摘要:

A pulsed 931‐A photomultiplier and TW‐10 traveling wave oscilloscope have been used to measure the scintillation decay times of (a) transtilbene, (b) terphenyl‐in‐toluene, and (c) polystyrene plastic containing one percent terphenyl, 0.03% &agr;‐NPO, and 0.01% zinc stearate. The times for 1/edecay are (a) 4±1×10−9sec, (b) 2.2±0.3×10−9sec, and (c) 2.2±0.3×10−9sec. The behavior of the multiplier with large collector currents was studied, using a synchronized flash lamp. Linear currents up to 1.5 amperes and maximum currents up to 15 amperes were obtained. Currents in the ampere range can give rise to an oscillation which may limit the application of pulsed photomultipliers.

ISSN:0034-6748    

DOI:10.1063/1.1715362

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The electrical properties of a polished surface of high‐purity silicon can be greatly modified by heavy ion bombardment. In particular, the change in the rectifying properties of silicon has been used as a detector of low energy ions striking the surface. By bombarding with He+ions through a silver film which was evaporated directly on the silicon, we determined the thickness of Ag at which ions no longer reached the silicon surface. By this method it was found that the range of 30 kev He+ions in Ag films is 2480±250 A. The lowest ion energy which produces an observable effect on the silicon is about 200 ev. Similar effects have been observed for hydrogen, argon, nitrogen, and oxygen ions. Other electrical properties of silicon surfaces which have possibilities as ion indicators are mentioned.

ISSN:0034-6748    

DOI:10.1063/1.1715363

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The microbial auxanometer, an instrument which automatically records the growth rate of a micro‐organism during its continuous growth under turbidostatic control, has been developed further to provide (1) interchangeable turbidostatic and chemostatic control, (2) automatic recording of culture density under chemostatic control or during uncontrolled growth, and (3) improvements in growth tube design which reduce cell trapping. The instrument delivers a continuous record of the growth history of the organism under either free‐growing or growth‐factor‐limited conditions and of changes in growth rate induced by physical or chemical means. It is well adapted to the study of spontaneous and induced mutation rates.

ISSN:0034-6748    

DOI:10.1063/1.1715364

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

``Jerk'' is defined as the time derivative of acceleration. Simple methods for designing jerkmeters are briefly discussed. The present design consists of a low‐frequency (20 cps) piezoelectric accelerometer, the output of which is electrically differentiated. The response of the instrument is flat within ±7% from zero‐frequency to 18 cps, at 21°C, but changes in response up to 33% are introduced in the range between 10 and 18 cps at temperatures between 12°C and 32°C. A ballistocardiogram is shown, with simultaneous displacement, velocity, acceleration, and jerk records.

ISSN:0034-6748    

DOI:10.1063/1.1715365

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715366

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715368

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715369

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715372

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715373

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715376

出版商:AIP    

年代:1956

数据来源: AIP