摘要:

The triode‐connected 5889 electrometer tube was found to be useful as a logarithmic element over a grid current range of 10−14to 10−6amp. The relationship of plate current to grid current was carefully studied over a span of three and one‐half decades as a function of the plate supply potential, the plate circuit load resistance, and the filament voltage. A circuit was developed for use in an ionization chamber survey instrument. Most 5889 tubes will work in the circuit after a 150‐hr aging period. Over‐all accuracy of ±10% of the reading is feasible.

ISSN:0034-6748    

DOI:10.1063/1.1716450

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A new type of mass spectrometer leak detector is described which has a sensitivity for helium of 10−13standard cc/sec with a signal‐to‐noise ratio of unity. Operating pressure is in the 10−5to 10−6mm Hg range, time for ⅔ of final response is 2 sec or less, and operating characteristics are similar to present helium‐sensitive mass spectrometer leak detectors.

ISSN:0034-6748    

DOI:10.1063/1.1716451

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

In determining the average numbern¯of tracks per bubble chamber picture, for purposes of determining cross sections, one usually cannot count all tracks, but counts tracks in only some of the pictures, selected at random. An alternative procedure is described here in which the pictures are not selected at random, but are those which contain the ``interesting events.'' The average of 1/nover this ``linearly biased'' sample equals 1/n¯, wheren¯is the desired average over arandomsample.The linear‐bias method has some advantages that are complementary to those of the usual random method.

ISSN:0034-6748    

DOI:10.1063/1.1716452

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A logarithmic radiation meter has been developed which uses an ac‐coupled logarithmic voltmeter to measure the random noise from a photomultiplier detector. A range of four decades has been obtained.

ISSN:0034-6748    

DOI:10.1063/1.1716453

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A small electrode mounted inside the face of a cathode‐ray tube gives a ``window'' comparable to its own dimensions when the bias voltages are set so that secondary electron emission current dominates. Under these conditions the device can be used for measurement of probability densities of random signals.

ISSN:0034-6748    

DOI:10.1063/1.1716454

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A five‐channel differential pulse‐height analyzer is described, designed specifically for the observation of action potentials in nerve fibers. By measurement of the pulse amplitudes, it is possible to follow the activity of one or more single nerve fibers continuously.

ISSN:0034-6748    

DOI:10.1063/1.1716455

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The propagation of stress waves generated by impact may be ``watched'' photoelastically with the use of the simple experimental arrangement described herein. In addition to providing control over the observed progress of the wave, the apparatus makes possible photography of the wave with conventional cameras. The equipment not only is a scientific instrument, but also provides a useful demonstration for instructional purposes.

ISSN:0034-6748    

DOI:10.1063/1.1716456

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Some analytical and experimental results are given for a transistorized distributed amplifier using the common emitter configuration. The characteristic impedances of the base and collector transmission lines are both 43.4&OHgr;. A 4‐section amplifier stage yields a mid‐frequency gain of 5.1 db and an upper half‐power frequency of 290 Mc. The low‐frequency response is reasonably constant down to 10 cps.

ISSN:0034-6748    

DOI:10.1063/1.1716457

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A reliable method of etching and mounting Wollaston wires is described. The method involves attaching one end of the wire to a specially prepared ceramic tube, dipping the pendant portion of the wire into an etching solution, and then after etching is completed, attaching the loose end of the wire to the ceramic tube, and finally, firing the tube and mounted wire to 1000°F. The thinnest wires handled by this method had diameters of 0.5 &mgr; and lengths of 2 mm.

ISSN:0034-6748    

DOI:10.1063/1.1716458

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A simple but exact derivation of the conditions for ground potential on the null instrument input in nongrounded ac bridges is given. It is shown that not only the ``Wagner‐earth,'' but also other networks and circuits between the power source and the ac bridge can easily fulfill these conditions. Advantages of such other networks and circuits are discussed. General considerations for optimum bridge details for measurements of highest obtainable accuracy are given. Practical supply circuits for ac bridges are described. Furthermore, it is shown how the adjustment of the earth capacity neutralizing system can be made in a minimum amount of time.

ISSN:0034-6748    

DOI:10.1063/1.1716459

出版商:AIP    

年代:1959

数据来源: AIP