ESTIMATION OF SUPPRESSION COEFFICIENTS OF SHOT NOISE FIELDS IN THE TUNGSTEN FILAMENTS

LaB6 emitters are becoming increasingly popular as direct replacements for tungsten filaments in the electron guns of modern electron-beam instruments. These emitters offer order of magnitude increases in beam brightness, and, with appropriate care in operation, a corresponding increase in source lifetime. They are, however, an order of magnitude more expensive, and may be easily damaged (by improper vacuum conditions and thermal shock) during saturation/desaturation operations. These operations typically require several minutes of an operator's attention, which becomes tedious and subject to error, particularly since the emitter must be cooled during sample exchanges to minimize damage from random vacuum excursions. We have designed a control system for LaBg emitters which relieves the operator of the necessity for manually controlling the emitter power, minimizes the danger of accidental improper operation, and makes the use of these emitters routine on multi-user instruments.Figure 1 is a block schematic of the main components of the control system, and Figure 2 shows the control box.

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Reduction of shot-noise in quantum conductors

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:1999203 ◽

1999 ◽

Vol 09 (PR2) ◽

pp. Pr2-23

Author(s):

L. Saminadayar ◽

A. Kumar ◽

D. C. Glattli ◽

Y. Jin ◽

B. Etienne

Keyword(s):

Shot Noise

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A Note on Shot-Noise and Reliability Modeling,

10.21236/ada151336 ◽

1984 ◽

Author(s):

A. J. Lemoine ◽

M. L. Wenocur

Keyword(s):

Shot Noise ◽

Reliability Modeling

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On the Intensity of Crossings by a Shot Noise Process.

10.21236/ada177077 ◽

1986 ◽

Author(s):

Tailen Hsing

Keyword(s):

Shot Noise ◽

Noise Process ◽

Shot Noise Process

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Suppression of Laser Shot Noise Using Laser-Cooled OptoMechanical Systems

10.21236/ada546917 ◽

2010 ◽

Author(s):

Jack G. Harris

Keyword(s):

Shot Noise ◽

Laser Shot ◽

Optomechanical Systems

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Collection and counting efficiency

10.1093/oso/9780199565092.003.0010 ◽

2017 ◽

Author(s):

A. G. Wright

Keyword(s):

Quantum Efficiency ◽

Standard Method ◽

Shot Noise ◽

Count Rate ◽

Detection Efficiency ◽

Collection Efficiency ◽

Counting Efficiency ◽

Single Electron ◽

Anode Current ◽

Secondary Electrons

Standards laboratories can provide a photocathode calibration for quantum efficiency, as a function of wavelength, but their measurements are performed with the photomultiplier operating as a photodiode. Each photoelectron released makes a contribution to the photocathode current but, if it is lost or fails to create secondary electrons at d1, it makes no contribution to anode current. This is the basis of collection efficiency, F. The anode detection efficiency, ε‎, allied to F, refers to the counting efficiency of output pulses. The standard method for determining F involves photocurrent, anode current, count rate, and the use of highly attenuating filters; F may also be measured using methods based on single-electron responses (SERs), shot noise, or the SER at the first dynode.

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