Tube Noise Research Articles

Evaluation of a Thin CaF2(Eu) Scintillator for Detecting Tritium

The primary objective of this project was to investigate the feasibility of using a CaF2(Eu) scintillator for detecting low-energy beta particles from tritium. A proof-of-principle detector was designed to flow tritium-spiked nitrogen gas across the surface of a thin scintillator, which was optically coupled between two low-noise photomultiplier tubes. Electronics for operating two photomultiplier tubes in coincidence eliminated most of the tube noise pulses and allowed detection of small pulses from the low-energy tritium beta particles.

Suction tube noise and myringotomy.

The possibility of a noice-induced hearing loss occurring as a result of a high level of sucker-tip noise in myringotomy for seromucinous otitis media is discussed. A group of twenty-four ears is investigated and the noise levels generated by the suction tube are measured at operation by means of a probe microphone lowered into the external auditory meatus. The conclusions reached are that, although the sound levels attained are at times quite high, they are not of sufficient amplitude, nor are they present for a sufficient length of time, to produce a sensori-neural hearing loss.

26. Exploring the limits of performance of third generation image intensifiers

A large number of papers have been written which describe various aspects of the GaAs photocathode, but very little has been published on the application of GaAs to image intensifiers. The little that has been published suggests that GaAs photocathode image intensifiers (third generation) will prove a significant improvement on existing tubes. The published data does very little to indicate whether the third generation has reached the limits of development or whether further improvements can be anticipated. This paper draws together the relevant published experimental and theoretical data and compares this with new experimental data from current developmental samples of third generation intensifiers. The main tube parameters, sensitivity, resolution, noise and life are examined in turn against this background information in an attempt to define the known physical and technological limitations to performance. This paper therefore explores the upper limits of the individual performance parameters of the third generation wafer tube, and explains some of the trade-offs between the various parameters. Finally, the limiting performance is compared with existing second and third generation devices, in an attempt to fit the third generation image intensifier into the general night vision background.

Quantization of PMT Signals for Meteorological Satellites

Quantization rules are examined for a satellite radiometer in the visual range. Effects of photomultiplier tube (PMT) noise on the detection of cloud brightness levels are of particular interest because the expected radiance levels are high. Effects of area integration are considered to improve the probability of detection at high radiance levels.

Dual Energy Analysis Using Phoswich Scintillation Detectors for Low-Level In-Vivo Counting

Electronics developed for a whole body counting system analyze the pulse heights of signals from both the sodium iodide (NaI(Tl)) and cesium iodide (CsI(Na)) crystals of a phoswich scintillation detector. Pulse shape discrimination is used to determine the origin of the scintillation, NaI or CsI, while rejecting coincident Compton-scattered events and photomultiplier tube noise. Both energy spectra are accumulated simultaneously in separate memory quadrants of a multichannel analyzer. The system allows for low-energy (5 keV - 125 keV) x-ray analysis from the NaI(Tl) crystal and high-energy (100 keV - 2.5 MeV) x-ray or ?-ray analysis from the CsI(Na) crystal. The discrimination system is better than 95% efficient over both energy ranges, with a low-energy (12-24keV) shielded background count of less than 2 cpm for a single 5-in.-diam phoswich detector. This system thus extends the detector's normal energy range by more than an order of magnitude.

Liquid scintillation solutions for pulse-shape discrimination

A systematic study has been made of some of the processes that contribute to the scintillation pulse shape, and this knowledge has been applied to pulse-shape discriminating solutions. The results indicate that pulse-shape discrimination is enhanced by materials that have a high phosphorescence yield and large radiative lifetime. Quarternary solutions have been developed that have a larger average pulse height and better discrimination efficiency than the commercial solution NE-213. The efficiency of discrimination is generally reduced by compounds that are susceptible to excimer formation. Yet, excimer emission in certain solvents can be used to advantage to invert the normal results and to obtain pulse contours produced by electrons, that have a larger percentage of long component radiation than pulses generated by α-particles. This latter type of solution may also be useful in differentiating between low energy β-particles and tube noise.

Investigation of electrometer tube noise: M A Shamrilo et al, Vopr Konstruir Tekhnol Kontrol Izgotovl Elektrovakuum Prib, Minsk 1970, 80–90 ( in Russian)

Investigation of electrometer tube noise: M A Shamrilo et al, Vopr Konstruir Tekhnol Kontrol Izgotovl Elektrovakuum Prib, Minsk 1970, 80–90 ( in Russian)

Noise analysis of current amplifiers with a dynamic capacitor

1. Total noise in general consists of two components: low frequency thermal noise between nodes 0 and 2 (the first term in Eq. (1)) and tube noise at frequencyωc (third and fourth terms in Eq. (2)). All remaining noise components are small enough to be neglected. 2. Capacitance C9 has considerable effect on the signal/noise ratio. To raise the signal/noise ratio, C9 must be decreased, C8 must be chosen equal to C9, g235 must be reduced, andωc must be raised. The condition C8=C9 is quite different from the recommendation current in the literature that C8=C5. 3. The relative advantage in the signal/noise ratio obtained by increasingωc increases with an expansion of the system pass band.

Experimental studies on the acoustic reflex of the intra-aural muscles and its clinical application

In order to establish an objective audiometry, the anther studied the intra-aural muscle reflex elicited by sound stimulation. The changes of acoustic impedance at eardrum i.e. effective volume change and air pressure change of the external ear canal caused by middle ear muscle reflex were measured by using modified Nagashima's *Aural Reflex Indicator* and electric micro-manometer, respectively. Measurements were performed on 60 normal subjects and the patients with peripheral facial nerve palsy (30), Eustachian tube stenosis (60) and noise induued deafness (40). In animal experiments, 30 rabbits and 40 guinea pigs were used. The following conclusion can be drawn from the results. 1) The effect of the acoustic middle ear mus- cle reflex was recorded by electric micro-manometer in 97% of the normal ears, while by Aural Reflex Indicator it was detected in 85%. 2) White noise is found to be most effective for eliciting the aural reflex in humann as well as experimental animals. 3) The aural reflex effect is almost undetect- able, is any, by Aural Reflex Indicator in cases of conductive type deafness and facial nerve palsy, but it is recorded remarkably by electric micro- manometer. 4) The individual susceptibility to noise ind- uced deafness could be presumed from the magni- tude of reflex activity. 5) The experimental study and the study in the patients with facial nerve palsy made it pos- sible to distinguish the reflex effect of the tensor tympany muscle and stapedial muscle.

Pulse Shape Discrimination System for 6LiF(ZnS) Scintillation Counters

A pulse shape discrimination system for 6LiF(ZnS) scintillators is described and its electronic layout discussed. Test results under typical operation conditions at the location of a neutron scattering experiment in a light water research reactor are given. They show that the system is able to suppress virtually all spurious (γ and tube noise) pulses down to a rather low discrimination level. By taking a low discrimination level it is possible to exploit the potentially high efficiency of the scintillator to a much larger extent. In our particular case the over-all counting efficiency could be doubled.

A fission product monitor for water cooled reactors

A Čerenkov detector for monitoring fission products in water cooled reactors is described. The selection of design parameters maximizes the Čerenkov radiation signal amplitude, thus eliminating problems associated with photomultiplier tube noise as well as retaining good beta energy discrimination. In this instrument a small sample (50 cc) of coolant water is exposed to a photomultiplier tube with S-13 response. The sample-detector geometry takes full advantage of the directional and spectral characteristics of the Čerenkov radiation, while the small sample volume serves to limit the signal input rate that the electronic system must process without pulse “pile-up”.

Quieting of Discharge Tube Noise by Externally Applied Radio-Frequency Energy

Quieting of Discharge Tube Noise by Externally Applied Radio-Frequency Energy

Measurements of electrometer tube noise

Measurements of electrometer tube noise

A Low Level Beta Scintillation Counter

An automatic scintillation counter for the measurement of low beta activity samples is described. Background is in the order of one (1) count per minute. Efficiency of counting for K-40 betas is thirty (30) per cent. The scintillator is a thin plastic phosphor mounted on the sample which makes a simple, rugged package suitable for automatic sample changing. Photomultiplier tube noise measurements, preamplifier circuit, and the mechanical details are discussed.

Measurement of the coherence of grid and anode tube noise

Measurement of the coherence of grid and anode tube noise

An ultra-low-noise wide-band traveling-wave tube

This paper describes the development of a 2-milliwatt, ultra-low-noise, wide-band traveling-wave tube intended for front-end receiver operation. Methods employed to achieve minimum tube noise figures as low as 2.5 db and broad-band noise figures of less than 3.5 db in the 2500-to-3700- megacycle frequency range are described. Such critical factors in low-noise performance as the cathode, beam-impedance transformation, and rf input sections are discussed, and the reduction of beam noise through proper shaping of the low-potential drift region adjacent to the cathode is considered in detail. The paper also discusses electron-gun design, favorable launching conditions for hollow electron beams, and the magnetic-field configuration required for optimum low-noise performance. In addition, a novel beam-focusing technique is described which permits a considerable reduction in the size, weight, and dc dissipation of the focusing solenoid with no adverse effect on the low-noise performance of the tube. The development of this low-noise traveling-wave tube is sponsored by the Advanced Research Project Agency, with the Rome Air Development Center, Griffis Air Force Base, N.Y., as the monitoring agency.

A Recommended Standard Resistor-Noise Test System

Summary--This paper describes a recommended standard resistor-noise test system, with the theory of operation given in considerable detail. The system provides for the measurement of a definitive resistor-noise quality Index. This Index, the microvolts-per-volt Index, is a modified form of the conversion gain index formerly used at NBS. The Index is a decibel expression for the number of microvolts of noise per volt of applied dc voltage transmitted in a frequency decade. A practical example is given to illustrate how the Index may be used to calculate the magnitude of current noise generated by fixed resistors in a given application. To complete the example, the combined effects of thermal noise, tube noise, and current noise are then considered. A description is also given of an existing test set which is based upon specifications associated with the recommended measuring system. The full specifications for this set are given and distinctive design features are discussed. The simple operation of the test Set and the computation of the Index are carefully explained.

Noise Spectra of a Probe in a Hot-Cathode Discharge

Measurements have been made with a floating and a biased probe of the low-frequency noise which occurs in hot-cathode discharges through mercury vapour at low pressures. As previously reported by Cobine and Gallagher, and Martin and Woods, the spectrum is continuous but there are no superimposed peaks of oscillation. The spectra agree with that of the tube noise in their general shape. It has been shown that the primary electrons from the cathode are not essential for the noise to be recorded from the probe.

New Mechanism of Noise Reduction in Electron Beams

Experiments have demonstrated that the basic noise quantities of an electron beam can be transformed and optimized by varying the field configuration and flow characteristics in the multivelocity region near the cathode. Tube noise figures as low as 2.9 db and numerical values of beam noisiness 2π/kTc(S−Π) <0.27 have been attained at microwave frequencies (S band). A detailed investigation of the conditions for minimum beam noisiness is presented. The beam is injected from the edge of the cathode into a highly divergent electric field and results in a distorted potential profile which greatly extends the low-velocity region below ½ v. It is shown that these features satisfy the physical conditions necessary for realizing a quasi-one-dimensional model in which the transforming properties of a ``multivelocity noise transducer'' can be adjusted by varying the rate of acceleration through this region. The experiments also suggest other models and possible approaches for further theoretical and experimental investigation.

Effects of Radiation on Vidicon Performance

A commercial one-inch vidicon was exposed to a total radiation dosage of approximately 1015 NVT in the Brookhaven National Laboratories Nuclear Pile Reactor. Quantitative tests were devised for measuring tube aperture response, signal, noise, and photoconductor "dark" current. No measurable degradation of performance occurred, except for decrease in signal output, which was attributed to radiation browning of the vidicon glass faceplate.