摘要:

A pulsed neutron source has been developed whose principal element is a sealed‐off vacuum tube in which a discharge between titanium tritide surfaces produces tritons, which then are accelerated to a deuterium‐loaded target. The construction of a tube producing approximately 107neutrons in microsecond pulses and having a life of several thousand pulses is described.

ISSN:0034-6748    

DOI:10.1063/1.1716948

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A study of the factors influencing the design of pulsed neutron generators is made. By using the reaction between tritium and deuterium, peak rates of 1013/sec should be obtainable from quite small sources.A method of keeping the pressure of deuterium gas substantially constant at the working pressure was evolved. This enabled a ``sealed‐off'' and hence portable source to be made.The development of a fast neutron generator or neutron tube based on these considerations is described. This was capable of producing neutrons at a rate of 5×1012/sec at a voltage of 100 kv. The tube was suitable for operation at pulse lengths of 20 &mgr;sec, and the neutron content of each pulse was 108. No difficulty was experienced in operating at 1 pulse/sec, and higher pulse repetition frequencies may be possible.

ISSN:0034-6748    

DOI:10.1063/1.1716949

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

Second‐order perturbation theory has been used to calculate the electron orbits in a ``flat'' beta‐ray spectrometer with an azimuth‐independent magnetic field having a symmetry plane. Abandoning first‐orderzfocusing, it is possible to obtain a much higher resolution at a given transmission compared with the usual &pgr;√2 instrument. The resolution depends, in the lowest power, only on fourth‐order terms of the radial and axial emission angles. The resolution does not depend on the first power of the source height. The focusing principle is applicable for a set of angles &thgr;, and the dispersion increases strongly with increasing angle. Several examples are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716950

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The paper describes the basic circuitry required for a high precision direct reading resistance thermometer with dials calibrated in degrees C and any standard platinum resistance thermometer as sensing element. A circuit has been developed which, through linear variations of the resistance elements, gives a quadratic law having the formR=R0(1+AT+BT2), whereBis negative, as is required for a platinum thermometer. At the same time it allows separate adjustments for slopeAand curvatureBorB/Aof the resistance vs temperature relation of the particular thermometer being used and also for the ice point resistanceR0. The auxiliary circuitry is given for comparing the computing circuit with the thermometer and for maintaining a constant recorder sensitivity of all temperatures; stability requirements for work to 0.001°C over a 700°C range are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716951

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

This paper presents the details of circuitry and construction for a direct reading resistance thermometer which has been built utilizing the design criteria formulated in Part I. By using any standard 25.5&OHgr; platinum resistance thermometer as a sensing element, the bridge gives subdivision of the temperature scale to 0.001°C between −50° and +700°C with an accuracy exclusive of that of the thermometer of about ±0.001°C. Methods are described that allow for variations of thermometer constants, for autocalibration of the bridge circuit, and for maintaining constant sensitivity by variation of the thermometer current. The bridge as described has performed satisfactorily for three years and has proved to be a useful and convenient laboratory tool.

ISSN:0034-6748    

DOI:10.1063/1.1716952

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

A new and relatively simple type of mass spectrometer ion detector is described. The positive ion is accelerated onto an aluminum surface releasing secondary electrons, and these in turn are accelerated onto an organic scintillator, viewed by a sealed‐off photomultiplier. Counting methods are used to measure the ion beams. The detector has a low noise level, 4×10−20amp, and the mass discrimination is small for ions in the high and low mass range.Admission of air to the vacuum system does not affect the gain of the detector, since no activated surfaces are situated within the vacuum.In the event of a fault occurring in the photomultiplier a new one can be substituted in a few minutes without letting air into the vacuum system.

ISSN:0034-6748    

DOI:10.1063/1.1716953

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An experimental high vacuum furnace with a platinum‐rhodium resistance heating element is described; it is operable also in oxygen or other gases up to pressures of at least 10−3mm Hg. The furnace is assembled from readily obtainable equipment, and knife‐edge vacuum seals are used throughout. The uniform hot zone is approximately1932in. in diameter and 2 in. long. The power required for 1400°C, the maximum safe operating temperature, is about 1 kw; at this temperature the pressure is ∼10−8mm Hg. This furnace is suitable for electrical conduction studies as well as for heat treatment, etc.

ISSN:0034-6748    

DOI:10.1063/1.1716954

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The problem of determining the distribution of path lengths of an isotropic flux of particles passing through a cylinder is solved analytically. The distribution function is shown graphically for cylinders of various height‐to‐diameter ratios and the mean path length is calculated in each case. The distribution function for some special cases of shielded cylinders also is discussed.

ISSN:0034-6748    

DOI:10.1063/1.1716955

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

An electromechanical shutter is described which will open and close a 20‐&mgr; spectrograph slit in 5 &mgr;sec after a delay of 20 &mgr;sec. The shutter incorporates a movable slit which is propelled across the stationary spectrograph slit by the thermal expansion of a Joule‐heated hairpin‐shaped Nichrome wire.

ISSN:0034-6748    

DOI:10.1063/1.1716956

出版商:AIP    

年代:1960

数据来源: AIP

摘要:

The performance of a windowless resistance strip magnetic multiplier for detection of extreme ultraviolet is described. The detector is characterized by a high spectral sensitivity for wavelengths below 1400 A and a low sensitivity to longer wavelength radiation. It is reproducible in spectral response and gain after exposure to air or after cleaning. A current gain of 108can be realized with the multiplier for an over‐all voltage of approximately 2000 v. The photomultiplier can be operated as a photoelectron counter with a well‐defined counting plateau for pressures below 10−4mm Hg. The background counting rate of the detector, at room temperature and typical operation in the plateau region, is less than 0.1 count/sec.

ISSN:0034-6748    

DOI:10.1063/1.1716957

出版商:AIP    

年代:1960

数据来源: AIP