Abstract: A gamma counter linearly moving two rows of linked trays each having a two-dimensional array of sample tubes. A noncantilevered crane plucks each of the tubes and carries them to the counting well. A coupling mechanism between trays allows the operator to add further trays while the instrument performs analyses on previously added sample tubes. A microprocessor in the instrument allows the operator to place into memory information for the assay contemporaneously with the addition of the new trays. Tabs on the tray interrupt photosensors on the instrument associated with the two channels of trays to properly stop the trays where the fingers on the crane can reach the rows of tubes. The fingers on the crane, when descending to grip a tube, do so off to the side of the tray to avoid contacting and possibly damaging the tops of the tubes. An internal standard of Iodine.sup.129 provides gamma particles and acts as a known sample.

Abstract: A sample tray carrying a two-dimensional array of sample tubes for analyses by an instrument. Tabs on the side of the tray inform the instrument as to the location of the rows of sample tubes within the tray. A short wide rack gear followed by two long thin rack gears cooperate with a pinion gear on the instrument to move the sample tray along a channel established by the instrument. The wide short rack gear serves to properly orient the tray in the instrument's channel. A C-hook at the rear of one tray can engage a T-tab at the front of a following tray to couple the two trays together. The coupling components do not extend below the upper half of the tray to assist the operator when coupling two trays together. Overhanging rack gear segments between the two coupled trays allow for their continuous propulsion by the instrument's cooperating pinion gear. The tray may take the form of a hollow shell into which fit holders providing the actual locations for the sample tubes.

Abstract: A method of calibrating a gamma counter that makes two separate measurements over the peak of the standard source of I.sup.129 and a computational technique to obtain the center of that peak. A microcomputer controlling the instrument's operation changes the high voltage on the instrument's photomultiplier (PM) tube to find the setting which generally brings the I.sup.129 peak into the range of the preset pulse height analyzer (PHA) window. Each measurement in the first pass takes a relatively short period of time and looks for the arbitrarily defined end points of the peak. The microcomputer temporarily defines the midpoint of this range as the location of the I.sup.129 peak. In the second pass, the instrument takes longer measurements, for greater accuracy, at six points on either side of the temporary peak.

Abstract: A reference cell simulating the light amplitude spectrum of an alpha scintillation cell containing radon.sup.222. The cell includes a gas-tight container having a transparent window. The interior of the container, aside from the window, has a coating of a luminescent material. Inside of the container lies an amount of radium.sup.226. The radium radioactively decays to produce alpha particles and radon.sup.222. The radon.sup.222 and its daughter particles also undergo radioactive decay to produce further alpha particles. The 1620-year half life of the radium.sup.226 assures an adequate supply of the radon.sup.222 for a greater time period than radon's 3.825-day half life. The production rate of the alpha particles within the container increases for a period of approximately 22 years after the cell's construction. Although the radium.sup.226 generally has a nonuniform distribution in the cell, the produced radon assumes a gaseous form and uniformly diffuses throughout the entire cell.

Abstract: A safety circuit employing pulse transformers to protect hospitalized patients from high-voltage currents. The circuit finds use on switches controlling the operation of a hospital bed's motors, as well as on other types of controls. The pulse transformers prevent the motor's high-voltage levels from reaching the switching devices contacted by the patient. To operate the bed, the circuit provides a high frequency, low-voltage current to the pulse transformer which transfers it to a controlling triac. When in receipt of this current, the triac assumes a conducting state. A separate frequency generator provides this high-frequency current. The circuit may employ electronic devices to control the performance of the bed or other load. CMOS components operate satisfactorily with nonregulated voltages, produce delay periods with small capacitances, and consume little power. The CMOS components may, however, require a buffer in order to provide the pulse transformers with sufficient current.

Abstract: A scintillation cell having cylindrical symmetry, thickened walls, and components with different coefficients of thermal expansion. A pliable epoxy bonds the components together and accommodates their varying expansions during temperature changes. The glass through which passes the luminescence produced by the radioactive particles to the photomultiplier tube sits inside of the cylindrical metal tube to which it attaches. This recessed configuration protects the glass when the cell contacts a flat surface. Producing the cell involves spraying the luminescent material onto the inside of a metal tube. The metal tube receives the luminescent material while both heated and spinning. The spinning, heated cell can receive a multitude of coats of material at each application and, thus, prepares for use rapidly and economically. Subsequently, the substantially clear glass bonds sufficiently far inside of the tube over its open end to provide the recessed configuration.

Abstract: A pulse height analyzer determining, by about the end of an input pulse, whether the pulse's magnitude falls within a preselected range. Two comparators, which establish the preselected range, couple to a coincidence means, such as a D-type flip-flop. The coincidence means provides one indication when the pulse falls within the selected range and another indication when the pulse exceeds the upper limit. Output means, typically one or more flip-flops, may then operate upon these indications to provide, as usual, one output pulse for each input pulse falling within the range. The circuit obviates the need for R-C delaying components and results in greater resolution between close pulses, quicker response times, and less sensitivity to the particular value of the components used. The timing for the output means may derive either from an external clock or from the effect of the input pulse itself upon the comparators.