摘要:

An electromechanical shutter for high speed spectroscopic studies is described. The device utilizes the energy of an electrically exploded metal foil to accelerate a movable slit, and propel it across a fixed slit. The minimum delay time is 19±2 &mgr;sec. A 20‐&mgr; fixed slit may be opened and closed in 2 &mgr;sec by a 20‐&mgr; moving slit. No medium is introduced into the optical path to alter spectral distribution.

ISSN:0034-6748    

DOI:10.1063/1.1718245

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The performance of bright and dark field optics in a bubble chamber is analyzed. A modification of the usual bright field scheme is proposed, so that very high contrasts may be achieved even in liquid hydrogen. The new scheme can also be used in a single‐window chamber. Results of tests of the scheme are presented to support this modification. Photography of bubbles smaller than the resolution limit is discussed; in this case a dark field scheme shows a clear advantage.

ISSN:0034-6748    

DOI:10.1063/1.1718246

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A low density parallel plate ionization chamber which exhibits a linear response to high intensity pulses of 3‐GeV protons is described.

ISSN:0034-6748    

DOI:10.1063/1.1718247

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The frequency of the ``reference'' oscillator in a coherent pulse echo apparatus is phase‐locked to the spacing in time of the acoustic echoes. A change in echo spacing is thereby converted to the same fractional change of oscillator frequency, which is measured continuously. Echo spacing changes of 2 to 3 parts in 108have been resolved at 12 Mc. The gated AFC circuit which controls the reference oscillator derives its error voltage from a phase‐detected echo. The error voltage is zero when the echo is in quadrature with the reference. When the echo spacing changes, the AFC shifts the reference frequency to preserve the quadrature condition. The system is largely insensitive to changes of echo amplitude because such changes do not affect the quadrature condition. The attainable accuracy is set mainly by the temperature stability of the sample. There is a detailed discussion of circuitry, performance, and suggested refinements.

ISSN:0034-6748    

DOI:10.1063/1.1718248

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A technique for the production of well‐defined, precisely timed nanosecond pulses of X‐band microwave power is described. A system for the investigation of extremely fast electron density fronts in shock tubes is outlined utilizing the transmitted and reflected pulses generated by this technique. The transmitted and reflected pulses are displayed on a 2000‐Mc, rastered oscilloscope.

ISSN:0034-6748    

DOI:10.1063/1.1718249

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

This paper describes an apparatus in which sodium chloride can be sublimed in a high vacuum, in amounts in the range 0.1 to 0.5 g, from a quartz tube on to a water‐cooled quartz condenser. Without breaking vacuum, the product can be scraped down into a receiver, transferred to a gas adsorption apparatus for surface area measurement, and introduced into a reaction system. The sublimate has a specific surface most commonly between 20 and 36 m2/g. It exhibits unusually high bulk reactivity for isotopic exchange of anions at room temperature.

ISSN:0034-6748    

DOI:10.1063/1.1718251

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An optical spectrometer for study of the optical absorption of monomolecular films spread on water is described. The spectrometer is a multiple‐pass instrument, suitable for measurements from approximately 3800 to 8000 Å. It employs a chopper‐stabilized monochromatic light source, with a collecting lens and integrating sphere combination to circumvent light shimmering noise. Detection is by means of a photomultiplier tube. Representative results for monomolecular films of chlorophyllaare presented.

ISSN:0034-6748    

DOI:10.1063/1.1718252

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An instrument is described, based on the reflectance principle of Fresnel, which will monitor the refractive index of a stationary liquid or moving stream. The device uses a unique ``rod prism'' optical system which serves as collimator, prism, and optical bench. Advantages of the device are high sensitivity, low cost, and simplicity of construction. Applications have been made to column chromatography, liquid‐liquid chromatography, fractional distillation, reaction kinetics, and process stream monitoring.

ISSN:0034-6748    

DOI:10.1063/1.1718253

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A simple camera designed to obtain x‐ray diffraction topographs of single crystals is described. The extinction technique, as developed by Lang, to study dislocations and other structural imperfections, is used. Topographs of silicon and quartz are shown. The dislocation image widths in a (220) diffraction from silicon are about 20 &mgr;.

ISSN:0034-6748    

DOI:10.1063/1.1718254

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A Mo¨ssbauer effect spectrometer utilizing a servomechanism to provide a constant velocity drive has been developed. The apparatus is useful to velocities up to 1 cm/sec, and provides velocities known to one part in 103. The moving portion is relatively massive and can be used to move a small furnace or cryostat.

ISSN:0034-6748    

DOI:10.1063/1.1718255

出版商:AIP    

年代:1963

数据来源: AIP