This device consists of a thin insulating foil of several tens of. A fast charged particle traverses the gas, causing ionization. On application of a difference of potential between the two electrodes, electrons released by radiation in the gas on one side of the structure drift into the holes, multiply and transfer to a collection region. Buy discounted electronmultipliers chromatography direct. New observations with the gas electron multiplier gem. Use of gas electron multiplier gem detectors for an advanced xray monitor ronald a. The avalanche is able to produce enough electrons to. The charge sharing and electrontransfer process of a gas electron multiplier gem with a high density of holes 60. Continuous secondary electron multiplier csem a csem figure 6. Electron multiplier tubes an electron multiplier tube is operated in a vacuum, and the ions, electrons, vuv radiation, or soft xrays to be detected are guided so as to enter the first dynode.
Gas electron multipliers for potential applications to. Gas electron multiplication technology is nding more andmore applications in beam instrumentation andat cern these detectors have recently been adapted for use in transverse pro le measurements at several of our facilities. Multipliers for all major mass spectrometers agilent, perkinelmer, varian, thermo fisher and others are available for immediate shipment to your laboratory. Gas electron multipliers versus multi wire proportional. Well beyond the ion source, at the other end of the mass analyzer, is the electron multiplier em. The standard cern gems consist of an insulator made of a thin kapton foil about 50. Gas electron multiplying detectors for medical applications. By studying the dynode surfaces of an etp active film multiplier, we have isolated the major factors influencing the deterioration of electron multiplier performance. Gas electron multiplier gem a novel particle detector. Other articles where electron multiplier is discussed. Measurements of the chargingup effect in gas electron multipliers. Although originally invented for the amplification of the tiny currents from a. The fragments that survive the journey through the analyzer shoot into the electron multiplier the detector of the gcms. The gem belongs to the family of holetype detectors made of.
Sharma a cern, ch1211 geneve, switzerland a vubulb brussels, belgium abstract we describe operating principles and results obtained with a new detector element. We describe recent measurements realized with the gas electron multiplier gem mesh added as preamplification element to a multiwire and a microstrip chamber. The discrete dynode electron multiplier comprises a series of becu alloy. Advances in thick gemlike gaseous electron multipliers. The avalanche is able to produce enough electrons to create a. An understanding of the aging process in electron multipliers is a necessary precursor to developing a verylonglife mass spectrometer detector. This chapter describes the process of electron avalanche multiplication, which is the only method known to detect the smallest possible electrical signal, a. Their robust construction and flexible discrete dynode design make them the detector of choice for this demanding application. Chapter 6 free electron fermi gas national tsing hua.
Gas electron multiplier detectors with high reliability. Some of the cookies we use are essential for parts of the site to operate and have already been set. Traditionally channel electron multipliers are not able to function efficiently at these pressures because of ion feedback. The most common detector in mass spectrometry is the electron multiplier. Chromatography direct would like to use cookies to store information on your computer, to improve our website and your experience. Multipliers can be either a discrete dynode type or a continuous dynode, generally known as a channel electron multiplier or channeltron. Table 42 provides typical values for useful energy range, energy. The first dynode excited by such particles or radiation. Ovchinnikov2 1institute for nuclear research of russian academy of sciences, moscow, russia 2national physical laboratory, teddington, middlesex, tw11 0lw, uk abstract the gas electron multiplier detectors with wire and metallic electrodes, with a gas filling in the. A gas electron multiplier gem is a type of gaseous ionization detector used in nuclear and. Large, stable combined gains are obtained, with good uniformity and energy resolution, in a wide range of filling gases including nonflammable mixtures. The thick ionization gap makes the thgem chamber a minidrift chamber.
Electron multipliers have a few weaknesses as detectors. Detector technology has developed an unconventional style of channel electron multipliers that has the capability of operating in this high pressure range. Inspired by the same basic concept, the gas electron multiplier electrode is a thin polymer foil, metalcoated on both sides and pierced with a high density of holes, typically 50100 mm. Both issues are addressed through the use of a conversion dynode, which is another electrode that is placed in front of the electron multiplier with an exceptionally high voltage applied to it. Handout 3 free electron gas in 2d and 1d in this lecture you will learn. We describe operating priciples and results obtained with a new detector component. Inserted between a drift and a charge collection electrode, and with the application of appropriate potentials, the gem electrode develops near the holes field lines and equipotential. Use of gas electron multiplier gem detectors for an.
Introduced by the author in 1997, the gas electron multiplier gem constitutes a powerful addition to the family of fast radiation detectors. In a process called secondary emission, a single electron can, when bombarded on secondaryemissive material, induce emission of roughly 1 to 3 electrons. Pdf gain properties of gas electron multipliers gems. A thick gas electron multiplier thgem chamber with an e ective readout area of 10 210 cm and a 11. Sauli in 1996 and is in use in high energy and medical physics, provides the possibility to avoid the problems mentioned on the pages about wire amplification.
The gas electron multiplier gem, placed in the drift volume of a conventional gas detector, is a conceptually simple device for producing a large gas gain by concentrating the drift electric field over a very short distance to the point that electron avalanching occurs. An electron multiplier is a vacuumtube structure that multiplies incident charges. Pdf introduced by the author in 1997, the gas electron multiplier gem constitutes a powerful addition to the family of fast radiation detectors find, read. Our core technology uses ion and electron optical simulation, magnetic modelling, and innovative electron emission materials combined with their bespoke dynode designs to provide. Electron multipliers etp scientific analytical west. It has very high secondary electron emission, which allows exceptional gain to. The simplest metals are the alkali metals lithium, sodium, potassium, na, cesium, and rubidium. The development of electronic techniques for television during the 1930s yielded a device of extraordinary sensitivity for measuring small electron beamsnamely, the secondary electron multiplier. Gas electron multiplier detectors with high reliability and stability b. This material has a number of properties that make it very suitable for use in an electron multiplier. Often boosting the small signal that makes it through the ionization and analysis stages in mass spectrometry by 100,000 times or more, the em plays a critical role in the successful operation of your instrument. Since most mass spectrometers and residual gas analyzers do.
Agilents high quality electron multiplier for icpms is an important accessory in an effective, precision system. Gas electron multiplying detectors for medical applications edward tsyganova, peter anticha, robert parkeya, serguei seliouninea, viacheslav golovatyukb, sergey lobastovb, valeriy zhezherb, alexei buzulutskovc a the university of texas, southwestern medical center, 5323 harry hines blvd. Scientific instrument services provides replacement detectors from the major manufacturers of electron multipliers. Principle of operation the basic element of the gem detector is a thin, selfsupporting threelayer mesh realized by the conventional photolithographic methods used to produce multilayer printed circuits. Hohlmann, florida institute of technology dsc muon summit, san diego 2 outline. Channel electron multipliers or channeltrons are detectors, which respond to the charged particles, hard and soft xrays, and ultraviolet radiation. Remarkable features of gas electron multipliers gems make them attractive for numerous applications in highenergy physics, nuclear physics, astrophysics, and the medicalimaging field.
A gas electron multiplier gem consists of a thin, metalclad polymer foil, chemically pierced by a high density of holes. The properties and some potential applications of these simple and robust multipliers are discussed. Gem are widely used as amplification stages in gaseous detectors exposed to high rates. The classical theory had several conspicuous successes, notably the derivation of the form of ohms law and the. This chapter describes another popular micropattern detector, the gas electron multiplier gem. Analytical west stocks a full line of replacement electron multipliers manufactured by detector technology detech and etp. Accepted for publication in nuclear instruments and methods a pacs. Handout 3 free electron gas in 2d and 1d cornell university. Gc electron multipliers gc electron multipliers product lines. The electron multiplier converts incident ions into an amplified electric current used to record measurements of the ion signal. Due to the high voltages involved, gas discharges that could destroy the sem can occur at high pressures of p 105 hpa. Thompson a wide variety of xray detectors is available, some counting single photons, some providing only measurements of count rate or total flux, others measuring the energy, position, andor incidence time of each xray.
Free electron gas in two dimensions and in one dimension density of states in kspace and in energy in lower dimensions ece 407 spring 2009 farhan rana cornell university electron gases in 2d in several physical systems electron are confined to move. The gas electron multiplier gem is a new device that amplifies an input electron cloud, while keeping its shape unchanged 1. The gas electron multiplier gem is a proven amplification technique for position detection of ionising radiation such as charged particles, photons, xrays and neutrons, in gas detectors. A first mass production of gas electron multipliers inspire. Etp ion detect work with mass spectrometry companies to discover, design, develop, test and manufacture the best ion detection systems available for an instrument. Figure 121 shows typical electron multiplier tubes. Electron multiplier article about electron multiplier by. The gem gas electron multiplier technology, which has been introduced by f. In the experimental areas of cern s antiproton decelerator, low energy gas electron multipliers successfully replaced. The gem is a detector containing a densely pierced polymer foil coated with electrodes on both sides which is able to achieve high amplification gains and performance at low cost, even. Electron multiplier an overview sciencedirect topics.
A gas electron multiplier gem is a type of gaseous ionization detector used in nuclear and particle physics and radiation detection all gaseous ionization detectors are able to collect the electrons released by ionizing radiation, guiding them to a region with a large electric field, and thereby initiating an electron avalanche. The operating principles of gems and their main characteristics, including. Vilhud acenter for space research, massachusetts institute of technology, cambridge, ma, usa blaboratory for nuclear science, massachusetts. If an electric potential is applied between this metal plate and yet another, the emitted electrons will accelerate to the next metal plate. The electron multiplier detects every ion of the selected mass that passes through the quadrupole analyzer. Electron multipliers use a process known as secondary electron.
The electron multipliers manufactured by etp use a proprietary dynode material. Our detectors are used in a wide array of applications including mass spectrometry. There the electrons gain so much energy that they cause further ionization. The valence electrons of the constituent atoms become conduction electrons and move about freely through the volume of the metal. Radiation detectors based on gas electron multipliers. It has a high surface resistance which forms a continuous dynode when potential is applied between the input and output end. Gaseous electron multipliers, radiation imaging detectors, gas avalanche multiplication, hole multiplication, uv photon detectors. Etp scientific electron multipliers etp active film multipliers are incorporated as original equipment in virtually every major quadrupole icpms instrument being manufactured today. Two modifications of the multipliers have been tested. As the voltage in the system increases the amplification factor or gain increases. Sauli in 1996 and is in use in high energy and medical physics, provides the. Electrons in one atom one electron in an atom a hydrogenlike atom.