摘要:

A recording fluxmeter has been developed which employs one or two integrators and a double element L and N Speedomax recorder for tracing magnetization curves directly on standard coordinate paper. The response of the recorder pen drive mechanism is proportional to the flux density,B,and is controlled by theBintegrator. The response of the paper drive mechanism is proportional to the magnetizing force,H,and is controlled either by the magnetizing current, when the specimen is in the form of a ring, or by theHintegrator when the specimen is in the form of a bar. Ayrton shunt networks provide flexibleBandHscale adjustments. High accuracy and sensitivity are obtained by minimizing the causes of drift. At maximum sensitivity, four interlinkages give a deflection of one mm.

ISSN:0034-6748    

DOI:10.1063/1.1745670

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A variable space liquid absorption cell is described for use in the infra‐red spectral region. Its range of thicknesses from 5 mm to less than 10 &mgr; makes it suitable for the compensation of absorption by solvents in a double beam spectrophotometer; its accuracy and reproducibility are sufficient for most direct qualitative and quantitative measurements. The minimum volume is approximately one cc, and the leakage is negligible. Its windows of rocksalt may easily be removed and repolished.

ISSN:0034-6748    

DOI:10.1063/1.1745671

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Measurements have been made on the time of decay of scintillations from organic phosphors irradiated with gamma‐rays. Interference between the output pulse from a photo‐multiplier and its reflection from a shorted line is used to determine the time constants.

ISSN:0034-6748    

DOI:10.1063/1.1745672

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

In order to obtain a versatile instrument for directional cosmic‐ray studies, and to investigate an indicated correlation of the soft component of cosmic radiation with the present cosmic‐ray burst studies being carried on at the University of Colorado a dual cosmic‐ray telescope was constructed. Each bank of the telescope consists of five counter trays with nine Geiger counters in each tray. The electronic circuits are connected to give three triple consecutive coincidence trains: 1, 2, and 3; 2, 3, and 4; 3, 4, and 5. By the insertion of eight centimeter‐thick lead blocks covering the sensitive area of a Geiger tray between trays 3 and 4, and 4 and 5; a separation of the components of the radiation is possible.The telescope is adjustable in zenith in 15 degree intervals from 0 to 75 degrees from the vertical. However, in azimuth, in order to investigate asymmetry characteristics, two positions 180 degrees apart are employed. The control of the telescope is entirely automatic with the recording of data being obtained by means of periodic photographs of the indicating panel, showing the counting rate, zenith and azimuthal positions, and the time and date of the measurement. The telescope changes in zenith and in azimuth every forty minutes; the changes in zenith and azimuth being displaced twenty minutes. A cycle of operation, which consists of the step change in zenith from 0 to 75 degrees with the associated alternate azimuthal changes, requires four hours.

ISSN:0034-6748    

DOI:10.1063/1.1745673

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A technique is developed for the rapid and precise measurement of the secondary electron emission properties of certain dielectric surfaces. The dielectric surface is bombarded by primary electrons having energies which produce a secondary emission ratio greater than unity. This establishes the surface potential at a known value. With the known potential difference between the dielectric surface and primary electron source, the energies of the primary electrons are automatically determined for the first instant of surface bombardment. The net current to the dielectric surface at any moment is measured by using a cathode‐ray oscillograph to observe the transient current to a metal plate which backs the dielectric. The method has been used to study metallic surfaces and has yielded results which agree very closely with those obtained using the conventional d.c. method of measurement.

ISSN:0034-6748    

DOI:10.1063/1.1745674

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

In order to keep the width of cloud‐chamber tracks down to less than 1 mm the time delay between passage of a ray and completion of an expansion must be 10−2sec. or less. When Geiger counter control is employed it may be difficult to obtain a sufficiently fast acting expansion control valve, particularly for a large cloud chamber. A valve combining a number of principles not all used by others has been constructed. By balancing pressures the movable valve parts can be made very light despite a large valve opening, and the controlling electromagnet can be quite small. Calculations were made concerning all the important design features. Even a small electromagnet must be laminated to insure sufficiently fast decay of its magnetic field. Most of the remaining time delay is caused by the aerodynamic resistance at the valve opening. For a valve diameter of 5.6 cm expansions are completed in 8×10−3sec. With a power consumption of 0.17 watt a small vacuum tube is sufficient for operation. By balancing pressures one could construct a much larger valve operating as fast as the valve described with only a slight increase in power consumption.

ISSN:0034-6748    

DOI:10.1063/1.1745675

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

By superimposing concentric radial elements on rectangular coordinate rulings, vernier systems may be constructed reading in two or three dimensions without the necessity of any particular angular orientation.A two‐dimensional vernier may consist of one transparent element ruled with concentric circles. The observed tangencies of the circles, with regard to a rectangular grid placed in contact, provide the reading of the additional decimal of the coordinates of the fiducial center of the circles on the grid.A three‐dimensional vernier system may be established by means of a binocular optical system presenting images of spheres concentric with the locating point and images of coordinate boxes in the same space. The tangency of a vernier sphere and coordinate plane indicates the last decimal of the reading.Angular orientation may be indicated by radial lines near the points of tangency.

ISSN:0034-6748    

DOI:10.1063/1.1745676

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

This paper describes a very simple low level coincidence circuit of moderate speed, which is suitable for use with two or more multiplier photo‐tubes in a scintillation detector of radiation. The operation of the circuit is analyzed, and performance data given to show its effectiveness in eliminating spurious counts due to noise pulses in the photo‐tubes. Some useful modifications of the circuit are suggested.

ISSN:0034-6748    

DOI:10.1063/1.1745677

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Shock waves close to the edge of explosive charges have been successfully photographed at rates exceeding 100,000,000 frames per second. These ultra‐high framing rates are obtained with a multislit focal plane shutter which is transported optically across the film plane by a rotating mirror. Linear shutter speeds up to 3000 meters per second are easily obtained, and the resulting framing rates with the proper selection of slit widths can be varied from 105to 109frames per second. Each individual frame is composed of a series of lines, and the degree of ``discontinuity'' across each frame is proportional to the total number of frames.

ISSN:0034-6748    

DOI:10.1063/1.1745678

出版商:AIP    

年代:1950

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1745680

出版商:AIP    

年代:1950

数据来源: AIP