摘要:

This instrument was designed to measure and control the flux density between the poles of an iron‐core electromagnet used in conjunction with a beta‐ray spectrometer. A sensing coil, rotating at 1800 rpm, generates 0.115 v (rms) per gauss. A comparison signal, against which the emf of the coil is bucked, is generated electrostatically by a dynamic condenser. Its rotor plates are shaped to produce a sinusoidal wave form. The amplitude of the comparison signal is determined by a dc voltage applied between two stator sections which are juxtaposed on opposite sides of the rotor shaft. This voltage thus provides a measure of the field strength. An unbalanced condition results in the appearance of a 30‐cps error signal at the stator sections (which are isolated with respect to ac). After amplification and synchronous rectification, this signal indicates the degree and phase of the imbalance. The motor speed is maintained constant by a precision 60‐cps tuning fork. The stability of the fluxmeter is of the order of one part in 2500, as determined by the reproducibility of the positions of internal‐conversion‐electron lines from Bi207and Cs137sources.

ISSN:0034-6748    

DOI:10.1063/1.1716672

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A rotor‐balancing technique is described in which conventional laboratory equipment may be used. The orbiting motion of a rotating shaft within its own fixed bearings is detected by capacitor probes. After passing through the transducer circuit, the signal is displayed on an oscilloscope. It is therefore possible to obtain the necessary balancing information at operating conditions.

ISSN:0034-6748    

DOI:10.1063/1.1716673

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Use of multiturn coil structure in the production of several hundred kilogauss pulsed fields is discussed with specific emphasis on coil life. The magnetic force that shortens the coil life is reduced by introducing a flux concentration device. Into the multiturn coil is inserted a rigid, slotted metal slug that generates induction current in such a way as to shift the magnetic flux from the multiturn to the central vacuum region and serves as a flux concentrator. Electromagnetically and mechanically this scheme is a convenient synthesis of the multiturn and single turn coils. The advantage of this scheme is most apparent for tape‐wound coil structures, and a quantitative analysis of the flux pattern relevant to this coil system is given. An analog computer is employed in solving the time dependence of the field. The results are documented by experimental tests carried out with a 3000‐&mgr;f, 4‐kv capacitor bank.

ISSN:0034-6748    

DOI:10.1063/1.1716674

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The design and performance of a low‐noise hydrophone preamplifier is described. Transistors are used throughout the circuit and it is shown that, although the noise figure is slightly worse than the equivalent circuit using vacuum tubes and transformers, in practice the over‐all performance is superior.

ISSN:0034-6748    

DOI:10.1063/1.1716675

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The equipment and techniques used to grow 6‐in. diam silicon and germanium crystals are described, and the effect of spin, radiation, and mode of heating on crystal growth from a melt is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716676

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

Apparatus and techniques are described for preparing metal diffusion couples by cleaning the sample surface and depositing an isotope layer by cathodic sputtering.

ISSN:0034-6748    

DOI:10.1063/1.1716677

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A mechanical analog computer is described which is suitable for the exploratory study of linear accelerator designs in the bunching region, at least in problems of the kind encountered in electron accelerators, where bunching is accomplished in comparatively short intervals and with relatively few phase oscillations. Particle phase is observed directly from a resolver; and particle momentum, particle velocity, and accelerating wave phase velocity are observed simultaneously as linear magnitudes whose relative change during calculation provides useful intuitive guidance in the choice of accelerator parameters. Some calculations are reported which were made with a rough apparatus capable of ∼5% accuracy.

ISSN:0034-6748    

DOI:10.1063/1.1716678

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A vibrating‐sample magnetometer, which measures the magnetic moment of a sample when it is vibratedperpendicularlyto a uniform magnetizing field, is described. With this instrument, changes as small as 10−5to 10−6emu have been detected, and a stability of one part in 104has been attained. In addition to permitting convenient measurements in the usual laboratory electromagnet, this instrument eliminates or minimizes many sources of error found in other methods. It is simple, inexpensive, and versatile, yet permits precision magnetic moment measurements to be made in a uniform magnetizing field as a function of temperature, magnetizing field, and crystallographic orientation. The mechanical design and detailed operating characteristics are presented. Applications and limitations of the method are outlined.

ISSN:0034-6748    

DOI:10.1063/1.1716679

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

The design and operation of an adiabatic low‐temperature calorimeter employing a somewhat different design of automatic shield control is described. Thermocouple difference is sensed by a dc &mgr;v amplifier, which is followed in the circuit by a recorder‐controller and a Leeds & Northrup Series 60 (current adjusting type) control unit. The output of the latter is used to control the voltage across the shield heaters through a Westinghouse ``Magamp'' saturable reactor. This design has been used successfully with a conventional low‐temperature adiabatic calorimeter (50‐ml sample size). In most cases the recorder showed no variation from zero (±0.002°) during heating and equilibrating periods, while momentary disturbance at ``on'' and ``off'' was less than 0.05°.

ISSN:0034-6748    

DOI:10.1063/1.1716680

出版商:AIP    

年代:1959

数据来源: AIP

摘要:

A cryostat is described consisting of a glass vacuum insulated inner vessel and a Styrofoam outer vessel. The inner Dewar narrows to a fine tip containing the sample at its lower extremity where it protrudes through the outer vessel, and extends into a microwave cavity.

ISSN:0034-6748    

DOI:10.1063/1.1716681

出版商:AIP    

年代:1959

数据来源: AIP