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The amplitude distributions and time durations of current pulses in a parallel-plate electron multiplier (PPEM) are reported. The performances of the PPEM and the channel electron multiplier (CEM) are compared and the differences in behaviour are pointed out.

A vacuum apparatus suitable for measurements of conversion electron Mo¨ssbauer spectra at temperatures up to 1200 K is presented. The apparatus allows CEMS measurements and in situ heat treatment of the samples under ultra-high vacuum conditions. The detecting system is based on the channel electron multiplier used in a close-to-sample geometry. A special technique of suppressing the background due to thermally activated electrons and ions is described. Examples of measurements with a metallic iron foil above the Curie point and with crystals implanted with 57 Fe ions are given.

The wall current and the charge distribution of a continuous channel electron multiplier are studied between 20 and 100°C. The influence of gas desorption is minimized to find the electronic structure of the emissive layer. Conduction current is characterized by an activation energy temperature dependence while mean charge analysis leads to a saturation process based on electronic conduction in a glassy solid.

We report direct measurements of the sensitivity of a channel electron multiplier to electrons with different spin orientations. Four regions of the multiplier cone were examined using polarized electrons at 100‐eV incident energy. Pulse counting and analog modes of operation were both investigated and in each case the observed spin effects were less than 0.5%.

We have found the useful lifetime of the channel electron multiplier during prolonged counting at moderate count rates, to be determined soley by the counting rate and operating voltage, and in the absence of any changes in these, an asymptotic value of gain can be expected to be maintained indefinitely. Electronic sensitivity criteria have also been established.

Photoabsorption coefficients of molecular nitrogen have been obtained to +or-3% accuracy in the 380-700AA region using a synchrotron radiation source and channel electron multiplier photodetection. Broad structure in the continuum is clearly observed with an absorption maximum at 540AA and a shoulder at 430AA.

Beams of monoenergetic positrons with energies of a few eV to many keV have been used in experiments in atomic physics, solid state physics and materials science. The production of positron beams from a new source, an electron linac, is described.

The problems involved in the use of brems Strahlung isochromat spectroscopy (BIS) as a tool for probing the unoccupied electronic states of solids are briefly reviewed and some simple applications of this technique are discussed.

In the tail of the energy distribution of electrons emitted from solids bom barded by keV ions one can notice, in certain cases, Auger electrons from the filling of inner-shell (core) holes of target atoms.

Because of its good depth resolution and high sensitivity, SIMS is ideally suited for determining the depth distribution of sample constituents in the 0.1–10 μm depth range. The accuracy of measured depth distributions is generally limited by instrumental distortions [1]. A primary goal in SIMS instrument development, therefore, has been to eliminate such distortions by careful instrument design. The most recent advance in this direction is the Physical Electronics Model 6300 SIMS system. In this paper, the design and operation of this system is briefly described. An example of a depth profile of a B implant in Si is presented that demonstrates the performance of the instrument.

Ultraviolet spectrophotometry in the 100–3000 A region is an old, reliable, proven technique used repeatedly and systematically up to now to study the upper atmosphere of the earth and of other planets. Therein, ironically, lies one of the main problems in convincing the scientific community of the usefulness of performing uv spectrophotometry from Spacelab. Have we not done all this before? Should we not think of something really new and exciting to do for such a futuristic experiment as Spacelab? These are but a few of the understandable first reactions of many scientists to the proposal. A second drawback at first glance stems from the common belief that uv spectrophotometry is useful only for the study of the atmosphere above 120 km. altitude while emphasis in Spacelab planning has been on the region below that level. Consequently, it would seem a difficult task indeed to assign a role, if any, to the ultraviolet in the 1980’s.

This survey concentrates on recent developments not covered in the invited paper of Kauppila and Stein (1982), given at the 1981 Toronto Conference, and the recent review articles of Griffith (1979) and Griffith and Heyland (1978). Updated information on this topic can be found in the reports of these authors presented at the Arlington Conference last year (Stein and Kauppila, 1982; Griffith et al., 1982). Electron total cross section measurements were thoroughly reviewed by Bederson and Kieffer in 1971. Their discussion of systematic errors is still up-to-date and also pertinent to measurements with positrons. The advantages and limitations of time-of-flight (TOF) methods in scattering spectroscopy were reviewed by Raith (1976).

A study of vacuum re-emission of positrons from high electric field stressed a-SiO2 layers is proposed. Measurements of positron re-emission energies and efficiencies would be of interest in understanding positron transport at high electric fields as well as offering the possibility of producing intense (up to 109e+/sec) positron beams in the laboratory.

In this paper we review the present status of experiments that test quantum electrodynamics (QED) using the simple atoms of hydrogen (H), muonium (Mu), and positronium (Ps). Since the recent developments in QED theory are reviewed separately (see G. P. Lepage — these proceedings) we need only introduce the results of such calculations for clarity and completeness. Emphasis will be given to the experimental techniques employed, the most recent experimental results, and the outlook for future improvement in the measurements.

In this communication we describe the technique we are currently developing for the purpose of measuring the energy distribution of positronium formed by positron-gas scattering. Preliminary results are presented which demonstrate the tunability of our Ps beam.

Satellites of the resonance lines in helium-like B, C, N, and O and in hydrogenic F have been observed using the beam-foil source. Preliminary lifetime measurements indicate transition probabilities for such lines of the order of 1012sec−1, consistent with recent theory.

The following material first presents the operating principles of the electron multipliers and the channel electron multiplier and the operating characteristics of single multiplying channels, then describes some of the manufacturing techniques used to make these devices, and finally describes some of the imaging devices which can be made using channel multiplier techniques and how, by using these manufacturing techniques, one can produce bundles of individual channel multipliers which can be used in various types of imaging systems.

Many forms of photoelectronic devices employ a gain mechanism dependent upon multiplication of the energy of electrons forming the image, the number or flux density of electrons forming the image, or both.

The article summarizes some of the recent advances in the techniques of solar space research, particularly over the last 4 years, in an attempt to review the current state of instrument technology. The present state of development in rocket and satellite vehicles for solar observations, far ultraviolet detectors, optical materials, ultraviolet reflection coatings, filters, and photographic film fogging, are among the topics described.

The history of intensifies cannot be divorced from the history of the signal-generating or camera tube itself. Interest in this area began shortly after the formalization of electron optics in the 1920’s. Much of this early work had as its ultimate objective the application of electron imaging to the problem of increasing the sensitivity of television camera tubes. The first published articles on image tubes appeared in the middle 1930’s and included papers by Holst et al.,1 Bruche and Shaffernicht,2 Zworykin and Morton,3 Heimann,4 and others. The image tubes described were, in general, single-stage converter tubes employing S-1 semitransparent cathodes. Their sensitivity to near-infrared radiation was one of the features of interest at the time.

Publisher Summary This chapter analyzes low-level performance of channel multiplier arrays. A simulation has been made of a channel electron multiplier, using an IBM-360 Model 40 computer to investigate effects of operational parameters and surface properties. Two models have been studied: planar and cylindrical. The simplified two-dimensional planar model always assumed the trajectory to lie across the channel diameter in the transverse plane and was used to study effects not dependent on the third dimension. A full three-dimensional study of a cylindrical multiplier was also made for purposes of comparison with experiments and to study parameters affected by the third dimension. Calculations are made to find, for each electron, the length of the trajectory, arrival energy, arrival angle, and transit time. These quantities are needed as initial conditions for the next multiplying event. The results show that effects of channel voltage, varied from 800 to 2000 V. As channel voltage increases, trajectories become longer and strike angles become more grazing. Both effects increase gain significantly, and the number of primary electrons completely lost is definitely reduced. The negative trajectory lengths correspond to electrons emitted with high velocities in a direction opposite to the applied field.

The total and direct ionization cross-sections for positron impact on molecular nitrogen have been measured in the energy range from 5 eV to 850 eV. The results are compared with other experimental and theoretical determinations.

A Channel Electron Multiplier Array is a readout well suited to detect the low light output of small diameter scintillating fibers.

A channel electron multiplier that detects secondary electrons emitted from a thin carbon foil is the basis of a time pickoff system used for pulsed charged-particle beams in the MeV region. This system provides reliable timing reference signals for beams of a wide range of intensities.

The Mossbauer spectra of 77.3 keV γ-transition in 197Au have been measured for the first time in the conversion electron scattering mode, with the use of a channel electron multiplier at low temperatures. The high magnitude of the resonant effect obtained makes the investigations of various phenomena in very thin gold films feasible. The application of the technique in studying other high-energy Mossbauer transitions is also possible.

The movable Faraday cup assembly of the varian LEED optics system has been modified by the addition of a channel electron multiplier. Signal‐to‐noise was increased by several orders of magnitude, rendering the assembly suitable for the measurement of energy distributions of photoelectrons with an angular resolution as small as ±2°.

The initial results of absolute proton efficiency measurements made in an auroral particle study by sounding rockets are given. The measurements were made at several counting rates from 1000 to 40,000 counts/sec on rocket-borne equipment. The results agree with those of Egidi et al. (1969) in the high energy range and show a disagreement at low energies.

Delay time and gain for a Bendix 4028 Channeltron was studied during accelerated life tests. The results are presented along with a suggestion for delay compensation. Novel means for synchronous stimulation of the multiplier and for measurement of the output charge are presented.

A commercial quadrupole mass filter has been modified to accept a channel electron multiplier. The modification is relatively simple and inexpensive. The resulting mass filter is very sensitive (gain > 107) and compact.

A spiral type continuous channel multiplier was used for pulse counting heavy positive ions. The shape of the output pulses was studied. The pulse risetime was found to be very long and composed of numerous after‐pulsing as revealed by the ``staircase'' appearance of the pulse. As a consequence, the count rate capability is greatly hampered. Detection of the positive ions by a catcher foil and collection of the secondary electrons lead to a smooth pulse clean of any after‐pulsing and to a greatly improved count rate capability.

The effects of a longitudinal magnetic field on the performance of a channel electron multiplier are studied and the gain variation due to the magnetic field is explained by considering hopping and gyrating motion of electrons.

The possibility of using the channel electron multiplier in the analog continuous current mode is pointed out. By combining this mode with the usual pulse counting mode, one can extend the dynamic range of the channel multiplier over several decades.

Large-area electron multipliers have been made which have operated successfully in CRTs. These multipliers consist of a stack of perforated metal dynodes separated by insulators. The aspects of multiplier performance which are important for use in CRTs are the gain and its uniformity, the maximum output current available and the spatial resolution. The multipliers have a uniform, high gain and can provide an output current of more than 1.5 mA per channel. The spatial resolution is determined by the technology of multiplier construction which is based on dynodes whose manufacture is closely related to that of delta shadow masks.

The efficiency vs operation voltage characteristics of a channel electron multiplier (CEM) with a negative voltage applied to the entrance cone are investigated in detail. In this negative bias operation, an abnormal increase in efficiency with operation voltage is found, arising from two main mechanisms. One is the change in potential distribution in the cone with the applied voltage. This is because the probability of secondary electrons ejected from the cone being pulled into the channel depends on the potential distribution in the cone. The other is the ionization of particles by leakage electrons from the gap between the CEM exit and the electron collector. Methods of solving these problems are also described.

Considerable differences in the current gain have been found in a channel electron multiplier when used as a detector of 100 keV N1+ ions, depending on the point of impact at the channel entrance. These differences occur at high current gains which are usually considered near to saturation. In contrast to the current gain, the detection efficiency shows no significant variation with the point of impact, suggesting that at least one of the electrons from the primary interaction of the ion with the secondary surface is multiplied by the channel to provide a detectable pulse.

The paper describes a cathode-ray tube in which the scanning and light generating functions are separated by a large-area electron multiplier. The multiplier is scanned by a low-voltage, low-current electron beam. The amplified electron output from the multiplier is accelerated to the fluorescent screen to produce a bright display. Suitable electron multipliers have been made and tested in a specially designed magnetically scanned CRT. The approach allows much more freedom in cathode-ray tube design and some examples of the advantages to be gained are described.