Abstract: The invention relates to a liquid scintillation counter comprising at least two photodetectors (2,3) for viewing a scintillation solution (1) in which both real multiphoton events and single photon events take place, and producing logic pulses and amplitude pulses in correspondence to these events, the amplitude of these amplitude pulses being a function of the number of photons that reach the photodetectors (2,3) for each of said events.

Abstract: A universal vibratory feeder has a removable tray provided with a continuous serpentine path. A plurality of carriers are received in the path, and articles of manufacture are carried by the carriers around the path in the tray. A vibrating platen beneath the tray has a plurality of bristles engaging the bottom of the respective carriers. The bristles are oriented in the direction of travel of the carriers around the path. The path in the tray is formed by a continuous through opening which separates the tray into two portions. The carriers straddle the thickness of the tray and are in substantial abutting relationship to one another throughout the path, thereby precluding the tray portions from separating.

Abstract: The disclosure relates to a method and apparatus for quantitatively evaluating radiation emissions of radiolabeled laboratory samples. These radiation emissions frequently include high energy beta and gamma radiation emissions resulting from .sup.32 P isotope decay. High energy beta and gamma radiation is detected by a solid state PIN photodiode and analyzed by a microprocessor to provide an indication of a radiation emission characteristic such as activity expressed in disintegrations per minute (DPM). An indication of sample activity is obtained from a detected sample count rate adjusted by a detector calibration constant which is determined by the microprocessor from a reference radiation emitting sample of known activity and volume. Indications of radiation emission characteristics may be displayed by an alpha-numeric liquid crystal display. Hard copy data may be produced from an expansion module in the form of a printer module adapted to receive data input from the microprocessor.

Abstract: In a liquid scintillation counter, a standard radioactive source is supported in a bead position of a bead chain, flexible conveyor. The conveyor is guided for movement along a closed-loop conveyor path in sliding engagement within a conduit guideway for conveying the source between an operating position adjacent the counting chamber and a remote shielded position. The conveyor may support one or more sources for conveyance to one or more counting chambers along the conveyor path.

Abstract: Quantities of radioactive material are dispersed at a user location. Billing is accomplished by monitoring the decay of material and the degree of activity following each user withdrawal.

Abstract: A method for use with liquid scintillation flow systems including flowing a mixture comprising a sample and a liquid scintillation medium through a flow detector, the liquid scintillation medium including a radionuclide marker having an energy distribution different from the sample. A pulse height distribution spectrum is determined and a unique point on the portion of the pulse height distribution spectrum representing the energy spectrum of the medium is found, a pulse height value related to such unique point providing a value related to the degree of quench present in the mixture. By comparing such pulse height value to a pulse height value obtained in a like manner for a calibration standard, a degree of quench present in the mixture is indicated.

Abstract: Method for calibrating a liquid scintillation counter comprising, for a number of reference solutions containing isotopes of known decay rates, the counting of a number of coincident pulses caused in at least two photodetectors by photons produced by the decay of the isotopes within a first known time interval, for obtaining the scintillation pulse frequency of each reference solution and the calculating of the counting efficiency for each reference solution by dividing said scintillation pulse frequency by the known decay rate.

Abstract: A liquid scintillation counter comprises a detector with a measuring chamber disposed on a horizontal plate having two holes and a device for delivering a test specimen to the measuring chamber, which is arranged under the plate and has a screw pair with a lead screw and a nut, guides with vertical slots to ensure progressive upward and downward movement of the nut and a shutter installed below at the outlet of the vertical slot. The nut mounts a receiving assembly secured so that it is found precisely within any hole in the plate after the nut is turned and lifted. Said nut has at least one roller secured on its butt end and interacting with the vertical slot, said roller cooperating with the shutter at the outlet of said vertical slot.

Abstract: Apparatus and a regionless method of ascertaining the activity of each radionuclide in a dual-label sample. A set of correlation curves is generated utilizing quench standards for both a low energy radionuclide and a high energy radionuclide. A test sample was then counted and the quench-indicating parameters for the test sample are compared with the quench-indicating parameters of the correlation curves to determine the appropriate contribution of each radionuclide to the overall energy spectra of the test sample. From this comparison the overall count rate for the test sample may be allocated between a low energy radionuclide and a high energy radionuclide. By dividing the count rates by efficiencies determined from another set of correlation curves the actual disintegration per minute (DPM) rate for each radionuclide may be ascertained.

Abstract: An apparatus uses a rapid and efficient method for conducting fluorescence measurements, such as immuno assay, of a plurality of samples of a substance using pulsed or continuous light energy, front-end fluorescent optics, a mechanism which allows for lateral and tranverse scanning of rows and columns of wells, and spectra emission analysis of the spectra from the excited samples.

Abstract: A transfer mechanism for movement of sample containing vials from a first position to a second position in an analyzer instrument such as a liquid scintillation or a gamma counting device. The apparatus is particularly adaptable where available space is limited. A flexible transport member permits the transformation of movement in one direction into movement in another direction. Sensors and adjusting screws are incorporated into the apparatus for precisely controlling the travel distance of the transport member as well as precisely orienting the direction of the transport member.

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 volume reducer for liquid scintillation counting is adapted to be used with an outer scintillation-counting vial and includes an elongate member adapted to be inserted into the vial. The elongate member has a bottom surface and a peripheral side surface and the side surface is spaced inwardly from an inner side surface of the vial to define an annular chamber in which the scintillation fluid is adapted to be retained. In certain embodiments the annular chamber is varied to either isolate certain segments thereof from each other or provide segments having differing volumes. The combination of the reducer and vial, as well as methods for preparing a scintillation fluid for testing also constitute parts of the instant invention.

Abstract: In a liquid scintillation counter a standard radioactive source is supported within the tubular bore of a flexible coil spring conveyor. Spacer elements within the coil spring retain the source at a predetermined axial position along the spring. The coil spring is disposed in sliding engagement along a conveyor guideway. A drive roller drivingly engages the spring for conveying the source along the guideway between an operating position adjacent the counting chamber and a remote shielded position.

Abstract: A method for ascertaining radiochemical homogeneity in a liquid scintillation sample reliably identifies inaccurate geometries is disclosed so that meaningful activity counts can be determined. The novel method involves measuring the activity level of a set of homogeneous quench standard to obtain quench indicating parameter, or the Spectral Index of the External standard (SIE). The endpoint of each standard sample is computed allowing the formation of a table so that a calibration curve for each radionuclide of interest can be computed. The activity level of the unknown sample is then measured and the SIE determined so that an endpoint can be calculated. Finally, the theoretical endpoint obtained from a calibration curve is compared to the computed endpoint; if the computed endpoint of the sample deviates by more than 4% for tritium and 5% for higher energy radionuclides from the theoretical endpoint, the sample is considered to be nonhomogeneous or heterogeneous.

Abstract: The radioactivity of radioactive fluid is monitored, in the presence of background radiation, without interruption of radioactivity detection with two successive volumes of radioactive fluid, the background being eliminated by subtraction. Typically the intrinsic responses are in the ratio of two to one for such successive measurements, when the proper volumes have been selected.

Abstract: A portable photo chamber for photographically recording the extent of a chemical reaction such as in an immunological test, wherein a substrate emitting radiation such as gamma radiation is supported in facing contact with a film and with intensifying means, so that exposure time is reduced as a result of emission of further radiation such as a visible light from the intensifying means and its recording on the film. The photo chamber includes retaining means for supporting the substrate, which itself is preferably enclosed in a container such as a pipette, and translating means for moving the substrate into closely facing relationship to the film and also to a spaced-apart position within the chamber. In a preferred embodiment, the photo chamber utilizes an instant photographic system with film processing means attached to the chamber, so that the photo chamber is both portable and self-contained for use in remote locations.

Abstract: Sample handling apparatus for circulating one or more sample holders along a rectilinear path in a sample holder storage compartment and past an operating station at which the holders may be removed from and then returned to the compartment. First and second parallel conveyors on opposite sides of the operating station drive the holders toward and away from the operating station. Lateral drivers engage the holders in longitudinal stop positions at opposite ends of the conveyors and drive them laterally between conveyors to lateral stop positions, one of the holders during lateral movement being driven into and away from an operative position at the operating station. A movable sample compartment divider between the conveyors is indexed in synchronism with the lateral drivers to engage and stabilize the sample holder at the operating station.

Abstract: Process of and apparatus for the simultaneous determination of the concentration of a plurality of radioactive gases. Radioactive gas containing several beta radionuclides is led into a separate chamber where their concentration is determined simultaneously and selectively by using a plastic multi-layer scintillator. The energy of the emitted beta radiation further identifies single radionuclides, and it determines them selectively and quantitatively by carrying out an amplitude discrimination of the registered impulses. The process can be carried out continuously or discontinuously. The multi-layer scintillation chamber is composed of a light-tight casing in which plates of plastic scintillators having suitable dimensions and location are placed in spaced relationship, such plates being connected on each end of the casing with a photomultiplier through a light-guide.

Abstract: An assembly for sealing the access passageway to a detector chamber in a scintillation counter instrument. The seal is designed to prevent the entry of any exterior light or environment that could affect the counting or scintillation process when a sample is positioned in the detector chamber. The sealing mechanism operates in conjunction with the scintillation instrument's flexible transport or elevator mechanism that moves a sample containing vial into the detector chamber. A plurality of rotating blades engage the elevator mechanism to form the tight seal. Included in the arrangement is a redundant system to provide a dual sealing capability. The sealing mechanism operates in conjunction with the flexible transport member which allows itself to be centered by the sealing mechanism to achieve the required light seal.

Abstract: Disturbances caused by static electricity in liquid scintillation counting are eliminated by an ionizing device. A liquid scintillation counter in a measurement chamber surrounded by a radiation protective device measures nuclear fissions occurring in a sample bottle moved into the measurement chamber along a predetermined path. The ionizing device ionizes the air by producing positive and negative ions in the path followed by the sample bottle into the measurement chamber. Ions produced by the ionizing device on the sample bottle before the bottle enters the chamber neutralize any electrostatic charge on the bottle.

Abstract: Apparatus for transporting elongated sample holders in a sample holder storage compartment past an operating station at which sample tubes contained in the sample holders may be removed and then returned to the sample holders. First and second parallel conveyors on opposite sides of the operating station drive the holders toward and away from the operating station. Lateral drive means engage the holders in longitudinal stop positions at opposite ends of the conveyors and drive them laterally between the conveyors to lateral stop positions, one of the holders during lateral movement being driven into and away from an operative position at the operating station. Encoded label means are displayed on each sample holder for indicating the incremental spacing between the sample tubes carried in the sample holder.

Abstract: A method for determining the quench corrected counting yield of samples which emit ionizing radiation that is subject to quenching in a liquid scintillation counter. The output signal of a photoelectric transducer device is used to measure the counting rates of the sample spectrum in different given pulse height ranges. A value characteristic for the quenching is derived from the measurement to determine a quench corrected counting a yield.

Abstract: An inner and outer cylindrical cathode are concentrically positioned about a vertical center axis. Vertical anode electrodes extend parallel to the center axis and are symmetrically arranged around the inter-cylinder space between the cathodes. The ends of the anode wires are supported by a pair of insulator rings mounted near the top and bottom of the cathode cylinders. A collection voltage applied to each anode wire for establishing an inward radial E field to the inner cathode cylinder and an outward radial E field to the outer cathode cylinder. The anode-cathode assembly is mounted within a housing containing a conversion gas. A radioactive sample is inserted into the inner cathode which functions as a tubular, deep well radiation window between the sample environment and the conversion gas environment.

Abstract: A method and related apparatus for the determination of a random coincidence count attributable to chance coincidences of single-photon events which are each detected in only a single detector of a scintillation counter utilizing two detectors in a coincidence counting technique. Real and apparent coincidences of pulses are accumulated in a first counting device (28), and all pulses from the detectors (12) are accumulated in a second counting device (38), without regard for coincidence in time. The two counting devices are monitored during at least one random coincidence monitoring time occurring simultaneously with part of a sample counting period. The length and frequency of occurrence of the random coincidence monitoring times can be selected for particular counting measurement applications.

Abstract: A method of quench correction in liquid scintillation counting which compensates for the effect of sample quench. A quench corrected pulse height window is established for measuring sample scintillations. A pulse height threshold is established distinguishing regions for which a measure of sample quench, derived conventionally, is either proportional to or not proportional to the actual effect of quench on the sample pulse height spectrum. The quench corrected window is compared with the pulse height threshold, and the relative position of the corrected window is adjusted if the comparison step indicates that the window lies in the region of nonproportionality.

Abstract: A method and an apparatus for isolating and measuring the intensity of gamma radiation or other type of radioactive radiation from a radiation active deposit contained within a liquid sample, in which the measurement is performed in step with a previous isolation of a sample by an intermittent advance (10) of the sample from an isolation station to a measuring station. The measurement is made in step with the intermittent advance of the sample in a plurality of immediately succeeding partial measurements in a measuring unit which comprises a plurality of successively arranged radiation detectors (36) corresponding to a predetermined number of partial measurements. Each partial measurement constitutes a part of the total measurement of the same corresponding to the step of advance. The measuring results from the individual partial measurements of the sample are summed up (60), and the sum is registered. The sample may be deposited on disc-shaped membrane filter carriers.

Abstract: A system for the measurement of radioactivity of a number of radioactive samples by a radiation detector which will be affected by radiation from a number of other sources having predetermined locations in addition to the sample being measured consists of first measuring the values of activity measured by the detector when a standard radiation source of known activity is placed in the detector and in each of the predetermined locations to determine the effect of the other sources on the measurements of the detector, storing the values thus determined and thereafter compensating the values of radioactivity of each sample measured by the detector with the stored values to obtain the actual values of radioactivity of the samples.

Abstract: An automatic rate analyzing method for determining a concentration of an item in concern contained in a sample to be analyzed comprises steps of irradiating the sample with light thereby to produce a transmitted light signal at a specific wavelength, converting the transmitted light signal into a corresponding electric signal and sampling the electric signal at a given interval thereby to produce a plurality of sample values. The plurality of sample values are grouped into groups each containing a predetermined number of sample values selected for every given number of the sample values. Each of the groups is deviated from the adjacent ones by a number of sample values smaller than the given number. The sample values in each of the groups are added together to produce sums associated with each of the groups.

Abstract: A background subtractor circuit is disclosed for subtracting a preselected number of pulses from a train of input pulses. Switches are provided whereby the operator selects the background pulse rate, attributed to environmental factors, and wherein a train of background pulses are subtracted, at a preselected rate, from the incoming pulse train.

Abstract: An automatic thermo-luminescence desimeter, comprising a thermo-luminescence dosimeter element which is composed of a card carrying a thermo-luminescence material and contained in an encasing member; a magazine adapted to accommodate therein a plurality of the thermo-luminescence dosimeter elements; means for transporting the magazine; card feeding means for extracting a thermo-luminescence dosimeter element from the magazine and feeding the element into a longitudinal groove formed in a housing; releasing means for releasing engagement between the card and the encasing member; means for feeding the card into a transversal groove formed in the housing; heating means for heating the thermo-luminescence material carried by the card fed to the transversal groove by irradiating with infrared rays; and photoelectric converter means for converting thermo-luminescence emitted by the thermo-luminescence material into an electric signal, whereby doses of exposed radiation of the individual theremo-luminescence dosimet

Abstract: A device to be used in an automatic gamma counter to move sample holders (4) into a measuring chamber (6). The device comprises a slide (1) which moves the holders into the measuring chamber (6) and at the entering completely seals the chamber.

Abstract: The radioactivity of discrete areas of radioactive material on a surface region of a support layer is monitored by converting the radioactivity emitted by these areas into light emissions with the use of a suitable scintillant, and scanning the surface region with at least one photodetector in a plurality of discontinuous steps. Each step places the support layer and the or each photodetector in relative positions in which the or each photodetector detects at least a proportion of the light emissions activated by a respective one of the areas of radioactive material over a finite interval of time. A plurality of output signals are therefore produced by the photodetector(s), each of which is proportional to the radioactivity of a respective one of the areas of radioactive material.

Abstract: The invention relates to a liquid scintillation spectrometry process and apparatus permitting the analysis of samples having a fluorescence efficiency quenching comprising chromatic quenching and chemical quenching. According to the invention, an external standard ionizing radiation source is used which is associated with a collimating means permitting the irradiation of the sample to be restricted to a small area. According to a first variant, two separate measurements are carried out on fluorescence radiations having different optical paths. These two measurements make it possible to determine a coefficient which represents the ratio between the chromatic quenching and the chemical quenching. In a second variant, the irradiation area is selected in such a way that the overall quenching is no longer dependent on this ratio.

Abstract: A nondestructive method for uniqely distinguishing among and quantifying the mass of individual fuel plates in situ in fuel drawers utilized in nuclear reactors is described. The method is both rapid and passive, eliminating the personnel hazard of the commonly used irradiation techniques which require that the analysis be performed in proximity to an intense neutron source such as a reactor. In the present technique, only normally decaying nuclei are observed. This allows the analysis to be performed anywhere. This feature, combined with rapid scanning of a given fuel drawer (in approximately 30 s), and the computer data analysis allows the processing of large numbers of fuel drawers efficiently in the event of a loss alert.

Abstract: In a high-pressure liquid chromatography system, a radioactive sample in the effluent from a chromatographic column can be detected by passing the effluent into a cell packed with a fluorescent composition comprising a scintillation material chemically bonded to an inert substrate. A suitable fluorescent composition is microparticulate didansyl-N-2-aminoethyl-3-aminopropyl silica. Radioactive emissions from the sample cause scintillations in the fluorescent composition that can be detected through the walls of the cell. In order to obtain a chromatogram of the radioactivity occurring in the column, aliquots of the effluent from the column may be passed sequentially into a plurality of cells arranged on a carousel support structure that is rotable in stepwise fashion so that each cell passes in turn through a fill station, a detection station, and a wash station. At the fill station, each cell in turn is filled with an aliquot of effluent.

Abstract: A sample vial guide for scintillation spectrometers or other sample handling systems in which sample vials are moved in a horizontal path to a first operating station, transferred vertically therefrom to a second station such as a radiation measuring chamber, and returned along the vertical path to the first station for continued movement along the horizontal path away from the first station. The sample vial guide includes first and second opposing jaws at the first station on opposite sides of the horizontal path and having opposing interior surfaces which surround and define a constrained area at the first station for a sample vial. The jaws are hinged to pivot laterally away from the horizontal path and include cam surfaces on each jaw for engaging a sample vial as it moves along the horizontal path to or from the first station to move the jaws to an open position to accommodate such horizontal movement of the vial.

Abstract: In an instrument for measuring radioactivity, the total measuring time for each sample is optimized by considering the maximum acceptable total counting error as well as the count rate. Each sample is counted for a period of time that is considerably shorter than the required measuring time but long enough to estimate the average pulse frequency, then the measuring time is determined as a function of the estimated pulse frequency and of the experimental error as determined by the channels ratio method.

Abstract: Improved means for expelling sample carriers which have been automatically elevated to the sample measuring chamber of a radiation measuring apparatus, from the measuring chamber. The means are collapsible within the instrument housing, as to remain therein as a sample carrier is elevated toward the measuring chamber. Additionally, the means comprise a disposable contamination member which can be removed and discarded in the event of contamination.

Abstract: A light seal for the counting chamber of a scintillation counter comprises a ring shutter mounted in the shielded housing which forms the counting chamber. The ring shutter is mounted for rotation between an open position where an aperture in the ring shutter is aligned with an opening into the shielding housing to permit transfer of sample vials in and out of the counting chamber, and a closed position where a shroud portion of the shutter covers the opening in the housing to block the entry of light. The ring shutter closely surrounds the sample vial in the counting chamber and is preferably formed of a radiation shielding material. The shroud portion of the ring shutter includes a cam for engaging a sample vial disposed within the shutter aperture when the shutter rotates from the open position to the closed position, for lifting the sample vial to a predetermined elevation within the counting chamber.

Abstract: Proposed is a device for radiochromatographic analysis of mixtures of substances containing components tagged by radioactive isotopes, such as soft .beta.-isotopes comprising a chromatographic column, a detector of nuclear radiation and a chromatographic detector connected in series along the flow of the substance being analyzed. The detector of nuclear radiation is provided with a cell made as a tube with a scintillator applied onto its inner surface in the form of a solid layer. The tube is provided with movable means for sequentialy cooling and heating the same and a light detector which is movable along the length of the tube. In operation, upon introduction of the portion of the mixture being analyzed into the column, with the heater interacting with the tube, the heater and cooler are moved so that by the time the last component of the mixture exits from the column, the cooler is in interacting relationship with the tube whereby the components of the mixture are frozen.

Abstract: A system for measuring radioactivity of labelled biopolymers which comprises an electric drive to ensure stepwise travel of a set of containers, a means for acid precipitation of biopolymers for proportioned feeding of biopolymers to the containers with a biological sample of a coprecipitator and a suspension of diatomite in an acid solution, a means for taking precipitated samples from the containers, and a means for filtering precipitated biopolymers. The system also includes a program unit with a control unit to interact with the above means. The mixture is fed to a detection chamber of a radioactivity measuring device.

Abstract: Apparatus for light flux attenuation particularly for additional quenching of scintillations in the determination of radionuclide activity comprising a body provided with a counting chamber containing a counting vial which is optically coupled with photomultipliers and between which is disposed a cylindrical spring. The opposite ends of the spring are secured in the body and the spring extends in surrounding relation with a rotatable bush mounted in the body. The bush is provided with a ring having a hole through which the cylindrical spring passes such that the ring divides the spring into a first portion surrounding the counting vial and a second portion surrounding the rotatable bush.

Abstract: An arrangement for continuously measuring the radioactivity of solutions of matters in a homogeneous mixture with a liquid scintillator, comprising two measuring chambers and a two-way tap valve connecting, in its first position, the first measuring chamber with the mixing device, and the second measuring chamber with a multi-channel pump, and in its second position, the first measuring chamber with the multi-channel pump, and the second measuring chamber with the mixing device.

Abstract: The invention relates to a liquid scintillation spectrometry process and apparatus permitting the analysis of samples having a quenching of the fluorescent efficiency resulting both from a color quenching and a chemical quenching. The invention makes it possible to measure a parameter B which gives the respective contributions of the two quenching types. According to the invention, parameter B is obtained in the following manner. A scintillation radiation produced by a standard fluorescent source placed in the vicinity of the sample to be measured is passed through the latter. This source comprises, for example, a solid scintillator exposed to an alpha or beta radiation source. The scintillation emitted by the standard source supplies an amplitude spectrum which is measured. One of the significant characteristics of this spectrum is determined, for example, the ratio of the counting rates in two different channels. This ratio gives parameter B.

Abstract: A method and apparatus for absolute activity determination of radionuclides, especially of low maximum energy pure beta-emitters as for instance .sup.3 H, .sup.63 Ni, .sup.14 C, .sup.35 S. The application of the invention can also be extended for activity determinations of other radionuclides, for example of those disintegrating through the electron capture. The method contemplates producing pulses of various multiples of coincidence simultaneously, and correlating the counts of the pulses to obtain a measure of the absolute activity. This is achieved by providing a scintillation head containing at least three photomultipliers optically coupled to the scintillator and the source whose activity is to be measured. The outputs of the photomultipliers are connected via amplifiers to coincidence gates having two and three inputs.

Abstract: A toothed sprocket wheel provides an idler for driving test tube holders into and out of sharp turns which occur in the track of an automatic sample changer employed in radiopharmaceuticals. The sprocket is provided with a selected number of well-defined teeth and is rotatably mounted at the center of a relatively sharp turn so as to transfer the linear motion from the test tube holder at its point of entry into the turn to the test tube holder at the point of exit from the turn. Also disclosed is a tensioner or positioner in a substantially linear alignment of the test tube holders such that, upon varying the degree of insertion of the sprocket teeth between successive test tube holders, the relative spacing between successive test tube holders, and the overall test tube holder train length may be adjusted to compensate for expansion/contraction of the holders due to environmental conditions.

Abstract: A rechargeable system is provided for the production of sterile, non-pyrogenic, isotonic solutions of radioisotopes such as sodium pertechnetate, which are useful as diagnostic agents in the medical field. A unique feature of the system is that transfer of the recharging supply of the parent isotope from the shipping shield to the generator contained in the generator shield can be effected with minimal exposure to radiation.

Abstract: An automatic spectrum scanning technique for use in a proportional counting instrument, such as a gamma counter or liquid scintillation counter, by means of which a pulse-height or energy spectrum of a sample can be obtained automatically and without multichannel instrumentation. A pulse-height analyzer in the counting instrument has its upper and lower discriminator limits set to define a relatively narrow counting window, and the limits are successively changed to scan the window across the energy spectrum and thereby obtain an accurate measurement thereof. Counting at each increment of the scan is continued for a preselected maximum time interval, but is quickly terminated if the count rate falls below a preselected low threshold value, and is terminated early if the count rate is relatively high, i.e., if the statistical error value associated with the count is relatively low.