ISSN:0034-6748    

DOI:10.1063/1.1740819

出版商:AIP    

年代:1947

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1740828

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A simple monochromator with a 4×6 inch replica gratingf:3.4, which covers the range 365–1000 m&mgr; is described. The dispersion is 3.55 m&mgr;/mm in the second order and 7.1 m&mgr;/mm in the first order. The slits are fixed in position and the wave‐length of the emergent beam is varied by rotating a mirror located between the telescope lens and the exit slit. It is useful for the production of monochromatic light with band widths of 10 m&mgr; or more. With a 2×34‐mm entrance slit it produces 4×10−2cal./min. of red light with a band width of about 28 m&mgr; from a 350‐w tungsten lamp. The total energy output, spectral distribution and percent of stray light are given for various wave‐lengths and slit settings. The transmission of the instrument is given for the wave‐length range 365–800 m&mgr;.

ISSN:0034-6748    

DOI:10.1063/1.1740811

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

This paper discusses the usefulness of common tube types for small current measurement and, after presenting the results of a detailed study of the three types 38, 954, and 959, offers recommendations of operating conditions for their use. The observations reported consist primarily in data showing the dependence of grid current upon applied potentials, and secondarily in information about the corresponding plate current characteristics. Grid currents less than 10−15ampere in the 959 tube are reported, associated with stability comparable with that of special electrometer tubes.

ISSN:0034-6748    

DOI:10.1063/1.1740812

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A description is given of a circuit using two one‐shot multivibrators, which can be used in experiments where large numbers of counter tubes are to be used in anticoincidence. Only vacuum tubes are used in the construction. The circuit has a 100 percent efficiency, and its operation is wholly independent of the shape and duration of the coincidence or the anticoincidence impulses. When operating with up to 100 large Geiger‐Mu¨ller tubes in anticoincidence less than 1 percent of the real anticoincident counts are suppressed owing to the blocking effect of the anticoincidence multivibrator. The same principle is used in the construction of a recording circuit which also uses only hard vacuum tubes, and which is able to actuate any fast impulse counter at its maximum speed, without jamming.

ISSN:0034-6748    

DOI:10.1063/1.1740813

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

The decrease of current sensitivity of photo‐voltaic and photo‐conductive cells with increasing load resistance can be avoided by maintaining constant voltage across the cell. Two stable electronic circuits are described which were designed to accomplish this end and to serve as amplifiers.

ISSN:0034-6748    

DOI:10.1063/1.1740814

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A transient recorder of the ``memory'' type for measuring transients applied to positioning servomechanisms is described in some detail. Essentially, the recorder consists of a bank of condensers, on which the transient voltages are successively impressed and later read off a CRO screen and plotted as a function of time to reveal the nature of the transient. In recording a transient, errors not exceeding ten percent are to be expected of the equipment. Rapidity of recording transients is one of the chief advantages of the system. Equipment for measuring the amplitude and phase response of a servomechanism, when subjected to an alternating input of variable frequency, is described. The measurement of the phases of input and output angles of a positioning servo is accomplished by means of a commutator driven by the sine wave generator, which supplies the alternating input to the servomechanism. The commutator has but one bar, and a vacuum tube voltmeter is connected to an angle‐measuring synchro, once each cycle, by a brush which may be moved to find the zero point of the modulated wave representing the alternating input. The phase angle between the input and output may be read as the difference between the angle positions of the brush used to locate the zero point of the modulated waves of the input and output. Phase angles may be measured with an error not exceeding one degree.

ISSN:0034-6748    

DOI:10.1063/1.1740815

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A proportional counter utilizing recoiling protons ejected from a thin hydrogenous radiator by elastic collision with incident neutrons is described in its design and its response. Comparison between experimental and calculated curves for sensitivityversusneutron energy, and sensitivityversuscounting bias, indicate that the response of the counter is calculable. It may be used as a directional threshold neutron detector, the value of the threshold being open to arbitrary choice.

ISSN:0034-6748    

DOI:10.1063/1.1740816

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A description is given of a recording vacuum grating spectrograph for the infra‐red region of the spectrum from 1 micron to 30 microns. The description contains the details of the recording and amplifying system and the method for stabilizing the power from the radiant source. Typical records are shown of well‐known infra‐red spectra. The lines from the two isotopes of HCl are completely separated in the fundamental band obtained in first order. The rotational lines of the 4.3‐micron band of CO2are completely separated in the first‐order spectrum. In most parts of the spectrum it is possible to resolve lines separated by intervals less than 1 cm−1.

ISSN:0034-6748    

DOI:10.1063/1.1740817

出版商:AIP    

年代:1947

数据来源: AIP

摘要:

A method based on some work of Thomas Davis is described for controlling the rotor speed of an air‐driven ultracentrifuge. A permanent magnet mounted on the shaft of the centrifuge induces an e.m.f. in a series inductance, capacity resistance circuit which has the same frequency as the rotor. When the rotor speed approaches the resonance frequency of the circuit, energy is absorbed, and the driving air pressureversusrotor speed relation increases abruptly. By regulating the driving air pressure at a few lbs./in.2above that necessary to maintain the speed of the centrifuge where resonance begins, the rotor speed is held constant to roughly 0.1 percent over the range of speeds employed.

ISSN:0034-6748    

DOI:10.1063/1.1740818

出版商:AIP    

年代:1947

数据来源: AIP