A review is presented of the history of radiation detection instrumentation. Specific radiation detection systems that are discussed include the human senses, photography, calorimetry, color dosimetry, ion chambers, electrometers, electroscopes, proportional counters, Geiger Mueller counters, scalers and rate meters, barium platinocyanide, scintillation counters, semiconductor detectors, radiophotoluminescent dosimeters, thermoluminescent dosimeters, optically stimulated luminescent dosimeters, direct ion storage, electrets, cloud chambers, bubble chambers, and bubble dosimeters. Given the broad scope of this review, the coverage is limited to a few key events in the development of a given detection system and some relevant operating principles. The occasional anecdote is included for interest.

A history of radiation detection instrumentation

If three resistors, which are kept at different temperatures, are arranged in form of a π network and if two of the thermal noise voltages appearing across the π network are multiplied together and...

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A new absolute noise thermometer at low temperatures

Varactor Diode Ampliﬁer at Liquid Helium Temperature* Previous experiments with parametric ampliﬁers” have indicated that the effec- tive input noise temperature of the ampliﬁer can be sL1bstantially reduced by refrigerat- ing the ampliﬁer down to liquid nitrogen temperature. It was also found that the noise temperature of the ampliﬁer with a gallium-arsenide diode decreased almost linearly as the ampliﬁer temperature was lowered from room temperature to 40°K.3 Our recent investigations of the junction capacitance of gallium-arsenide diodes have shown that the change in junction capaci- tance from liquid nitrogen temperature to liquid helium temperature is much smaller than that from room temperature to liquid nitrogen temperature; similar results have also been obtained with some epitaxial sili- con diodes. It has also been found that the dynamic quality factor (3 of gallium-ar- senide diodes improves continuously down * Received October 26, 1962. 1 M. Uenohara, “An extremely~low—noise 6—Gc non~ degenerate parametric ampliﬁer,” PROC. IRE (Cor- respondence), vol. 50, pp. 208-209; February, 1962. 2 M. Uenohara, M. Chruney, K. M. Eisele, D. C. Hanson and A. L. Stillwell, “4 Gc Parametric Ampli- ﬁer for Satellite Communication Ground Station Re- ceiver,” presented at the 1962 WESCON,Convention, Los Angeles, Calif.; August 21-24. 3 M. Uenohara, “Noise Characteristics of Refriger- ated Degenerate Variable Capacitance Ampliﬁer at 6 Ge,” Bell Telephone Labs, Inc., Murray Hill, N. J.. BTL Internal Memo., Sept., 1961 (unpublished). Fig. l-Input impedance loci of 4-Gc parametric am- pliﬁer as a function of bias voltage. the ampliﬁer for the Telstar ground station receiver.’ The external idler load is re- moved, however, to accommodate the am- pliﬁer to an available helium dewar. The input frequency is 4.17 Gc and the pump frequency is 23 Ge. The varactor diode used in this ampliﬁer is the gallium-arsenide point-contact diode originally developed by W. M. Sharpless and further developed by N. C. Vanderwal.” The experimental re- sults are tabulated in Table I. The accuracy of noise—temperature meas- urement is believed to be i3°K. The noise ﬁgure of the mixer and IF ampliﬁer was 8.3 db and the theoretical noise temperature was calculated based on the measured R,/R...’ The pump power required for 20-db gain was 30 mw at the input of the dewar. The pump circuit was tuned from outside the dewar and only a few milliwatts were dis- sipated in the ampliﬁer. Fig. 2——Photograph of 4~Gc parametric ampliﬁer. to liquid helium temperature. Blake and others at the MIT Lincoln Laboratory have recently measured 10°K excess noise tem- perature for an L-band parametric ampliﬁer operated at liquid helium temperature.‘ This correspondence presents the experimental results of a 4-Gc parametric ampliﬁer at liquid helium temperature. The input impedance loci of the 4-Gc ampliﬁer with a gallium-arsenide diode measured at three different temperatures, i.e., 298°K, 77°K and 4.2°K, as a function of bias voltage are shown in Fig. 1. All three impedance loci were measured at 4.17 Gc with all circuit conditions maintained constant for the entire experiment. Notice that the resonant bias voltage shifted from -1.25 V at 298°K to -0.94 v at 77°K and to -0.85 v at 4.2°K. From the capacitance measured at room temperature and the data in Fig. 1, one can determine the eﬁ°ec— tive diode capacitance at each temperature. The series resistance R, also decreased as the temperature was lowered to liquid helium temperature, as is shown by the increase in the VSVVR at the resonant point as the temperature is reduced. The 4-Gc nondegenerate parametric am- pliﬁer was operated successfully at liquid helium temperature. The effective input noise temperature of the ampliﬁer, including the insertion loss of the room—temperature circulator and a 17-inch-long input Coaxial line, was less than 24°K; of this, only 2°K is believed to be due to the ampliﬁer itself. Fig. 2 shows a photograph of the ampliﬁer. The ampliﬁer mount is identical to that of 4C. Blake, L. VV. Bowles, E. P. McCurley and J. A. Nuttal, “Helium cooled parametric ampliﬁer,” J. Appl. Phys. Letl., to be published. TABLE I Ampliﬁer temperature (°K) 298 77 4.2 Dynamic quality factor Or at 4.17 Ga 9.4 11.6 12.0 Normalized generator im- pedance R0/R3 5.0 5.4 5.9 Measured over-all noise tem- perature (°K) at 20 db gain 192 79 42 30 db gain 24.5 35 db gain 23.5 Noise temperature, paramp only (with 17q line) (°K) 154 46 9.0 Calculated noise temperature at 20-db gain (without 17” line) (°K) 154 38 2.0 In a future experiment, the ampliﬁer to- gether with a circulator will be refrigerated down to liquid helium temperature. We be- lieve that the over-all noise temperature of the parametric ampliﬁer will be as good as that of the maser. The parametric ampliﬁer has deﬁnite advantages over the maser, 27.6., broader bandwidth, higher saturation power level, lower pump frequency and power, and a simpler cryogenic system be- cause the operating temperature is not critical. H. J. FINK D. C. HANSON M. UENOHARA Bell Telephone Labs., Inc. Murray Hill, N. J. 5 VV. M. Sharpless, “Gallium-arsenide point-con- tact diodes,” IRE TRANS. ON MICROWAVE THEORY AND TECHNIQUES, vol. MTT—9, pp. 6-10; January, 1961. 6 M. Uenohara, “An extremely low noise 6 Ge nondegenerate parametric ampliﬁer,” I962 I7zle1&#39;nat’l Solid-State Circuit Conf. Digest of Tech. Papers, Lewis Winner, New York, N. Y., pp. 60-61; February, 1962. 7 M. Uenohara and H. Seidel, “961 Me lower side- band up-converter for satellite-tracking radar,” Bell. Sys. Tech. J., vol. 40, pp. 1183-1205; July, 1961.

A scaler unit is described which has been designed for counting pulses from Geiger-M?ller counters or ionization chambers in a decimal system. The unit consists of two electronic scales-of-ten with either neon lamp or meter indication, followed by a mechanical counter. The resolving time of the scaler can be made as low as 3 ?sec. and the unit is capable of recording counting rates up to 1000 per sec. It is built on a standard G.P.O. panel, suitable for rack or bench mounting.

Scale-of-Hundred Counting Unit

A detailed description is given of a semicircular focusing β-particle spectrograph in which a thin source is centrally placed and sheaves of oppositely moving electrons are investigated using two thin-windowed Geiger counters. These counters can be used in a coincidence arrangement, and each is capable of movement so as to accept electrons which have been focused with any radius of curvature between 2.5 cm. and 6 cm. The arrangement was tested using sources of thorium active deposit. During this work the (coincidence) β-particle spectrum for the ThB.C transition leading to the 238 keV. state of ThC was obtained separately for the first time and its end-point determined as 355 keV. A feeble higher-energy β-component due to ThB was also detected and the end-point estimated at 589 keV. Redeterminations of the end-points of the β-particle spectra of ThC and ThC'' (by β-γ coincidences) gave values of 2.256 MeV. and 1.805 MeV., respectively. The intensity of the F-line of ThB was found to be 0.288 photoelectrons per disintegration.

Investigations using a Permanent-magnet Double β-Ray Spectrograph with Coincidence Counting - I. Experiments with Thorium Active Deposit

A direct‐coupled pentode trigger pair, previously described, is made the basis of two simple ring‐of‐ten circuits for high speed counting. One of the circuits is especially suited for the counting of sharp pulses up to a frequency of 105 cycles per second. The other circuit is especially suited for frequency measurements on periodic currents of arbitrary wave form and of frequency from zero to above 105 cycles per second. The number of pulses or cycles counted by one ring‐of‐ten is indicated on the screen of a cathode‐ray oscilloscope tube. Several of these ring‐of‐ten units, each with its cathode‐ray tube, can be connected in cascade to make electronic counting with direct indication of the decimal figures possible.

Decade Counting Circuits

A trigger circuit using two pentodes with direct plate‐to‐screen coupling is described. The mechanism of electrical stability and instability and the process of triggering are discussed. Sample diagrams for a pulse generator, an electronic switch, and a scaling circuit are given.

Design and Use of Directly Coupled Pentode Trigger Pairs

A ring‐of‐ten circuit is described, using ten pentodes, ten twin‐triodes, ten resistors, and no condensers, per ring. Two pairs of input terminals are provided for clockwise and counter‐clockwise feeding, respectively. This circuit can be used for electronic adding and subtracting, as well as for differential counting‐rate measurements on two sources. With the addition of five resistors to a ring, the number of counted events can be indicated on the screen of a small cathode‐ray tube. This circuit counts up to 5×105 evenly spaced events per second.

Reversible Decade Counting Circuit

A detailed description is given of the preparation of all‐metal, argon‐alcohol filled, Geiger counter tubes for cosmic‐ray work. Two different possibilities are discussed for the construction of the feed‐through insulator.

Victor H. Regener

Papers

Decade Counting Circuits

Design and Use of Directly Coupled Pentode Trigger Pairs

Reversible Decade Counting Circuit

All‐Metal Fast Geiger Counters for Cosmic‐Ray Research