We improved procedures to analyze boron contents in volcanic rocks by using neutroninduced prompt γ-ray. The improvements include: (1) calculation of boron peak area only for the high energy half portion to avoid sodium peak overlap effect, (2) increase of sample weight by using pressed powdered pellets to save irradiation time, and (3) correction of count rate fluctuations and effect of sample geometry using silicon as an internal standard. Precisions of the 3-4 determinations of boron in GSJ (Geological Survey of Japan) volcanic standard rocks were less than 9 %. Our boron analyses agree well with the recommended values.
A digital signal processor (DSP) based position calculation circuit was developed and tested for beta camera. The position calculation circuit uses four analog-to-digital (A-D) converters for A-D conversion of the four analog signals from a position sensitive photomultiplier tube (PSPMT) . The DSP reads the four A-D signals and calculates the ratio of Xa/ (Xa+Xb) and Ya/ (Ya+Yb) in event by event basis. The DSP also magnifies the image to fit the useful field of view (FOV) and rejects the events out of the FOV. The line artifacts in the image due to the differential non-linearity of the A-D converters was almost eliminated.
In order to evaluate the influence of external particulate matters on the trace element concentrations in the soft parts of mussels, kept and not-kept samples and the excreta after keeping were analyzed by neutron activation analysis. The concentrations of major constituents of rocks, Al, Ca, Mg, Fe, K, andNa, were markedly high in the excreta, and the differences betweenAl, Ca, Cr, Fe, K, MnandScconcentrations in the soft parts of the kept and not-kept mussels were significant at a significance level of 0.01. The amount of particulate matters contained in the not-kept mussels was estimated to 20mg/gdry soft part. In addition, reported data were compared with ours, and a possibility of some overestimations ofScandFein the reported data was demonstrated, suggesting the importance of the keeping treatment in the monitoring of sea water quality by mussel analysis.
The purpose of this study is to estimate the energy response of a SKIN DOSE MONITOR (SDM model 104-101), which was developed to measure and assess medical exposure conveniently. The energy responses of pre-calibrated sensors were estimated by comparative measurements in the same calibration fields with sensors calibrated by Japan Quality Assurance Organization. The relative energy responses obtained for the precalibrated sensors agreed approximately with those of the calibrated sensors. The differences of the calibration factors in different calibration fields for the pre-calibrated sensors were 5 percent at the most in the range from 30keVto 40keVof effective energies. The sensor and coupling optical fiber of the SDM are faintly visible on a radiograph taken under ordinary operating conditions. The influence on diagnosis of this phenomenon is to be considered hereafter.