摘要:

The advisability of calibrating only carefully selected thermometers is emphasized. The relation between calibration point spacing and the weighting method used in curve fitting the calibration is discussed and then illustrated by various fits to different data sets for a particular germanium thermometer. Apart from different end effects, which could be minimized by a higher density of points at each end of the range, there is little significant difference between the results of the various methods tried.

ISSN:0034-6748    

DOI:10.1063/1.1134283

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An improved analysis of continuous wave (cw) NMR detection by Q‐meters is presented which explicitly includes parallel resistive loading of the sample coil and frequency dependent losses caused by the rf skin effect. A versatile MOSFET Q‐meter is described which operates at frequencies up to 60 MHz and rf input levels between 2 and 100 mV peak‐to‐peak. The noise figure is shown to be less than 3 dB at 8 MHz and a 7 mV peak‐to‐peak rf level. A comparison of Q‐meters with other types of cw NMR detectors is given, and their advantages for accurate line‐shape and susceptibility experiments are discussed.

ISSN:0034-6748    

DOI:10.1063/1.1134284

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A new quartz laser tube, which can operate at 1000°C for metal vapors, has been built. The tube was operated in a three‐zone oven, with the Brewster windows at a slightly higher temperature than the main laser body. Thus, a buffer gas was not necessary to prevent condensation of the metal on the windows. A technique for fusing the quartz windows to the quartz tube, without degrading the optical flatness, has been developed. Molybdenum ribbons fused into quartz cylinders provide vacuum‐tight electrode connections.

ISSN:0034-6748    

DOI:10.1063/1.1134285

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A high pressure microcalorimeter based on the differential scanning calorimeter (DSC) principle is described. In the present investigation this device was used for the determination of heats of transformation at pressures up to 2200 bar. The procedure for calibrating this apparatus is discussed. The temperature accuracy is considered to be ± 1 K in the range from −20 ° to +200 °C and to be about ± 5% for the determination of heats of transformation.

ISSN:0034-6748    

DOI:10.1063/1.1134286

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An alumina‐filled casting epoxy (trade name Stycast) was found to reliably seal to thin stainless steel edges and 1 mm diam stainless steel feedthrough pins. All seals retained their integrity after typically 50 cycles from −196 ° to 20 °C and 10 cycles from −196 ° to +100 °C. Several chambers were constructed using the epoxy both as a vacuum‐tight wall and as an electrical insulator for a large number of multi‐kV feedthroughs. The largest of these was 18 cm in diameter and contained 125 feedthrough pins. The chambers were immersed in a Freon‐11 bath at −105 °C, filled with liquid xenon, and tested for the presence of electronegative impurities. After degassing, the contamination levels measured were slightly higher than those we commonly observe for chambers constructed only of glass and metal.

ISSN:0034-6748    

DOI:10.1063/1.1134287

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A passive dosimetric technique was used which maps electron current density with a spatial resolution of 0.013 cm at 300 keV. Electron divergence and emittance angles are distinguished and can be mapped at any point in an intense electron beam with an accuracy of 10%. The technique applies to beams of up to 50 kA/cm2and 100 keV–3 MeV.

ISSN:0034-6748    

DOI:10.1063/1.1134288

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A spectrometer for making absolute absorption measurements is described. The system is especially suitable for work with solid state samples at low temperatures. Both sample and reference beams pass through the same set of Dewar windows, making compensation for the losses in these unnecessary. Simplicity and low cost are achieved by using a chopper wheel of special configuration rather than the usual rotating mirror. Direct measurement of optical densities as high as 4.0 is possible.

ISSN:0034-6748    

DOI:10.1063/1.1134289

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A simple, inexpensive device for long term solvent extractions of highly reactive compounds with low boiling solvents and gases is described.

ISSN:0034-6748    

DOI:10.1063/1.1134279

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The fabrication of highly characterized DT‐filled, hollow glass microsphere targets is described. The DT is loaded by gas permeation through the glass walls at 420 °C. The DT fill is nondestructively measured by counting the emitted x rays with a proportional counter. The counter system is empirically calibrated by individually crushing microspheres in an ionization chamber. Outer diameters are measured optically with a split‐image eyepiece. Wall thicknesses and sphericities are measured by light interference. For a 40‐&mgr; diam microsphere and 1‐&mgr; walls, we estimate our best absolute accuracies of measurement to be, o.d., ±1.6%; wall thickness at any point, ±10%; overall microsphere sphericity, ±7%.

ISSN:0034-6748    

DOI:10.1063/1.1134280

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

With the advent of high speed computers, the digital processing of data became a common practice among many researchers. The recent trend among geophysical researchers has been to establish their own computer system by use of a minicomputer rather than time sharing of a larger system. In developing such a system, a question arises as to how reliable is the newly acquired computer system. A method of evaluating the performance of such a computer system is presented. The method consists of processing data of known characteristics and comparing the results. The quantities calculated include probability densities, higher order moments, spectra, cross spectra, and a coherency spectrum.

ISSN:0034-6748    

DOI:10.1063/1.1134281

出版商:AIP    

年代:1975

数据来源: AIP