摘要:

The vibrating‐coil magnetometer measures the magnetization of a small sample of magnetic material placed in an external magnetizing field by converting the dipole field of the sample into an ac electrical signal. To allow space for temperature‐ or pressure‐generating apparatus around the sample, the measurement is made at distances up to 2 cm from the sample. The measurement is continuous and can be recorded on a chart as a function of time, temperature, crystallographic orientation, or magnetizing field. The present stable sensitivity is such as to provide one percent accuracy for a dipole moment of 8.56×10−4amp‐m2(the saturation moment at room temperature of a nickel sphere 1.5 mm in diameter).

ISSN:0034-6748    

DOI:10.1063/1.1715538

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The response function of NaI(Tl) scintillation detectors for gamma radiation has been calculated by the Monte Carlo method. Summary results of this calculation are presented in terms of the photofraction, i.e., the ratio of the area under the photopeak to the total area of a scintillation spectrum. Values of the photofraction are given for collimated monoenergetic radiation with energies between 0.279 and 4.45 Mev incident centrally on the endface of cylindrical crystals ranging in size from 0.25 in. (radius)×0.5 in. (length) to 2.5×9 in.

ISSN:0034-6748    

DOI:10.1063/1.1715539

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A magnetic vacuum valve is described which isolates a vacuum system from its mechanical pump should a power failure occur. Also, during the isolation process, air is let into the backing pump. The valve is characterized by low cost, low power consumption, simplicity, and reliability of operation.

ISSN:0034-6748    

DOI:10.1063/1.1715540

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A cloud chamber is described which measures either the absolute or relative concentration of nuclei in an aerosol. Water droplets are condensed on aerosol particles in a small sample, and the resulting water droplets are photographed on 16‐mm film by flashtube illumination and then counted in a microprint reader. Two types of expansion cloud chambers were found to work satisfactorily: the volume‐defined and the pressure‐defined. The apparatus is completely automatic and will operate continuously on a one‐minute cycle. It can measure aerosol concentrations that range from 200 particles/cm3to 2×106particles/cm3.

ISSN:0034-6748    

DOI:10.1063/1.1715541

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

An electronic wattmeter has been constructed to give a pointer indication of the average product of two electrical signals in the audio‐frequency range. The frequency response is flat (±0.17 db) between 20 cps and 20 kc/sec.

ISSN:0034-6748    

DOI:10.1063/1.1715542

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A study has been made of the pulse heights obtained from &agr; particles in a gas scintillation counter using argon, krypton, and xenon. Measurements were made with an RCA‐6342 photomultiplier viewing the scintillations directly and also with the aid of a quaterphenyl wavelength shifter. Pulse heights from xenon were about 10 times as great as those from argon and 3.6 times those from krypton. The gain in pulse height with a wavelength shifter was about a factor of 15 for each gas. The rise time of the light pulses was of the order of one m&mgr;sec or less. Pulse height was found to be a linear function of energy for protons, deuterons, and helium ions in a xenon counter with a wavelength shifter. The pulse height was independent of the type of particle producing the scintillations and depended only on the energy lost in the counter.

ISSN:0034-6748    

DOI:10.1063/1.1715543

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A mercury selector switch designed for use in telemetering may be modified by using high‐frequency techniques to make a fast rise time pulse generator with high pulse repetition rates. The pulse rise times are less than 0.002 &mgr;sec at repetition rates in excess of 10 kc with peak pulse power of 50 watts.

ISSN:0034-6748    

DOI:10.1063/1.1715544

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

The quartz or glass sheathed cylindrical cathode probe of the conventional rf ion source has been eliminated. The conventional glass pad electron beam ``back stop'' has been replaced by nonfracturing porcelain. Commerical Pyrex pipe has been used in the construction of the glass thimble in which the plasma is formed, and the thimble sealed to the base with O‐ring pressure seals. The anode probe is removable for ease in cleaning. The source produces 300 &mgr;a of H+; it also produces 200 &mgr;a of He+, and at low operating gas pressures, usable amounts of He++, as large as a few tenths of a percent of the He+output.

ISSN:0034-6748    

DOI:10.1063/1.1715545

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A negative hydrogen ion source has been built which will yield from 25 to 30 &mgr;a of H−ions focused on a ¼‐inch diameter spot. This is accomplished by first producing positive ions in a magnetic ion source. These ions are extracted and accelerated by at most 17.5 kv. The ions then pass through an electron pickup capillary tube into the center of which the electron donating gas is introduced. The H−ions emerging from this tube are accelerated by an additional 20 to 30 kv while the emerging secondary electrons are electrostatically repelled. The negative ions are then focused by an electrostatic ``saddle field'' lens and magnetically analyzed. An Evapor‐ion pump is used to maintain the pressure in the ion source container less than 10−4mm Hg.

ISSN:0034-6748    

DOI:10.1063/1.1715546

出版商:AIP    

年代:1956

数据来源: AIP

摘要:

A simple sputtering apparatus that consistently deposits opaque films of nickel and the noble metals in 3 to 10 min has been made. The chamber is constructed from a standard Pyrex pipe reducer. By use of a large‐diameter aluminum rod as the cathode support and a hemispherical aluminum shell as a shield for the pump orifice and base plate, the glow discharge has been confined primarily to the volume between the cathode and the work stand. The efficiency of the coating unit has thereby been increased. Films of nickel, iridium, ruthenium, and osmium formed on glass or quartz substrates were very adherent and were not readily scratched with a steel scribe.

ISSN:0034-6748    

DOI:10.1063/1.1715547

出版商:AIP    

年代:1956

数据来源: AIP