摘要:

A Hopkinson bar wire strain gauge technique has been developed for the measurement of projectile penetration force as a function of time. The elastic strain wave resulting from projectile impact and penetration of the bar end is measured with oscillographic equipment; this strain pattern is a direct and continuous measure of the penetration force. Comparison of impacts measured by the bar with those obtained by a previously developed precision optical chronograph have shown increased accuracy, and a simplification of test procedure and analysis with the new method.

ISSN:0034-6748    

DOI:10.1063/1.1715238

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A lithium fluoride crystal when irradiated with deuterons from a cyclotron develops a yellow color; if the deuterons are stopped within the crystal, there is a sharp demarcation in color between the irradiated and unirradiated portions. It has been found that the measurement of the depth of penetration of the color into lithium fluoride can be used to determine accurately (±0.1 Mev at 20 Mev, ±0.2 Mev at 10 Mev) and rapidly the energy of deuterons in a cyclotron beam. A single exposure of a crystal to the deuteron beam allows one to determine not only the energy of the deuterons but also the angular orientation of the beam trajectories.

ISSN:0034-6748    

DOI:10.1063/1.1715239

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A new time‐delay analyzer encompassing a wide flexible time base is described. Time channels of 0.001, 0.01, 0.1, 1, and 10 sec width are provided; these may be combined in progressive sequence or used individually for essentially an infinite number of channels. Provision is made for either photographic or electric recording. Data obtained with the new analyzer agree with a conventional ten‐channel time‐delay analyzer over the limited range of the latter. A simple procedure is given for checking correct operation of the system.

ISSN:0034-6748    

DOI:10.1063/1.1715240

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Betatron oscillations in the University of Michigan synchrotron have been investigated by exciting these oscillations with a transverse electric field. The results indicate that the betatron oscillation is composed of a group of component frequencies which are separated by the frequency of synchrotron phase oscillation. The suggested explanation of the observed splitting is the modulation of the betatron oscillation frequency by the synchroton oscillations.

ISSN:0034-6748    

DOI:10.1063/1.1715241

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Cˇerenkov counters are described which we have used successfully in measurements of the flux of primary cosmic‐ray alpha particles. They consist of cylindrical Lucite radiators 2.5 cm thick viewed by end‐window photomultipliers. Fast singly charged particles that pass through the effective area in directions roughly parallel to the counter axis give pulse‐height distributions with 35–45 percent relative width at half‐maximum for effective areas up to 60 cm2. An analysis of factors that influence the resolution of Cˇerenkov counters is given.

ISSN:0034-6748    

DOI:10.1063/1.1715242

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Small differences in surface tension have been measured by a new method. The method makes use of a horizontal capillary tube, which may, for example, have a temperature gradient along its axis. The velocity of a small sample within the capillary may then be measured, or brought to zero by tilting the tube. As a check, the temperature coefficient of surface tension of benzene andn‐decane was measured to within 2 percent of previously published values. The method seems to be particularly adapted to the investigation of small samples.

ISSN:0034-6748    

DOI:10.1063/1.1715243

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The fabrication and properties of thin glass membranes are described. Foil thicknesses are a few tenths of a micron, corresponding to energy losses for 1‐Mev protons of 10–20 kev.

ISSN:0034-6748    

DOI:10.1063/1.1715244

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A bent crystal monochromator, for Geiger counter diffractometry, was constructed to monochromate the specimen‐reflected x‐ray beam. This results in very low backgrounds, due to the elimination of fluorescent scattering from the specimen. Adequate resolution and diffracted energy were obtained.

ISSN:0034-6748    

DOI:10.1063/1.1715245

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A 3‐MevX‐band microtron (electron cyclotron) particularly suited for laboratory use in nuclear and electron physics is described. About twelve electron orbits, in operating modes representing energy gains per turn up to 255 kev, may be obtained. By means of a magnetic shield probe, electrons may be extracted from any orbit for external experiments. Final orbit currents of 10−7av amp and x‐ray yields of 0.5 r/min at 10 cm are obtained. Ellipsoidally shaped sealed‐off glass microtron tubes are under development.

ISSN:0034-6748    

DOI:10.1063/1.1715246

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A vacuum dilatometer based on the use of a linear variable differential transformer has been constructed. Expansion or contraction of the specimen moves a silica pusher‐rod which, in turn, changes the position of the core of the linear transformer. The output of the transformer is directly proportional to the displacement of this core. The output is amplified, rectified, and fed into the chart‐moving circuit of a function‐plotting potentiometer. The transformer is supplied by a 2000 cycle per second oscillator. By varying the input voltage to the transformer, magnification of the expansion curves can be increased or decreased as desired. The instrument has been used for about a year for the detection of solid phase transformations in alloys. Several curves are reproduced to illustrate the performance of the instrument.

ISSN:0034-6748    

DOI:10.1063/1.1715247

出版商:AIP    

年代:1955

数据来源: AIP