摘要:

A3He&sngbnd;4He dilution refrigerator has been used to cool a 32 g polycrystalline cobalt rod to 0.034 K. The rod is held in a longitudinal magnetic field of 6.5 kOe and has a nuclear polarization of 0.38. The cobalt piece will be used to study the scattering of polarized and unpolarized fast neutrons from polarized59Co.

ISSN:0034-6748    

DOI:10.1063/1.1684618

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A solid state switch for use in spark chamber pulsing systems has been developed which permits delaying the recharging of the spark chamber driving capacitor and thus allows high charging current and rapid recycling. This system has been tested in a recent Bevatron experiment at the Lawrence Radiation Laboratory.

ISSN:0034-6748    

DOI:10.1063/1.1684619

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A tantalum hollow cathode used in an argon ion laser as an electron emitter for large currents is described. If the emitter is used in combination with an auxiliary anode, which serves as a starting electrode and as an evaporation shield, we found this cathode a good choice especially for large currents in excess of 100 A.

ISSN:0034-6748    

DOI:10.1063/1.1684620

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

We have compared with good precision between 1.5 and 20 K the specific heat of two well characterized copper samples with residual resistivity ratioR(293 K)/R(4 K) of approximately 2000 (Calorimetry Conference, Argonne National Laboratories) and 30 000 (National Bureau of Standards, Boulder), and find that the electronic specific heat of the former is about 1% higher in the range 1.5–5 K, although the Debye temperatures are the same. The total specific heat of the former is up to 0.8% higher throughout the 1.5–20 K range. This discrepancy indicates that the specific heat may depend on the residual resistivity ratio. The germanium thermometer used in the measurements was calibrated against the National Bureau of Standards acoustic temperature scaleT65, and so a test has been made of the smoothness of that scale.

ISSN:0034-6748    

DOI:10.1063/1.1684621

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Simplified construction of an He&sngbnd;Cd laser is described where the quartz tube containing the cadmium vapor is made separately. The quartz tube is dosed with cadmium before sealing into the Pyrex envelope. Tube processing using a flow‐through technique is described.

ISSN:0034-6748    

DOI:10.1063/1.1684622

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The RSM can be used to detect magnetic moment (vM≥5×10−6emu), rotational hysteresis (vWR/H≥10−2emu), spin flop (vM≥5×10−5emu), and properties related to anisotropy energy [vK/H, v(&khgr;⊥−&khgr;∥)HandvMx≥5×10−6emu], i.e., anisotropy constants, anisotropic susceptibility, and anisotropic spontaneous magnetization. Samples are either symmetric about, or offset from, an axis of rotation which is set parallel or perpendicular to an applied dc field. Coils are oriented to sense magnetization along or normal to the field axis. For measuring specific parameters, a phase sensitive detector, an electronic integrator, or an oscilloscope is employed. Detailed expressions relating magnetic properties and signal output are presented, along with illustrative experimental results.

ISSN:0034-6748    

DOI:10.1063/1.1684623

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

The design procedure and the experimental details are given for the construction of a magnetic deflection system which has been used in an electron beam spectrometer to measure the angular distribution of the energy loss spectra of thin solid films. A collimated electron beam is deflected in such a way that it is incident on the specimen at the angle of scatter at which measurements are required. Electrons which emerge normally from the far side of the specimen are then momentum analyzed. The deflection was found to be proportional to current up to an angle of at least 0.04 rad.

ISSN:0034-6748    

DOI:10.1063/1.1684624

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

A 5–100 kHz square wave voltage of amplitude variable between 100–2000 V p‐p is generated by the described instrument. Capacitive loads of up to 300 pF can be driven at the highest voltage and frequency of operation. Modulation is provided to enable subsequent synchronous detection. A fast response shutoff circuit protects against overloads and accidental shorts.

ISSN:0034-6748    

DOI:10.1063/1.1684625

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

By use of a capacitance diaphragm manometer operated at low temperatures, it is possible to measure the vapor pressure of cryogenic liquids without the uncertainties introduced by thermomolecular pressure gradients (thermal transpiration). Since the zero of this manometer is more stable at low temperature than at room temperature, useful sensitivity is increased. Because of the increased sensitivity at low pressure as well as great convenience and simplicity, this technique appears to have wide application in precise vapor pressure thermometry and similar work.

ISSN:0034-6748    

DOI:10.1063/1.1684626

出版商:AIP    

年代:1970

数据来源: AIP

摘要:

Pyrophyllite, a mineral used for high pressure gasketing, exhibits wide sample‐to‐sample variations in density and in mechanical properties. Samples of varied initial densities, after compressions to uniform density, are found to have uniform mechanical properties in subsequent use. Large improvements in work hardening response of tungsten carbide anvils are obtained through use of precompressed pyrophyllite gaskets.

ISSN:0034-6748    

DOI:10.1063/1.1684627

出版商:AIP    

年代:1970

数据来源: AIP