Table of contents

The factors which determine the resolution and sensitivity of electron spectrometers are discussed. Various types of instruments commonly used in X-ray or ultraviolet photoelectron spectroscopy are reviewed, mainly from an electron-optical point of view. The influence of fringing fields and preretardation on resolution and sensitivity is considered. Three different schemes for monochromatizing the exciting X-radiation are compared.

An electronic system has been developed which generates two phase and harmonically related signals for use in gas laser frequency stabilization. One waveform is a square wave and the other a sine wave of variable phase, at one third of the square wave frequency. The sine wave has a harmonic content of less than 0.1% at the square wave frequency.

A technique is described which enables a vacuum cell containing an evaporated thin film of hygroscopic material to be opened and rotated inside an evacuated spectrometer. This allows the incident radiation to fall directly and obliquely on the specimen for reflection measurements without any intervening window. Satisfactory spectra have been obtained for films of LiCl.

A very simple moire technique is described which is easy to use and interpret, and yet capable of high accuracy. In addition to magnification checking, it can be used for location of self-conjugate planes and hence for focal plane location of objectives. Applications include optical testing and inspection and education.

A sine wave pump of constant amplitude and variable frequency is described. It is simple, inexpensive and portable, requiring a minimum of workshop facilities. The pump is used for respiratory measurements on human lungs.

A modified split Hopkinson bar has been developed for the measurement of dynamic stress-strain relationships at strain rates up to 10⁵ s^-1 and for true strains greater than 2.0. The normal input bar has been removed and a hardened projectile allowed to impact the specimen directly. Specimen strain is measured independently by measuring the position of the back end of the projectile using a coaxial capacitor. A new circuit for measuring rapid capacitance changes is described.

A curve digitizing apparatus constructed from instruments available in the laboratory is described. A simple circuit has been designed to convert single channel digital recording systems to two channels for this application.

An evaporation technique is described for the preparation of thin-film superconducting weak links with a width smaller than 1 mu m and tunnel junctions with area smaller than 1 mu m*20 mu m. The technique utilizes two precision spheres for ball bearings with diameter 390+or-1 mu m. The spheres are ground and polished to hemispheres and placed in a mechanical arrangement in such a way that it is possible to place them less than 1 mu m apart on a glass substrate. The evaporation takes place between the two hemispheres on the glass substrate. Examples of (I,V) characteristics and the influence of microwaves are shown.

A simple inexpensive photon collecting system for cathodoluminescent operation of the JSM 2 scanning electron microscope has been designed for application to biological specimens. Cathodoluminescence from skin and tissue culture callus is demonstrated.

A vacuum furnace with a temperature control unit was constructed to make Bragg intensity measurements on large samples with small thermal gradients. The heating of the sample is by irradiation, and the temperature can be varied from room temperature to 10³K at present, being controlled to within 0.2 K. Thermal expansion of copper was studied for calibration purposes and the results were found to be in a good agreement with the standard values.

An electrostatic mirror consisting of a cylindrically symmetric three-electrode system is described. The electric field is solved and the electron trajectories are determined. The effective vertex and radius of curvature are determined for various values of the electrode potentials. This mirror system is the type used in the prism-mirror-prism electron energy filter.

A simple flashlamp that produces light pulses of about 15 ns decay time and 10¹¹ photons per flash has been developed. It can work at frequencies up to 5 kHz. By using different gases in the spark chamber a wide range of wavelengths is obtained. It is stable for several hours and is very suitable for use with signal averaging techniques.

A demountable thermostat jacket of small volume, suitable for use with rigid coaxial lines, is described. The jacket does not impede assembly or disassembly of the line when mounted, and so is well suited for use in time domain spectrometry.

A scanning attachment for a transmission electron microscope is used to investigate domain structures in thin ferromagnetic films. Contrast mechanisms similar to those employed in the transmission microscope are demonstrated and a brief comparison of the techniques is made.

Describes the design and construction of a package of X-ray telescopes launched in the NASA satellite Copernicus (OAO-3), which began stellar observations in September 1972. It contains three grazing incidence reflectors covering a range of wavelengths from 0.3 to 8 nm, and having a combined collecting area of 40.9 cm², with angular resolutions up to 1 minute of arc. This is believed to be the first satellite application of such reflectors in stellar X-ray astronomy. A collimated detector of wavelengths 0.1-0.3 nm has a 17.8 cm² collecting area. A visible light star tracker detects package misalignment if this should occur.

For the measurement of the frequency response of photodetector system, a light modulator consisting of a Michelson interferometer with a vibrating mirror has been developed. The mirror is displaced by an ultrasonic vibrator which is capable of a peak speed of 42 m s^-1, vibrating at 55 kHz, and has a mechanical quality factor of 1.4*10⁴. Using the red light of a helium-neon laser, the peak frequency of modulation is 133 MHz. Results of a typical measurement of frequency response are given.

The design and construction of a polarization analysis instrument for use with long wavelength neutrons is described. LONGPOL uses the partially polarized neutron beam, obtained on transmission through iron filters, to separate spin-flip from nonspin-flip scattering processes. Experiments can be performed between 4.2 and 300 K using 0.36 nm neutrons with a polarization of 33 %.

A theoretical analysis and experimental measurements of spin-flip and nonspin-flip neutron scattering from nuclear spin and magnetic systems are described. The suitability of polycrystalline iron as a polarization filter for long wavelength neutrons has been tested using the double transmission effect TD. This effect has been measured as a function of neutron wavelength and at different thicknesses of iron filters. For neutrons with a wavelength of 0.36 nm and for an iron thickness of 6 mm, for which depolarization of the neutron beam is small, TD is about 22 % corresponding to a neutron polarization of 33 %.

The nuclear spin scattering from samples of vanadium and hydrogen in water measured at 0.36 nm is found to occur as 2/3 spin-flip and 1/3 nonspin-flip in agreement with the theory. The paramagnetic scattering from MnO, MnF2 and 5 at. % Cu-Mn has also been measured at 0.36 nm, and it is found that for MnO and MnF₂ not all of the magnetic scattering is observed as spin-flip scattering. This is explained by the inelasticity of 0.36 nm neutron scattering from these systems with critical temperatures 122 K and 77 K respectively. Good agreement between measured and calculated values of spin-flip and nonspin-flip cross sections is obtained for scattering from the Cu-Mn specimen with a critical temperature of the order of 10-20 K.

A time-of-flight mass-spectrometer system has been developed to analyse and time-resolve the events in the afterglow of pulsed gas discharges similar to those used in CO₂ and N₂O lasers. The gases in the discharge tube are sampled through a pinhole into a two-chamber vacuum system using molecular beam techniques to avoid collisions. Signal averaging was carried out for up to 512 pulses to improve the signal-to-noise ratio of the mass-peak waveform. The technique is applicable to the monitoring and elucidation of collisional processes with time constants between 200 μs and 500 ms, the time resolution being limited by the range of particle velocities in the beam.

This paper discusses the phenomenon of moving striations in gas laser discharges and reports on an experimental study of frequency spectra of the discharge current and laser power output for hot and cold cathode laser tubes.

A positive-displacement dry meter has been designed to meet the special needs of gas calorimetry. The mechanical design, operational features and method of calibration are described.

A detector composed of wheels wound with resistance wire rolls along the contour of a metallic die plate, and the instantaneous gradient of the curve is continuously detected. A recorder simultaneously draws a curve similar to the contour on horizontal recording paper.

It is shown that a Michelson type interferometer, where one arm includes the vibrating surface, can be used for the analysis of the vibration. There are no requirements about the optical quality of the surface, as the principle of the operation requires only diffuse reflection and not a specular one. The system utilizes the Doppler shift due to surface motion, and the frequency structure of the reflected light is obtained from the spectrum of the photocurrent of the detector. This spectrum contains the information about the frequency and amplitude of the vibration.

Disturbances to the resonant ion motion caused by the ionizing electron beam and by the nonresonant ions present may be reduced by a separation in time of the ionization and the ion accelerating processes. This pulsed operation allows for an increasing sensitivity at low pressure by raising the ionization current up to 100 μA. A theoretical model is developed to calculate the maximum ionization current at high pressure. The calculated maximum electron current is inversely proportional to the total pressure, which is in agreement with the experiments. Comparative measurements between the pulsed mode and the stationary mode operation are given. Besides the increasing sensitivity, there is an improvement of the linearity and the resolution.