
Radical Reactions ◽  
Gas Evolution ◽  
Dose Rates ◽  
Dose Rate Effects ◽  
Rate Effects ◽  
Colloidal Sulphur ◽  
Dose Rate Effect

Small concentrations of certain additives can greatly modify the effects produced by radiation of macromolecules such as polymers and biological systems. Various mechanisms of protection can be envisaged, and these lead to different kinetics in protection effects. Most published work studies the elimination of the additive, rather than the change in the macromolecule. In previous papers in this series, the dose rate effects expected for radical reactions were observed for anthracene solutions in hexane and cyclohexane. With anthracene in dimethylsiloxane polymers, however, no such dependence was observed. This problem is studied in greater detail in the present paper. The additives studied were anthracene, iodine, sulphur and benzophenone, and their protective effect on the crosslinking of dimethylsiloxane polymer was investigated a t various dose rates. Contrary to generally accepted views on reaction mechanisms no dose-rate effect was observed; anthracene provided no protection against crosslinking, although it was itself destroyed. Iodine and colloidal sulphur provided a considerable measure of protection, but had no effect on gas evolution. Benzophenone also offered protection, but also reduced the gas yield. To explain these very different patterns of behaviour, it is necessary to modify some present views on the nature of the protection offered; this leads to a discussion as to the mechanism of crosslinking.

Ion lifetimes in gaseous radiolysis systems

1967 ◽  
Vol 45 (24) ◽  
pp. 3071-3078
Author(s):  
C. J. Wood ◽  
R. A. Back ◽  
D. H. Dawes
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Applied Field ◽  
Wave Period ◽  
Ion Currents ◽  
Square Wave ◽  
Dose Rates ◽  
Phase Combination

A technique is described for measuring ion lifetimes in irradiated gases. Gases were irradiated continuously, and lifetimes were determined by measuring average ion currents, obtained with an intermittent square-wave applied field, as a function of square-wave period. The dose rates, pressures, and vessel geometry were similar to those commonly used in radiolysis experiments, so that the information obtained can be applied directly to an understanding of radiolysis mechanisms. The theory of the method and analysis of ion-loss processes are discussed in some detail.Measurements in oxygen at pressures from 30 to 300 Torr and dose rates from 1.5 to 56 × 1010 eV cc−1 s−1 gave mean ion lifetimes ranging from 0.014 to 0.082 s. The dependence of lifetime on dose rate and pressure indicated that ion loss under these conditions was almost entirely by gas-phase combination. Values of α, the gas-phase combination coefficient, are compared with those measured by other methods.

Isotope effects in the gas phase radiolysis of H2S and D2S

1976 ◽  
Vol 54 (17) ◽  
pp. 2767-2772
Author(s):  
Robert D. McAlpine ◽  
O. A. Miller ◽  
A. W. Boyd
Keyword(s):  
Dose Rate ◽  
Gas Phase ◽  
Isotope Effects ◽  
High Dose ◽  
Dose Rates ◽  
Kinetic Isotope ◽  
A Value ◽  
Straight Line ◽  
Separation Factors ◽  
Very High

Gas phase radiolysis studies have been carried out on mixtures of H2S and D2S using as irradiation sources, either a Gammacell or a Febetron 705 pulsed electron accelerator. Separation factors (α = (H/D)prod ÷ (H/D)react) were obtained for various values of xD (the mole fraction of D2S), dose rate and temperature, as well as with the addition of SF6. All of the observed α values, for 0.2 ≤ xD ≤ 0.8, fall on the following empirical straight line.[Formula: see text]The addition of neon to a D2S/H2S mixture gives a value of α which decreases as the partial pressure of neon increases. For a 70% D2S/30% H2S mixture, &([a-z]+); = 1.9 ± 0.1 for the pure mixture and 1.28 ± 0.08 when 90 kPa of neon has been added to 10 kPa of the mixture. The &([a-z]+); values described by eq. 1 are interpreted as arising from kinetic isotope effects in the reactions of (translationally) hot H or D atoms with H2S, HDS, or D2S to form H2, HD or D2.Hydrogen yields from the gas phase radiolysis of pure H2S and pure D2S have been determined for dose rates from 4 × 1016 to 2 × 1028 eV g−1 s−1. Using dose rates of up to 2 × 1027 eV g−1 s−1, ΔG = G(H2) − G(D2) = 0.5. For the highest dose rate used (2 × 1028 eV g−1 s−1), ΔG = 1.5. The larger value of ΔG at very high dose rates is thought to arise from the dissociative neutralization processes. A possible mechanism is discussed.

scholarly journals The effect of dose-rate on the yield of translocations and dominant lethals following spermatogonial irradiation of mice

1964 ◽  
Vol 5 (3) ◽  
pp. 468-472 ◽  
Author(s):  
R. J. S. Phillips ◽  
A. G. Searle
Keyword(s):  
Dose Rate ◽  
Low Dose ◽  
Previous Experiment ◽  
Male Mice ◽  
Dose Rates ◽  
Neonatal Lethality ◽  
Full Explanation ◽  
X Irradiation ◽  
Dominant Lethals ◽  
Dose Rate Effect

1. F1 (CSH♀ × 101♂) male mice were given 1200 r. 60Co Υ-irradiation over welve weeks and mated twelve weeks after the end of irradiation. The incidences of foetal and neonatal lethality and of semi-sterility in their offspring were compared with those in controls.2. Embryonic survival to 15 days in the irradiated series was 98·2% that of controls, while the incidence of semi-sterility was 0·9% compared with nil in the controls. Neither of these differences is significant.3. Comparison of these results with the significant rates of induction of dominant lethals and translocations in a previous experiment, in which a dose of 1200 r. acute x-irradiation was given to males of the same hybrid stock, show the existence of a dose-rate effect. Its magnitude cannot at present be accurately estimated.4. The reasons for this effect are discussed. It is concluded that the main cause of the lowered translocation yield is that restitution of breaks will be favoured at low dose-rates, with less opportunity for the formation of interchanges. This could partly account for the lowered rate of induction of dominant lethals as well, but a full explanation is not yet possible.

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