A simple read-out method of position signals for a two-dimensional proportional chamber has been investigated. The chamber has two parallel cathode planes and a multi-wire anode, the latter being placed at the mid-plane of the former. One of the cathodes is split into a number of strips at right angles to the anode wires to yield position information (Y-coordinate) perpendicular to the one obtained from the anode (X-coordinate) . Each anode wire is connected to two charge sensitive amplifiers through coupling capacitors, the capacities of which are weighted according to the position of the wire; that is, the i-th anode wire from one end is coupled to amplifiers A1 and A2 through capacities C1i and C2i, respectively, given by the following equations, C1i=Cx⋅i/ (n+1) and C2i=Cx⋅ (n+1-i) / (n+1), where n is the total number of the anode wires and Cx is the constant capacity. The set of C1i and C2i was formed by etching an epoxy print-circuit plate. The position signal is given by V1/ (V1+ V2), where V1 and V2 are the outputs of the amplifiers. A pulse ratio circuit is used to perform the calculation, when the energy signal, V1+ V2, passes a single channel pulse-height analyzer. The read-out of the Y-position signal is performed similarly from the cathode strips. Performance of the system was tested using 5.9keV X-rays from a55Fe source. The position resolution along the X-axis was restricted by the spacing of the anode wires, 3 mm, because most of the electron avalanches occur mainly near only one wire. The resolution along Y-axis was, however, not limited by the width of the cathode strips, 5 mm, and was far better than this. The reason for this is that the movement of positive ions toward the cathode strips induces signals on a number of the strips near the avalanche and an interpolation effect expected.
This paper describes a theoretical analysis of the influence of amplifier noise on the energy resolution and spatial resolution of a multi-wire proportional chamber using “weighted coupling capacitor method” in position signal read-out. The weighted coupling capacitor method is a kind of the pulse dividing methods: each anode wire (or cathode strip) is coupled to two charge-sensitive amplifiers through two capacitors, the capacities of which are weighted linearly to the position coordinate of the wire. The analysis shows that the fluctuation of the position signal due to the amplifier noise is proportional to the fluctuation of energy signal. If we assume that only the i-th anode wire delivers a charge, the fluctuation of position signal expressed in terms of standard deviation, σXA, is given by: σXA/LX=√i2- (n+l) i+ (n+1) 2/2/ (n+1) ⋅σEA/E (1) where Lx is the effective length of the chamber, E the energy imparted by radiation, σEA the fluctuation (standard deviation) of E, and n the total number of the anode wires. If we assume that the equivalent noise charge (rms-value) of the charge-sensitive amplifiers at the input is expressed approximately by A+B⋅Cext., where A and B are the characteristic constants of the amplifier and Cext. the capacity existing at the input, the fluctuation of energy signal, σEA, is given by: σEA =√2W/M⋅ [A⋅Cx+Cd/Cx+B⋅ (1+ 1/n+1) ⋅n⋅Cx/6+n⋅Cd/2 +λ⋅Ca/n+1] (2) where W is the W-value of the counting gas, M the gas multiplication factor, Cx the sum of capacities of the two coupling capacitors connected between an anode wire to the amplifiers (Cx is constant for all the anode wires), Cd the stray capacity between an anode wire and the cathodes, Ca the stray capacity between two adjacent wires, and λ a constant near unity. It can be seen, from Eq. (1), that the degradation of spatial resolution due to amplifier noise depends on the position of radiation incidnece and is minimal at the center of the chamber and maximal at both the end of it. It is also seen, from Eq. (2), that the effect of Ca is usually neglected when n>>1. It is important to note that Cx has an optimal value with which σEA and σXA are minimized. The optimal value of Cx, obtained from d (σEA) /dCx=0, is equal to [6A⋅Cd⋅ (n+1) / (n+2) ⋅n⋅B] 1/2.
As an analytical method of Pb-210 in environmental sample, the radioactivity of Bi-210 built up from Pb-210 after the electrode position of Pb on platinum plate from nitric acid solution was measured by using an aluminum absorber (8 mg/cm2), and the radioactivity of Pb-210 in the sample was determined by calculation from the counting rate of Bi-210 activity, the counting efficiency of Bi-210 activity, and the chemical recovery of Pb carrier. The separation of Pb-210 together with stable Pb carrier from the sample was based on the extraction of its iodide complex ion with methyl isobutyl ketone after the treatment of sample with HF and HClO4and on the reextraction of Pb in mehtyl iso-butyl ketone with 2N HNO3. By the above mentioned procedure, the recovery of Pb from nitric acid solution by electrode position was quantitative and the chemical recovery of Pb from soil was 82%. However, as the chemical form of Pb carrier deposited on the platinum plate was weighable PbO2, the radioactivity of Pb-210 in the soil sample could be determined by correcting the found counting rate with the ratio of the weight of Pb carrier added to that of Pb carrier found.
Various elements contained in human hair have been used for an index of environmental pollution effect to human beings. In this report, nondestructive neutron activation analysis was applied to hair samples on 61 inhabiLints at a local district which is free from air pollution. The hair samples were irradiated for 3 minutes or 15 hours (5 hours/day, 3 days) in TRIGA Mark II Reactor at Rikkyo University with a neutron flux of 1.5 × 1012 n/cm2/sec and the activities were measured by a Ge (Li) detector. The contents of 18 elements could be determined: Al, Br, Ca, Cl, Cu, I, Mg, Mn, Na, S and V with the 3 minutes irradiation method, and As, Au, Cr, K, La, Sb and Zn with the 15 hours irradiation method. Concentration-distribution histograms, differences in distribution patterns of these elements by permanent wave treatment, sex and age were discussed.
The conversion of external sugars to internal sucrose in morning-glory callus cells was investigated by administration of14C-glucose, 14C-fructose and14C-sucrose in the external medium, subsequent determinations of sugars and invertase in the medium and assays for intracellular distribution of some enzymes involved in sucrose biosynthesis. 1) 14C-glucose administration: In callus cells, the label first appeared in glucose, which remained at relatively low level. Sucrose was subsequently labeled to continue a remarkable steady increase. Fructose was labeled very weakly, suggesting that free fructose might not be involved in sucrose biosynthesis. Labels also appeared in sucrose phosphate, glucose phosphate and fructose phosphate. In addition equal amounts of label appeared in the glucose and fructose moieties of sucrose. It was, therefore, inferred that sucrose was synthesized via sucrose phosphate. 2) 14C-fructose administration: In further support of the above inference, the labeling patterns were similar to those in, i. e., 14C-glucose administration, except that fructose was more strongly labeled than glucose. 3) 14C-sucrose administration: In callus cells, sucrose was labeled subsequent to the monosaccharides and monosaccharide phosphates, it suggested that its direct penetration, if any, preceded by hydrolysis. 4) Intracellular distribution of the enzymes involved in sucrose metabolism: In cell wall fraction, acid invertase and acid phosphatase were presented. In cytoplasma fraction, acid and neutral invertase, hexokinase, glucosephosphate isomerase, UDPG-ppase, sucrose synthetase, sucrose-6-phosphate synthetase, and acid and alkaline phosphatase were present. Sucrose phosphorylase was not detected in both fractions. These results suggested that internal sucrose was synthesyzed via sucrose-6-phos-phate from external sugars and that, prior to sucrose penetration, external sucrose was hydrolized by cell wall-bound invertase. On a basis of these findings, a possible scheme for sucrose metabolism in callus cells was proposed.
Both67Ga and111In are concentrated in tumor and inflammatory lesions as well. Research in these regards was extended to radiopharmaceuticals that had recently been introduced: 169Yb-citrate, 99mTc-Pertechnetate, 99mTc-Bleomycin, and57Co-bleomycin. All of them revealed affinity to the experimental V2 carcinoma in the rabbit. Typhoid vaccine-induced, polymorphonuclear infiltrates also concentrated these radio-pharmaceuticals, too. Inflammatory concentration of the tumor-imaging agents would lead to a false positivity. However, it should also be bore in mind that inflammatory changes, bacterial or aseptic, accompanying the tumorous lesions would increase deposition of the agents in the such lesions.
The clinical application of57Co-bleomycin as the tumor scanning radio pharmaceutical was firstly reported by Nouel and Maeda respectively. We have been conducting studies on the diagnostic significance of this tumor scanning agent and the results obtained in 40 patients with malignant and non malignant lesions are here presented. Six and 24 hours after the injection of 500μCi of57Co-bleomycin, the scintigram was taken with a 3-inch scintiscanner. Positive scans were found in 20 cases out of 36 patients of various malignant tumors, among 20 patients with lung cancer, positive scans were obtained in 17 cases (85%) and among 6 of breast cancer, 3 cases showed positive scans. False negative scans were obtained in another 10 cases of malignant tumors (3 cases of thyroid carcinoma, 4 cases of hepatoma, 1 case each of gastric carcinoma, peritoneal carcinomatosis, and reticulum cell sarcoma) . In 4 patients of non malignant disease, one case of pulmonary tuberculosis showed positive scan. In 8 cases of lung cancer and 6 of breast cancer, relationship between the size of the excised tumor and scintigram findings was studied. The smallest tumor detected by scintigram was 2 cm in lung cancer and 3.2 cm in breast cancer.