摘要:

A simple particle analyzer has been developed using a modified high speed flow‐through technique and absorption measurements of a continuous He–Ne laser beam. From pulse‐shape analysis and the integration of absorption pulses, size distributions of stained or unstained cells can be derived. The range of 5–300 &mgr; is covered without changing the flow system and a rate up to 200 000/sec can be achieved. Typical applications in cell analyses are shown.

ISSN:0034-6748    

DOI:10.1063/1.1134399

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Equipment is described for electrical measurements under hydrostatic pressures to 30 kilobar over the low to room temperature range. The piston and cylinder type pressure vessel of the high‐pressure cryostat is actuated directly by a hydraulic ram at room temperature. Thermal isolation is achieved through use of long tension and compression members. Details about the self‐stressing, double‐walled cylinder are provided. Both the Bi I–II transition and an n–InSb manometer have been used for pressure calibration.

ISSN:0034-6748    

DOI:10.1063/1.1134400

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A low‐impedance coaxial feedthrough has been developed for nanosecond‐pulsed high electric field investigations to 20 kilobar. This feedthrough is compatible with stripline conductors and has been used at low and room temperatures.

ISSN:0034-6748    

DOI:10.1063/1.1134401

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A digital counting circuit is described that generates output pulses at intervals geometrically increasing at a rate proportional to the elapsed time, thus making it suitable as a logarithmic time base generator. The design procedure to deliver any number of pulses per decade of time and for any number of decades of time is discussed, and a prototype giving 37 pulses per decade of time with an accuracy of ± 0.5% of the output per decade is described. The unit is capable of starting at 1 &mgr;sec and has an analog output covering approximately seven decades with a range of (0–10) V.

ISSN:0034-6748    

DOI:10.1063/1.1134385

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A simplified method for determining the mass‐to‐charge ratio of single pulse‐field evaporated atoms in a time‐of‐flight (TOF), atom‐probe, field‐ion microscpoe (FIM) is described. The method is rather insensitive to the value of the pulse factor (&agr;). This is achieved physically by making the pulse voltage a constant small fraction (f) of the steady‐state imaging voltage, wherefis much less than unity and is as small as possible to maximize the mass resolution. Examples of the W+3and W+4spectra of specimens pulse‐field evaporated at ∼25 K in a background vacuum of 6×10−10Torr are presented. The W+3spectrum exhibited very clearly the five naturally occurring isotopes (180W,182W,183W,184W, and186W) with isotopic abundances that are in good agreement with the handbook values. The value of &agr; chosen has only a very minor effect on the exact shape of the W+3and W+4spectra. The ratio of W+4events to the total number of events (W+3and W+4) is 0.17 for the (551) plane.

ISSN:0034-6748    

DOI:10.1063/1.1134386

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A simple, on‐line treatment chamber for surface studies using a knife‐edge sealing construction is described. In it samples can be treated with gases up to a pressure of 1 bar and up to a temperature of 600 °C at a leak conductance of about 10−8liter/sec to the ultrahigh vacuum analyzing chamber.

ISSN:0034-6748    

DOI:10.1063/1.1134387

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An electronic system was developed for coincidence measurements in the presence of a high level of accidental coincidences, assuming the true coincidence rate is constant. This system eliminates the distortions produced by the use of two independent coincidence modules for measuring accidental coincidencesnaand the sum of accidental and real coincidencesns. The two quantities are measured by the same coincidence module during successive periods of 40 msec. The system was tested under conditions such that the accidental coincidence counts exceeded the number of real coincidences by a factor of 102. The accuracy of the measurement of real coincidences was limited only by statistical fluctuations of accidental coincidences.

ISSN:0034-6748    

DOI:10.1063/1.1134388

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A method of coarse alignment and fine tuning of the cavity of a gas laser is presented. The laser cavity to be aligned is treated as a Fabry–Perot cavity, and its transmission of a frequency‐swept laser is maximized. An experiment is described showing that this fine‐tuning procedure results in maximum power output when the laser is operated. The method is particularly well‐suited to laser manufacturing.

ISSN:0034-6748    

DOI:10.1063/1.1134389

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A precision isoperibol calorimeter with automatic data acquisition and processing, capable of operating over a wide temperature range, has been constructed and tested. The calorimeter was designed to have a very low thermal modulus and fast equilibration time. A small vapor space above the liquid and a vapor trap make the calorimeter useful for measurements with nonaqueous solvents. Time–temperature data are automatically recorded in digital form on magnetic tape and processed on a Univac 1106 computer. A series of electrical calibrations causing a temperature rise of 0.13 K were reproducible to about 0.01%. Several determinations of the enthalpy of reaction of a standard sample of Tris (hydroxymethyl) aminomethane with 0.1NHCl gave an average value of 29.764±0.013 kJ/mol, which agrees satisfactorily with published results.

ISSN:0034-6748    

DOI:10.1063/1.1134390

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Current research directed towards establishing the use of laser Raman spectroscopy as an effective means of making rapid determinations of isotope abundance ratios in at least nitrogen, carbon, oxygen, and hydrogen has necessitated the construction of a spectrometer of unique capabilities. The instrument, an automated, photon‐counting Raman spectrometer contains as many state‐of‐the‐art components as is feasible. The spectrometer is described along with the automatic data retrieval system, which offers the unique capability of unlimited integration time while running unattended. A concrete example of its performance, the resolution of the Q branch of16O16O, is presented.

ISSN:0034-6748    

DOI:10.1063/1.1134391

出版商:AIP    

年代:1975

数据来源: AIP