摘要:

A slow neutron spectrometer that uses a rotating single crystal to chop and monochromate the reactor neutron beam is described. A high transmission mechanical chopper is operated in phase with the rotating crystal to eliminate undesired crystal reflections, higher order contamination, and to suppress the background of time uncorrelated neutrons. Pulsed neutron beams of high quality can be obtained from the thermal energy range to greater than 0.5 eV. Energy widths as low as 1% with burst widths around 7 &mgr;sec can be attained at 0.3 eV. Intensities are adequate for inelastic scattering studies. The spectrometer is designed primarily for downscattering measurements. Scattering measurements are conducted in a completely shielded scattering chamber with eleven scattered neutron detectors arranged at scattering angles of 15° to 165°. Time of flight techniques are used to determine the scattered neutron spectra. The design, construction, and performance characteristics are given. Some representative measurements made on zirconium hydride are presented.

ISSN:0034-6748    

DOI:10.1063/1.1720299

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A surface ionization source using spherical powder porous tungsten generates up to 9 mA of cesium ions with only a few percent of neutral atoms.

ISSN:0034-6748    

DOI:10.1063/1.1720300

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

Apparatus for the photoelastic study of propagating stress waves by a repetitive stroboscopic technique has been developed in a form suitable for seismic modelling. Using a 30 cps repetition rate the transient waves propagate forward or backward or are ``locked'' in position on the viewing screen at the control of the operator. An impact device capable of very brief contact time (1 msec) and high source strains (⅓ cm penetration) produces a very brief but intense mechanical transient. This impacter, coupled with the large size of the models used (46 cm square), permits wave propagation to be studied over a significant length of travel path, suitable for certain seismic propagation problems. Isochromatics and isoclinics of propagating waves are shown.

ISSN:0034-6748    

DOI:10.1063/1.1720301

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

What is effectively a single tube adaptation of the quasistatic method of measuring vapor pressure has been devised. The method is suitable for use in an inert atmosphere box in studying air sensitive systems. The applicability and limits of operation of the technique are described. Precision and accuracy were checked against a known system, pure sodium.

ISSN:0034-6748    

DOI:10.1063/1.1720302

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A transistorized Wheatstone bridge suitable for precise current or resistance measurements is described. The bridge is inexpensive, compact, and versatile, and was used for measuring hydrogen atom populations by the recombination wire probe method.

ISSN:0034-6748    

DOI:10.1063/1.1720303

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A simple Omegatron mass analyzer used for measuring density and temperature of nitrogen in the 100 to 350 km region of the upper atmosphere has been developed. The mechanical and electrical configurations have been designed for rocket flight application, and the operating parameters optimized for the upper atmosphere measurement. This Omegatron is calibrated and flown as part of a sounding rocket experiment known as the Thermosphere Probe, which also contains an electron temperature probe for determining electron temperature and density. Several successful flights have shown that the Omegatron is a reliable device for this application.

ISSN:0034-6748    

DOI:10.1063/1.1720304

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

The construction of a glass cell with rectangular cross section for measuring Hall coefficients of liquids is described. The cell can be hermetically sealed and is bakeable under vacuum. Probes for the detection of the Hall voltage have been accurately aligned by alternately grinding the holes through the cell wall and measuring their misalignment. In this way, it has been possible to reduce the misalignment of the voltage probes to half a micron or less.

ISSN:0034-6748    

DOI:10.1063/1.1720305

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A circuit is described for driving the abscissa of an X‐Y recorder as the inverse of the magnetic field (H−1) of a superconducting solenoid. The output is independent of the sweep rate for any sweep within the range of the instrument and the error in the resultant plot is less than 0.5% of full scale for any 10 kG sweep of the magnet.

ISSN:0034-6748    

DOI:10.1063/1.1720306

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

An improved system for plotting spin wave instability threshold data is described. The system combines analog and digital techniques and eliminates many of the drawbacks of a method previously described by the author [Rev. Sci. Instr.35, 558 (1964)].

ISSN:0034-6748    

DOI:10.1063/1.1720307

出版商:AIP    

年代:1966

数据来源: AIP

摘要:

A cryostat is described which is capable of somewhat lower operating temperatures than has previously been possible. This improvement has been achieved through the use of a pumping line to the3He which is of larger than normal diameter, particularly at the low temperature end. Therefore, it is concluded that the major limitation in previous designs has been the pressure drop in the pumping line.

ISSN:0034-6748    

DOI:10.1063/1.1720308

出版商:AIP    

年代:1966

数据来源: AIP