Flow Proportional Counter Research Articles

537. ガスフロー比例計数管用の計数系

A counting system for use with gas flow proportional counters has been examined and the advantages are discussed of a specially developed pre-amplifier of current to voltage conversion type. The system proposed, embodying a conventional voltage amplifier as main amplifier, retains the advantages of the current mode signals from a flow counter. The present method has the further convenience of using a commonly adopted general purpose voltage amplifier with pole/zero cancellation, a base-line restorer, and other nuclear instrument modules (NIM).Good plateau characteristics were obtained for both α- and β-particles from RaDEF source with double and triple differentiation pulse shaping. Furthermore a slope of less than 0.1%/100V was obtained with 32P source at a counting rate of 2, 000cps. A noise level of 0.03μA peak-to-peak was realized without particular selection of transistors permitting detection of 2-3 ion pairs of ionization.

Fluorescent X-ray spectrometric analysis of oxygen

A fluorescent X-ray analysis was applied to determine the oxygen in both organic and inorganic compounds. A Rigakudenki vacuum path single channel X-ray spectrograph (D-9C, SX type) with a sealed Rh target X-ray tube (3 kW) and lead myristate (2d= 80.5 A) as an analysing element was used for the determination of oxygen. Exited O Kα was measured by a gas flow proportional counter with aluminum coated 1 μ thick polypropylene film window.Calibration curves were prepared from appropriate standards of both organic and inorganic reagents. Typical conting rate of O Kα spectra for boric acid, lithium carbonate and magnesium oxide were 2326, 145 and 103 counts/sec. and reproducibility expressed as standard deviation of measured intensities were 0.39%, 0.51% and 0.88%, respectively.

Eine einfache apparatur zur gasversorgung von durchflussproportionalzählrohren bei beliebigem betriebsdruck

Stabilization of gas pressure in flow proportional counters is an important problem since for example a relative variation of gas pressure of only 2.2 × 10 −3 induces a change of gas gain of 1% under optimal operating conditions (defined by the maximum possible gas gain within the range of proportionality). This paper describes the construction and operation of a simple apparatus which reduces the variation of gas gain to less than 1% and which functions as a pycnostat under changes of temperature.

Dip counting of aqueous solutions of tritiated sodium dodecyl sulfate using a thin end window poly(mono-chloro-p-xylylene) flow proportional counter

This investigation describes the determination of the adsorption of tritiated sodium dodecyl sulfate (TNaDDS) from aqueous solutions at the poly(monochloro-p-xylylene) interface by dip counting. The TNaDDS used in this study has a high chemical and radiochemical purity. The areas occupied at the surface per adsorbed TNaDDS molecule decrease as the bulk TNaDDS concentration is increased. At and above the critical micelle concentration (c.m.c.) the areas per adsorbed molecule computed from our radiotracer measurements are essentially constant in agreement with earlier measurements at solution-air and solution-hydrocarbon interfaces. No experimental evidence is found to confirm the observations of others that an essentially constant area per adsorbed molecule is attained when the bulk surfactant concentration is about half the c.m.c.

Semiconductor X-Ray Detection in the Electron Microscope

With the introduction of solid state detectors having resolutions of 300 eV or better, the feasibility of an efficient, nongeometry dependent X-ray detector of high resolution became a reality. The use of X-ray detecting systems in conjunction with electron microscopes has been limited to the dispersive type which is highly dependent on geometry or to the gas flow proportional counter which has poor resolution. Recently, high resolution solid state detectors have been used with scanning electron microscopes; however, no use has been made of them in the conventional transmission electron microscope. The usefulness of an elemental analysis together with morphological and crystallographic information is obvious.

Thin windows for flow proportional counters in x-ray fluorescence spectrometers

Makrofol K G, the polycarbonate of 4.4 prime-dihydroxydiphenyl-2.2 prime-propane, which can be obtained as 2 μm thick film, is suitable for flow proportional counter windows. When correctly fitted it is durable and, of commercially available films, has the largest transmission for the K-radiation of the light elements, Z=11-16.

Some Characteristics of the Extreme Ultraviolet Spectrum Emitted by the Plasma Produced by Laser Impact on an Aluminium Target

Spectral emission from plasmas produced by ruby or Nd laser impact on an Al target was studied in the 100–200-Å region using both flow proportional counter and photographic techniques. The maximum intensities of continuous and Al IV line emissions were found to occur in quite different spatial zones of the plasma. The results are compared with those for Al V and Al VI spectra. From the appearance times of the 160.073-Å Al IV line a value of 107 cm sec−1 was obtained for the expansion velocity of the plasma.

A re-entrant well gas flow proportional counter for radioactivity measurements of solutions containing 35S and other radionuclides

A re-entrant well gas flow proportional counter for radioactivity measurements of solutions containing 35S and other radionuclides

Further studies of a universal method for the continuous radioactivity measurement of3H- and14C-labelled compounds after GC

Further experiments and experiences with a method of radio gas chromatography, which has been in use for over three years, are given. A gas chromatograph is connected to a reactor in which3H- or14C-labeled substances are cracked and hydrogenated or oxidized. The effluents of the reactor, mixed with methane, stream through a proportional flow counter. Various catalysts were tested. Substances containing oxygen, nitrogen, sulfur or halogens do not disturb the counter performance. For the analysis of high boiling14C-labeled substances the oxidative method is more suitable. Using the reactor unit without the gas chromatography very rapid analysis of vaporizable14C- and apparently all soluble3H-labeled substances can be carried out by direct injection into the reactor. An anticoincidence arrangement for measuring very low radioactivities is described.

Application of Spherically Curved Crystals for X-Ray Fluorescence

A general purpose x-ray fluorescence spectrometer has been constructed that employs the focusing properties of large spherically curved crystals. The 10 cm X 10 cm single crystals are bent to a 63.5-cm radius of curvature, and ground to the 31.75 radius of curvature of the focal circle. A motor-driven remotely controlled interchange mechanism has positions for four of these crystals. Also provided are: interchange of gas flow proportional counter or scintillation counter, and of chromium or tungsten target x-ray tubes, and a wide range of entrance and detector slitwidth combinations. Resolution and sensitivity are greatly superior to those of flat crystal optics.

Natural thermoluminescence of Cretaceous limestones in terms of alpha activity

Thermoluminescent dating of limestones is based on buildup of thermoluminescence due to natural α activity. The method cannot be used in limestones whose thermoluminescence growth has reached saturation. In this investigation we consider whether thermoluminescence buildup has reached saturation in typical limestones of Cretaceous age. To do this we measured natural thermoluminescence in terms of natural α activity in single limestone beds where variations in thermoluminescent properties are negligible. We selected four beds in which α activity varied by a factor of two or more. Natural thermoluminescence was determined in samples from each bed and plotted against α count. Natural thermoluminescence was measured in terms of intensity of the 600°K glow peak. These measurements were normalized with respect to intensity produced by irradiation with a Po 210 source. Natural α activity was measured with both scintillation and gas flow proportional counters. Results showed that natural thermoluminescence was independent of α activity in all four beds. We interpret this to mean that thermoluminescence buildup has reached saturation in average limestones of Cretaceous age. Our results also show growth of the 600°K peak has been influenced by temperature and saturation has occurred without complete filling of traps.

Absolute intensity calibration of a grazing-incidence spectrograph in the wavelength region 10-120 Angstrom.

A method is described for determining the absolute sensitivity of a grazing-incidence spectrograph. This makes use of an x-ray source of discrete K-lines, the intensity of which is monitored by a flow proportional counter, acting as an absolute photon flux detector. Experimental results are given for Ilford Q2 emulsion used with a two-metre 600 lines per mm platinum coated blazed grating at an angle of incidence of 88°. The resultant curve compares well with a relative calibration obtained by using the radiation from a 335 MeV electron beam in a synchrotron.

An X-Ray Spectrometer Attachment for the Philips EM-200/EM-300 Electron Microscopes

An X-ray spectrometer has been developed to extend the analytical capability of the Philips EM-200/EM-300 Electron Microscopes to studies of sample chemistry. It attaches directly to the objective aperture port of the rotating/tilting specimen stage.Shown in Figure 1, the spectrometer is a high resolution instrument, employing a mica crystal which is continuously curved to fulfill the X-ray focusing conditions over the entire angular range. Equipped with a flow proportional counter, it is capable of analyzing characteristic X-ray lines of any element from Na through U. With the rotating/tilting specimen stage and a replacement aperture installed in the microscope, the spectrometer may be attached to or removed from the instrument in less than five minutes. It may also be left in situ during normal use of the microscope.Supplementing the present ability of the electron microscope to investigate morphology and crystal structure (by electron diffraction), the spectrometer allows the simultaneous determination of chemical composition by microprobe X-ray fluorescence analysis of areas approximately one micron in diameter.

Band Structure and the Titanium LII, III X-Ray Emission and Absorption Spectra from Pure Metal, Oxides, Nitride, Carbide, and Boride

The titanium LII, III x-ray emission and absorption spectra (λ∼27.5 Å) from pure metal, oxides, nitride, carbide, and boride have been investigated using a plane-crystal vacuum spectrometer with electron-beam excitation and flow-proportional counter detection. Emission spectra were studied over a wide range of accelerating voltages and takeoff angles, showing that satellite emission and self-absorption effects can significantly distort the band shapes and energy positions of intensity maxima. A replica of the LII, III absorption spectrum can be constructed solely from emission spectra affiicted with widely different amounts of self-absorption. The LII, III emission spectra from the oxides, nitride, and carbide exhibit an important crossover transition from the 2p level of the anion to the LII and LIII levels of titanium. Results indicate formation of a 3d band in titanium compounds which is only partially filled, giving rise to metallic conduction. X-ray data is compared to density of states calculations for TiO, TiN, and TiC. The energy shifts of emission bands and absorption edges indicate a transfer of charge from titanium to anion in the oxides, nitride, and boride but that in TiC there is a transfer of charge from carbon to titanium. Energy separations between anion 2p band and titanium 3d band are measured and it is shown that both bands contribute significantly to the TiLII, III spectra from the compounds.

Carbon Characteristic X-Rays from Gaseous Compounds

Carbon spectra from CH4, C2H6, C3H8, C4H10, CCl4, CBr4, CF4, benzene, cyclohexane, ethylene, acetylene, CO, and CO2 have been measured in an ultrasoft x-ray spectrometer using electron-beam excitation, a lead stearate multilayer analyzer, and a thin window flow proportional counter. The spectra have been corrected for background and normalized so that the height of the largest peak of each spectra is the same. Similar molecular species exhibit similar spectra. Furthermore, for the alkanes, a correlation is observed between the position of the main peak and the first ionization potential of the molecule.

A sensitive, low background detector for radio gas—liquid chromatography

The design of a novel detector assembly for radio gas—liquid chromatography is described. The assembly comprises a gas flow proportional counter, plastic phosphor anti-coincidence guard counter and graded gamma shield. The net background count rate is 1.01 c.p.m. The operational advantages of low background detector systems are discussed and the merits of digital display of counting information described.

On the plateau characteristics of 2π gas flow proportional counter

On the plateau characteristics of 2π gas flow proportional counter

New window flow proportional counter for counting radioactive gas-liquid partition chromatography effluents

New window flow proportional counter for counting radioactive gas-liquid partition chromatography effluents

Effect of Alloying on the Aluminum K and Iron L X-Ray Emission Spectra in the Aluminum-Iron Binary System

The aluminum K and iron L emission bands and the aluminum Kα3 and Kα4 satellite lines from a series of aluminum-iron binary alloys have been studied using 6-kV electron excitation and a flat crystal x-ray vacuum spectrometer equipped with a flow proportional counter. It is found that the AlK band energy position and the AlKα4/Kα3 intensity ratio are both linearly dependent on alloy composition. As the aluminum concentration is lowered, the AlK band intensity maximum shifts to lowery energy and the band becomes more symmetrical in shape. In general, these results are very similar to those obtained previously from the aluminum-nickel system. The FeLIII band undergoes very little change in shape but shifts to higher energy as the aluminum-to-iron ratio is increased. The spectral changes are interpreted as indicating that the predominately metallic bond in the pure metals acquires a certain amount of covalent-like character in the alloys with the aluminum atoms behaving as electron donors.

On frictional polymer

Frictional polymer, a dark amorphous product formed in tiny amounts from organic vapors at the site of rubbing platinum-family metals, was first reported by Hermance and Egan 1. Its formation must involve platinum-metal catalysis but a number of factors are inconsistent with a picture involving only catalysis. Experiments using a proportional flow counter show that the rubbing members can give rise to charged particle emission. This suggests that frictional polymer, a carbonaceous structureless product, is formed by combined processes of catalysis and charged particle bombardment. Inhibitor activity in frictional polymer formation was found in some organometallic compounds, particularly tetraethyl lead. Iodine and a number of organic iodides also had marked inhibitor activity. The effectiveness of both types of compounds point to a free radical step in the reactions leading to frictional polymer.