摘要:

It is generally assumed that it is essential to use a cylinder of circular section as the cathode if a good counter of the point or wire type is to be made. Investigation of various geometrical forms of cathode with a wire as anode shows that counters may be made in a large variety of shapes and yet operate satisfactorily. Thus a large rectangular vessel with a wire placed symmetrically within the volume or mounted close to one wall has been found to operate as a self‐quenched counter.The use of such shapes is shown to result in improved performance in several important respects, e.g., reduced operating voltages, shorter dead‐times. By the use of several wires in the same vessel, coincidence arrangements are made easily possible. This can be applied successfully to the construction of a counter which has a reduced natural counting rate but still presents a large solid angle to an external source. Various other applications are considered.

ISSN:0034-6748    

DOI:10.1063/1.1741220

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

An oscillator is described which employs inductive feedback between plate and cathode with the grid grounded. This arrangement results in some desirable characteristics.

ISSN:0034-6748    

DOI:10.1063/1.1741221

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Present industrial methods of photoelectric measurement are incapable of approaching the theoretical sensitivity limit set by thermal agitation noise because of various practical limitations restricting the maximum useful gain. A new method is described for converting the d.c. space currents in photo‐tubes into a.c. voltages capable of amplification to the point where only fluctuation noise limits the accuracy. This conversion consists in the magnetic deflection or suppression of space currents with the use of an alternating magnetic modulating field applied transversely across the path of photoelectrons. A practical circuit is described with which photo‐currents were measured close to the threshhold of agitation noise without use of other than commercial radio components. The new method affords complete separation of the actual photo‐currents from all leakage currents in the input circuit without the use of a.c. light sources or light‐chopping mechanisms.

ISSN:0034-6748    

DOI:10.1063/1.1741222

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A simple two‐way valve and a method of making a seal are described, both well adapted to large or small port openings in high vacuum work. The valve gate consists of two rigid flat surfaces on which are mounted the gaskets. The plates are normally drawn together but can be pushed in front of the ports and forced apart by the action of a cam fixed to rod. A round rubber gasket held in a special groove of one surface pushed against another flat surface produces an excellent vacuum seal. The metal‐to‐metal seat prevents injury to the rubber from excessive pressure or the exposure of the rubber to the vacuum system.

ISSN:0034-6748    

DOI:10.1063/1.1741223

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

An electrometer circuit is described in which it is possible to choose the resistances such that the plate voltage is independent of the supply voltage. When the circuit is used as the input stage of a direct‐coupled amplifier, this leads to a simplification of the amplifier design. The equations determining the circuit constants in terms of the electrometer parameters are derived and applied to a G.E. Type FP‐54 electrometer tube. The possibility of obtaining a higher order of balance is briefly discussed.

ISSN:0034-6748    

DOI:10.1063/1.1741224

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The theory, design, and some experimental results relative to linear electron accelerators are discussed. It is shown that, though the orbits are unstable, this instability is so small as to be negligible in general, provided the electrons are injected at relativistic velocities. Likewise, space‐charge spreading may be neglected. The optimum loading design is found for various types of power feeds and curves are given by means of which any design may be evaluated. A number of illustrative cases are discussed. Operation of a low power, 38‐section accelerator is described.

ISSN:0034-6748    

DOI:10.1063/1.1741225

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The magnitude of the charge circulating in a betatron orbit is determined from its magnetic effect. The results indicate that the charge accelerated to high energy per second, in a 22‐Mev betatron operating at 180 cycles per second, corresponds to an average current of about 0.15 microampere.

ISSN:0034-6748    

DOI:10.1063/1.1741207

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

There are at least two types of short time delays in the firing of Geiger counters. The first is due to the transit time of the secondary electrons as they migrate toward the central wire. This time can be measured when beta particles are sent parallel to the axis of the counter, creating secondaries at known distances from the axis. In a typical counter, 2.2 cm in diameter, the maximum secondary electron transit time is measured at about 11×10−8second.The second delay occurs between the time the electron arrives near the center wire, and the time a pulse is detected on the output of a wide band amplifier connected to the center wire. Increasing the voltage on the counter from the threshold to an over‐voltage of 250 volts, decreases this delay by 10 to 20×10−8second. It is suggested that this delay is due to the time required to form the initial part of the ion sheath.

ISSN:0034-6748    

DOI:10.1063/1.1741208

出版商:AIP    

年代:1948

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1741211

出版商:AIP    

年代:1948

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1741212

出版商:AIP    

年代:1948

数据来源: AIP