摘要:

Experiments involving pulsed magnetic fields of a half‐megagauss and more are shown to be practical. Some basic concepts are developed regarding the construction of impact resistant solenoids and the selection of the appropriate power supply. Operation of various high‐field magnets in the pulse range 50 to 10 000 &mgr;sec is discussed, and some techniques for associated solid state experiments are given. Magnetoresistance measurements up to 600 000 gauss have been made for germanium. Operation of a 175 000 gauss Helmholtz‐type magnet for nuclear track plate work with the 95‐Mev Harvard synchrocyclotron is described.

ISSN:0034-6748    

DOI:10.1063/1.1715520

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A 2.5×2.5×10‐cm hydrogen bubble chamber has been developed for experiments on the scattering of particles from the 450 Mev synchrocyclotron. Seventy‐five thousand pictures have been taken at the rate of one every two seconds and are being scanned at the rate of two thousand per day. The average track length per picture is about one gram per square centimeter. The characteristics of the bubble chamber are described and examples of the pictures are shown.

ISSN:0034-6748    

DOI:10.1063/1.1715521

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A system is described for the control of the position of the ion beam in a mass spectrometer. The instantaneous position of the beam with respect to the point of maximum collector current is presented on a cathoderay tube indicator. The beam can be held at this maximum point either manually using this indication, or by automatic control circuits. In automatic operation the beam first ``searches'' for the peak by sweeping slowly across the region of the collector plate. It is then ``locked in'' and hunts about the point of maximum current. The amplitude of the hunting can be made sufficiently small so that the average collector current does not differ greatly from the peak current. The beam remains locked in position during slow drifts of magnet current and acceleration voltages. After large sudden fluctuations it returns to search operation and locks in shortly thereafter. The method of control is an adaptation of principles used in automatic frequency control of radar receivers.

ISSN:0034-6748    

DOI:10.1063/1.1715522

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Ordinarily, the performance of electron lenses in electron imaging devices employing photoelectric surfaces can be evaluated only after sealed‐off vacuum tubes containing the processed photoelectric surfaces are made. After processing, such tubes cannot be opened to air for alterations without destroying the photoelectric surfaces. Three distinct types of structures for providing area sources of low‐energy electrons simulating photoelectric sources are discussed. These structures can be inserted in demountable vacuum systems and are not destroyed by subsequent exposure to air.

ISSN:0034-6748    

DOI:10.1063/1.1715523

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A technique is described for the accurate measurement of angular errors using photoelectric detectors. Utilizing two types of rugged, compact cartridges, a wide range of characteristic curves may be synthesized. Examples of various systems are shown, including one for a high accuracy servo. The latter has a coverage of 360 degrees, a null accuracy of one minute, and is in current use in Aerobee Rockets.

ISSN:0034-6748    

DOI:10.1063/1.1715524

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A high precision electromechanical analog computer is described. The mechanical system is a torsion pendulum. Programmed torques provide an equation of motion which is identical to the equation:y″+f(x)y+g(x)=0. The solutions are obtained by recording the motion by means of a recording camera. The analog computer is used to study the betatron oscillations and the effects of resonances for the strong‐focusing Cornell synchrotron.

ISSN:0034-6748    

DOI:10.1063/1.1715525

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Description of a transducer system which permits the conversion of mechanical displacements into electrical signals. The system is based upon a high‐frequency discharge in a gas under reduced pressure. Different modifications permit the detection of either very small movements (<1 mm) or large movements (several cm), or small changes of capacitance (fraction of a micro‐microfarad).

ISSN:0034-6748    

DOI:10.1063/1.1715526

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The output pulses from scintillation detectors are amplified in conventional feedback amplifiers and transformed into a bipolar wave form, which passes the discrimination level of the following EFP 60 trigger circuit at a given time after inception of the scintillation pulse, independent of its amplitude within a wide range. If these standard pulses are shaped and fed into a fast coincidence circuit, even for NaI(Tl) resolving times of the order of 10−8sec can be obtained. The main limitation of the method is due to time jitter of the standard pulses caused by statistical fluctuations of the rising edge of the photomultiplier pulses which results in a reduction of coincidence efficiency.

ISSN:0034-6748    

DOI:10.1063/1.1715527

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A nuclear induction spectrometer for the measurement of short relaxation times and the study of saturation and related phenomena is described. Radio‐frequency intensities of up to 10 gauss are attainable from four to ten megacycles. Novel features of the apparatus are an rf head for use in a liquid helium cryostat, transmitter output level stabilization circuit, and a calibration circuit for comparing the intensity of the absorption at different rf levels.

ISSN:0034-6748    

DOI:10.1063/1.1715528

出版商:AIP    

年代:1956

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1715531

出版商:AIP    

年代:1956

数据来源: AIP