摘要:

Methods are described for exciting gases to states from which they emit coherent spontaneous radiation in the microwave frequency region. The excitation is produced by the application of short pulses of microwave power. The power subsequently radiated by the gas is calculated for several cases, and experimental methods used to detect the radiation are described. The problem of sensitivity is discussed and compared to the sensitivity obtainable in a continuous absorption experiment. The operation of a high resolution microwave spectrometer, which produces lines substantially narrower than the usual Doppler width, is described. The method used to stabilize the klystron used in these experiments, which is a modification of the Pound i.f. method, is given.

ISSN:0034-6748    

DOI:10.1063/1.1715156

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Studies have been made of effects encountered in the use of a gridded parallel‐plate ion chamber for energy measurements. These effects are: gas multiplication about the grid structure, capture of electrons by the grid, and variation of saturation characteristics between various gases and gas mixtures. Curves relating to these are presented for He, Ne, A, Kr, N2, He+3% CO2, A+3% CO2, and A+5% N2. It is found that the field conditions necessary to prevent electron capture by the grid may be correlated with electron lateral diffusion. Anomalies in connection with the behavior of argon‐carbon dioxide mixtures are pointed out, and several possible explanations for these are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715157

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A circuit for the measurement of time intervals down to 10−10sec is described.The circuit works on the principle of transforming the delay &tgr; to be measured into a flat‐topped signal whose amplitude is proportional to &tgr;, and whose length is independent of &tgr; and controllable at will within wide limits (up to about 100 &mgr;sec). The precision and stability of the circuit are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715158

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

This paper describes an equipment for the precision measurement of short time intervals as defined by two successive electrical pulses. It features two identically constructed mercury ultrasonic delay lines, one in each of two channels. These lines are precision built and extensible in length by approximately 10%. The measurement is made by first adjusting the lines for equal delay, feeding the pulses into the two channels, respectively, and then noting the extension of the line receiving the prior pulse which is required to bring the two output pulses into coincidence. A continuous range of measurement of 0 to 40 &mgr;sec is available, and the upper limit can be extended as desired by inserting fixed delays in one channel externally. Aside from the continuously variable feature, the instrument is characterized by relatively high precision capabilities, ease of measurement, versatility, and reliability of operation.

ISSN:0034-6748    

DOI:10.1063/1.1715159

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A new type flash illumination unit for use with flash tubes, electric sparks, and exploding wires is described. The system is controlled by a thyratron tube, however, in a manner different than up to now; the controlled energy does not pass through the thyratron tube. The basic circuit of the apparatus consists of two flash tubes or spark gaps connected in series. The flash tubes or spark gaps are ignited by giving double voltage first to the one and, when it is ignited, to the other spark gap or flash tube by means of the thyratron tube. The flash tube illumination circuit makes the simultaneous operation of more than two flash tubes or sparks possible. The thyratron tube igniting the illumination unit may be controlled by electric or by mechanical means.

ISSN:0034-6748    

DOI:10.1063/1.1715160

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An automatic arrangement is described for operating an electrometer. Double parallel optical slits replace the ordinary eyepiece‐reticule scale, or the scale of a mirror‐scale arrangement. Photoelectric signals are produced when the real image of the electrometer needle or the light beam crosses the optical slits. These signals operate the electrometer itself and a time‐interval printer. Both current and sensitivity measurements are left on a printed record. Continuous or intermittent‐continuous operation make the apparatus completely automatic.

ISSN:0034-6748    

DOI:10.1063/1.1715161

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Data are presented on the short and long term energy stability of the 22‐Mev betatron at the University of Illinois. The data were taken in the course of a detailed study of the O16(&ggr;,n)O15yield curve. It is concluded that the machine was often stable to better than ±3 kev for periods of several hours, and that the maximum energy fluctuation which was observed over an eighteen month period was 40 kev at 17 Mev.

ISSN:0034-6748    

DOI:10.1063/1.1715162

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

Chambers 2½ inches and 4 inches in diameter have been constructed of brass with pyrex ports and sealed with lead‐wire gaskets. Metal walls and a copper heat leak eliminate the need for a surrounding pressurized bath. The required fast‐pulsing techniques and use of a heat regenerator are described in detail. Schematic diagrams show the chambers, pressure‐ and temperature‐monitoring devices, and illumination method, and photographs of typical tracks and events are included.

ISSN:0034-6748    

DOI:10.1063/1.1715163

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

A homogeneous magnetic field beta spectrometer and its completely automatic control system are described. Momentum resolution is such that a monoenergetic line has a full width at half maximum intensity of 0.22%. The instrument was used to analyze the conversion line spectrum of the 411‐kev gamma ray from Hg198. The data give for the conversion ratiosK:L:M:Nvalues of 1:0.361:0.100:0.027; and for (LI+LII):LIII, the value 5.9.

ISSN:0034-6748    

DOI:10.1063/1.1715164

出版商:AIP    

年代:1955

数据来源: AIP

摘要:

An aligning jig for use with Schulz‐type metal orientation goniometers is described. A procedure is given for calibrating the locating surface of the jig and using it to permit interchangeability between the Schulz head and the standard spectrometer specimen mount. The jig can be moved out of the way after aligning a sample without disturbing the sample.

ISSN:0034-6748    

DOI:10.1063/1.1715165

出版商:AIP    

年代:1955

数据来源: AIP