摘要:

The details of the construction and calibration of high frequency magnetic probes, used to measure the transient magnetic fields in a linear pinch device, are described. A simple and reliable calibration technique, using conventional laboratory electronic equipment, was developed to measure the absolute sensitivity of magnetic probes in the frequency range of 1–50 Mc. Factors affecting the frequency response of magnetic probes are considered, and high frequency design and construction are discussed. A double probe, which measures two magnetic field components simultaneously is described. The use of these probes is briefly mentioned.

ISSN:0034-6748    

DOI:10.1063/1.1719473

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The repulsive longitudinal space‐charge forces between particles being accelerated in a linac weaken the total phase‐focusing force which arises from the rf accelerating field. The stable longitudinal phase‐space area decreases as the particle phase‐space density increases. In this paper the techniques used in Nielsen and Sessler's treatment of the longitudinal space‐charge problem in circular accelerators are applied to the longitudinal space‐charge problem in linacs. A method for determining the dependence of the available longitudinal phase‐space area on the beam current is outlined. An example is worked out using the parameters of a linac designed at MURA for various values of stable phase angle, drift‐tube hole radius, and beam radius. Numerical results show that there is a significant decrease in stable longitudinal phase‐space area for instantaneous beam currents larger than about 100–200 mA.

ISSN:0034-6748    

DOI:10.1063/1.1719474

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The techniques of modern network theory have been applied to some of the problems of pulse shaping in nuclear pulse amplifiers. A technique referred to as pole‐zero cancellation has been evolved which permits a system designer to specify the pulse decay time at the amplitude‐limiting section of the system and the pulse shape at the final output as completely independent parameters. The deadtime of the amplifier system can be reduced by orders of magnitude without degrading the signal‐to‐noise ratio. In addition, the usual charge‐injection system has been examined, and a simple, linear lumped‐element network has been evolved which makes possible an improved evaluation of the amplifier response to detector charge pulses.

ISSN:0034-6748    

DOI:10.1063/1.1719475

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

The rolling ball technique of measuring viscosity was adapted for use at temperatures up to 400°C under pressures up to 5 kbar. At 75°C, log10viscosity of glycerol was found to increase linearly with pressure up to 5 kbar.

ISSN:0034-6748    

DOI:10.1063/1.1719476

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

An ion source with magnetron geometry for mass spectrometric analysis of low vapor pressure materials is constructed. Using the magnetron configuration of this source a new method for obtaining the ion beams of low vapor pressure elements is developed. The material to be analyzed is fixed to the hot cathode, so that the cathode can be used simultaneously as a hot support for charge material and as a source of electron emission. The vapor of the material is produced by the combined effect of filament heating of charge material and cathode sputtering by the ions of carrier gas. The method was successfully applied in obtaining ions of Cr, Fe, Ti, Ir, La, Ta, Nd2O3, Re, Ce2O3, and ZrO2. The collector ion currents range up to 10−11A. The energy spread is measured by means of both the retarding potential and the beam deflection methods. It is found that there was no difference in the energy spread of this source and a classical Nier's ion source for mass spectrometry. The advantages of the source are also described.

ISSN:0034-6748    

DOI:10.1063/1.1719477

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

An improved recording rotational high shear viscometer has been developed. The instrument employs concentric steel cylinders with unusually narrow and precisely defined shear clearances. Both shear rate and stress are continuously and independently recorded. Improved cylinders and other additional features have led to accurate viscosity measurements at shear rates from 5×102to 2×106sec−1. The temperature range is −20 to +150°C with a viscosity range which varies inversely with the desired shear rate for measurement. The shear rate range and the upper limit, 2×106sec−1, exceed all previous reports of measurement at defined conditions in a homogeneous, isothermal shear field.

ISSN:0034-6748    

DOI:10.1063/1.1719478

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

A resistance type heating device is described which adapts a standard high temperature x‐ray camera for use in diffraction studies where uniformity of temperature is required. With this device, a volume 6×6×3 mm can be maintained within ±6°C at a temperature of 550°C.

ISSN:0034-6748    

DOI:10.1063/1.1719479

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

In the study of photoluminescence, simple spectra obtained by dc excitation often do not contain sufficient information for complete analysis of the kinetics of the luminescent light emission. This paper describes a system with which the spectral emission can be studied at controlled times after photoexcitation. The system uses separate mechanical chopping of the photoexcitation source and the photoluminescent emission. The two light choppers are hysteresis synchronously driven from a single alternating current source and their relative positions are, therefore, phase locked. Their relative positions and, therefore, the time between termination of photoexcitation and detection of photoluminescent emission is controlled by a 0–360° precision electrical phase shifter placed between the common alternating current source and the power amplifier driving one of the chopper motors. This time controlled system is described. The photoluminescence is wavelength resolved by a spectrometer, detected by a photomultiplier and lock‐in amplifier, and automatically recorded as a function of wavelength by an X‐Y recorder. X‐Y recorded tracings of photoluminescent spectra at various times after termination of photoexcitation are shown to illustrate the capabilities of the system.

ISSN:0034-6748    

DOI:10.1063/1.1719480

出版商:AIP    

年代:1965

数据来源: AIP

摘要:

Experimental techniques in nuclear physics often call for arithmetic operations on pulses whose amplitudes convey the experimental data. An instrument capable of pulse height multiplication, division, exponentiation, as well as pulse height addition and subtraction is described. These operations are performed in about 0.5 &mgr;sec with a precision of ±0.1% of full scale over a pulse height range of 20:1. At room temperature the computer exhibits a drift of about 0.05%/C° or ±0.3%/day. With an input rate of 10 000 counts/sec the pulse height distribution shifts 0.2%, and with 25 000 counts/sec it shifts 1%. Multiplication, division, and exponentiation are performed by using logarithms and antilogarithms. The log and antilog function generators are based on the fact that the emitter‐base voltage of a silicon planar transistor is proportional to the logarithm of its collector current. Addition and subtraction are performed by using linear operational amplifiers. Results of experiments are shown in which the computer was used for identification of charged particles, pulse shape discrimination, measurement of mass yield distributions in fission, as well as for other on‐line data reduction techniques.

ISSN:0034-6748    

DOI:10.1063/1.1719481

出版商:AIP    

年代:1965

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1719482

出版商:AIP    

年代:1965

数据来源: AIP