Yuko Murase

Excitation functions and yields for the production of 87mY and preparation of a 87mSr generator

Abstract Excitation functions and thick-target yield curves have been measured by means of the stacked foil technique for 3He and 4He reactions producing 85 Y , 85m Y , 86m Y , 87m Y and 88Y for rubidium chlori It has become apparent that the radionuclides of yttrium that pose a problem as contaminants are 85Y and 85mY, although it has not been reported in the past. Considering the results obtained, the optimum bombarding conditions to maximize the yield of 87mY and minimize the yields of contaminant were proposed. In order to make the chemical processing method quantitative, the distribution coefficients, D, of strontium and yttrium between an anion-exchanger resin and 0.5% citric acid solution were measured. Based on the results obtained a simple and reliable anion-exchange method was developed to provide a 87Y−87mSr generator.

The zero detection threshold of a liquid scintillation spectrometer and its application to liquid scintillation counting

Abstract The zero detectin threshold of a liquid scintillation spectrometer is found to be 2.4 ± 0.10 keV below zero pulse-height by measuring standardized 3H samples with a commercially-available liquid-scintillation spectrometer. Based on the results, a high accuracy modified integral counting method which extrapolates the integral pulse-height spectrum to the zero detection threshold is proposed.

Effect of air luminescence counts on determination of 222Rn by liquid scintillation counting

Abstract The pulse-height distributions from known amounts of 222 Rn and its daughters were measured as a function of the volume of the scintillator solution and compared with the air luminescence spectrum from α-particles in air. The results indicate that 222 Rn and its daughters in the gaseous space above the liquid scintillator produce the air luminescence counts which lead to errors in quantitative determination of 222 Rn by liquid scintillation counting unless necessary corrections for the counts are made. The error inherent in the conventional determination of 222 Rn by liquid scintillation counting is evaluated. Methods for correcting the air luminescence counts are discussed.

Determination of air luminescence spectra for alpha-emitters with liquid scintillation spectrometers

Abstract Air luminescence spectra have been measured for 210 Po, 238 U and 241 Am with two commercially available liquid scintillation spectrometers. Since the measured end-point of the air luminescence spectra is approx. 18 keV, they can be determined by liquid scintillation counting in the 3 H detection region. The average counting efficiencies measured with the two counting systems were found to be 33.3 and 33.7%, respectively. The air luminescence effect on liquid scintillation counting of gaseous α-emitters is mentioned.

The effect of temperature on fluorescence for liquid scintillators and their solvents

The pulse-height distributions for 241Am and 131mXe in PPO solutions of the aromatic hydrocarbons, i.e. benzene, o-xylene, m-xylene, ethylbenzene and cumene are found to shift toward higher pulse-heights with decreasing temperature. Under u.v. excitation, the fluorescence intensity of these pure aromatic hydrocarbons increases markedly and the fluorescence maximum is found to shift to longer wavelengths with decreasing temperature. In conjunction with observations of the pulse-height shift in liquid scintillators and the fluorescence emission from the pure solvents, the pulse-height shifts observed are interpreted in terms of excimer formation in the aromatic hydrocarbons.

A modified integral counting method and efficiency tracing method for measuring 222Rn by liquid-scintillation counting

Abstract The integral counting method of liquid scintillation counting has been modified by extrapolating the integral pulse-height spectrum to the zero detection threshold of the liquid-scintillation system rather than to the zero pulse-height, and applied to the determination of 222 Rn samples. The results have been compared with those obtained by the conventional integral counting method and the efficiency tracing method. The modified integral counting method gives more accurate results than the conventional integral counting method and the efficiency tracing method. The possibilities and limitation of the efficiency tracing method has been discussed.

Assay of 222Rn in water samples by a modified integral counting method

22Rn activity concentrations in water collected from 163 private wells and 14 springs in Tokyo were measured with a liquid scintillation spectrometer using a modified integral counting method. The activity concentrations of 222Rn range from 0.2 to 22.9 Bq/L and average 4.8 Bq/L. The errors due to the air luminescence counts and the interferences from 220Rn and 219Rn are discussed and evaluated. 222Rn samples of 0.2 Bq/L can be assayed within an overall uncertainty of 3.1%. The liquid scintillation method involving agitation of the sample water directly with a liquid scintillation cocktail was compared with the present method and evaluated.