摘要:

A gas‐recoil fast neutron spectrometer based on the collimation scheme of R. Giles has been constructed and its behavior analyzed. The principal effort has been directed to improving peak‐to‐valley ratio of the instrument. Electron capture has been minimized and anticoincidence end‐effect counters included in the present design. A graphical analysis has been made of the collimation scheme and the results predicted by the analysis compared with experiment. Li7(p,n)Be7and D(d,n)He3neutron groups have been observed using, in turn, palladium‐filtered hydrogen and pure propane as spectrometer fillings. Energy spreads of 10% and under with efficiencies exceeding 10−4have been obtained with peak‐to‐valley ratios of 10 to 1. Neutron groups from the Be9(d,n)B10, C12(d,n)N13, O16(d,n)F17, and A40(d,n)K41reactions have been observed.

ISSN:0034-6748    

DOI:10.1063/1.1715996

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A liquid scintillator having an area of five square meters has been developed for the observation of the extensive air showers in cosmic rays. The scintillating liquid, in the form of a disk 10 ft in diameter and 6 in. deep, is viewed by a single 14‐in. Dumont type K1328 photomultiplier tube. The associated circuitry provides a gate whose length is proportional to the logarithm of the scintillator pulse height over a range in pulse height of 2000:1. The length of this gate can be either measured and recorded on a Berkeley EPUT timing meter or converted linearly to a pulse height and analyzed by a multichannel discriminator.

ISSN:0034-6748    

DOI:10.1063/1.1715994

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Systems are described which automatically and continuously correct for dynamic errors of transducers during transient and steady‐state measurements. They enable high‐speed measurement to be made with improved accuracy even in regions beyond a transducer's natural frequency. Transient phenomena with rise time of a fraction of a microsecond can be measured directly with a minimum of amplitude and phase distortion. High‐speed electronic analog circuits form an integral part of the transducer system to obtain the wave forms of the unknown physical phenomena, and to enable quantitative determination to be made with simple static calibration procedure. Post‐measurement amplitude and phase corrections are made virtually unnecessary.

ISSN:0034-6748    

DOI:10.1063/1.1715995

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A micromanometer is described for the measurement of differential pressures greater than 10−4in. of water with tolerable accuracy. The instrument uses concentric tubes to form the fluid passages and provides for remote indication of the level in the central tube by means of a mirrored float and telescope and scale arrangement. The highest instrument sensitivity obtained by the authors was 3.15×10−5in. of water applied pressure per mm of scale reading, but with suitable refinement in the optical system, it is felt that greater sensitivities are possible.

ISSN:0034-6748    

DOI:10.1063/1.1715997

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A new and more sensitive gamma‐ray camera for visualizing sources of radioactivity is described. It consists of a lead shield with a pinhole aperture, a scintillating crystal within the shield viewed by a bank of seven photomultiplier tubes, a signal matrix circuit, a pulse‐height selector, and a cathode‐ray oscilloscope. Scintillations that fall in a certain range of brightness, such as the photopeak scintillations from a gamma‐ray‐emitting isotope, are reproduced as point flashes of light on the cathode‐ray tube screen in approximately the same relative positions as the original scintillations in the crystal. A time exposure of the screen is taken with an oscilloscope camera, during which time a gamma‐ray image of the subject is formed from the flashes that occur. One of many medical and industrial uses is described, namely the visualization of the thyroid gland with I131.

ISSN:0034-6748    

DOI:10.1063/1.1715998

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A method is given for the determination of the thickness of films using x‐rays diffracted from the substrate. The x‐rays pass through the film and are diffracted by the substrate back to the counter, the intensity being reduced by absorption due to the double transmission through the film. No assumptions need be made about the substrate reflection. Unknown conditions of the substrate are eliminated by measurement of the intensity of two orders of a reflection, or measurement of the intensity of a reflection using two different incident radiations. The method is suitable for all types of film, and is particularly useful in measurements of films containing elements of the substrate for which cases x‐ray fluorescence techniques are of little value. The procedure is illustrated with a measurement of the thickness of zirconium nitride on a zirconium substrate.

ISSN:0034-6748    

DOI:10.1063/1.1715999

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An infrared hygrometer is described which utilizes a light beam as the principal sensing element. Composed of two narrow bands of infrared radiation, this beam traverses a 12‐in. path through a sample atmosphere containing the humidity concentration to be measured. Wavelength isolation is by means of germanium narrow band‐pass interference filters. One band, centered near a wavelength of 2.60 &mgr;, is subject to attenuation by water vapor, the other located near 2.45 &mgr; is not. Thus the ratio of transmitted band energies is sensitive to the concentration of water vapor in the path. This ratio is effectively maintained at unity through use of a servo‐operated glass wedge which moves to compensate for energy unbalance caused by changes in absorbing vapor. Wedge position is given electrical significance through use of an appropriate transducer, calibrated in terms of vapor density, grams per cubic meter. Included in the design is a dry‐gas purge standardization system whereby periodic checks of the zero point enable compensation for drift factors. Because of the potential use of the method in airborne applications, the instrument was used in tests to determine the character of pressure effects. These showed that vapor concentration (W), total pressure (P), and partial pressure (p) of water vapor, may be related to fractional absorption (A):A=CW0.5(P+p)0.23.Conditions under which other, simpler relations may be used are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716000

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

This refractometer is used in conjunction with a light scattering apparatus to determine high molecular weights. The self‐balancing feature relieves the operator of the tedium of making delicate visual observations while retaining high sensitivity and accuracy. Mounted on a shop surface plate it measures 15 in. wide by 18 in. long by 7 in. high exclusive of the light source transformer. A Brown Electronik amplifier and servo motor are used to position the photocells on the light beam with a repeatability of about 30 microinches. The beam deflection is read on a counter and vernier dial. The range of the instrument is 0.0175 RI unit and the stability and accuracy are within 5×10−7RI units.Differential refractometers are also useful in following fractionation by distillation or adsorption, in determining concentrations of colorless solutes in dilute solutions and in studying sedimentation equilibrium.

ISSN:0034-6748    

DOI:10.1063/1.1716001

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An apparatus is described for the measurementin situof adsorption of solutes on solids and kinetics of film formation on solid surfaces. The technique is applicable only to very dilute solutions in which the solute can be tagged with a &ggr;‐ or hard &bgr;‐emitting isotope. The adsorbed radioactivity of the surface is determined through a continuously replenished thin layer of solution. The kinetics and equilibrium conditions of adsorption, desorption and exchange reactions can be determined conveniently; simultaneously, the electrochemical behavior of the surface can be studied. Some measurements are reported.

ISSN:0034-6748    

DOI:10.1063/1.1716002

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

This paper describes a rapid response microwave hygrometer for continuously recording the water vapor pressure of atmospheric air over a wide ambient range. The principle employed involves the measurement by means of a cavity resonator of the contribution of water vapor to the refractive index of atmospheric air. The device described also has potential application to the continuous measurement of the degree of contamination of one gas (or of gas mixtures) by another gas (or gases).

ISSN:0034-6748    

DOI:10.1063/1.1716003

出版商:AIP    

年代:1958

数据来源: AIP