ISSN:0034-6748    

DOI:10.1063/1.1717652

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Apparatus has been developed for the mass spectrographic study of ion‐molecule reactions occurring under gas‐kinetic conditions. Ions are produced by electron bombardment inside a long drift tube containing gas at a pressure of up to about 0.7 torr. The ions diffuse down the drift tube under the influence of a weak electric field. A sample of the ion population at the end of the drift tube is extracted through a two‐stage, field‐free differential pumping section and passed into a 60° magnetic deflection mass spectrometer. The number of ion‐molecule collisions in the drift tube may be varied over a wide range by changing the source position and/or the gas pressure. Information concerning the nature and probability of the reactions occurring is revealed by the resulting changes in the ionic mass spectrum.

ISSN:0034-6748    

DOI:10.1063/1.1717656

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The construction and calibration of a Knudsen gauge of the Klumb‐Schwarz modification is described. A practical method of correcting for nonlinearity in response is developed.

ISSN:0034-6748    

DOI:10.1063/1.1717672

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A body cross‐section scan phantom has been designed to study problems involved in the external detection of radioactivity in human organs. It is based upon the use of serial cross‐sectional drawings of a particular body area reproduced in metallic paint. A commercial scanning mechanism moves a small electrode over one of the cross sections, and simultaneously moves a small radioactive source through a tank of water. The entire system is aligned in three dimensions relative to the position of a scintillation detector. Each organ area drawn on the cross‐section is part of an individual scaling circuit which is activated by the moving electrode. Thus, by scanning the drawing, a summation of the counts due to activity in each of these cross‐sectional areas can be automatically registered. The three dimensional response is determined by graphically integrating the data from all the cross sections.

ISSN:0034-6748    

DOI:10.1063/1.1717645

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A description is given of the properties of a linear thermal detector irradiated by a modulated radiation field and operated simultaneously with a periodic bias current. The method is a generalization of the more common operation of passive thermal detectors with a constant dc bias and may be applied for barretters with a sufficient small time constant. A barretter has been developed with a time constant of approximately 14 &mgr;sec in air and 3 &mgr;sec in a hydrogen atmosphere such that modulation frequencies up to 10 kc, and for hydrogen filling up to 50 kc, are still feasible.

ISSN:0034-6748    

DOI:10.1063/1.1717650

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A new method for measuring adsorption of organic molecules at the metal/solution interface as a function of potential is presented. The method is designed primarily for studying the adsorption of C14‐ or S35‐labeled organic compounds but can also be used for the adsorption of tagged inorganic species. The main feature of this method is that the large background usually present in this type of experiment has been eliminated. Any metal, which can be obtained in the form of a thin tape of sufficient tensile strength or which can be plated onto a base of sufficient tensile strength, can be investigated by this technique. Some results of the adsorption of thiourea on nickel are given.

ISSN:0034-6748    

DOI:10.1063/1.1717651

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A flash method for the measurement of the thermal diffusivity of metals up to 1800°C is described. A high intensity short duration light pulse is absorbed in the front surface of a thermally insulated specimen a few millimeters thick heated in an induction furnace and the resultant temperature history of the rear surface is measured by a lead sulfide cell, displayed on an oscilloscope, and photographed by a Polaroid Land camera. The thermal diffusivity of the material is determined from this temperature versus time curve provided the theoretical boundary conditions are experimentally satisfied. Measurements of the thermal diffusivity of Armco iron, molybdenum, and titanium have been made.

ISSN:0034-6748    

DOI:10.1063/1.1717653

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A method of digitizing the deflections of a reflecting galvanometer and presenting the results directly on electromagnetic counters is given. The use of expensive dc amplifiers and/or multipoint recorders can often be avoided and automatic integration for time mean values of physical quantities is conveniently achieved.

ISSN:0034-6748    

DOI:10.1063/1.1717654

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The line shape, amplitude as well as half‐width, to be expected experimentally from a natural linewidth thin source and a natural linewidth Mo¨ssbauer absorber has been computed as a function of the thickness of the absorber. The experimental result using stainless steel source and absorber and correcting for background has double the expected width, but nearly the correct fractional change in rate. This is compatible with a blurring due to dissimilar microenvironments of about ±0.10 mm/sec.

ISSN:0034-6748    

DOI:10.1063/1.1717655

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A detailed description is given of a device which is capable of increasing the effective resolving power of a mass spectrometer. An improvement in resolution by a factor of eight has been achieved. The design is based on a general analog technique for improving the resolution of analytical instruments. The device, which can be regarded as a resolving‐power multiplier, consists of an electronic analog mass spectrometer connected to memory and feedback circuits. Fully resolved spectra are displayed on the screen of an oscilloscope. Information sufficient for the design, construction, adjustment, and operation of similar systems is given. Results obtained with experimental resolving‐power multipliers are described.

ISSN:0034-6748    

DOI:10.1063/1.1717657

出版商:AIP    

年代:1962

数据来源: AIP