摘要:

As part of the program to investigate the properties of the Thomas cyclotron, a 20‐in. diam proton cyclotron was constructed. In such a three‐dee three‐phase system it is possible to accelerate protons, deuterons, and tritons at the same setting of frequency and magnetic field but on different modes of the rf. For stable operation in the proper mode and with balanced voltages, it has been found necessary to provide both phase servos and amplifier efficiency servos. The dees could not be servoed individually until the inter‐dee capacity was neutralized. Under such conditions it was possible to attain steadily 6.0 ma of protons at 1.0 Mev in the forward mode and 6.5 ma of deuterons at 0.5 Mev in the reverse mode.

ISSN:0034-6748    

DOI:10.1063/1.1715616

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

Two model constant‐frequency cyclotrons based on the principle of L. H. Thomas, as extended by David L. Judd, are described. Both accelerated electrons to speeds of half that of light in magnetic fields of three‐fold azimuthal periodicity. Three 60°‐wide wedge‐shaped electrodes, driven 120° out of phase, provided an energy gain per revolution of 3eV0, whereV0is the peak electrode‐to‐ground voltage. Electrons were accelerated to 75 kv withV0=23 v, implying a minimum of one thousand revolutions in the cyclotron. The beam reached full energy without axial loss and it was demonstrated that essentially all of the circulating current will emerge from this type of accelerator without the use of additional deflecting systems. The success of this development program has shown the feasibility of a high‐current, high‐energy cyclotron based on the Thomas principle.

ISSN:0034-6748    

DOI:10.1063/1.1715617

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A mass spectrometer employing a cycloidal‐focusing mass resolving system is described. The mass analyzer proper, including the magnet and a high‐speed continuous‐flow inlet system, weighs approximately seventy pounds. The resolving system shows good mass resolving power, sensitivity, and analytical accuracy up to about mass 150 amu, and adequate service life. The mass resolving power can be extended substantially in cases where some loss of sensitivity and analytical accuracy is tolerable.

ISSN:0034-6748    

DOI:10.1063/1.1715618

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

In a cycloidal‐focusing mass spectrometer, nonuniformities in the magnetic and electric fields may cause either an actual deterioration of the image quality or merely a shift in the focal point. The latter effect is the more usual one and it can be compensated easily.

ISSN:0034-6748    

DOI:10.1063/1.1715619

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

In a curtate‐cycloidal‐focusing mass spectrometer, the first‐order effect of space charge is not to impair the quality of the focus but to shift the focal point out of the plane of the resolving slit. For a given ion mass and ion current, the magnitude of the effect is about four times as large in a cycloidal‐focusing instrument as in a 180° magnetic sector mass spectrometer operating in the same magnet.

ISSN:0034-6748    

DOI:10.1063/1.1715620

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A description is given of a machine designed to produce microelectrodes from a standard 3‐mm Pyrex glass tube. The glass tube is heated by a platinum coil and drawn into microelectrodes by a vertical two‐stage pull. The first pull is by gravity and the second by an electromagnet. The operation is entirely automatic. After the machine is switched on adjustable microswitches control the sequence of operation and finally switch the machine off when the microelectrodes are drawn. Two identical microelectrodes are produced per minute. The microelectrode tip diameters may be varied from 0.5 to 10 &mgr;. The taper towards the tip may also be varied within wide limits to suit different experiments.Advantages of the machine over earlier microelectrode pullers are discussed together with a description of a rapid method of filling microelectrodes with conducting solutions.

ISSN:0034-6748    

DOI:10.1063/1.1715621

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The instrumentation for the magnetic focusing and analysis of the external beam of the Michigan cyclotron is described. It provides to a scattering chamber in an adjacent room a beam of deuterons of a few tenths microampere monoenergetic to within 15 kev at a mean energy of 7.8 Mev. A double‐focusing analyzer magnet of mean radius one meter, focuses reaction products of magnetic rigidity less than or equal to that of a 20‐Mev proton. At the optimum energy resolution of the system, proton groups from (d,p) reactions differing inQby about 20 kev can be resolved. Particles can be observed over a continuum of angles from −7° to +112° relative to the incident beam. The determination of reaction energies and the measurement of relative differential cross sections are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1715622

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A thin‐walled liquid hydrogen‐deuterium target has been developed which makes use of the boil‐off vapors from liquid helium as a coolant. Approximately three liters of liquid helium are required to condense the hydrogen and 0.13 liter per hour thereafter.

ISSN:0034-6748    

DOI:10.1063/1.1715623

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

One of the major problems of analysis in the soft x‐ray region is the limitation due to low transmission of the window materials of sealed‐off x‐ray detectors. This paper describes the properties and use of a gas‐flow proportional counter system for the x‐ray analysis of elements in the third period of the periodic table, with special reference to aluminum and silicon. The use of gases flowing continuously through the counter at atmospheric pressure in conjunction with helium also at atmospheric pressure in the optical path permits the use of ultra‐thin nonvacuum‐tight windows with high transmission in this region. Comparative data, obtained on a Norelco fluorescence spectrometer, show a tenfold increase in counting efficiency for AlK&agr; over detectors previously available for this application.

ISSN:0034-6748    

DOI:10.1063/1.1715624

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

An all‐electronic generator is described which provides a voltage which varies linearly with time between adjustable positive and negative limits. Such a generator lends itself well to the automatic recording of current‐dependent phenomena. Linear variation is obtained on both the rising and falling half‐cycles, so that complete reversal of slow processes may be assured. The maximum current provided in either direction is 3 amps. The limit is determined by the number of output tubes connected in parallel. Cycling periods up to 1 min in length are provided.

ISSN:0034-6748    

DOI:10.1063/1.1715625

出版商:AIP    

年代:1956

数据来源: AIP