摘要:

A supersonic mercury vapor jet has been developed for use in stripping electrons from a beam of heavy ions. The required surface densities (2 to 20 &mgr;g/cm2) were obtained with the apparatus described. The increase in pressure caused by the jet was less than 3×10−7mm Hg at the end of a 10‐in. beam tube.

ISSN:0034-6748    

DOI:10.1063/1.1715842

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A liquid propane chamber 3.25 by 6.5 by 13 in., operating in a magnetic field of 22 000 gauss, is described. A simple compact dark‐field type of illumination is used; this is discussed. For personnel and equipment safety a secondary pressure vessel is incorporated in the design. Special reference is given to some of the construction and design problems.A brief summary of the operation of the propane chamber in the 6.2‐Bev neutron beam is given.

ISSN:0034-6748    

DOI:10.1063/1.1715843

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The energy of an electrostatic accelerator is modulated over a range of 50 kev by applying an alternating potential of 50‐kv amplitude to an insulated target at a frequency of 10 cps. A sample of the modulating voltage and the signals from a nuclear detector are fed to a so‐called ``function sampler,'' which furnishes an output pulse whose height is proportional to the instantaneous value of the target voltage. Analysis of the pulse‐height spectrum by means of a 100‐channel analyzer then affords a presentation of the spectrum of nuclear events as a function of accelerator energy over a 50‐kev range, each channel of the analyzer corresponding to an energy width of 500 ev. Advantages of this system are discussed for high resolution work with an electrostatic accelerator.

ISSN:0034-6748    

DOI:10.1063/1.1715844

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A system is described for measuring high resolution (e.g., 1 kev) total neutron cross sections at high counting rate in the range above 50‐kev neutron energy using as a neutron detector a thick proton recoil detector. The pulsed‐beam time‐of‐flight technique is used to identify the neutrons of interest, which are produced in the target of an electrostatic accelerator. Energy modulation of the accelerator makes it possible to make observations at 100 energy points simultaneously. Illustrative results are given on the 585‐kev resonance in sulfur and on aluminum in the neighborhood of 585 kev. The gain in speed of taking data over conventional systems is greater than a factor of 100.

ISSN:0034-6748    

DOI:10.1063/1.1715845

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The properties of a thermometer based upon the temperature variation of the pure quadrupole resonance frequency (&ngr;0) of the Cl35nucleus in granular KClO3have been investigated. In the range ∼10°K<T<300°K, the thermometer has a very high sensitivity, being better than ±0.002° at 273°K and ±0.004° at 77°K. The accuracy at 20°K is estimated as at least ±0.02°. The thermometer is exactly reproducible if care is taken that the KClO3is of high chemical purity. No hysteresis effects were observed. Establishment of the thermometer requires a single precise determination of the &ngr;0versustemperature curve using the fundamental temperature standards to measure the temperature.

ISSN:0034-6748    

DOI:10.1063/1.1715846

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

Single crystal ``bridges'' of suitably doped germanium have been encased in a strain‐free manner within nonmagnetic platinum‐glass capsules to provide resistance thermometers with desirable low‐temperature electrical properties. The stability of the resistance of these thermometers with repeated cycling between room temperature and liquid helium temperatures and their relatively constant sensitivity (percent change in resistance per percent change in temperature) between 2 and 35°K for a wide range of resistivities are improvements over existing thermometers for this temperature range. Thermometers of this type are believed to be suitable for the most precise measurements, such as calorimetry, and are being further investigated.

ISSN:0034-6748    

DOI:10.1063/1.1715847

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

A principle of measurement of magnetization is described which uses a sample in a uniform magnetic field such that the sample does not affect the uniformity of the field and the sample itself is uniformly magnetized. The measurement is absolute in that it requires only a measurement of a current and dimensions. The method uses a cylindrical specimen on which a small pitch fine wire coil is wound. The proper current through the coil required to restore the uniformity of the field in all space gives a direct measurement of the magnetization. Uniformity of the field is detected by an induction technique. The method is suitable for most magnetic measurements but in the case of strongly ferromagnetic materials and superconductors requires currents in the coil that are too large. This principle has been incorporated in an apparatus for measurements of magnetizations from liquid helium temperatures to room temperature.

ISSN:0034-6748    

DOI:10.1063/1.1715848

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The original method of Stevenson has been used to develop an apparatus capable of yielding high precision for the drift velocities of electrons moving in an electric field. Measurements have been made of the electron drift velocity in argon, nitrogen, methane, carbon dioxide, ethylene, cyclopropane, and a few mixtures of some of these gases. The results for argon and nitrogen agree with those of Nielsen.

ISSN:0034-6748    

DOI:10.1063/1.1715825

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

The Geodimeter has been analyzed as to limitations on its precision in range measurement imposed by uncertainties in the velocity of propagation of light in the atmosphere. The instrument has been found elsewhere to be somewhat more consistent than the best current value of the velocity of lightin vacuo, that is, to about one part in 3 million. On the basis of the analysis reported here, routine measurements to one part in 106are concluded to be warranted, as far as propagational errors are concerned, up to ranges of about 100 km. Higher precisions, up to 1 in 107, are concluded to be attainable.

ISSN:0034-6748    

DOI:10.1063/1.1715826

出版商:AIP    

年代:1957

数据来源: AIP

摘要:

An electronic gate circuit is described which has better than 1% linearity for pulses in the range 1 to 70 volts. The circuit gives an inverted output with a gain very close to unity and accepts positive inputs. The leakage of a 70‐volt pulse through the closed gate is 0.6 volt and the largest negative going portion of the gating transient is 0.2 volt. The gate can be reliably opened with positive trigger pulses in the range 4 to 9 volts and the time jitter over this range is the same as the rise time of the trigger pulses. The inherent rise time of the gate output is about 50 millimicroseconds.

ISSN:0034-6748    

DOI:10.1063/1.1715827

出版商:AIP    

年代:1957

数据来源: AIP