摘要:

A bent‐crystal gamma‐ray spectrometer of the transmission type having a focal length of 7.7 meters has been built for studying neutron capture radiation. The source is placed inside the reactor CP‐5 in a horizontal straight‐through hole. The instrument is designed to utilize a 30 cm×30 cm quartz plate cut normal to the (310) planes. Undiffracted radiation is absorbed by a baffle consisting of 108 Pb plates each 40×11×0.040 inches mounted between tapered spacers so as to focus on the virtual image of the source. The detector is an array of 16 NaI (Tl) crystals comprising a volume 10½×10½×2 in. The drive system rotates the crystal one second of arc in 20 seconds. The 2:1 motion required between the crystal and the detector is maintained by an optical lever system. The Bragg angle is measured with an interferometer. The instrument now operates with a 10×15×0.6 cm crystal.

ISSN:0034-6748    

DOI:10.1063/1.1715849

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A neutron time‐of‐flight spectrometer developed for the 1‐ to 20‐Mev region is described. The instrument makes use of the phase bunching of deuterons in the Michigan 42‐inch cyclotron and an external beam pulsing system to provide isolated bursts of neutrons of 4‐m&mgr;sec time duration. Flight times are measured with an improved version of the chronotron capable of a precision of ±3×10−10sec. The energy spread for a 5‐meter flight path varies from 3.5% at 0.5 Mev to 10% at 20 Mev. The available neutron flux permits an improvement of at least a factor of three by lengthening the flight path. The Be9(d,n) thick target and the O16(d,n) thin target spectra are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715850

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The principles of Cranz‐Schardin flash cinematography are described. This method uses up to thirty separate lenses and air sparks to produce an equivalent number of ``still'' photographs. The framing rate and exposure times are determined by the characteristics of the light sources; framing rates of over one million per second have been reported. A modified version of the Cranz‐Schardin camera which uses only one microscope objective lens and eight air sparks to produce eight micrographs is described. The performance to be expected and some possible applications are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715851

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

This report describes the construction and performance of a high‐speed cinemicrograph capable of producing a series of 200 pictures at 100 000 frames per second. The basic principle of this ``image‐dissecting'' camera consists of reproducing each scene in half‐tone (i.e., breaking the picture up into an array of widely‐spaced dots) and interspersing succeeding frames on the same composite plate by moving the plate one dot diameter between successive frames. After processing, the frames are ``played back'' in sequence.The technique of image dissection is further improved by the use of a plate of small, spherical lenslets to produce the dot structure. This advance considerably increases the light‐gathering power and ultimate top speed of the camera, making it possible to do high‐speed cinemicrography using a commercial Vickers projection microscope for magnifications up to 2000× with various illumination techniques.The cine´ record so produced is of quite high quality; each frame conveys about the same information as a standard 16‐mm cine´ frame. Some examples of ``movie'' scenes are shown for visual comparison.

ISSN:0034-6748    

DOI:10.1063/1.1715852

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A technique is described for measuring the heat of mixing, excess volume, specific heat, and other thermodynamic properties of liquid systems at low temperature (e.g., CO, CH4, A, Kr). Experiments are carried out at constant pressure, without any vapor phase in the calorimetric vessel.

ISSN:0034-6748    

DOI:10.1063/1.1715853

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Diagrams are presented showing the variation of relative sensitivity with zenith angle for a vertically directed cubical meson telescope of the type recommended as standard equipment for the International Geophysical Year.

ISSN:0034-6748    

DOI:10.1063/1.1715854

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An all‐metal system, made of copper, is herein described. It is suitable for working with those chemicals which do not attack copper. In particular it has been found very useful in the purification of BF3and B(CH3)3. Some important features of such a system are (1) a complete absence of contaminants; (2) reactions may be carried out up to 500°C; (3) pressures up to several hundred pounds per square inch may be used; (4) flow of gases from very low to very high pressures may be easily controlled; (5) the system is very rugged. This latter point is particularly desirable where noxious or inflammable gases (such as B(CH3)3) are used. A method is also described whereby gases from sealed‐off containers under either high or low pressures may be easily retrieved without introducing impurities. Other important advantages of such a system are mentioned in the text.

ISSN:0034-6748    

DOI:10.1063/1.1715855

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A system is described for producing a highly homogeneous, variable, and directable magnetic field. This system, which was used in gyromagnetic ratio experiments, was directed against the earth's magnetic field to obtain very nearly a field free space. Horizontal fields in this working space were held to less than 0.01% of the earth's horizontal component.

ISSN:0034-6748    

DOI:10.1063/1.1715856

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The first derivative with respect to wavelength of the transmission curve has been used to detect overlapping spectral bands. The commercially available Perkin‐Elmer Model 13 Ratio Recording Spectrophotometer may be easily adapted to record directly the derivative spectrum throughout the ultraviolet, visible, and infrared regions.

ISSN:0034-6748    

DOI:10.1063/1.1715857

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

For the investigation of silver halides, crystals of very high purity are required. Methods for preparing such crystals are described. They include the procedures used for the preparation of the dry precipitates, for crystal growing in controlled atmospheres, and for the preparation of specimens for the study of optical, electrical, and photochemical properties. The crystals are optically clear and have a sharp absorption edge with no detectable impurity absorption, even in samples several centimeters thick. For the silver chloride crystals, the ionic conductance was found to show the familiar break point at an unusually low temperature, and the interior of the crystal shows extremely little darkening even upon very strong exposure. For spectrochemical determination of the purity of the crystals, a concentration series of internal standards were prepared for seventeen elements. For the more important impurities, the molar concentration does not exceed 10−7.

ISSN:0034-6748    

DOI:10.1063/1.1715858

出版商:AIP    

年代:1957

数据来源: AIP