Gas electron multiplier detectors with high reliability and. We are developing dose imaging detectors based on gas electron multipliers gem with the goal of improving dose measurement linearity, position and timing resolution, and to ultimately allow pretreatment verification of dose distributions and dose. Development of gas electron multipliers with resistive. 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. Introduction xray astronomy is our primary window to the portion of the universe characterized by high temperatures and explosive behavior. Chapter 6 free electron fermi gas national tsing hua.
Multipliers can be either a discrete dynode type or a continuous dynode, generally known as a channel electron multiplier or channeltron. The operating principles of gems and their main characteristics, including the physics of multistage. Radiation detectors based on gas electron multipliers. Contrasting differences between discrete and continuous electron multipliers. Electron multipliers have a few weaknesses as detectors. Our core technology uses ion and electron optical simulation, magnetic modelling, and innovative electron emission materials combined with their bespoke dynode designs to provide. Chromatography direct would like to use cookies to store information on your computer, to improve our website and your experience. Electron multiplier an overview sciencedirect topics. In a process called secondary emission, a single electron can, when bombarded on secondaryemissive material, induce emission of roughly 1 to 3 electrons.
Gas electron multiplying detectors for medical applications. 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. Other articles where electron multiplier is discussed. 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. A fast charged particle traverses the gas, causing ionization. Valence electrons form the electron gas electron gas model in metals ez a ez az ez figure 1. 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. The properties and some potential applications of these simple and robust multipliers are discussed. The discrete dynode electron multiplier comprises a series of becu alloy dynodes arranged. A gas electron multiplier with metal electrodes springerlink. Scientific instrument services provides replacement detectors from the major manufacturers of electron multipliers.
Gas electron multipliers versus multi wire proportional. As one progresses from visible light to the extreme uv, our view of the cosmos beyond the local. The novel ion detector overcomes the performance barriers on traditional electron multipliers and will provide the most suitable results to meet users requirements. His achievements include inventing the gas electron multiplier gem, which is. The fragments that survive the journey through the analyzer shoot into the electron multiplier the detector of the gcms. The simplest metals are the alkali metals lithium, sodium, potassium, na, cesium, and rubidium. Electron multiplier definition of electron multiplier by. Xray detectors, gas electron multipliers, coded masks, xray astronomy, allsky monitors 1. Sauli in 1996 and is in use in high energy and medical physics, provides the. Read open access proceedings from science conferences worldwide books. After an introduction on the operation of gaseous detectors, the book. Due to the high voltages involved, gas discharges that could destroy the sem can occur at high pressures of p 105 hpa.
The main advantage of these gas electron multipliers compared to standard ones consists in their increased stability and reliability. An understanding of the aging process in electron multipliers is a necessary precursor to developing a verylonglife mass spectrometer detector. Gas electron multipliers gems, thick gas electron multipliersthgems, etc. 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 gap. Structure electron multiplier r8811 features an offaxis structure and a faraday cup, required for ion detection in quadrupole mass spectrometers that can make accurate. 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. In particular, gas electron multipliers gems are one of the most widely used micro patterned gaseous detectors. We measured the gain curve of regem using an 55 fe radioactive source in the gas mixture of ar 70% and co 2 30%. Gas electron multiplier detectors with high reliability and stability b.
The gem gas electron multiplier technology, which has been introduced by f. We successfully produced resistiveelectrode gem regem that was applied resistivekapton to electrodes. The operating principles of gems and their main characteristics, including the physics of multistage gems and. The gem belongs to the family of holetype detectors made of. 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. If an electric potential is applied between this metal plate and yet another, the emitted electrons will accelerate to the next metal plate and induce. Electron multipliers etp scientific analytical west. 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. The standard gas electron multiplier gem invented by f. Although originally invented for the amplification of the tiny currents from a photocathode, it soon.
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. We have developed various type gems using a laser etching technique. The gas electron multiplier gem is a new device that amplifies an input electron cloud, while keeping its shape unchanged 1. 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 under harsh. Detector technology has developed an unconventional style of channel electron multipliers that has the capability of operating in this high pressure range. 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. This chapter describes another popular micropattern detector, the gas electron multiplier gem. Sauli 1 consists of high density holes etched in 50. Feb 01, 2011 we are developing dose imaging detectors based on gas electron multipliers gem with the goal of improving dose measurement linearity, position and timing resolution, and to ultimately allow pretreatment verification of dose distributions and dose delivery monitoring employing scanning beam technology. Gas electron multipliers versus multi wire proportional chambers. The valence electrons of the constituent atoms become conduction electrons and move about freely through the volume of the metal. Gas electron multipliers versus multiwire proportional chambers serge duarte pinto, tu delft, netherlands jens spanggaard, cern, geneva switzerland abstract gas electron multiplication technology is nding more andmore applications in beam instrumentation andat cern these detectors have recently been adapted for use in trans. 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. Dose imaging detectors for radiotherapy based on gas.
A gas electron multiplier gem is a type of gaseous ionization detector used in nuclear and. Electron multiplier article about electron multiplier by. Continuous secondary electron multiplier csem a csem figure 6. Pdf remarkable features of gas electron multipliers gems make them attractive for numerous applications in highenergy physics, nuclear. Development of gas electron multipliers with resistive kapton.
Monographs on particle physics, nuclear physics and cosmology book 36. Their robust construction and flexible discrete dynode design make them the. Analytical west stocks a full line of replacement electron multipliers manufactured by detector technology detech and etp. 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. The most common detector in mass spectrometry is the electron multiplier. Gas electron multipliers for potential applications to. The standard cern gems consist of an insulator made of a thin kapton foil about 50.
Etp scientific electron multipliers etp active film multipliers are incorporated as original equipment in virtually every major quadrupole icpms instrument being manufactured today. The first dynode excited by such particles or radiation. The gas electron multiplier detectors with wire and metallic electrodes, with a gas filling in the gap between them were proposed and tested. Multipliers for all major mass spectrometers agilent, perkinelmer, varian, thermo fisher and others are available for immediate shipment to your laboratory. Electron multipliers are grouped into the following basic types. Buy discounted electronmultipliers chromatography direct. 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 as shown in fig. A gas electron multiplier with metal electrodes, which is characterized by simplicity and high manufacturing accuracy, reliability, and stability, has been fabricated and tested. The classical theory had several conspicuous successes, notably the derivation of the form of ohms law and the relation between the.
There the electrons gain so much energy that they cause further ionization. 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. Advances in thick gemlike gaseous electron multipliers. As voltage increases the amplification factor also known as gain. Gaseous electron multipliers, radiation imaging detectors, gas avalanche multiplication, hole multiplication, uv photon detectors. By studying the dynode surfaces of an etp active film multiplier, we have isolated the major factors influencing. Compact electron multiplier for positive ion detection. 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. Gas electron multipliers the gem gas electron multiplier technology, which has been introduced by f. Pdf gain properties of gas electron multipliers gems. The electron multiplier detects every ion of the selected mass that passes through the quadrupole analyzer.
Pdf gain properties of gas electron multipliers gems for. Dose imaging detectors for radiotherapy based on gas electron. The main peak at 27kev is not well pronounced because an electron after photoabsorption has a range of about 2mm and often escapes the 4mm drift gap. This device consists of a thin insulating foil of several tens of. Use of gas electron multiplier gem detectors for an. The low noise currents created are used to measure the ion signal from sample in a wide variety of icpms applications. First performance evaluation of a multilayer thick gaseous. Introduced by the author in 1997, the gas electron multiplier gem constitutes a powerful addition to the family of fast radiation detectors. Gas electron multipliers gems have been overcoated with a high resistivity 10e14 10e15 ohms square amorphous carbon layer. Electron multipliers use a process known as secondary electron. This chapter describes the process of electron avalanche multiplication, which is the only method known to detect the smallest possible electrical signal, a. Our detectors are used in a wide array of applications including mass spectrometry, rgas, process monitoring, photon detection, and esca. Innovative applications and developments of micropattern. We obtained the maximum gain of about 300 at an applied voltage of 740 v.
Gas electron multiplier detectors with high reliability. Highphotonyield scintillation detector with arcf4 and. Electrons in one atom one electron in an atom a hydrogenlike atom. An electron multiplier is a vacuumtube structure that multiplies incident charges. 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. Different from conventional holetype multipliers e. Figure 121 shows typical electron multiplier tubes. Among them is their inability to readily detect negative ions and their mass discrimination. Introduced by the author in 1997, the gas electron multiplier gem has been developed since by many research groups and used in a wide range of applications, from fast trackers in particle. Some of the cookies we use are essential for parts of the site to operate and have already been set. First performance evaluation of a multilayer thick. The agilent electron multiplier converts incident ions into an amplified electric current in a stable, precision process.
1201 1201 614 1042 1169 414 279 253 501 1541 458 1237 693 644 52 602 1348 340 1347 1407 1403 76 310 775 1088 1110 284 55 274 511 264 1131 1555 211 9 560 1063 1317 337 354 824 375 1385