摘要:

This paper is concerned with certain aspects of the technique of all‐metal, kinetic vacuum systems which have proven their reliability. A brief account is given of the constitution of a system to operate down to pressures of the order of 10−5mm. Precautions to be observed in assembling such a system and in its general care and maintenance are discussed. In all systems reliable, high speed valves are needed. Some which are quite satisfactory for many uses are available. In the event that it is necessary to construct such a valve, a modification of a standard brass gate valve is described. The problem of rubber gaskets is discussed in some detail, and suggestions are made which may relieve some of the difficulties which are occasionally encountered with them. The attention of experimenters is called to the usefulness of O‐rings and a number of examples of their use is given.

ISSN:0034-6748    

DOI:10.1063/1.1741308

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A Geiger‐Mu¨ller counter with a spherically shaped cathode is described. The pulse shape from this counter is similar to that of cylindrical counters. It may be used satisfactorily in ordinary coincidence work.Some of the counters, slightly modified to avoid spurious discharge, were filled with boron trifluoride and used as proportional counters for detection of neutrons.

ISSN:0034-6748    

DOI:10.1063/1.1741309

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

An investigation of the factors which influence the opening time of Fussell‐type cloud‐chamber valves has been made. In particular, the action of auxiliary triggering coils has been examined. The feasibility of constructing such a valve which is held shut by a permanent magnet is demonstrated. It is shown that valves can be easily made, whose opening time is limited not by electrical but by mechanical parameters.

ISSN:0034-6748    

DOI:10.1063/1.1741310

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A quenching circuit is described that works on the multivibrator principle but uses two different grids of the input tube for the signal and for the regenerative feedback. The initial discharge in the counter excites the counter to one oscillation during which the counting voltage is kept below threshold and the counter has time to recover. At the end of the oscillation (after about 0.2 millisecond) the countervoltage and all other voltages are rapidly restored to their initial values. Thus the next count will take place under exactly the same conditions as the first; all amplifier pulses will be equal; no discharges will take place in the Geiger counter while the amplifier is unable to quench them; and corrections for dead time will be quite simple.

ISSN:0034-6748    

DOI:10.1063/1.1741311

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

This paper describes the construction and performance of a differential manometer with a sensitivity of 0.001 mm of mercury over the range of absolute pressures from 1 mm of mercury to 1 atmosphere. The sensitive element employed is a pair of nesting diaphragms, displacement of which is measured by the resistive unbalance of an unbonded electrical displacement gauge to which the diaphragms are attached. Calibrations are presented for the sensitivity at 1‐ and 10‐ma gauge current. Data are presented which indicate the operating characteristics under varying conditions of absolute pressure, temperature, gauge current, and geometric orientation.

ISSN:0034-6748    

DOI:10.1063/1.1741312

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The removal of the ion beam of 190‐Mev deuterons from the magnetic field of the 184‐inch cyclotron is complicated by the fact that at large radii the ion increases its radius very little in one revolution. The usual type of deflector did not appear to be usable. Consequently, a pulsed electric deflector was designed that would give an additional radial oscillation to the ions which could be as much as seven centimeters. This permits deflection of the ions outward to a magnetic deflector which is outside the range of the circulating ions. The field is sufficiently reduced inside the magnetic deflector to permit the ions to leave the magnetic field of the 184‐inch cyclotron. Approximately ½ percent of the circulating beam appears in the external beam.

ISSN:0034-6748    

DOI:10.1063/1.1741313

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

The object of this study was the development of a portable self‐contained instrument which would record the rates of inspiratory air flow through protective canisters under actual field conditions. This instrument was developed so that observations made in the laboratory could be checked under actual field conditions. Measurements of air flow on subjects in tanks or parachute troops or men moving in industrial operations cannot be obtained without a portable instrument.The essential requirements of this instrument are that it obtain records of air flow, air volume, and respiration rate while worn by or held closely to the individual under observation. The apparatus should be rugged and independent of positional effects or a reasonable amount of rough handling. Its operation should be automatic and not require attention by the subject.

ISSN:0034-6748    

DOI:10.1063/1.1741314

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

Design and operating characteristics of an electronic device for measuring over‐all efficiencies of Geiger counters are provided. The device will rapidly, and without any standard tube, yield these data as well as provide a means of checking the relative sensitivity of various sections of a counter tube.

ISSN:0034-6748    

DOI:10.1063/1.1741315

出版商:AIP    

年代:1948

数据来源: AIP

摘要:

A glow tube with thorium electrodes can be used to measure the intensity of ultraviolet light. The simple circuit used for this purpose does not give reliable results for photo‐currents below 10−10amp., and the exposure time to light may become several hours. The writer has devised certain improved methods which can measure small photo‐currents of the order of 10−13amp., requiring an exposure time of only a few minutes. If the exposure time is increased to several hours, then it is possible to measure currents even below 10−14amp., provided the components are carefully insulated.

ISSN:0034-6748    

DOI:10.1063/1.1741316

出版商:AIP    

年代:1948

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1741318

出版商:AIP    

年代:1948

数据来源: AIP