摘要:

A device utilizing pulse techniques has been built for automatic measurement of changes in radio wave travel times. The equipment uses a combination of amplitude, time, and frequency selection for discrimination against unwanted signals. The received signals from U. S. time standard station WWV are sampled at 1‐sec intervals to measure changes in the time of reception of the 1‐sec timing pulses transmitted by WWV. The changes in travel time can give information on the vertical velocity of a virtual reflection point in the ionosphere and other factors of interest in the study of the ionosphere.

ISSN:0034-6748    

DOI:10.1063/1.1716880

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A system is described for digital measurement and automatic recording of linear or angular position. An adding‐subtracting scaler is used to accumulate pulses generated by the digitizing element. Several of the major components are commercially available. The performance of the system as used for coordinate measurements on bubble chamber photographs is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716881

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An underwater sound velocity meter is described which employs an open‐end heavy‐walled tube for a resonant cavity. The water column is excited into vibration by a sound source near one end, while a hydrophone probe at the tube center registers the pressure amplitude. A sharp resonance (Q=450) permits making relative measurements with an uncertainty of less than 0.2 m/sec when the fundamental mode (f≈570 cps) is used.

ISSN:0034-6748    

DOI:10.1063/1.1716882

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The potential and electric field distributions in a traveling wave deflection system are derived for a sinusoidal deflecting signal. They are then generalized for application to arbitrary deflecting signals. It is shown that a longitudinal field exists and depends on the odd derivatives of the signal. This component of the field modulates the velocity of the beam and gives rise to errors in focusing and time axis position. The velocity modulated beam is then dispersed by the time axis deflection system. The nonuniformity which must exist in the deflecting component of the field is shown to depend on the even derivatives of the deflecting signal. The nonuniformity gives rise to dispersion and errors in deflection of the beam by the traveling wave deflection system. Generalized expressions for these errors are derived, and the errors are evaluated for a representative set of conditions.

ISSN:0034-6748    

DOI:10.1063/1.1716883

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A device for generating a linear, highly ionized, low temperature cesium plasma is described. The plasma is generated by having the output of cesium atomic beam ovens impinge on hot tungsten plates placed at both ends of a cylindrical vacuum chamber. The walls of the chamber are cooled so that neutral cesium condenses on them. The theory of the device, designated as the Q machine, is presented and some experimental results given. The maximum density achieved was 2×1012/cm3, with an estimated fractional ionization of 99%, and a confining field of 5900 gauss.

ISSN:0034-6748    

DOI:10.1063/1.1716884

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A description is given of a simple resistance‐heated apparatus for pulling germanium dendrites. Two distinct types of growth are obtainable. When the correct conditions are achieved, growth may continue indefinitely. A typical product is a 2 m length of essentially uniform ribbon 1.5 to 3 mm in width, and 0.1 mm thick.

ISSN:0034-6748    

DOI:10.1063/1.1716885

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A calorimeter has been constructed which adiabatically deforms metals with a known mechanical energy. The energy which is stored in the sample as a result of the deformation is the difference between the supplied energy and the heat which is found by the increase in sample temperature. It is also possible to follow subsequent energy releases which take place immediately following the deformation; for some materials this release can be an appreciable fraction of the stored energy. The results for the stored energy are considered to be accurate to approximately 10%.

ISSN:0034-6748    

DOI:10.1063/1.1716886

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Herewith is described a modified form of the x‐ray powder camera that employs a flat specimen mounted normal to the direct beam which proceeds along the axis of the cylindrical film, as first constructed by L. L. Hawes [Acta. Cryst.12, 443 (1959)]. Also presented are details of the techniques for mounting specimens, measuring films, and correcting these for errors. Theoretical discussion of the advantages and disadvantages of this type of camera, together with a simplified least‐squares technique for interpreting the data, are given in two papers by Hawes now in press. An example of the high accuracy obtained with this camera is described in Hawes.

ISSN:0034-6748    

DOI:10.1063/1.1716887

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Two total absorption gamma‐ray spectrometers utilizing anticoincidence shielding are described. One of these consists of a 5‐in. diam by 5‐in. thick NaI(Tl) well crystal enclosed in a 26‐in. diam by 30‐in. high plastic phosphor. The plastic phosphor serves as the anticoincidence guard. The second spectrometer consists of a 3‐in. diam by 3‐in. thick NaI(Tl) crystal with a 9⅜‐in. diam by 8½‐in. thick NaI(Tl) well crystal as its anticoincidence guard. With the anticoincidence shielding, and a point source in the well of the 5×5‐in. crystal, the Compton portion of the Zn65spectrum is reduced by a factor of about 5, while the Compton portion of the Co60spectrum (below 1 Mev) is reduced by factors of 20 to 25. With these point sources on top of the 3×3‐in. solid crystal, these Compton regions are reduced by factors of about 4 and 14, respectively. These anticoincidence shielding arrangements also provide background reductions of a factor of 2 to 5 in the energy region below 3 Mev. The response of these spectrometers to other gamma‐ray energies is included. The photomultiplier mounting arrangements for the large NaI(Tl) and plastic phosphors, and the resolutions of the plastic and NaI(Tl) crystal are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716888

出版商:AIP    

年代:1960

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1716890

出版商:AIP    

年代:1960

数据来源: AIP