摘要:

A new technique was developed to make magnetic observations of weakly magnetized materials under hydrostatic pressure up to 12 kilobars in a wide temperature range from liquid helium temperature up to 200°C. We have designed a special type of nonmagnetic pressure vessel in which the materials to be measured were pressurized. For measuring magnetization, the above pressure vessel was connected to a torsion pendulum and its deflection in a magnetic field was measured. For measuring the anisotropy of ferromagnetic crystals, the vessel was connected to an air‐jet supported magnetometer having an unbonded strain gauge detector and its torque moment in a uniform magnetic field was determined.

ISSN:0034-6748    

DOI:10.1063/1.1720668

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

An instrument is described that counts automatically according to size aerosol particles of certain specific chemical compositions. The technique employed depends on converting to current pulses the ions produced from airborne particles passing through the combustion zone of a flame. Because the amplitude of the current pulse resulting from an ionized particle passing through a flame is dependent on both the mass and the ionization potential of the particle, the FIPAPA can aid in submicron aerosol particle identification when used in combination with instruments employing other sensing zone types. By use of electronic pulse‐height circuits, these current pulses are subsequently counted in six ranges of magnitude. The minimum size particle detectable was found to be 0.15 &mgr; diam for KOH and 0.25 &mgr; diam for NaCl.

ISSN:0034-6748    

DOI:10.1063/1.1720669

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A new technique is described for constructing vapor cooled leads used to introduce electrical currents into liquid helium. Using this method, leads can be constructed to carry optimum currents ranging from low values (less than 100 A) to very high values (several thousand amperes). The current carrying elements are small (No. 38) silver‐plated copper wires woven into the shape of cylindrical tubes (i.e., electrostatic shielding). This fine division of the current carrying elements allows very good heat exchange with the helium boil‐off gas. Helium losses are approximately 2.71×10−3liter/h A for a pair of leads operating at the optimum current.

ISSN:0034-6748    

DOI:10.1063/1.1720670

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The intensity distribution and dimensions of the x‐ray tube focus can be recorded accurately and rapidly by scanning with a pair of molybdenum rod slits and a scintillation counter. Two methods were used: (1) the image‐forming slit mounted near the x‐ray tube remains fixed and the image is scanned with another slit mounted on the detector; (2) both slits and detector are translated as a unit across the focus. The vignetting was analyzed and can be made negligible in both methods. Magnification of the image is not possible with method (2), but it has the advantage of minimum vignetting and easier alignment.

ISSN:0034-6748    

DOI:10.1063/1.1720671

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The sensitivity of the Spicer‐Berglund retarding‐potential method for the determination of photoelectron energy distributions may be improved by an order of magnitude by a more effective cancellation of the capacitative component of the signal. A double modulation technique, in which energy distributions can be traced from saturated photocurrents of the order of 10−11A, is also described. This method can be employed to eliminate steady thermionic or photoelectric currents many orders of magnitude greater than that under investigation.

ISSN:0034-6748    

DOI:10.1063/1.1720672

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

The authors have developed an apparatus which will allow the measurement of internal friction with a precision of ±1.3% with data processing time a matter of seconds. The apparatus was designed for the range of 2–20 cps; however, the principle can readily be applied to a much broader frequency range.

ISSN:0034-6748    

DOI:10.1063/1.1720673

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A device is described for the repeated mechanical scanning of a very short section of magnetic recording tape. The tape section, in a shuttle‐like holder, is moved backwards and forwards in front of a play‐back head. To obtain a constant speed movement, the tape holder is made to follow the contour of a cardioid curve section cut along the periphery of a rotating disk. The length of the scanning stroke is determined by the depth of the cut. A synchronizing contact is provided so that by triggering and adjusting the sweep of a cathode‐ray oscilloscope a stationary display may be presented on the screen. Typical applications are described.

ISSN:0034-6748    

DOI:10.1063/1.1720674

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

A model magnet has been constructed to study the behavior of a large superconducting coil on an iron yoke at room temperature. The coil, wound with niobium stannide ribbon, has an average diameter of 40 cm, a maximum excitation of 5×105ampere‐turns, and a stored energy of 85 kJ. The superconductor carries the same current, 120 A, on the pole and yoke as it did when removed from all iron. Nylon spacers served as compression members of low thermal conductivity to support the 18 000 kg magnetic force.

ISSN:0034-6748    

DOI:10.1063/1.1720675

出版商:AIP    

年代:1967

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1720676

出版商:AIP    

年代:1967

数据来源: AIP

ISSN:0034-6748    

DOI:10.1063/1.1720677

出版商:AIP    

年代:1967

数据来源: AIP