ISSN:0034-6748    

DOI:10.1063/1.1749114

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749115

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749116

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

A determination of the number of &agr;‐particles emitted per unit areas per unit time by materials usually used in the construction of ionization chambers has been made. The radioactive contamination of a few gases was examined and methods of removing radioactive material from surfaces were investigated. A FP54 vacuum tube, operated at about one‐tenth of the maximum sensitivity, was used with a photographic recorder for detecting the &agr;‐particles. With this sensitivity &agr;‐particles of a range in air of 2 mm or more could be detected. Cold rolled steel which emitted about 3 &agr;‐particles per 100 cm2per hour was the freest from contamination of any material examined. Brass and copper were the next best materials. Careful sandpapering of a surface was very effective in removing radioactive material. It was also found that a clean surface when exposed to air became contaminated. This made it necessary to keep such surfaces in an atmosphere of nitrogen or some gas which was free from radioactive contamination. Celluloid which was cleaned with alcohol and painted with good drawing ink made a satisfactory material for ionization chamber windows. Amber emitted no more &agr;‐particles than steel but Pyrex glass emitted about 5 times as many &agr;‐particles as steel. Methyl bromide, good quality carbon dioxide, and nitrogen were found to be suitable gases for filling ionization chambers.

ISSN:0034-6748    

DOI:10.1063/1.1749117

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

An amplifying lever system used for measuring piezoelectric deformations of quartz and tourmaline plates is described. Interference fringes are formed between a semi‐transparent coating of silver on glass and a mirror on the long end of a lever. With an arm ratio of 1864 to 1 the sensitivity of the lever is such that a displacement of a knife edge on the short end of about 0.15A can be detected. The chief difficulty in its use was found to be disturbance from vibrations. Sources of error, possible improvements, and possibilities for other uses are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1749118

出版商:AIP    

年代:1933

数据来源: AIP

摘要:

In this method acapacitanceis compared with a mutual inductance in a 1000‐cycle a.c. network. The secondary of themutual inductanceis in the telephone bridge circuit and carries zero current. By using a Wagnerground circuitthere is complete silence in the telephone at the balance point. When used as asubstitution methodtwo nearly equal condensers can be compared with each other with anaccuracythat is much greater than that of the resistances employed. The final balance is obtained by adjusting a small variableself‐inductancein series with the primary of the mutual inductance. For a given capacitance and frequency the value of this self‐inductance is directly proportional to thepower factorof the condenser, and the scale of this inductance can be calibrated toread directlythe value of the power factor.Vector diagramsare given to show the relations among the capacitance, power factor, and the inductances, and a fewtypical measurementsare recorded.

ISSN:0034-6748    

DOI:10.1063/1.1749119

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749120

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749121

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749122

出版商:AIP    

年代:1933

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1749123

出版商:AIP    

年代:1933

数据来源: AIP