US3538328A - Scintillation-type ion detector employing a secondary emitter target surrounding the ion path - Google Patents

Scintillation-type ion detector employing a secondary emitter target surrounding the ion path Download PDF

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Publication number
US3538328A
US3538328A US710382A US3538328DA US3538328A US 3538328 A US3538328 A US 3538328A US 710382 A US710382 A US 710382A US 3538328D A US3538328D A US 3538328DA US 3538328 A US3538328 A US 3538328A
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Prior art keywords
ion
bore
scintillation
ion detector
scintillator
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Expired - Lifetime
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US710382A
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English (en)
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Yale E Strausser
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Varian Medical Systems Inc
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Varian Associates Inc
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
    • G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
    • G01T1/16—Measuring radiation intensity
    • G01T1/28—Measuring radiation intensity with secondary-emission detectors
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J49/00—Particle spectrometers or separator tubes
    • H01J49/02—Details
    • H01J49/025—Detectors specially adapted to particle spectrometers

Definitions

  • a scintillation-type ion detector includes an evacuable envelope structure containing a secondary emitter target electrode structure having a bore therethrough which is preferably of conical shape.
  • the inside surface of the bore is bombarded by the ions to be detected and is made of a material that emits secondary electrons on being bombarded by ions.
  • the secondary electron emission from the walls of the bore is focused onto a scintillator disposed facing the exit end of the bore to give an optical photon output which is transmitted through a window to a photo multiplier.
  • the principal object of the present invention is the provision of an improved scintillation-type ion detector.
  • One feature of the present invention is the provision of a scintillation-type ion detector having a secondary emitter electrode structure with a bore therein which is coaxially disposed of the ion beam path to be detected.
  • the ions to be detected are collected on the inside surfaces of the bore to produce secondary electron emission.
  • the secondary electrons are focused out the downstream end of the bore and onto a scintillatorphotomultiplier disposed in axial alignment with the ion 3,538,328 Patented Nov. 3, 1970 beam path and bore, whereby the geometry of the scintillation-type ion detector structure is simplified.
  • Another feature of the present invention is the same as the preceding feature wherein the bore in the secondary emitter electrode structure is conically shaped with the small end of the bore facing upstream of the ion beam path and the large end of the bore being disposed facing a plate-shaped scintillator, whereby focusing of the secondary electron emission onto the scintillator plate is facilitated to provide improved ion detection sensitivity.
  • FIG. 1 is a schematic, longitudinal sectional, line diagram of a scintillation-type ion detector of the present invention
  • FIG. 2 is a sectional line diagram of the structure of FIG. 1 taken along line 2--2 in the direction of the arrows, and
  • FIG. 3 is an enlarged sectional view of a portion of the structure of FIG. 1 delineated by line 3-3.
  • the ion detector 1 includes a tubular body 2, as of stainless steel, flanged at one end 3 for being sealed in a vacuum-tight manner to the vacuum envelope of a structure which produces a beam of ions 4, the current of which, is to be measured.
  • the other end of the tubular body member 2 is provided with a flange 5 for making a vacuum-tight connection to an annular metallic frame member 6 of a circular plate-like optically transparent window 7, as of glass, which is sealed across and closes off the downstream end of the tubular body section 2.
  • a transverse conductive disc 81 is disposed across the upstream end of the detector body 2 and includes a centrally disposed ion beam aperture 9 through which the beam 4 enters the detector 1.
  • a secondary electron emitter electrode structure 11, having an axially directed bore 12 therethrough, is disposed on the axis of the beam path 4 intermediate the beam entrance partition 8 and the window 7.
  • the inside surface of the bore 12 is made of a material having a good secondary electron emission ratio such as stainless steel.
  • the emitter electrode 11 is fed with a suitable negative potential as of minus 0:140 kv. relative to the body 2 via lead-in insulator structure 13 and a lead 14.
  • a scintillator layer 15 is disposed on the face of the window plate structure 7 facing the secondary emitter electrode 11.
  • the structural detail of the scintillator 15 and window are more fully disclosed .in FIG. 3.
  • the window member comprises a circular disc or plate 7 of glass having the scintillator phosphor layer 15 deposited thereon to a thickness of approximately 10 microns.
  • a photomultiplier tube 17, such as an RCA 4517 photomultiplier, is disposed in axial alignment with he ion beam path 4 adjacent the outside surface of the WlllClOW 7.
  • a tubular adapter 18 holds the photomultiplier tube 17 to the tubular detector body 2.
  • the spectral distribution of the phosphor 15 should be matched to the spectral response of the photomultiplier tube 17.
  • a suitable phosphor 15 is either a Sylvania or RCA P-4 phosphor.
  • a thin pinhole free conductive coating as of aluminum 16 is deposited, as by sputtering, over the inside surface of the phosphor 15 to a thickness of approximately 2000 A.
  • the aluminum layer 16 should be free of pinholes to form an opaque barrier between the beam entrance slit 9 and the phosphor 15 and photomultiplier tube 17 to prevent photons of light passing into or generated within the ion detector chamber 2. from passing through the layer .16 into the photomultiplier to produce background noise or currents.
  • the aluminum layer 16 serves as an electron permeable electrode structure and is electrically connected to ground potential or to the potential of the tubular body 2. Alternatively, the electrode structure 16 may be operated at an independent potential, if desired.
  • the aluminum electrode 16 also serves to reflect photons through the window 7 that are back-scattered from the scintillating event within the phosphor 15, thus improving the efficiency with which the electrons are converted into useful photons, i.e., photons which are detectable by the photomultiplier tube 17.
  • the secondary electron emission yield is improved, since the ions are more likely to be collected on the secondary emitting surface 12 at a glancing angle of incidence, thereby improving the secondary electron emission yield.
  • the conical shape for the bore 12 facilitates focusing of the emitted electrons into a spot on the scintillator 15, thereby reducing the chance that certain of the electrons will escape without producing photons in the scintillator '15-. Focusing the electrons to a spot on the phosphor 15 reduces the size of the required entrance aperture in the photomultiplier tube 17, thereby reducing the unwanted dark current output thereof.
  • the axial symmetry of the detecotr 1 facilitates its construction and thereby results in lower manufacturing costs.
  • the ion detector 1 of the present invention is especially useful for measuring the ion beam output of a mass spectrometer or ion vacuum gauge and is particularly desirable for use in an electrostatically focused mass spectrometer.
  • the surrounding nature of the secondary electron emitting electrode facilitates collection of ions having substantial components of velocity transverse to the ion beam path 4.
  • the ion detector 1 may also be utilized to advantage in magnetically focused mass spectrometers, but in such cases it is generally desirable to provide a magnetic shield surrounding the ion detector 1 to shield the magnetic field of the spectrometer out of the regions of the secondary emitting electrode 11 and photomultiplier tube 17.
  • the gain of the ion detector 1 may be readily varied by varying the potential applied to the secondary emitting electrode 11.
  • the gain is variable from to 10 by varying the minus potential applied to the secondary emitter etlectrode 11 from 500 volts to -7.5 kv.
  • Use of the stainless steel secondary emitting structure 11 allows the ion detector 1 to be unaffected by surface gases which tend to collect on the surfaces of the electrodes in use.
  • the ion collector electrode 11 had a cone angle of 40, i.e., the half angle of the cone was 40.
  • a scintillation type ion detector means forming a secondary emitter electrode structure for bombardment by the ions to be detected to give off secondary electron emission, means forming a scintillator for bombardment by the emitted secondary electrons to produce optical photon emission, means forming an evacuable envelope containing said secondary emitter electrode and said scintillator, means forming an optically transparent gas-tight window portion of said evacuable envelope for transmission of the optical photons through the wall of said envelope to an optical detector, the improvement wherein, said secondary emitter electrode structure has a bore surrounding the ion beam path and wherein the walls of said bore form the secondary electron emitter such that the ions are admitted into said bore at one end thereof and are collected on the inner surfaces of said bore to produce the secondary electrons which are focused by the inside surfaces of said bore onto said scintillator, wherein said bore in said secondary emitter electrode structure is conically shaped and said conical bore being disposed with its small end facing upstream of the ion path.
  • said optical Window is a plate with said scintillator disposed upon the inside face of said plate, the plane of said plate being substantially perpendicular to the longitudinal axis of said bore, and said downstream end of said bore being disposed facing said plate for focusing the secondary electrons out the downstream end of said bore onto said scintillator.
  • the apparatus of claim 2 including means forming a photomultiplier disposed adjacent the outside surface of said window plate for detecting the optical photons, said photomultiplier means being disposed in axial alignment with the longitudinal axis of said bore.

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Molecular Biology (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Measurement Of Radiation (AREA)
US710382A 1968-03-04 1968-03-04 Scintillation-type ion detector employing a secondary emitter target surrounding the ion path Expired - Lifetime US3538328A (en)

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US71038268A 1968-03-04 1968-03-04

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US (1) US3538328A (enrdf_load_stackoverflow)
DE (1) DE1908395A1 (enrdf_load_stackoverflow)
FR (1) FR2003139A1 (enrdf_load_stackoverflow)
GB (1) GB1202004A (enrdf_load_stackoverflow)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3676674A (en) * 1970-07-16 1972-07-11 Nasa Apparatus for ionization analysis
US3916187A (en) * 1971-10-14 1975-10-28 Nasa Cosmic dust analyzer
US4101771A (en) * 1975-08-04 1978-07-18 Hofer Wolfgang O Ion electron converter
EP0002152A1 (fr) * 1977-11-15 1979-05-30 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Spectrographe de masse
EP0002153A1 (fr) * 1977-11-15 1979-05-30 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Détecteur panoramique d'ions
FR2410290A1 (fr) * 1977-11-23 1979-06-22 Commissariat Energie Atomique Detecteur panoramique d'ions
US4223223A (en) * 1977-11-30 1980-09-16 Max-Planck-Gesellschaft zur Foerderung der Wissenschafter e.V. Broad-range ion mass spectrometer
US4649276A (en) * 1985-03-13 1987-03-10 Capintec, Inc. High-energy radiation detector and method of detection
US20040262531A1 (en) * 2002-08-08 2004-12-30 Gerlach Robert L. Particle detector suitable for detecting ions and electrons
DE19752209B4 (de) * 1996-12-26 2009-07-30 Shimadzu Corp. Ionendetektor
US20100294931A1 (en) * 2009-05-24 2010-11-25 Oren Zarchin Charged particle detection system and method
US8164059B2 (en) 2007-06-18 2012-04-24 Fei Company In-chamber electron detector
CN103127743A (zh) * 2012-12-29 2013-06-05 聚光科技(杭州)股份有限公司 离子萃取装置及方法
CN103984002A (zh) * 2014-04-28 2014-08-13 中国工程物理研究院流体物理研究所 含混合离子束流的h+离子截面信号采集系统和方法
US9053892B2 (en) 2010-12-30 2015-06-09 Walter Kidde Portable Equipment, Inc. Ionization device
JP2017224596A (ja) * 2016-05-03 2017-12-21 レインツリー サイエンティフィック インストゥルメンツ （シャンハイ） コーポレーションＲａｉｎｔｒｅｅ Ｓｃｉｅｎｔｉｆｉｃ Ｉｎｓｔｒｕｍｅｎｔｓ （Ｓｈａｎｇｈａｉ） Ｃｏｒｐｏｒａｔｉｏｎ 帯電粒子検出装置

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2160798A (en) * 1936-11-20 1939-05-30 Bell Telephone Labor Inc Electron discharge apparatus
US3041453A (en) * 1959-07-31 1962-06-26 Atomic Energy Authority Uk Positive ion detector

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2160798A (en) * 1936-11-20 1939-05-30 Bell Telephone Labor Inc Electron discharge apparatus
US3041453A (en) * 1959-07-31 1962-06-26 Atomic Energy Authority Uk Positive ion detector

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3676674A (en) * 1970-07-16 1972-07-11 Nasa Apparatus for ionization analysis
US3916187A (en) * 1971-10-14 1975-10-28 Nasa Cosmic dust analyzer
US4101771A (en) * 1975-08-04 1978-07-18 Hofer Wolfgang O Ion electron converter
EP0002152A1 (fr) * 1977-11-15 1979-05-30 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Spectrographe de masse
EP0002153A1 (fr) * 1977-11-15 1979-05-30 COMMISSARIAT A L'ENERGIE ATOMIQUE Etablissement de Caractère Scientifique Technique et Industriel Détecteur panoramique d'ions
FR2408910A1 (fr) * 1977-11-15 1979-06-08 Commissariat Energie Atomique Spectrographe de masse
US4322629A (en) * 1977-11-15 1982-03-30 Commissariat A L'energie Atomique Mass spectrograph
US4398090A (en) * 1977-11-15 1983-08-09 Commissariat A L'energie Atomique Panoramic ion detector
FR2410290A1 (fr) * 1977-11-23 1979-06-22 Commissariat Energie Atomique Detecteur panoramique d'ions
US4223223A (en) * 1977-11-30 1980-09-16 Max-Planck-Gesellschaft zur Foerderung der Wissenschafter e.V. Broad-range ion mass spectrometer
US4649276A (en) * 1985-03-13 1987-03-10 Capintec, Inc. High-energy radiation detector and method of detection
DE19752209B4 (de) * 1996-12-26 2009-07-30 Shimadzu Corp. Ionendetektor
US20040262531A1 (en) * 2002-08-08 2004-12-30 Gerlach Robert L. Particle detector suitable for detecting ions and electrons
US7009187B2 (en) 2002-08-08 2006-03-07 Fei Company Particle detector suitable for detecting ions and electrons
US8164059B2 (en) 2007-06-18 2012-04-24 Fei Company In-chamber electron detector
US20100294931A1 (en) * 2009-05-24 2010-11-25 Oren Zarchin Charged particle detection system and method
US8222600B2 (en) 2009-05-24 2012-07-17 El-Mul Technologies Ltd. Charged particle detection system and method
US9053892B2 (en) 2010-12-30 2015-06-09 Walter Kidde Portable Equipment, Inc. Ionization device
CN103127743A (zh) * 2012-12-29 2013-06-05 聚光科技(杭州)股份有限公司 离子萃取装置及方法
CN103984002A (zh) * 2014-04-28 2014-08-13 中国工程物理研究院流体物理研究所 含混合离子束流的h+离子截面信号采集系统和方法
JP2017224596A (ja) * 2016-05-03 2017-12-21 レインツリー サイエンティフィック インストゥルメンツ （シャンハイ） コーポレーションＲａｉｎｔｒｅｅ Ｓｃｉｅｎｔｉｆｉｃ Ｉｎｓｔｒｕｍｅｎｔｓ （Ｓｈａｎｇｈａｉ） Ｃｏｒｐｏｒａｔｉｏｎ 帯電粒子検出装置

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Publication number Publication date
FR2003139A1 (enrdf_load_stackoverflow) 1969-11-07
DE1908395A1 (de) 1969-09-25
GB1202004A (en) 1970-08-12

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