摘要:

The energy sensitivity of counters using recoils from a radiator or recoils produced in a gas is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1740911

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A chronograph is described which measures time intervals up to 2000 microseconds with an error not exceeding one microsecond. The chronograph traces a spiral on a cathode‐ray tube at a known constant angular velocity; the spiral trace starts with the reception of an electrical pulse marking the beginning of the time interval and stops with the reception of a second pulse marking the ending of the interval so that the number of revolutions in the spiral is a direct measure of the time interval. The cathode‐ray tube screen is of long persistence so that an immediate measurement of the time interval, as well as a photographic record, is obtained. Measurements may be made as rapidly as one every 30 seconds. A circuit used in conjunction with the chronograph selects the beginning of a slowly rising pulse, sharpens the pulse to one rising in about 0.2 microsecond, and blocks all subsequent pulses from the chronograph until reset manually.

ISSN:0034-6748    

DOI:10.1063/1.1740912

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A helium cryostat which is cooled by the isentropic expansion of helium without the aid of liquid air or other refrigerant provides a cold chamber for experiments at any temperature down to 2°K. Any gas can be liquefied and delivered to external receivers as desired. Three expansion devices are described. One is a diaphragm engine having a mechanically supported diaphragm and unusual valves which require no valve gear. The others are piston‐cylinder‐crankshaft assemblies in which leakage is controlled by extreme close fitting of piston to cylinder, and in which wear of unlubricated surfaces is avoided by constructing the piston and cylinder of nitrided alloy steel and by mounting the piston on a thin flexible piston rod which operates under tension. The piston thereby has enough freedom to permit perfect alignment within the cylinder.

ISSN:0034-6748    

DOI:10.1063/1.1740913

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

The article gives a detailed description of design and construction of a variable speed rotational viscosimeter to measure the rheological properties of systems within a viscosity range of 10−1to 104poise. The use of a strain gauge to measure the torque is discussed briefly.

ISSN:0034-6748    

DOI:10.1063/1.1740914

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A National Technical Laboratories Model DU Quartz Spectrophotometer has been converted into an automatic recording spectrophotometer by (a) utilizing the monochromator with unchanged optics, (b) introducing a common motor drive for the wave‐length and all mechanical parts, (c) dividing the exit beam into two parts by a beam‐splitter, (d) using a ``blank'' absorption cell in one beam and a ``sample'' absorption cell in the other, (e) placing an amplifier photo‐tube in each exit beam to measure the transmitted light, (f) amplifying the photo‐tube signals with linear cathode‐follower type d.c. amplifiers, (g) recording the ratio of the amplifier outputs as percent transmission of the ``sample'' relative to the ``blank'' as a function of wave‐length on a ratio potentiometer strip‐chart recorder, (h) providing for automatic monitoring of the monochromator slits to maintain constant energy in the ``blank'' light beam, and (i) providing a ``correction device'' for automatic correction of all errors due to mis‐matching in the relative intensities of the beams from the beam‐splitter, in the transmission characteristics of the absorption cells, and in the spectral sensitivity characteristics of the photo‐tubes. The instrument which has been developed has considerably greater resolution than the original spectrophotometer, has completely automatic high speed operation which permits recording of the spectrum from 4000 to 2000 angstroms in less than 15 minutes, and has an accuracy of transmission measurement very nearly equal to that obtainable with the original manual instrument.

ISSN:0034-6748    

DOI:10.1063/1.1740915

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A circuit for gas tube applications is described by means of which it is possible selectively to reverse the polarity of pulses entering a given set of input terminals so as to obtain monopolar output pulses for bipolar input signals; this is accomplished without a serious time delay difference through the network for input signals of either polarity.

ISSN:0034-6748    

DOI:10.1063/1.1740916

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

This article contains a description of a simple micromanometer designed to measure very small pressure differences at an absolute pressure in the neighborhood of one atmosphere.

ISSN:0034-6748    

DOI:10.1063/1.1740917

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A method for preparing pressed Ra+Be fast neutron sources is described in detail. Such sources can be made to contain as much as 5 g of Ra. They have the advantage of small volume and constancy of neutron output. The yield of fast neutrons per sec. per g of Ra can be obtained from the relationshipyield=1.7×107MBeMBe+MRaBr2.

ISSN:0034-6748    

DOI:10.1063/1.1740918

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A small magnetostriction gauge is described which can be used for the comparison of supersonic intensities. The gauge consists essentially of a small rod of nickel wound with a few turns of wire. The acoustic pressures present in the liquid produce changes in length of the rod which in turn, because of the inverse magnetostrictive effect, induces voltages in the coil.

ISSN:0034-6748    

DOI:10.1063/1.1740919

出版商:AIP    

年代:1947

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1740921

出版商:AIP    

年代:1947

数据来源: AIP