摘要:

A slotted‐disk, mechanical velocity selector has been constructed and tested. It is similar to that reported by Hostettler and Bernstein, but may be used at velocities more than five times higher (to 6000 m/sec). Its velocity spread is somewhat less (3.4%), and its fractional open time is about the same (34.8%) as the Hostettler‐Bernstein instrument. A lithium beam has been velocity analyzed and found to be in agreement with the calculated distribution.

ISSN:0034-6748    

DOI:10.1063/1.1717986

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Although new boron‐ and lithium‐loaded scintillators yield very fast photographic response for thermal neutrons, it is pointed out that reciprocity‐law failure responses will complicate intensity analyses of diffraction pattern films made with these techniques. The magnitude of this effect for a B10‐loaded scintillator and type F x‐ray film is such that the response is decreased by a factor of at least 4 times at a neutron intensity of 3×103neutrons/cm2‐ sec when compared to the response at a neutron intensity 100 times higher. This objection, and that of image nonuniformities, can be eliminated by using slower response metal screens and film detectors. A rhodium‐gadolinium screen combination used with a fast x‐ray film such as type KK is shown to be a fast technique which will yield diffraction patterns having useful intensity information.

ISSN:0034-6748    

DOI:10.1063/1.1717987

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A tensile testing instrument of the soft type which has been specifically designed to facilitate accurate axial alignment of submicron whiskers or filaments is described. The load is applied by a dead‐weight loading mechanism similar to that used in chain balances and strain is measured photographically. The limiting feature on the accuracy of the results is the diameter variation which occurs within individual whiskers rather than the instrument. Tensile data are presented for a 0.35‐&mgr;‐diam Cr fiber extracted from a unidirectionally solidified ingot of Cu‐Cr eutectic alloy.

ISSN:0034-6748    

DOI:10.1063/1.1717988

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

An internal friction apparatus based upon the principle of the torsion pendulum is described. Attached to the inertia member of the pendulum are two coaxial coils which are located in the field of a permanent magnet. Oscillations of the pendulum induce an emf in one coil (the pick‐up coil). The signal is amplified and converted into a square wave of constant amplitude which is used to energize the other coil (the driver coil). Interaction between the driver coil and the magnetic field maintains the system in oscillation, the amplitude being proportional to Q. The output of the pickup coil is measured on a strip chart recorder. After a straightforward calibration procedure, theQof the system is quantitatively related to the output. The device has been used from 4°K to 150°C.

ISSN:0034-6748    

DOI:10.1063/1.1717989

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

In studying the mechanism of deformation, it is often desirable to be able to stretch a thin sample inside an electron microscope while the specimen is under observation. Dislocation movements and interactions can be directly observed. A new specimen stretching stage for the Siemens Elmiskop electron microscope is described which combines the advantages of tilting, fast response, sensitivity, and reversibility. A uniform strain is applied.

ISSN:0034-6748    

DOI:10.1063/1.1717990

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

The construction and operation of an all glass ice calorimeter which allows the rapid and moderately precise (approximately 0.5%) measurement of heat changes in a system is described. In addition to the usual advantage of an ice calorimeter of being able to measure slow heat changes, the instrument described here is extremely simple to construct and operate. The use of a calibrated capillary tube to determine the volume change due to melting or freezing of ice eliminates the need of an analytical balance and simplifies operation of the instrument.

ISSN:0034-6748    

DOI:10.1063/1.1717991

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A new wavemeter of simple design is described. The principle of operation makes use of a new development in physical optics. The actual performance of the device was measured and compared with the theory.

ISSN:0034-6748    

DOI:10.1063/1.1717992

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

A system is described for the projection, digitizing, and recording of photographed spark chamber tracks. A Slo‐Syn‐driven projector automatically frames the film and projects the tracks on a screen mounted in a precision commercial plotting board. A reticle projector, mounted on the plotting board pen holder, is manually positioned by means of the plotting board drive tapes which also drive the encoders of an accumulating digitizer system. A photoelectric gap counting device can be substituted as an alternate for one of these encoders. The all‐transistor digitizer system is equipped with manual switches for labeling of tracks, inserting frame numbers, etc., and has a versatile output format on seven hole paper tape. The paper tape with its track coordinate information is used as the input for computer programs designed to calculate the particle physics evidenced by the track.

ISSN:0034-6748    

DOI:10.1063/1.1717993

出版商:AIP    

年代:1962

数据来源: AIP

摘要:

Neutron counters using He3gas at absolute pressures up to 10 atm have been constructed and tested. The relative detection efficiency for thermal, epicadmium, and fast neutrons was measured as a function of pressure from 1 to 10 atm, and compared with similar data from a boron trifluoride counter of the same size filled to a pressure of 65 cm of B10F3gas. The ratio He3/BF3increases approximately linearly with pressure for epicadmium and fast neutrons, reaching values of 26.6 and 21.6, respectively, at 10 atm He3pressure. This ratio shows a saturation effect for thermal neutrons, becoming 4.45 at 10 atm He3pressure. The gamma‐ray response has been found to be low with proper pulse shaping. High voltage plateau curves for 3‐ and 7‐atm counters are given and indicate operating regions at least 100 V wide at a counter high voltage of about 1200 V.

ISSN:0034-6748    

DOI:10.1063/1.1717994

出版商:AIP    

年代:1962

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1717996

出版商:AIP    

年代:1962

数据来源: AIP