摘要:

The surface temperature of a body is equal to the temperature of the measuring junction of a thermocouple, if this temperature has been, by heating or by cooling, so adjusted that the meter in the couple circuit does not deflect when the measuring junction makes a brief contact with the surface being measured. The validity of this principle was confirmed experimentally by measuring a surface whosetruesurface temperature was known independently. The new method does not sensibly affect the surface conditions as long as the junction is very small in comparison with the object being measured and the contact is short and light. It was shown that the temperature rise due to the proximity of the measuring junction was negligible in the case of a 0.4‐mm thick glass sheet or the human skin. The new method can give the correct surface temperature even when radiation comes from above or from below. Consequently the opacity of the surface layer does not matter as in the case of the radiation pyrometry.

ISSN:0034-6748    

DOI:10.1063/1.1745413

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

In the schlieren apparatus described in the following, the conventional knife‐edge elements are replaced by multiple slit‐gratings. The main advantage gained by this design is the fact that larger‐sized working fields can be achieved with an objective lens of given aperture. Also, in some cases, greater intensity of image illumination is obtained, and usually the over‐all length of the system is reduced.

ISSN:0034-6748    

DOI:10.1063/1.1745418

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A design study is presented for a proton synchrotron (to be called a ``Cosmotron'') to accelerate protons to energies of the order of three billion volts. Protons are injected from a four‐million volt Van de Graaff machine. They are deflected electrostatically into a racetrack orbit including four quadrants of thirty‐foot radius of curvature, and four straight sections ten feet long. The energy gain per revolution supplied by the radiofrequency system will be about 1000 ev. Acceleration will continue to 1.0 seconds to a final energy of about three Bev. Construction of this machine is now in progress.

ISSN:0034-6748    

DOI:10.1063/1.1745428

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Precise pressure measurement in the range from 5 to 100 atmos. is quite a difficult problem. A set of high pressure mercury manometers is very unwieldy and difficult to use, while Bourdon gauges require frequent recalibration and are inherently inaccurate. The most likely solution for this problem is to use a simple piston‐in‐cylinder pressure balance, which, for these pressures and for accuracies of the order of 0.05 percent, can be relatively crude, and does not require excessively precise machining or care in use. A simple pressure balance was constructed for use in the pressure range from 25 to 35 atmos., and used for both pressure measurements and density change determinations. It proved perfectly satisfactory, giving pressures reproducible from day to day to about 0.01 atmos.

ISSN:0034-6748    

DOI:10.1063/1.1745414

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

Gas flows through two restrictions in series, the second one or both being a nozzle operating with sonic throat velocity so that discharge is independent of the downstream pressure. For fixed restrictions, the ratio of entrance pressures at the two restrictions depends on their relative sizes and the ratio of entrance temperatures. After calibration, the pressure ratio may be used to measure temperature with a sensitivity of 1°C or better over a range of 2000°C. With the same arrangement, the temperature being constant, the intermediate pressure is a direct measure of mass flow. A sensitivity of better than 0.1 percent is possible in this measurement. For given temperatures, the device can be used as a ``pressure divider,'' with the intermediate pressure controlled by adjusting the restrictions, or as a pneumatic micrometer. Gas analysis is accomplished by removing one component of the gas flow between nozzles. A vacuum pump is used, if necessary, to ensure critical discharge through one or both nozzles; divergent cones on nozzles may be used to minimize pressure drop.

ISSN:0034-6748    

DOI:10.1063/1.1745415

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

This report discusses the design and use of piezoelectric gauges for the measurement of rapidly varying hydrostatic pressures of large amplitude in gaseous and liquid media. Reasons are given for the selection of tourmaline in preference to other types of crystal. Fundamental principles of design are stated, and gauge construction is described in the light of these principles. A simplified theoretical analysis of transient response characteristics is presented.

ISSN:0034-6748    

DOI:10.1063/1.1745416

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A method for eradication of accumulated background on Ilford C‐2 plates, 100–200&mgr; thick, without reducing their sensitivity to medium ionizing particles, is described. The method involves a mild oxidation of the emulsion by air saturated with water vapor at 35°C for a period of about 16 hr. The plates are then dried and are ready for experimental exposure. Analysis of grain counts shows no loss of sensitivity in proton tracks over their last 200&mgr; range when the plates are developed with a mild hydroquinone developer. Complete eradication of background alpha‐tracks and stars is secured as well as destruction of latent images of the less ionizing proton recoils instigated by external neutron bombardment. Grain density studies on proton tracks located at different depths in the emulsion indicate substantially uniform sensitivity after eradication except for the uppermost 50&mgr; which develop with about a 10 percent reduction in mean grain density as compared with tracks deep within the recording medium.

ISSN:0034-6748    

DOI:10.1063/1.1745417

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

The various corona gap forms suitable for the convenient investigation of corona phenomena of both signs in the laboratory that are capable of yielding quantitative data involving the Townsend integral for the thresholds of the manifold phenomena are discussed. For laboratory study the most convenient form of gap is the hemispherically capped cylindrical point‐to‐plane system. Analysis of the potential fall along the axis in such gaps by means of electrolytic model studies indicates that the essential parameter isL/r,the ratio of gap length,L,from point surface to plane relative to the point radius,r.The model study potentials are, however, incapable of giving accurate values of the field strength. These fields must be obtained by computation. Laboratory studies of corona indicate the desirability of relatively large values ofL/r.Practical considerations based on studies at atmospheric pressure indicate point radiirof 0.025 and 0.05 cm with a ratioL/r=160 to be those giving the greatest flexibility and most widely separated thresholds at convenient potentials. The use of such point systems to standardize data is recommended. On this basis the field along the axis for the hemispherically capped cylindrical point‐to‐plane gap as computed by E. E. Dodd is given and here applied to the calculation of the point‐to‐plane Townsend integral for pre‐onset burst pulse thresholds in air as observed by H. W. Bandel. The value is compared with the values obtained by W. N. English for confocal paraboloids where the fields are accurately known. The results are satisfactorily consistent. Discrepancies in the fixing of burst pulse thresholds by various observers are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1745419

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A method is described which permits discrimination between noise pulses and pulses of small light flashes. The arrangement consists of three multipliers facing the three faces of one and the same crystal. One multiplier acts on the ``Y'' axis, another on theXaxis and the third one on theZ(intensity) axis of an oscilloscope. Light flashes induce pulses in all multipliers simultaneously, whereas noise‐pulses occur at random and produce triple‐coincidence pulses only very rarely. Triple coincidences are easily recorded with the scope. Pictures are presented illustrating the operation of the arrangement. The original noise being of the order of three thousand per second was dropped to one noise pulse in three seconds.

ISSN:0034-6748    

DOI:10.1063/1.1745420

出版商:AIP    

年代:1950

数据来源: AIP

摘要:

A flexible method of detecting coincidences and short time intervals has been devised in which a photo‐multiplier tube views the screen of a cathode‐ray tube. By using one pulse as initiator of a sweep and the other in vertical presentation, coincidences can be observed in a fixed portion of the screen while the remainder of the screen is masked off. In present use the method is limited only by the pulses available (5×10−8sec.). The method appears to be capable of extension to time intervals of the order of 9×10−10second or smaller.

ISSN:0034-6748    

DOI:10.1063/1.1745421

出版商:AIP    

年代:1950

数据来源: AIP