摘要:

Mass absorption coefficient data published by Allen, Bragg, and Victoreen for the wavelength region 0.1 to 50 A are plotted for several common x‐ray tube and counter windows (Al, Be, and mica) and gases (Xe, Kr, A, and Ne) used in x‐ray detectors. A graph of the calculated percentage transmission of the windows is presented. The calculated quantum‐counting efficiencies for the range 0.1 to 15 A are shown for an end‐window argon‐filled Geiger counter, side‐window Xe, Kr, A, and Ne proportional counters and an NaI·Tl scintillation counter. Some of the factors to be considered in the choice of detectors for x‐ray diffractometry and x‐ray spectroscopy are discussed particularly with respect to the spectral sensitivity.

ISSN:0034-6748    

DOI:10.1063/1.1771299

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Geiger counter x‐ray diffractometer patterns of samples with moderate to high radioactivity give a high background, which reduces the precision of the x‐ray‐line intensity and profile measurements. The large amount of lead shielding required to reduce the background is not practical in modern precision goniometers and could not bring as great a reduction as can be achieved with scintillation or proportional counters using pulse‐height discrimination and no shielding. This paper describes a technique using a scintillation counter which permits the measurement of x‐ray patterns from strongly radioactive specimens. A scintillation counter with 0.56 in.×0.16 in.×0.017 in. thick NaI·Tl crystal, 0.005 in. Be window and DuMont 6291 photomultiplier is described, which reduced the background of an 84 mr/hr/10 cm Co60sample from 785 c/sec, measured with a Geiger counter, to 26 c/sec and increased the sensitivity to CuK&agr; by a factor of about 2.5 to 3.

ISSN:0034-6748    

DOI:10.1063/1.1771300

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

By employing A37as a tracer it has been possible to show that quantities of argon as small as 10−9cc can be circulated in a vacuum system containing furnaces, charcoal traps, electrical discharges, and stopcocks without measurable loss of argon. Further, it is shown that argon is not desorbed from charcoal at liquid air temperatures in appreciable quantities during prolonged evacuation.

ISSN:0034-6748    

DOI:10.1063/1.1771302

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

The instrument described contains an illuminated scale of which a virtual image is formed at infinity by means of a spherical mirror and a glass plate. The image of the scale is superimposed on the normal field of view of the naked eye, enabling direct measurement of angles in that field.

ISSN:0034-6748    

DOI:10.1063/1.1771303

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A metal absorption cell is described for the measurement of absorption spectra of alkali‐halide crystals at low temperatures. The cell is specifically designed for the Cary automatic‐recording spectrophotometer. The crystal holder of the cell can also be heated electrically to several hundred degrees centigrade for crystal bleaching experiments, or rotated out of the spectrometer beam to expose the crystal to x‐rays. Design and performance data are given.

ISSN:0034-6748    

DOI:10.1063/1.1771304

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An amplifier and power supply for a stable, high‐frequency, electronic, bristle flowmeter is described. The transducer element is the RCA 5734 tube. The difficulty in applying this tube to blood flow measurements is overcome by use of a 500 000 ohm load resistor instead of the 75 000 ohm value recommended by the manufacturer. The advantages of this device are commercial availability of flow‐sensing element, high signal‐to‐noise ratio, good maintenance of the zero flow base line, response to backflow as well as forward flow, and provision for the recording of either phasic or mean flow.

ISSN:0034-6748    

DOI:10.1063/1.1771305

出版商:AIP    

年代:1955

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1771307

出版商:AIP    

年代:1955

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1771308

出版商:AIP    

年代:1955

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1771309

出版商:AIP    

年代:1955

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1771310

出版商:AIP    

年代:1955

数据来源: AIP