1-[125I]Iodo-[114C]dodecane was prepared using the phosphorus halide/alcohol-reaction. Since the conventional synthesis of iodoalkanes requires apparatus and procedures which do not conform to radioprotection standards, a new apparatus was also constructed. Apparatus and method can also be used for the synthesis of other halogen-alkanes.
Photon attenuation coefficients in certain tissue equivalent compounds, perspex, polyethylene, polycarbonate and teflon are measured at energies 13.37, 17.44, 22.10, 32.06 and 44.23 keV. Agreement is within a few percent (∼3%) between the theory and experiment, thus supporting the sum or mixture rule to estimate the attenuation coefficients in compounds theoretically from those of the constituent elements approximately. From the measured coefficients the effective atomic numbers for total photon interaction in these compounds are derived. It is noticed that, in general, the effective atomic number decreases as the energy increases.
The d-glucosazine ligand was synthesized in absolute methanol and its u.v. and i.r. spectra recorded after extensive purification from unreacted reagents. A new Tc-d-glucosazine complex was prepared following different routes that consisted of either a one-step or a two-step synthesis or a ligand exchange reaction. Complex composition and stability in aqueous media were examined through u.v. spectra. Experiments on ligand exchange reactions suggested that Tc(V) is the most likely oxidation state of the metal in the complex.
Narrow beam mass attenuation coefficients, μ/ρ, of 320 keV photons, emitted from the 51Cr radioisotope have been measured in various high Z materials such as Pb; BiPO4; (CH3COO)2·Pb·3H2O; Pb(NO3)2; Na2WO4·2H2O, using a broad beam geometrical configuration, employing a 2′' × 1′' (5.1 cm × 2.54 cm) (0.051 m × 0.025 m) NaI (Tl) detector spectrometer system coupled to a 1 k multichannel analyser. The measured μ/ρ values in cm2/g for the above materials in the transmission range from 50% to 20% respectively are 0.34 ± 0.01 (0.35); 0.295 ± 0.002 (0.30); 0.23 ± 0.01 (0.24); 0.256 ± 0.003 (0.26); 0.255 ± 0.003 (0.256). The values given in parentheses are estimated theoretically from the mixture rule using tabulated values of Hubbell (1982). It is observed that for high Z compounds at low energies, the exponential law of attenuation will be valid even for a broad beam set up in the transmission range from 50% to 20%. The attenuation coefficients of elements derived from this method agree fairly well with the tabulated narrow beam attenuation coefficients indicating the validity of the mixture rule in this region of transmission.
The peak-free spectrum Ib(n) can be obtained by transform of initial spectrum I(n), where is the operator of linear smoothing and q ≈ 0.5 σ if m = 1 and q ≈ 0.2 σ2 if m = 2, σ is the full width at half maximum for peaks.
In the present work, a set of soda glass slides in the form of a stack has been exposed normally, as well as at an angle of 60° w.r.t. the detector surface, to 238U and 56Fe ions with energies 144 and 199 MeV/n respectively from the heavy ion accelerator (BEVALAC) at Berkeley, U.S.A. After opening the stack, the slides have been etched under optimum etching conditions. The variations of track diameter and other parameters with the etching time have been studied and also the total range for these ions has been determined. Theoretical calculations of stopping power and range for these ions, as well for some other heavy ions in different media have been made using the formulations of Benton and Henke, Mukherjee and Nayak, Ziegler and Manoyan and Hubert et al. Finally a comparison has been made with the experimental results.
ESR spectral analysis of γ-ray irradiated lyoluminescence (LL) phosphor powder, Tris (hydroxymethyl) aminomethane—referred to as ‘Tris’ showed the presence of two free radical species. It was observed that at higher exposure levels radical II with a singlet spectrum shows a higher growth compared to radical I with a three component spectrum. Radical I had been identified as RĊHOH. The ESR-LL correlation studies indicate that the RĊHOH radical formed in a low dose range is responsible for LL emission and the radical II either inhibits or does not have any role in the LL process. The LL yield of Tris measured under deoxygenated conditions showed a 40% reduction in the yield in luminol solution and 87% in distilled water. The range of linearity of the γ-ray response extends further from 200 to 2000 Gy when the LL is measured under oxygen equilibrated condition.
Based on the results observed, two models for the mechanism of LL in Tris have been proposed. The first LL model of Tris envisages the production of a dinegative luminol molecule and a restored Tris molecule when the LL enhancer luminol is used as the solvent. This is based on the hydrogen abstraction reaction of the RĊHOH radical. The luminol dianion reacts with O2 to produce the excited singlet state of the aminophthalate ion which gives the LL emission. The second model proposes that the oxidation of RĊHOH radicals will yield organic peroxy radicals which in turn produces hydroperoxy (HO2) radical and a superoxide anion. The HO2 disproportionates, or reacts with the superoxide anion to give a singlet oxygen. The LL process in distilled water is probably due to the liberation of these singlet oxygen molecular pairs which are chemiluminescnt. H2O2 which is also produced on the disproportionation of HO2, or one of the interconversion products OH, can also oxidize the luminol molecule to give the emission. The LL saturation, and subsequent reduction at the increasing free radical concentration, are also discussed.
Relative γ-ray intensities in the decay of 160Tb were precisely measured using two semiconductor detectors. These intensities were used to calculate particle and γ-ray emission probabilities along with their corresponding uncertainties by employing equations derived with standard mathematical error propagating technique (Browne, 1986, 1988).
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