摘要:

A positive ion detector has been developed that is capable of simultaneously measuring two ion beams. It is made up basically of two scintillation detectors back to back. Ion beams enter a chamber on either side of a thin dividing partition. They are attracted to two electrodes at 40 kV where they release secondary electrons. A magnetic field directed along the axis of the incoming positive ion beam deflects the two electron beams so that they strike opposite walls of the ion detector. Two small organic phosphors situated in the walls at the electron impact points produce light signals that are recorded by photomultipliers. Focusing of the electron beams and the efficiency of detection for gas and heavy metal ions have been investigated. Measurements of tungsten isotopic ratios have shown that the stability of the system is such that the precision of measurement is defined almost entirely by the statistics on the number of ions counted.

ISSN:0034-6748    

DOI:10.1063/1.1718146

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A pressure transducer is described which operates by balancing the pressure to be measured with that due to a known hydrostatic head. The precision is ±0.0025 psi over a range of about 1 psi with less than 0.0025‐psi drift in 8 h, and it requires very small fluid displacement. However, it can be used only where response to frequencies above about 0.2 cps is not required. A differential transformer monitors the height of the meniscus in one arm of a flexible, mercury‐filled U tube. This meniscus is displaced by changes in pressure transmitted hydraulically from a sensing head. The output of the transformer controls a servomechanism that continually restores the meniscus to its original height by raising or lowering the other arm of the U tube. Changes in pressure within the sensing head thus cause proportional changes of height of the mobile arm of the U tube, which are monitored and recorded.

ISSN:0034-6748    

DOI:10.1063/1.1718147

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A noninterrupting method for measuring a charged particle beam current consisting of a series of periodic pulses is presented. The pulsed beam is allowed to pass through a high permeability toroid on which is wound a multiturn coil. If the distance traveled by a beam particle during one pulsing period is large compared with the toroid dimensions, then the voltage induced in the coil consists of a series of impulses, the time integral of each impulse being proportional to the beam current. Since this voltage is equal to that induced in the coil by a one‐turn loop wound on the toroid and carrying a current identical to the beam current, it is possible to vary this current, and employ the multiturn coil as a null indicator to indicate equality of the beam and loop currents. If now a capacitor adjusted to resonate with the multiturn coil is placed across the coil, the sensitivity of the null circuit is increased by a factor equal to theQof the resonant circuit. Using this resonant magnetometer and a 1000‐cps chopping rate, currents of 3×10−7A peak have been measured with an accuracy of ±10−8A.

ISSN:0034-6748    

DOI:10.1063/1.1718148

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A beam‐profile detector that employs a pair of continuously moving scintillation counters as a detector and a PHA as a multichannel scaler is described. The number of counts per fixed number of incident particles at every 0.1 in. of travel is recorded in consecutive channels of the analyzer. A total of 7 in. is traversed in 42 sec after which the profile may immediately be displayed on the CRT readout of the PHA. The device is useful in its present form at accelerators having high beam repetition rates. Plans for its adaptation for use at pulsed accelerators are also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1718149

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

An instrument is described which measures the transport properties of high‐conductivity semiconductors. It employs a microwave turnstile junction to determine the complex orthogonal amplitudes of the reflected waves from a magnetized sample. The data are obtained by a double‐bridge technique of high sensitivity. Some experimental results on germanium at room temperature are presented.

ISSN:0034-6748    

DOI:10.1063/1.1718150

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A contamination‐free motor suitable for use in high vacuum is described. Torque, speed, power, and temperature rise data are given.

ISSN:0034-6748    

DOI:10.1063/1.1718151

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A double Dewar attachment has been designed for use with a Norelco x‐ray diffractometer. Operating temperatures are the points fixed by the coolant used or by pumping on the inner Dewar, although data can also be taken on a warming cycle. Experiments on Mn3O4at liquid helium temperature give no evidence for a crystal structure change associated with the ferrimagnetic transition at 43°K.

ISSN:0034-6748    

DOI:10.1063/1.1718152

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Motivated by a desire to determine the quantum efficiency of a relatively large number of GaAs injection lasers in order that some understanding of the relation between performance and structural parameters could be derived, a simple system for measuring the total light emission from such devices was sought. The method finally employed (and described herein) is generally applicable to any enclosure in which the walls are reasonably good diffuse reflectors. The calibration of the transfer efficiency of light from the source to a detector is effected by introducing a light absorbing element of known relative absorption coefficient and area.

ISSN:0034-6748    

DOI:10.1063/1.1718153

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The magnetic fields on a sample in the Philips EM 100B electron microscope have been calculated as a function of objective lens current. Experimental measurements gave values of 6180 Oe/A for the high resolution pole piece and 1860 Oe/A for the diffraction pole pieces. These values are about 20% lower than calculated. This discrepancy is attributed to the uncertainty in the position of the sample. The calculations and measurements are applicable to other electron microscopes.

ISSN:0034-6748    

DOI:10.1063/1.1718154

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A self‐contained jig for the spot plating of fine wires, as are employed in hot wire anemometry, is described. The unit consists of a plating bath fixture, Schmitt trigger intervalometer circuit, plating current control and measuring circuit, and power supply, all housed in a 6×4×4 in. instrument cabinet. Setup time is of the order of 5 min and production rates of 30 wires/h may be achieved.

ISSN:0034-6748    

DOI:10.1063/1.1718155

出版商:AIP    

年代:1963

数据来源: AIP