Alanine Dosimeters Research Articles

Fast neutron irradiation effects—III. Sensitivity of alanine systems for fast neutron having an energy of ∼ 1 MeV

Relative G-values of alanine dosimeters for fast neutron with an energy of 1 MeV are determined to be 0.4 as compared with 60Co γ-ray irradiation. The values are almost independent of paraffin content. The neutron irradiation process in alanine dosimeter is discussed

A spectrophotometric readout method for free radical dosimetry

An accurate and inexpensive spectrophotometric readout method is given for free radical dosimetry. The stable free radicals in irradiated alanine/glutamine powder, when dissolved in a solution containing ferrous ammonium sulphate and xylenol orange in 0.05 N H 2SO 4(FX), oxidize ferrous ions and the xylenol orange forms a complex with ferric ions produced in the solution. The absorbance of the complex is measured at 525 nm for alanine and at 540 nm for glutamine. The influence of various parameters, such as size of the container, weight of the powder dissolved, xylenol orange concentration, purity of distilled water, postirradiation stability and dose-rate dependence on the response of the dosimetric technique, has been investigated. It was found that the dosimetric response is independent of dose-rate. Alanine does not show any significant postirradiation fading. Irradiated glutamine powder is stable for about a month, the fading is less than 2% up to three months later, and it increases to only about 5% over a period of six months. The reproducibility of the method is better than ±2%, and it offers an alternative to ESR and lyoluminescence techniques for free radical dosimetry. A dose of 0.01 to 4 kGy can be measured with an alanine dosimeter and 0.1 to 100 kGy with a glutamine dosimeter. Empirical relationships between absorbance and dose are given.

Fast neutron irradiation effects—I. Dosimetry

A dosimetry of mixed field, neutron and γ-ray, has been carried out by the activation method in a fast neutron source reactor “YAYOI,” which has been used for the study of fast neutron irradiation effects on organic materials and microorganisms. Neutron flux and energy distribution were obtained by an unfolding calculation based on the activation analysis. Absorbed dose was determined as a function of the distance from the center of the reactor core in a hole called “Glory Hole” used for irradiation of various materials. Contribution of absorbed dose from γ-rays coexisting with neutron was evaluated by measuring peroxide radicals formed in irradiated polytetrafluoroethylene, PTFE, which is insensitive to the neutron component. After evaluating the radiation field, relative sensitivities of popular dosimeters such as red acrylate, radiachromic, and alanine dosimeter for last neutron irradiation were determined by comparison with 60Co γ-ray irradiation. Characteristics of the mixed field dosimetry and LET effect of recoil protons in samples at different neutron fields are discussed.

Alanine Dosimetry of 14 MeV Neutrons in FNS Target Room

Click to increase image sizeClick to decrease image sizeKEYWORDS: alanine dosimeterMeV range 10–100neutron beamsmixed radiationsscattered neutronsgamma radiationgold foilactivationkermaabsorbed dosesneutron fluxESR measurementcharged particle equilibrium

Influences of physical parameters on high-level amino acid dosimetry

The effect on the fading of the dose-dependent ESR signals of irradiated alanine dosimeters resulting from the ambient influences of temperature, humidity and light were studied. Under non-extreme conditions the observed variations are smaller than 5% each and can be corrected for.

A comment on absorbed dose measurement in a mixed field of fast neutron and γ-rays by the fricke and ceric sulphate dosimeters

A dosimetry of mixed field, neutron and γ-ray, has been carried out by the activation method in a fast neutron source reactor “YAYOI,” which has been used for the study of fast neutron irradiation effects on organic materials and microorganisms. Neutron flux and energy distribution were obtained by an unfolding calculation based on the activation analysis. Absorbed dose was determined as a function of the distance from the center of the reactor core in a hole called “Glory Hole” used for irradiation of various materials. Contribution of absorbed dose from γ-rays coexisting with neutron was evaluated by measuring peroxide radicals formed in irradiated polytetrafluoroethylene, PTFE, which is insensitive to the neutron component. After evaluating the radiation field, relative sensitivities of popular dosimeters such as red acrylate, radiachromic, and alanine dosimeter for last neutron irradiation were determined by comparison with 60Co γ-ray irradiation. Characteristics of the mixed field dosimetry and LET effect of recoil protons in samples at different neutron fields are discussed.

ESR-resonance in doped GaAs and GaP

The feasibility of lithium lactate (Li-lactate: CH3CH(OH)COOLi) as an electron spin resonance (ESR) dosimeter material has been studied and compared with lactose and a conventional alanine dosimeter. The ESR spectra of Li-lactate and lactose with the spectroscopic splitting g-factors of 2.0029 ± 0.0003 and 2.0043 ± 0.0003 respectively show hyperfine splitting with an intensity ratio of 1:3:3:1 and hyperfine coupling constants (A/gβ) of 1.82 ± 0.06 and 1.88 ± 0.06 mT, respectively. The radical formation efficiency (G-value), i.e. the number of free radicals per 100 eV for alanine, Li-lactate and lactose were 0.95, 1.0 and 3.0, respectively. The sensitivity of Li-lactate to γ-rays is 10 times higher than that of alanine and 0.3 of lactose. The signal stability of Li-lactate was greater than that of lactose.

The Use of Alanine as a Solid Dosimeter

Electron spin resonance has been found to be a satisfactory technique for the calibration and measurement of radiation doses by means of alpha - alanine dosimeters. Powdered alpha -alanine dosimeters have been calibrated for the measurement of doses from gamma -, BETA -, proton, and x radiation in the range of l00 r to beyond l0/sup 5/ r. At low doses there are measurable differences in the number of free radicals created by each of the various types of radiation. The alpha alanine is less sensitive to x rays than to the gamma - rays, electrons, or protons studied so far. Plastic holders are satisfactory for measuring doses above l000 r. Below 1000 r, better results are obtained with glass holders. However, selected quartz is to be preferred for general usage because of freedom from residual signals. Further studies in this laboratory are being conducted with quartz holders designed for optimum sensitivity. For some dosemeters, Teflon holders are recommended, since the ma terial itself can be made into a possible dosimeter also. Dosimeters from alpha -alanine were found to be stable, having about 5% decay after 90 days. (auth)