ISSN:0034-6748    

DOI:10.1063/1.1769781

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

An apparatus is described for accelerating protons up to 400 kv with which to irradiate biological specimens in vacuum. The voltage is supplied by an air‐insulated electrostatic generator used with a multiple section tube. The protons are produced by a convenient and reliable source, which is described. Details of the irradiation of spores of the fungusAspergillus nigerwith protons are mentioned.

ISSN:0034-6748    

DOI:10.1063/1.1769782

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

The purpose of the present paper is to describe an instrument which is capable of measuring small d.c. voltages (of the order of 10−3volt full scale) without drawing any but an infinitesimal current, and which at the same time is as easy to use and as reliable as an ordinary d.c. instrument. When properly shunted, it can be used as an accurate, direct indicating ammeter for measuring currents of the order of 10−12ampere full scale.

ISSN:0034-6748    

DOI:10.1063/1.1769783

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

A vacuum tube sweep circuit is described which permits the transit of the oscilloscope beam to cover any desired interval of time during the cycle of events under observation, controllable delays being possible both before and after the transit. The circuit may also be used for single sweep work. A simple method for impressing time base markings is also described. Applications of the circuit are discussed and adaptations to multiple sweep photography are suggested.

ISSN:0034-6748    

DOI:10.1063/1.1769784

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

A method is described for measuring the thickness of thin metallic films, using &lgr;=3654A filtered from the mercury arc spectrum as the source of light for the Michelson interferometer. The shorter wave‐length light source produces a proportionally greater fringe shift in the interference pattern and thus thinner films can be measured with a greater accuracy. This method is used satisfactorily for films of the range 150–600A.

ISSN:0034-6748    

DOI:10.1063/1.1769785

出版商:AIP    

年代:1941

数据来源: AIP

摘要:

The design and operation of a 12‐stage electrostatic multiplier tube as a photon counter are discussed. The tube has a pure tantalum photoelectric surface, the multiplying electrodes being covered with oxidized beryllium. With 300 volts between successive electrodes the tube has a background counting rate of about 3 to 5 pulses per minute and records about one photon in 500 at a wave‐length of 10−8cm. The multiplication is about 18,000.

ISSN:0034-6748    

DOI:10.1063/1.1769786

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1769787

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1769788

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1769789

出版商:AIP    

年代:1941

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1769790

出版商:AIP    

年代:1941

数据来源: AIP