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The IBEX Background Monitor (IBaM) provides a small and lightweight method for independently measuring IBEX’s high-energy proton background by integrating the flux of >∼14 keV protons over a ∼7° conical FOV. The IBaM is part of the IBEX-Hi sensor and has a co-aligned look direction. This paper describes the principle of the IBaM and details its design and responses. In particular, we show the response of major components to both ions and ultraviolet (UV) light background. We also provide the geometric factor and calculate expected count rates.

The channel electron multiplier (CEM) current flicker noise was examined for different parameters of its operation. In particular, the dependence of CEM power spectral density function on its output current value has been verified. Also the dependence of the CEM power spectral density function on the input electron energy was investigated.

The spectral density function of the channel electron multiplier noise has been investigated. The existence of flicker noise ( 1/f α ) has been shown. Changes of the exponent α versus the multiplier current have been observed and the relationship between them has been established.

We have constructed ion optics which, when interfaced with a channel electron multiplier (CEM), make possible quantitative measurements of positive and negative ion fluxes. We describe the design and operation of a detection system using these optics and present a calibration of the CEM for low energy (0.2–8.7 keV) positive and negative oxygen ions.

The spectral density of the current fluctuations (noise) of the channel electron multiplier (channeltron) working in the analogue mode has been measured. The results for the channeltron operating in the pulse counting mode have been analysed and compared with those for the analogue mode. In both cases the existence of `flicker noise' (i.e. a spectral density function of the 1/fα (f is the frequency) type) has been observed unless the current has reached high enough values.

In this paper we discuss background counting rate minimization of a channel electron multiplier (CEM) using it in simple pulse counting mode. The minimization was investigated by a variable additional bias voltage applied to an aluminium source carrier set in front of a CEM entrance tube. For an optimal bias voltage of −20 V we found the background counting rate to be reduced to one twenty fifth of its value with no additional bias voltage applied.

Precise control of atomic motion is an up-to-date and important subject not only for atomic physics, including high-resolution laser spectroscopy, but also for the sophisticated technology of crystal growth. Since an optical near field can be localized in a nanometric region, it is very suitable for atom manipulation with high spatial accuracy. This chapter covers several methods of guiding and manipulating atoms by means of an optical near field. First, before discussing details, we will give an outline of the control of atomic motion based on the near-resonant mechanical interaction between an atom and an optical near field.

Using coincidences between pulses from the silicon detector that measured alpha particles produced in the 209Po decay and pulses from the channel electron multiplier (CEM), the gain ratio of the CEM for 205Pb ions and conversion electrons was measured. From the obtained values the absolute efficiency of CEM is derived as a function of the incident 205Pb ion energy.

It was not until five years after the discovery of low-energy electron diffraction (LEED) [9.1] that the positron was first observed [9.2]. By the time it became possible to form controllable, albeit very weak, low-energy positron beams in the 1970s, LEED had become an ubiquitous and powerful tool in surface structure determination. Thus, when the first observation of low energy positron diffraction (LEPD) was made in 1979 [9.3] one could well question whether it was too late for LEPD to be of any practical value in surface physics. As this review will chronicle, during the past ten years, LEPD has evolved from being a novelty to becoming a valuable technique for surface structure determination. The differences between LEPD and LEED are nontrivial; they not only raise questions of fundamental interest but also suggest that in some cases LEPD ultimately may prove superior to LEED for quantitative surface structure determination.

チャンネル型電子増倍管 (CEM) の出力電子のエネルギー分布 (EDOE) を未飽和および飽和の全動作領域で測定し, EDOEの半値幅HWの全般的特性を明らかにした.また, 実験的に求めた動作中のチャンネル内電位分布に基づいてEDOE曲線を計算し, HWの挙動について検討した.さらに, CEM出力端部分にAlを蒸着することによりEDOE特性が著しく改善されることを示した.

Photoabsorption coefficients of krypton and xenon have been measured to +or-5% accuracy in the 48-210 AA region using a synchrotron radiation source and channel electron multiplier photodetection.

The output charge distribution of seven channel electron multipliers was accurately measured in order to determine the influence of the count rate on the decrease of the mean gain. A law was established between secondary electron (S.E.) and conduction currents. This law holds for tubes operating in a saturated mode independent of the tube length or axial electric field strength.

Orthopositronium (o-Ps), formed on the cone of a channel electron multiplier by 400- eV positrons, is shown to diffuse quickly into an Mgo-coated evacuated chamber with en- ergies up to 0.8+ 0.2 eV. The decay rate of o-Ps is measured to be 7.09+0.02 @sec where the error is due principally to systematic effects. This result is interpreted to be the first direct measurement of the vacuum decay rate of the o-Ps. It is in disagreement with the theoretical value of 7.242+ 0.008 p, sec ' and previous experiments in gases as well. In a previous Letter' Gidley, Marko, and Rich (GMR) reported the decay rate of orthopositron- ium (o-Ps) in powders of SiO, to be a linear func- tion of the free volume density. The result of ex- trapolating the decay rate to zero density was 7.104+0.006 psec ', This result is (1.9+0.1)g below the theoretical value' of 7. 242 + 0.008 psec ' and more than 2/q below the results of two experiments in gases, " 7.262+ 0.015 p.sec and 7.275+0.015 p.sec '. GMR noted that their result could plausibly be interpreted as the vac- uum decay rate. Ford, Sander, and Witten, ' after a detailed consideration of the possible interac- tions of Ps with the surface of SiO" found no rea- son to doubt that the extrapolated value is the free-space decay rate. We report here the re- sults of a completely different experiment in which 0-Ps is demonstrated to be decaying in vacuum. The decay rate is found to be in agree- ment with the reported value of GMR. Our method for measuring the vacuum decay rate is based on the observation' that 0-Ps is ef- ficiently formed at or near the surface of a solid by slow positrons (F. & 1 keV) and then diffuses into the surrounding vacuum. In order to meas

The response of a large area (4.6×13 cm) multianode channel electron multiplier array (CEMA) detector to energetic neutrons was investigated. The measured neutron detection efficiencies of the chevron microchannel plate (MCP) were 1.7×10−3 and 6.4×10−3 counts/neutron, respectively, for 2.5 MeV‐DD and 14 MeV‐DT neutrons. The apparently higher efficiency observed for the 14 MeV neutrons is attributed to neutron‐induced background gamma radiation.

The intermediate state between single pulsing and oscillating cascades of a straight channel electron multiplier operated in ion feedback conditions is studied. The observation of the transient waveforms produced by a large number of superposed pulses of the same height is reported and their behavior is analyzed with the help of an RC equivalent circuit model.

The relative efficiency versus energy of a type 4028 Bendix Channeltron has been measured for electron energies in the range 10–1000 eV. A theoretical curve, derived from Lye and Dekker's theory of the secondary emission permits to derive the absolute values of the efficiency from the experimental data. Moreover the dependency of the efficiency on the operating voltage has been investigated and the experimental results are in agreement with the theoretical previsions.

The threshold of detection for charged particles is largely reduced by using a windowless channel electron multiplier. The main characteristics of this detector are: a gain higher than 10 7 , a good detection efficiency for electron between 100 eV and 40 keV, a count rate higher than 10 5 counts/sec. This detector can work independently of the pressure from 10 −3 Torr: thus its use is possible on rockets. Magnetic spectrometers can be made with channel multipliers to study the spectrum and angular distribution of auroral electrons from 100 eV to 40 keV.

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.

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%.

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 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.

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.

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 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.

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.