摘要:

Sixteen photomultiplier tubes have been studied to determine the relation between the uniformity of their photocathodes and the resolution obtained from a &ggr;‐ray scintillation spectrometer using each of them. The sensitivity contours of the tubes have been plotted. The resolution was found to be related to theaveragesensitivity but could be improved by concentrating the light on the most sensitive part of the photocathode. Techniques for studying sensitivity with an artificial light flasher are described.

ISSN:0034-6748    

DOI:10.1063/1.1770874

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A preliminary report on our first extensive measurements of the cosmic‐ray intensities at medium underground (5880 m water equivalent) is given. In these experiments, carried out during 1951 and 1952, two identical portions of photographic plates, one bare and one shielded with Cd, were exposed at identical temperature. For the controls, which were exposed at the surface of the earth, there was found a good agreement between our results and those obtained by Yagoda and Kaplan for slow neutrons. The Cd difference counts obtained at the underground station were much higher than the controls.

ISSN:0034-6748    

DOI:10.1063/1.1770882

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Relaxation oscillators are described of which the fundamental frequency is a high‐order (up to 10 000) subharmonic of the frequency of a quartz crystal which serves as the controlling element. Except for the addition of the crystal, the circuits are no more complicated than conventional ones.

ISSN:0034-6748    

DOI:10.1063/1.1770889

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The basic slotted section measurements of VSWR and the location of the voltage minimum are affected by the variety of errors inherent in the slotted section. Considered here are those effects, important for precision measurements, introduced by discontinuities due to the end of the slot, and due to possible adaptors, coupling elements, bead supports, etc., and by the presence of the slot in creating a guide wavelength and characteristic impedance slightly different from that of a guide without a slot. A calibration procedure is presented which compensates rigorously for these effects in a simple fashion.

ISSN:0034-6748    

DOI:10.1063/1.1770875

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The uniformity of the product of thickness and density (i.e., mass per unit area) of materials of constant mass absorption coefficient is determined by measurements of the variation in gamma‐ray transmission. The radiation is detected with a scintillation detector and vibrating‐reed electrometer. For a given incident intensity, maximum sensitivity is attained when a source is chosen which emits gamma rays whose mean free path in the material under investigation equals the thickness, assuming the detector response is a slowly varying function of quantum energy. This optimum condition for cobalt‐60 radiation obtains for thicknesses of 3, 1, and ½ in. of Al, Fe, and U, respectively; using a one‐curie source, variations of 0.01 percent in the uniformity of plates of these thicknesses have been measured. The method may be applied also to the scanning of curved surfaces and extended materials where the source and detector cannot permanently be fixed with respect to each other. For this latter case, the problem of compensating for the effect of misalignment of source and detector is considered.

ISSN:0034-6748    

DOI:10.1063/1.1770876

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Evidence is presented for neutron counting by the S(n,p)P32endothermic reaction in ZnS(AG) powdered phosphors. Preliminary studies have been made on the possible application of this reaction in sulfur‐containing crystals to neutron scintillation spectrometry above ∼2 Mev.

ISSN:0034-6748    

DOI:10.1063/1.1770877

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A general review of fluid pressure transient measurement and instrumentation is presented. The review is designed to acquaint the reader with the basic problems encountered in transient measurement and to discuss the various types of pressure gauges available. The measurement problems include such topics as frequency response, thermal and electrical stability, calibration techniques, and interpretability of results. Some of the more important gauge types covered are mechanical, piezoelectric, condenser, strain, inductance, and optical. The discussion of these gauges includes a critical evaluation of the important characteristics of each, followed by a table comparing them with each other on the basis of these characteristics. With this background, the choice of a gauge best suited for a particular transient measurement problem should be facilitated.

ISSN:0034-6748    

DOI:10.1063/1.1770878

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A simple method is described which enables the direct reading of phase‐difference angle between voltages applied to horizontal and vertical deflecting plates of a cathode‐ray oscilloscope equipped only with a transparent cross‐section scale. Accuracies approaching plus or minus one degree are attainable.

ISSN:0034-6748    

DOI:10.1063/1.1770879

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The design of a barometer is described which achieves a logarithmic response over a wide range of pressures by the use of two fluids and a tube of varying cross section. Application of the principle to barometers with other useful nonlinear scales is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1770880

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The 200‐atmos mercury manometer described in previous papers is studied experimentally and revised, especially by removing the mercury reservoirs from the measuring system. A rotating loaded piston is used to provide a constant test pressure, and details as to its construction and use are given, as also for the toluene pump, valves, unions, Invar tape, and cathetometers. The temperature control of the manometer and the management of its fluids are described. The barostat piston was known to vary 2 to 3 parts per 104in. cross section. By means of a screw‐driven plunger the barostat was held manually at the same vertical position during each of a series of 8 readings of the barostat pressure. The maximum divergence from the mean of the series is 0.83 part per 104, and the average of the absolute values of the divergences from the mean is 0.30 part per 10. It is concluded that the manometer can be relied on to measure a pressure of about 200 atmos to within 1 part in 104.

ISSN:0034-6748    

DOI:10.1063/1.1770881

出版商:AIP    

年代:1954

数据来源: AIP