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Topic: Dynode

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	Olympus FluoView Resource Center: Electronic Light Detectors: Photomultipliers
		The impact of a photoelectron on the first dynode releases additional electrons (usually between 5 and 10) that are accelerated in turn toward the next dynode, which also has a potential difference of about 100 volts with respect to the first.
		Upon exiting the dynode chain, the pulse of multiplied electrons is collected on the anode, which usually has a potential difference of approximately 1000 volts with respect to the photocathode.
		By carefully matching dynode shape and proximity to the large interspersed electric fields, the output pulse on the anode can be reduced to several nanoseconds in duration to preserve the temporal profile of the initial optical signal.
	www.olympusconfocal.com /theory/pmtintro.html (5857 words)

	Dynode - Wikipedia, the free encyclopedia
		A dynode is one of a series of electrodes within a photomultiplier tube.
		Each dynode is more positively charged than its predecessor.
		Such an arrangement is able to amplify the tiny current emitted by the photocathode by typically one million.
	en.wikipedia.org /wiki/Dynode (81 words)

	Venetian blind type secondary electron multiplier for secondary electron multiplier tubes - Patent 4950951
		In the Venetian blind dynode structure, the dynode structure includes a series of slats or vanes disposed at a slanting angle with respect to the direction of propagation of photoelectrons which have been emitted from a photoemissive surface of a photocathode or of secondary electrons which have been emitted from the preceding dynode stage.
		However, the thin plates corresponding to one of the adjacent dynodes are slanted at an opposing angle with respect to the thin plates corresponding to another of the adjacent dynodes.
		A portion of second dynode 4 corresponding to a width dimension "d" of the thin plate 41 of second dynode 4 is disposed vertically transverse to first dynode 3 and aligned with the distance or gap between thin plates 31 and 32 corresponding to the geometrically transparent part of the first dynode 3.
	www.freepatentsonline.com /4950951.html (2647 words)

	Penning discharge ion source with self-cleaning aperture - Patent 4344019
		When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode.
		The smaller dynode is represented by the reference numeral 10a, and the one piece anode is 20a.
		A switch S.sub.1 between the cathodes and the dynode 10 (or a power supply between the anodes and dynode) may be activated to place a negative voltage on the dynode, thereby to reduce the minimum gas flow required to strike the arc.
	www.freepatentsonline.com /4344019.html (4066 words)

	PHOTOMULTIPLIERS and HOW THEY OPERATE (Site not responding. Last check: 2007-10-30)
		Each dynode, the photocathode, the anode, and often a focus electrode preceding the first dynode, are separated by insulators and are independent of one another; connections to individual pins in the base bring operating voltages to each of the elements.
		Since the dynode and the grid are at the same potential and the grid is largely open, most of the electrons pass through and strike the dynode resulting in secondary-emission multiplication.
		Thermionic electrons, from the photocathode and first few dynodes released at room temperature due to their very low work functions, are multiplied up the dynode chain; electrons from the later dynodes are less a problem as they are not subject to as much multiplication.
	www.inus.com /docs/pmt.htm (1416 words)

	Photomultiplier - Wikipedia, the free encyclopedia
		Each dynode is held at a more positive voltage than the previous one.
		On striking the first dynode, more low energy electrons are emitted and these, in turn, are accelerated toward the second dynode.
		The geometry of the dynode chain is such that a cascade occurs with an ever-increasing number of electrons being produced at each stage.
	en.wikipedia.org /wiki/Photo_multiplicator (544 words)

	pmt?.html
		The electrons are focused onto the first dynode by an electric field, and when they strike the dynodes, more electrons are emitted.
		A potential difference between the photocathode and the first dynode causes the electrons to accelerate toward the dynode and an electric field focuses them onto the dynode.
		The electron-multiplier system amplifies the primary photocurrent using a series of dynodes to produce a measurable current at the anode of the photomultiplier.
	www-boone.fnal.gov /pmt2/pmtwhat.html (650 words)

	LSU EE 4770 Lecture Notes
		The plate exposed to light called the cathode, one plate called the anode, and the rest are called dynodes.
		Dynodes are placed between cathode and anode, and are ordered.
		(That is, one dynode is closest to the cathode, one is second closest, and so on.) The closest dynode is called the first dynode, the second-closest dynode is called the second dynode, and so on.
	www.ece.lsu.edu /ee4770/1999/lsli08.html (2256 words)

	Photomultiplier - Wikipedia, the free encyclopedia
		Photomultipliers are constructed from a glass vacuum tube which houses a photocathode, several dynodes, and an anode.
		As they move towards the first dynode they are accelerated by the electric field and arrive with much greater energy.
		(Negative high voltage supplies are usually preferred.) Voltages are distributed to the dynodes by a resistive voltage divider, though variations such as active designs (with transistors or diodes) are possible.
	en.wikipedia.org /wiki/Photomultiplier (544 words)

	Detectors (Site not responding. Last check: 2007-10-30)
		The ion beam from the mass analyzer is focused onto the conversion dynode, which emits electrons in direct proportion to the number of bombarding ions.
		Amplification is accomplished through a "cascading effect" of secondary electrons from dynode to dynode.
		Each stage (copper-beryllium dynode) is connected to a successively higher potential by a voltage divider, and the final collector is connected to a conventional amplifier.
	www.sou.edu /chem/ch425/MassSpec-Chapter20/tsld023.htm (64 words)

	Olympus Microscopy Resource Center: Photomicrography - Interactive Flash Tutorials - Photomultiplier Tubes
		Upon impacting the first dynode, a photoelectron will invoke the release of additional electron that are accelerated toward the next dynode, and so on.
		The surface composition and geometry of the dynodes determines their ability to serve as electron multipliers.
		Because gain varies with the voltage across the dynodes and the total number of dynodes, electron gains of 10 million (Figure 1) are possible if 12-14 dynode stages are employed.
	www.olympusmicro.com /primer/flash/photomultiplier/index.html (611 words)

	Phototube Detectors
		The drive is to produce phototubes with fast transit times from the cathode to the output dynode (this is on the order of tens of nanoseconds) with a jitter in the time of much less than 1 nanosecond.
		When an electron impacts on a dynode surface, energy is transferred directly to the electrons in the dynode material thereby allowing a number of secondary electrons to escape.
		Electrons on the central axis reach the beginning stage dynode before electrons from the edges if they have the same energy simply because the path length is about three times shorter along the central axis than from the edge.
	www.physics.upenn.edu /balloon/phototube.html (2992 words)

	Electron detection system (Site not responding. Last check: 2007-10-30)
		Since statistics for the electron measurement were not a problem, the trigger was pre-scaled by factor of 4, in order to reduce the load on the data acquisition system.
		The neutron detectors could also be used for electron detection by utilizing a fast signal from the dynode of the photo-multiplier.
		A separate trigger, called telescope or simply Tel trigger, was implemented which required a triple coincidence of two plastic scintillators and the dynode signal, with the latter energy also recorded.
	musr.physics.ubc.ca /theses/Fujiwara/node62.html (278 words)

	HED 2000 (Site not responding. Last check: 2007-10-30)
		It is well known that when using a conversion dynode, increased sensitivity is seen when analysing high masses (see figure 1).
		In the past, the upgrade process was very lengthy and expensive because of the requirements for an additional feedthrough and an external power supply.
		The converter output is -4.5 kV, which is the voltage applied to the dynode (see figure 2).
	home.btconnect.com /ssscientific/hed.htm (340 words)

	GIS
		The dynodes in the PSPT have a plane geometry, and in each dynode plane runs a number of parallel grids of triangular cross section.
		This dynode configuration keeps the electron path from the photocathode to the anode plane straight and the cloud size small.
		The pulse-height signal from the last dynode is first examined by the upper and the lower discriminators and then processed by the pulse-height and rise-time ADCs.
	heasarc.gsfc.nasa.gov /docs/asca/ao7/appendix_e/node7.html (2933 words)

	Radiation Notes: Detectors
		Thus the electron is accelerated toward the dynode, striking it with a kinetic energy 100 eV greater than the at most few eV that it had as it left the cathode.
		Beyond the first dynode there is the second dynode, which is maintained at a potential roughly 100 V more positive even than the first.
		The most positively charged electrode is the anode, which is near the last dynode and is maintained at a sufficiently positive potential to collect all of the electrons ejected from that dynode.
	oak.cats.ohiou.edu /~piccard/radnotes/detectors.html (5353 words)

	Measurement of Radiation, Sodium Iodide Detector (Site not responding. Last check: 2007-10-30)
		These electrons are then pulled towards a series of plates called dynodes through the application of a positive high voltage.
		When electrons from the photocathode hit the first dynode, several electrons are produced for each initial electron hitting its surface.
		The sequence continues until the last dynode is reached, where the electron pulse is now millions of times larger then it was at the beginning of the tube.
	www.physics.isu.edu /radinf/naidetector.htm (233 words)

	Introduction to Gain--Part 4 (Site not responding. Last check: 2007-10-30)
		The initial electron caused the dynode to emit two secondary electrons.
		All eight are accelerated to the fourth dynode, and each will produce two more secondary electrons.
		At the sixth dynode there will be 64 electrons, 128 at the seventh, and so on.
	quarknet.fnal.gov /projects/pmt/student/gainill4.shtml (216 words)

	Detectors (Site not responding. Last check: 2007-10-30)
		Important step - electron trajectory from photocathode to first dynode such that the photoelectrons emitted are efficiently focused onto the first dynode; collection efficiency is the ratio of # of e- landing on the effective area of the first dynode to the number of emitted photoelectrons.
		Basic characteristics of dynodes - different types are available and are used for different characteristics w/different collection efficiency and current amplificationDynode types and features - structure and number of stages will determine time response, efficiency, uniformity, current amp.
		Current amplification - d (secondary emission ratio) is function of the interstage voltage of dynodes, E: d = aEk, where a is constant and k is determined by structure and material of an electrode (generally 0.7-0.8); suggests that current amplification is dependent on power supply variations (drift, ripple, temperature stability, etc.)
	www.chm.colostate.edu /erf/teaching/c532/detectorsi.htm (2874 words)

	Electron Multiplier for Finnigan OWA, 1020 MS
		After August 1981, the Burle Model 4752-OWA multiplier with a single conversion dynode and either a 50 megaohm or 25 megaohm dropping resistor was installed on OWA instruments.
		The multiplier must be of the style with a conversion dynode and dropping resistor and the conversion dynode and dropping resistor must be in usable condition.
		The Burle multipliers are the original continuous dynode electron multipliers used by Finnigan MAT in all the OWA instruments.
	www.sisweb.com /ms/finnigan/owamult.htm (569 words)

	Optical Modules (Site not responding. Last check: 2007-10-30)
		At each dynode the number of accelerated electrons multiply, due to the energy gain of the electrons falling through the voltage applied across each gap.
		After the fourteenth dynode the avalanch of electrons is collected by an anode which supplies the output signal.
		The amplitude of a one photoelectron pulse of the high gain PMT, typically 0.5 to 1.5 V, is large enough to be transmitted directly by a coaxial or twisted pair cable.
	www.ps.uci.edu /~youngs/amanda/main/node22.html (590 words)

	Olympus FluoView Resource Center: Side-On Photomultipliers - Interactive Java Tutorial
		These ejected photoelectrons have trajectories angled at the first dynode, which in turn emits a larger quantity of electrons angled at the second dynode (and so on).
		The tutorial initializes with a cutaway drawing of a side-on photomultiplier appearing in the window, and having the photocathode oriented to the left and the anode nested within the last dynode.
		As they pass from one dynode to the next, the electrons multiply when they impact the surface of the walls, and eventually are absorbed by the anode.
	www.olympusfluoview.com /java/sideonpmt/index.html (658 words)

	How a two-wire PMT probe works (Site not responding. Last check: 2007-10-30)
		the upper dynodes must be bypassed to ground so that they are not pulled upwards with each
		There is no bypassing at the anode because this is where the signal is tapped off.
		Dynode resistors need to be substantially larger than the anode resistor.
	home.austin.rr.com /cthompson15/PMT_theory.html (287 words)

	[No title] (Site not responding. Last check: 2007-10-30)
		a first dynode placed at a position in the tube axial direction for multiplying the photoelectron impinging thereon from the photocathode to emit a secondary electron, the first dynode having a proximal end which is close to the anode;
		a second dynode placed at a substantially same position as the position of the first dynode in the tube axial direction, the second dynode multiplying the secondary electrons impinging thereon from the first dynode to emit a secondary electron, the second dynode having a proximal end which is close to the anode;
		a third dynode provided on an anode side of the first and second dynodes in the tube axial direction for multiplying the secondary electrons impinging thereon from the second dynode to emit secondary electrons; and
	www.uspto.gov /web/patents/patog/week25/OG/html/1307-3/US07064485-20060620.html (316 words)

	Introduction to Gain--Part 8
		A photon struck the photocathode of the photomultiplier tube to the left, and an electron is being accelerated to the first dynode.
		Since the voltage between the photocathode and the first dynode is 160V, four secondary electrons are emitted.
		The potential between the first and second dynode is once again 160V, so each of the four electrons emitted by the first dynode ejected four more electrons, totalling sixteen electrons.
	quarknet.fnal.gov /projects/pmt/student/gainill8.shtml (210 words)

	ORTEC 266 Photomultiplier Base
		It provides capacitively-coupled linear output signals from the anode and the tenth dynode that can be used in either timing or linear pulse height analysis systems.
		ither the anode or dynode signal may be processed through an ORTEC Model 113 Scintillation Preamplifier that is connected to a main shaping amplifier such as the ORTEC Models 450, 460, 570, 571, 572, 575A, or 590A.
		A C-24-1 Cable is recommended for connecting the dynode output to a Model 113 Preamplifier.
	www.ortec-online.com /electronics/pmt/266.htm (487 words)

	Methods of Ion Detection
		The dynode electrode is made of a secondary emitting material like CsSb, GaP or BeO.
		A Faraday cup uses one dynode and as a result produces one level of signal amplification.
		In the photomultiplier (or scintillation counter) the ions initially strike a dynode which results in electron emission.
	www.chm.bris.ac.uk /ms/theory/detection.html (496 words)

	[No title] (Site not responding. Last check: 2007-10-30)
		Dynodes having the same shape as a shape of a second dynode (Dy2) are used as an (n−2)
		dynode (Dy8, Dy9), while smaller dynodes than the second dynode (Dy2) are used as a third dynode and a fifth dynode (Dy3, Dy5), the first to n
		dynodes are arranged so that a path formed in a spaces between opposing dynodes crosses the tube axis, a mesh type of anode is used as the anode (A), the mesh type of anode is placed on an opposite side of the second dynode (Dy2) with respect to the tube axis (X).
	www.uspto.gov /web/patents/patog/week38/OG/html/1298-3/US06946792-20050920.html (273 words)

	Electron Multipliers - Tutorial - Development Library - National Instruments
		The construction and operation of the multiple-dynode detector is similar to that of the photomultiplier that acts in a vacuum.
		Each incoming electron that reaches the first dynode ejects several other electrons by secondary emission.
		This process of multiplication is repeated at each succeeding dynode by applying a higher potential to it than to the preceding dynode.
	zone.ni.com /devzone/conceptd.nsf/webmain/3F70C576A158A9DF06256857007BB4A5 (268 words)

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