摘要:

An iron‐free intermediate‐image beta‐ray spectrometer has been constructed having a momentum spread (full width at half‐maximum) for a point source of conversion electrons continuously variable between limits of 0.5&percent; and 4&percent; with corresponding transmissions of 1&percent; and 8&percent; of 4&pgr;, respectively. The line half‐width contribution due to source size is 0.3&percent; per mm of diameter. At a power dissipation of 100 kw the spectrometer focuses electrons of 9‐Mev energy allowing positron‐electron pair lines corresponding to transitions of up to 19 Mev to be measured using a double‐crystal statistical‐separation detector together with a fast coincidence circuit. In tests with the 6‐Mev nuclear transition in O16using a Van de Graaff beam spot 1 mm in diameter the momentum half‐width of the pair line can be varied from 0.56&percent; to 2.5&percent; with corresponding absolute transmissions of 0.07 to 6.3 pair counts per 105source transitions, respectively. The energy of this transition has been determined as 6.065±0.009 Mev. Electron‐gamma and electron‐electron coincidence measurements on radioactive sources may be made with the spectrometer in conjunction with crystal detectors placed near the source.

ISSN:0034-6748    

DOI:10.1063/1.1715471

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The design of a magnet for producing a uniform field is described. The magnet model used in the calculations is that of cylindrical cores surrounded by rims. The positions of the central pole faces and rims can be adjusted independently. A calculation, based on the assumption that the pole pieces are uniformly magnetized, shows that, for a certain positioning of the cores and rims, thez2andz4correction terms toHzcan be simultaneously canceled. Practical limitations to uniformity that result from a slight asymmetry in the geometry and from the effect of nonuniformity in magnetization because of domain structure in the iron also are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715437

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Small variations in the fields of magnets, caused by structures or domains in the pole faces, were investigated by moving a small coil in a circular path. It was found that for a given pole face the variations in the field were all about the same size, and decreased exponentially from the pole face. None of the materials tested as pole faces produced strikingly better fields than another.

ISSN:0034-6748    

DOI:10.1063/1.1715438

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Ferromagnetic wires, that have been suitably conditioned, generate electrical potentials when subjected to changes in elastic strain. Conditioning the wires involves alignment of the circumferential component of the magnetic field, due to domains, in a preferred direction. This is accomplished by the magnetic field associated with a current passed through the wire. A disturbance which changes this established circumferential field causes a potential to appear between the ends of the wire.

ISSN:0034-6748    

DOI:10.1063/1.1715439

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A high‐temperature x‐ray diffraction unit for powder specimens is described, which can be attached to standard room‐temperature cameras. The evacuable heater‐specimen space is surrounded by a beryllium cylinder with cellophane windows and the heater, either a small, gap‐divided spiral, holding the specimen capillary, or a Pt wire with coated‐on specimen, can be slipped in it and rocked during exposures. Temperatures up to 1000°C can be obtained with power consumption ofca10 w. Specimen temperatures are determined from line‐shifts in the pattern of added internal standard or the pattern from the platinum heater wire.

ISSN:0034-6748    

DOI:10.1063/1.1715440

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

This article describes the construction of a conductive glass resistor intended for operation in a sealed high vacuum system. The resistor is small, having a body size of 0.195 in. long and ⅛ in. diameter, and resistance values from 0.25 to 15 megohms can be achieved. A power dissipation of 25 milliwatts is normal and in vacuum, the operating temperature is approximately 65°C. After suitable initial outgassing, no appreciable amount of gas is evolved into the vacuum system as a result of operating the resistors.

ISSN:0034-6748    

DOI:10.1063/1.1715441

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Two temperature control thyratron relays for use with contact thermoregulators are described, posessing long life, high reliability and low control power requirements. In addition, simple phase shift circuits have been incorporated allowing continuous control of system thermal hysteresis.

ISSN:0034-6748    

DOI:10.1063/1.1715442

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The theory of the method of measurement of liquid level by measurement of the resistance of a heated wire is developed, and it is applied to the design of a liquid‐nitrogen‐level indicator having a power dissipation of 3.4 mw/in. of length and a deviation from linearity in the calibration of less than 0.1 in. over its working length of 2.0 in. The apparatus should be applicable to the measurement of level of low viscosity liquids and its sensitivity is limited only by the temperature coefficient of resistance of the heated wire.

ISSN:0034-6748    

DOI:10.1063/1.1715443

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A simple reliable process is described for recording the amplitudes of individual pulses on magnetic tape. This enables the pulse analysis to be performed after the experiment, and under optimum conditions. Low counting rates may be recorded with the tape moving slowly, and then speeded up on playback, so that, for example, a twenty‐four hour run may occupy only seven minutes analyzer time. The recording process is strictly linear over a range of signal/rms noise of up to 300/1. A maximum rate of 4000 pps may be recorded. The resolution varies with pulse amplitude, but, over the upper two‐thirds of the linear range the relative spread assumes a very nearly constant value of about 3&percent;.A further development is described in which gated time coincident pulses are recorded simultaneously on twin tracks of the same tape. In data gathering power this system is better than an array of thirty conventional thirty channel pulse analyzers. It may also be applied to the simultaneous recording for separate analysis of the outputs of up to about ten independent detectors.

ISSN:0034-6748    

DOI:10.1063/1.1715444

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A recording microdensitometer is described that has a resolving power of 800 lines/mm when the scanning aperture is 1 &mgr; wide and 200 &mgr; long. The response is linear in density to 3.0 for the same aperture. By narrowing the aperture to 0.1 &mgr;, the resolving power can be increased to 1800 lines/mm. The record is made either on chart paper with rectangular coordinates, on punched cards, or on both.

ISSN:0034-6748    

DOI:10.1063/1.1715445

出版商:AIP    

年代:1956

数据来源: AIP