摘要:

A high‐speed digital recording system has been developed for studying the de Haas‐van Alphen (dHvA) effect (and related phenomena) in impulsive magnetic fields. The data obtained during each pulse are stored in a small memory, from which they can be recovered at leisure and analyzed by computer. Use of this digital recording instrumentation has resulted in a substantial improvement in the reliability of the values of the dHvA frequencies as determined in impulsive fields, and has also led to an enormous saving in the time required for data reduction and analysis. The calibration of the magnetic field is also discussed.

ISSN:0034-6748    

DOI:10.1063/1.1683703

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A novel technique involving a straightforward modification of an ion cyclotron resonance spectrometer has been developed which utilizes the excitation of the characteristic oscillatory motion of the ions, due to the trapping field, for ejecting ions from the cyclotron resonance cell. By pulsing the rf ejection field and referencing the detection system to the pulsing frequency, a spectrum of ions whose number density is modulated by the pulsed ejection field is obtained. This is directly applicable in studying ion‐molecule reactions for the determination of product ion distributions, even when other processes, such as direct ionization or concurrent ion‐molecule reactions, contribute to product ions of interest.

ISSN:0034-6748    

DOI:10.1063/1.1683704

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An easy method of making a parallel plate electron multiplier, which is used for detection of x rays, electron beams, and charged particles, is developed. The multiplier consists of two continuous dynodes, which are prepared by evaporating aluminum onto glass substrates on which carbon has been evaporated in advance. The gain is in the range of 108to 109, when the applied voltage is 3 kV. Some of the features are quite good linearity of response except for the saturation region, extremely small noise and long lifetime, and ease in handling. It also can be used for pulse counting techniques.

ISSN:0034-6748    

DOI:10.1063/1.1683705

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An apparatus is described which is capable of measuring simultaneously the local amplitudes of two magnetic field components, their squares, and the sum of their squares. It consists of a two‐coil magnetic probe and a voltage signal squaring circuit. Details of the construction and calibration of the apparatus are given and an application of the complete system is briefly outlined.

ISSN:0034-6748    

DOI:10.1063/1.1683706

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A voltage divider board composed of 1152, 22 M&OHgr; composite carbon resistors used to measure the terminal voltage of a 3 MeV Dynamitron was investigated. The board was calibratedin situusing the9Be and D photoneutron threshold reactions and a magnetic analyzer. The present calibration of the divider board which was made after over 5 years of extensive accelerator usage agrees within 2% with the original factory calibration. The linear temperature coefficient of resistance was measured to be +(0.85±0.10)×10−3/°C in the range 25 to 35°C. The divider board resistance decreased linearly with voltage (−1.1×10−5%/V) up to 2 MeV which corresponds to 1750 V on each resistor. The results show that composite carbon resistors and the techniques described can be applied with confidence to the measurement of high voltage.

ISSN:0034-6748    

DOI:10.1063/1.1683707

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A coupled cavity CO2‐laser interferometer is described. The feedback is achieved either with (a) a rotating corner mirror or (b) an oscillating mirror. For method (a) a sensitivity of∫ndl≥5×1014cm−2and time resolution of 0.2 &mgr;sec is obtained. Method (b) is more sensitive(∫ndl≥1013cm−2)but the time resolution is limited by the fact that signal amplitudes are strongly frequency dependent above 350 kc. The interferometer has been used to measure plasma densities of the Scylla IA &thgr; pinch.

ISSN:0034-6748    

DOI:10.1063/1.1683708

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We describe in this paper a program to calculatea posteriorithe coordinates of a set of points photographed byncameras, together with the positions and orientations of the cameras, also not knowna priori. The coordinates of the cameras are obtained by an unique fit, requiring the points measured on the pictures to be images of true points, existing somewhere in space. The coordinates of the points photographed are then easily obtained.

ISSN:0034-6748    

DOI:10.1063/1.1683709

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A cesium plasma with a useful volume of 3 by 15 cm is produced inside a hot cylindrical tantalum cavity at temperatures around 1400 K. Ions are produced by contact ionization at the wall while electrons are obtained from an internal filament. The plasma potential determines the energy of the electrons, and this can be varied such that the electron‐ion temperature ratio ranges from 1 to 2.4. In the vicinity of 1011ions/cc the background noise is about the same as found in Q machines.

ISSN:0034-6748    

DOI:10.1063/1.1683710

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

We describe a controller for regulating the temperature of a pumped liquid helium bath. The controller is a considerable improvement over previous controllers in that it is much simpler and less expensive. These improvements are due mainly to an uncommon direct‐coupled alternating current circuit, and to extensive use of the recently introduced integrated semiconductor circuits. The controller operates by measuring the resistance of a carbon radio resistor immersed in the liquid helium bath, and then feeding back a proportional correction current to a heater. The controller will control a bath to within 100 &mgr;K over a period of 20 min, at 2.1 K, and could be used to control the temperature of a copper block over a wide range of temperatures.

ISSN:0034-6748    

DOI:10.1063/1.1683711

出版商:AIP    

年代:1969

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1683713

出版商:AIP    

年代:1969

数据来源: AIP