摘要:

A method is described whereby a commercial oscilloscope such as the Tektronix Model 535 can be easily modified to give a pulsed X‐Y presentation. The application to voltage‐current plots is given in detail. For this case, a portion of the pulse voltage placed across the sample to be measured is applied to the horizontal sweep system of the oscilloscope superimposed on the regular time base while the pulse current information is applied to the normal vertical deflection system. By using the sweep delay circuits within the oscilloscope, any point of the pulse can be viewed as the start of the delayed sweep, the horizontal deflection of the starting point corresponding to the magnitude of the pulse voltage and the height corresponding to the pulse current. A family of such curves is obtained as the applied pulse voltage is changed, the locus of points of the start of the delayed sweep tracing out the desired V‐I characteristics. This is recorded photographically and has resulted in rapid V‐I plots having accuracies to within tenths of one percent.

ISSN:0034-6748    

DOI:10.1063/1.1716707

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The measurement of the diameter and index of refraction of spheres whose diameter is larger than the wavelength of the light used and whose index, relative to the surround, is close to unity is described. The measurements are based on the angular position of the first dark ring and first bright ring in the Fraunhofer diffraction pattern.The instrument is of novel design, its main advantages being that all the light scattered under a given angle is used in the measurement and that the peaks and valleys in the recorded graph are very prominent and easy to locate. The resolving power of the instrument is inversely proportional to the diffracting angle. The use of the Van de Hulst approximate diffraction theory for obtaining the diameter and the index of the diffracting spheres from the recorded diffraction pattern is described in detail. Application to the measurement of human blood cells, the main purpose of this work, is also completely worked out and experimental results are given. Very good agreement between the mean cell hemoglobin as measured with the standard procedures and the one described here has been found.

ISSN:0034-6748    

DOI:10.1063/1.1716708

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The theory of variable permeability torque measuring devices, such as that described by Beth and Meeks in 1954, is developed. Certain design requirements and methods for such instruments are set down. Experimental results on an improved version of their instrument are given for torques up to about 75 in.‐lb in a ½‐in.‐diam shaft, and indicate that accuracies between 1% and 5% may be expected.

ISSN:0034-6748    

DOI:10.1063/1.1716709

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Equipment is described to analyze diffusion couples and phase boundaries by means of x‐ray absorption, in conjunction with the G.E. XRD diffractometers. Analysis may be carried out automatically with the system described here over a minimum distance of 14 &mgr;. The equipment will not interfere with normal diffraction work over the range 0–106°2&thgr; and, therefore, can be left fixed to the diffractometer when not in use.

ISSN:0034-6748    

DOI:10.1063/1.1716710

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A photoelectric recording interferometer for gas analysis is reported. Central part of interference fringes is projected on the single slit of a photomultiplier through a polarizer P1with its principal axis perpendicular to fringes and a field splitting polarizer P2whose two Polaroid planes are split by a line parallel to fringes and oriented to ±45° to the principal axis of the polarizer P1and a rotating Polaroid disk. When the center of a fringe is brought in line with the splitting line of polarizer P2, alternating photocurrent becomes zero. Any change of position of the center line of the fringe relative to the splitting line generates an alternating photocurrent with an amplitude which is a function of the fringe shift and a phase which is a function of the direction of the shift. The shift of fringes which is proportional to gas concentration is detected; this shift makes a servo‐motor start to put the fringes back to their original position optically. The angle of rotation of the servo‐motor is proportional to the shift of fringes indicating the variation of the refractive index, i.e., the variation of the content ratio of the mixed gas. The sensitivity of this apparatus is observed to be about 1×10−8index unit, or in the case of CO2gas in air, about 0.01% by volume.

ISSN:0034-6748    

DOI:10.1063/1.1716711

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A filament furnace is described which is suitable for heating gram quantities of materials to 3000°C under reduced pressures or in various atmospheres. A quartz window and shutter assembly permit the observation of the specimen during the heating cycle by long working distance microscopes.

ISSN:0034-6748    

DOI:10.1063/1.1716712

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The parameters that control a blocking oscillator's pulse shape are reviewed. Limitations in previous techniques of pulse duration control are described. It is shown that the pulse duration may be determined either by tube (or transistor) saturation or by saturation of the transformer core material. The latter mode of operation is preferred because it confers stability against aging of tubes or transistors, variations of ambient temperature, and changes in loading. Design criteria for establishing either mode of operation are given. The means by which an externally applied magnetic bias can be used to control the pulse width over more than a 10:1 range are described. A blocking oscillator circuit designed according to the principles discussed is presented, along with specific performance data.

ISSN:0034-6748    

DOI:10.1063/1.1716713

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The liquids C3F8, C4F10, SF6, C2ClF5, and CBrF3, and mixtures of SF6with C2ClF5have been found to possess a number of desirable properties for use in large bubble chambers, designed primarily for particle decay studies. These properties are relatively short radiation length, convenient operating pressure and temperature, chemical inertness, and nontoxicity. Some properties of TeF6are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716714

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

An apparatus allowing a straightforward determination of the &pgr; equivalent circuit of alloy junction transistors is described. The principle of measurement is based on the simulation of wave forms. The possibility of a simple determination of the equivalent circuit at any working point of the transistor enables a rapid evaluation of the current or voltage dependence of the circuit elements. The equipment, having an upper frequency limit of 10 Mc, can be used for transistors of much higher alpha cutoff frequencies, since for the measurements the common emitter configuration is chosen. Examples are given to demonstrate how some physical and dimensional values of the transistor can be calculated from the measured parameters.

ISSN:0034-6748    

DOI:10.1063/1.1716715

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A high‐precision thermometer system has been developed using a carbon resistor (Allen‐Bradley type) as the sensing element. The resistor is in the frequency determining circuit of a stabilized Wien bridge oscillator. Thus temperature changes are displayed as frequency shifts. The frequency is read directly from a Hewlett‐Packard type 523B counter. When operated in the neighborhood of 100 kc at 4.2°K the sensitivity is approximately 50 kc/deg. This corresponds to a temperature resolution of 20 &mgr;deg, when used with the above counter. Resolution can be improved by observing higher harmonics. The power input to the resistor is of the order of 10−2&mgr;w. The time for a temperature measurement is 1 sec, and response times to changes are limited only by equilibrium in the thermometer. Absolute accuracy is essentially limited only by the determination of the helium vapor pressure during calibration.

ISSN:0034-6748    

DOI:10.1063/1.1716716

出版商:AIP    

年代:1959

数据来源: AIP