摘要:

The full energy spread‐out bremsstrahlung beam of the Berkeley synchrotron was shown to be emitted in sharp bursts with the 47.7‐Mc/sec frequency of the electrons in the doughnut. A two‐counter telescope, located about 20 inches away from a one‐fourth inch thick lead target and about 20 degrees from the photon beam direction, was used to measure an accidental coincidence counting rate as a function of the length of delay line in one input to the coincidence circuit. When the length of delay cable was chosen equal to integral multiples of the period of the radio‐frequency oscillator, the coincidence counting rate was of the order of 100 counts per unit of integrated beam; on the other hand, when the length of delay line was chosen to be equal to one‐half of odd integral multiples of the period of the radio‐frequency oscillator, the coincidence counting rate was less than about two counts per unit of integrated beam.An estimate of the width of a single pulse of photons can be obtained from the measurement by unfolding a Gaussian resolution function of the coincidence circuit. If the time variation of the intensity of the photon beam is assumed to be a Gaussian function, then the rms value of that Gaussian is found to be less than 1.5×10−9second.A calculation by Lloyd Smith indicates that the measured radio‐frequency fine structure should provide a rather accurate picture of the phase‐stable bunch of electrons at the end of the acceleration period.

ISSN:0034-6748    

DOI:10.1063/1.1771126

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A small automatic furnace has been designed for the study of the thermal decomposition of wood and other combustible materials. After a sample has been brought nearly to thermal equilibrium at any desired temperature, the furnace temperature control system is automatically changed to allow the sample to self‐heat up to a temperature of 500°C with small external heat loss or gain. Weight changes of the specimen during the test are continuously monitored and recorded. The control system is designed to stop the operation automatically after the specimen temperature has increased to some previously selected level.

ISSN:0034-6748    

DOI:10.1063/1.1771127

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An instrument, employing the principle of a slide multiplier, has been constructed for reading electron diffraction patterns and computing the corresponding crystal lattice spacings. The constant of the electron diffraction camera can have a value of from zero to 5.000 A cm, and the instrument can record ``dhkl'' spacings from 0.600 to 7.000 A. These spacings are printed, together with estimated line intensities, on adding machine paper. The instrument decreases the possibility of accidental error in copying numbers, and also eliminates considerable fatigue when many patterns have to be read.

ISSN:0034-6748    

DOI:10.1063/1.1771128

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Experimental problems which arise in the operation of diffusion cloud chambers are discussed. Particular attention is paid to methods of cooling the base of the chamber and design features of this type of chamber. Some of the limitations of the instrument are mentioned, and there is a discussion of symptoms which can arise when the conditions of operation are defective.

ISSN:0034-6748    

DOI:10.1063/1.1771129

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

The mechanical design features and operating characteristics of a hot‐cathode arc‐discharge type ion source are described. Proton currents of 500 milliamperes have been obtained under dc test conditions. A maximum current of 3 milliamperes of 22‐Mev protons has been obtained with the source installed in the ORNL 86‐inch cyclotron. Distinguishing features of the ion source are its arc chamber of carbon, its heavy tantalum filament heated with dc, and its use of a specially shaped accelerating electrode.

ISSN:0034-6748    

DOI:10.1063/1.1771130

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A fast neutron‐scintillation spectrometer employing two organic crystals in coincidence has been investigated experimentally. Considerations are made of some factors involved in the efficiency, resolution, neutron energy range, and background effects. The role of the carbon in the scintillation crystal is considered not to be important except in its increase of the plural scattering in the analyzing crystal. The D(d,n), T(d,n), and Li(d,n) spectra as taken with this instrument are presented.

ISSN:0034-6748    

DOI:10.1063/1.1771131

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

Two ion sources have been developed for the production of milliamperes of N+, N2+, N3+, and N4+ions. Under good operating conditions, 28 ma of N3+and 10 ma of N4+are produced. Details of source construction are given and a method for analyzing the source output is presented. Characteristics of both sources as a function of arc current and arc voltage are investigated.

ISSN:0034-6748    

DOI:10.1063/1.1771132

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A means of accurately and rapidly measuring the radii of curvature of many cloud‐chamber tracks is described. The apparatus includes a photographing‐reprojecting system and a curvature‐measuring device. This device is capable of measuring radii of reprojected tracks in the range from 0.5 cm to 100 cm with the poorest accuracy of the order of 3 percent occurring at 100 cm.

ISSN:0034-6748    

DOI:10.1063/1.1771133

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

An electron‐diffraction unit incorporating a rotating sector has been developed which makes possible the accurate and objective measurement of the intensity of electrons diffracted by free atoms and molecules. The diffraction data afforded are sufficiently precise to permit the calculation of the distribution of electrons in atoms and the amplitude of vibration of atoms in molecules, as well as interatomic distances that are comparable in accuracy in suitable cases to those obtained by microwave spectroscopy. A description of the essential components of the unit is given together with some data on performance and discussion of the use of the apparatus.

ISSN:0034-6748    

DOI:10.1063/1.1771134

出版商:AIP    

年代:1954

数据来源: AIP

摘要:

A mechanical respirator with synchronized respiratory partitioning valve for guinea pigs is described. This apparatus is used for the separate determination of dust retention in the upper respiratory tract and deep lung spaces. The partitioning valve separates the exhaled air into three fractions beginning with the earliest portion of upper respiratory air and continuing to the terminal fraction of deep lung air. The same volumetric fractions from successive exhalations are collected over a test period of any practical duration. In principle, the apparatus is similar to one previously described (Rev. Sci. Instr.22, 81, 1951) for the study of dust retention in human lungs.

ISSN:0034-6748    

DOI:10.1063/1.1771135

出版商:AIP    

年代:1954

数据来源: AIP