摘要:

An earlier work on a Mattauch‐Herzog type mass spectrograph with a two‐stage electrostatic field is extended to investigating the conditions for simultaneous elimination of &agr;&bgr; and &bgr;2aberrations for all masses. In the course of study, the condition for obtaining a real image of ion source between two electrostatic fields is abandoned, and by this extension two series of solutions are found in neighborhood of &Jgr;e2=&pgr;/√2. The design parameters are numerically computed and tabulated for several examples. The &agr;2aberrations are calculated and the total image defects are evaluated and found to be very small for a wide mass range.

ISSN:0034-6748    

DOI:10.1063/1.1720539

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A ring heat source probe has been developed for the rapid determination of thermal conductivity of rocks. In addition to the short period of time required to run the test (2–3 min), sample preparation is minimal, requiring only that parallel flats approximately two cm in diameter be cut or ground on opposite sides of the sample. A calibration chart can be provided with each probe so that thermal conductivity can be obtained from simple experimental data without elaborate calculation.

ISSN:0034-6748    

DOI:10.1063/1.1720540

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A low inductance three‐electrode spark source for the vacuum ultraviolet fed by a 20‐kV, 13‐&mgr;F capacitor is described. Its main feature is its ability to generate spectra of very high degrees of ionization. A 6‐kV spark produces spectra of CVand CVIas well as FeXVI, while a 17–18‐kV spark yields FeXVIII, AlXII, and AlXIII.

ISSN:0034-6748    

DOI:10.1063/1.1720541

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An apparatus has been designed and built for scanning the surface of a semiconductor device with a light spot. The apparatus uses a modified commercial television set for the display of the photoresponse and a miniature CRT as flying spot source. Photoresponse pictures of lithium‐drifted silicon radiation detectors as well as of surface barrier type detectors are shown and interpretation is attempted.

ISSN:0034-6748    

DOI:10.1063/1.1720542

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A collimator is described which restricts a beam of charged particles to a few microns in radial extent. The collimator is a double aperture device and provides a pressure differential of one atmosphere with no foil window.

ISSN:0034-6748    

DOI:10.1063/1.1720543

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A device for generating a fully‐ionized barium plasma column is described. It is similar to the previously described Q1 device except for the substitution of rhenium ionizing surfaces for tungsten, and barium for the alkali metals. The main motivation for the use of barium is that singly‐ionized barium has its resonance lines in the visible wavelength range, and thus allows the use of spectroscopic techniques for the determination of various plasma parameters. The special problems of barium in a Q device, and the spectroscopic techniques, including range of applicability and achievable accuracy of the measurements, are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1720544

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A technique for compensating magnetic field gradients over small regions (300 cc sphere) is described. With five pairs of bar magnets the maximum field variation over a 10 cm distance was reduced from 2.2 mG to less than 0.08 mG.

ISSN:0034-6748    

DOI:10.1063/1.1720545

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Changes in the dark current and noise pulse spectrum of photomultiplier tubes due to ionizing radiations are reported. Tubes studied were the RCA 7265 and various versions of the ``ruggedized'' RCA 6199. Measurements were made both at 25°C and −40°C under exposure to60Co &ggr; rays, cosmic rays,241Am alpha particles, and90Sr &bgr; rays. All ionizing radiations incident on the phototube face were observed to produce additional dark current, and a considerable enhancement of the pulse spectrum, particularly at pulse sizes corresponding to several cathode photoelectrons. Each cosmic ray and interacting60Co &ggr; ray produced one large pulse, equivalent to about 10 single photoelectrons, and about 10 smaller pulses. The241Am and90Sr produced less than one noise event per incident particle. In order to explain the effects, three mechanisms seem to be required. Cˇerenkov radiation will produce the large pulses due to relativistic cosmic rays and Compton scattered electrons by60Co &ggr; rays. Scintillations in the glass with an efficiency of about 10 photons/MeV produce the effects due to the nonrelativistic alpha and &bgr; particles. It is suggested that phosphorescence induced by the short wavelength Cˇerenkov quanta can account for the many small pulses observed. These effects significantly alter the signal‐to‐noise characteristics of phototubes on balloons and satellites when applied to the detection of weak light sources, or low intensity x rays in the environment of space.

ISSN:0034-6748    

DOI:10.1063/1.1720546

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A technique for the measurement of velocity and strain of acoustic surface waves is proposed. It utilizes very thin vacuum deposited conductors in an applied magnetic field, which permits an unimpeded evaluation of the strain, velocity, and power of a propagating ultrasonic surface wave. The proposed method of measurement is simple and accurate. An example of a 10 MHz surface wave on glass is utilized to illustrate the measurement of particle velocity and power density of the longitudinal component of the wave.

ISSN:0034-6748    

DOI:10.1063/1.1720547

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The effect of baseline restoration on signal‐to‐noise ratio in pulse‐amplitude measurements is determined theoretically and experimentally. It is found that the signal‐to‐noise ratio with baseline restoration normalized to that without restoration is &eegr;r/&eegr;=[1+&agr;− 2&agr;½kx(&tgr;)]−½, wherekx(&tgr;) is the noise correlation factor at the output of the filter (amplifier), &tgr; is the measurement interval, and &agr; is the attenuation of noise power due to integration by the restorer capacitance and switch resistance (&agr;=1 for fast restorer). Methods of calculation of correlation functions are outlined. A method for measurement of correlation functions by oscilloscope is described. The results are presented for the three commonly used filters: CR‐RC filter, quasi‐Gaussian filter, and delay‐line filter. Baseline restoration is found to degrade the signal‐to‐noise ratio. The amount of this degradation can be reduced to negligible proportions in filters with long memory (such as CR‐RC) by a small degree of integration in the restorer. Peak‐to‐peak amplitude measurement of double‐differentiated signals performs, in effect, baseline restoration and, in addition, improves signal‐to‐noise ratio compared to peak‐amplitude measurement.

ISSN:0034-6748    

DOI:10.1063/1.1720548

出版商:AIP    

年代:1967

数据来源: AIP