APXS is also an abbreviation for APache eXtenSion tool, an extension for Apache web servers.
An alpha particle X-ray spectrometer (APXS) is a spectrometer that analyses the chemical element composition of a sample from scattered alpha particles and fluorescent X-rays after a sample is irradiated with alpha particles and X-rays from radioactive sources.[1] This method of analysing the elemental composition of a sample is most often used on space missions, which require low weight, small size, and minimal power consumption. Other methods (e.g. mass spectrometry) are faster, and do not require the use of radioactive materials, but require larger equipment with greater power requirements. A variation is the alpha proton X-ray spectrometer, such as on the Pathfinder mission, which also detects protons.
Alpha particle X-ray spectrometer (top left), APXS at the back of the Mars Pathfinder Sojourner rover(top right), MSL Curiosity's alpha particle X-ray spectrometer, with a ruler (bottom).
Several forms of radiation are used in APXS. They include alpha particles, protons, and X-rays. Alpha particles, protons, and X-rays are emitted during the radioactive decay of unstable atoms. A common source of alpha particles is curium-244. It emits particles with an energy of 5.8 MeV. X-rays of 14 and 18 keV are emitted in the decay of plutonium-240. The Mars Exploration Rovers' Athena payload uses curium-244 with a source strength of approximately 30 millicuries (1.1 GBq).[10]
Some of the alpha particles of a defined energy are backscattered to the detector if they collide with an atomic nucleus. The physical laws for Rutherford backscattering in an angle close to 180° are conservation of energy and conservation of linear momentum. This makes it possible to calculate the mass of the nucleus hit by the alpha particle.
Light elements absorb more energy of the alpha particle, while alpha particles are reflected by heavy nuclei nearly with the same energy. The energy spectrum of the scattered alpha particle shows peaks from 25% up to nearly 100% of the initial alpha particles. This spectrum makes it possible to determine the composition of the sample, especially for the lighter elements. The low backscattering rate makes prolonged irradiation necessary, approximately 10 hours.
Protons
Some of the alpha particles are absorbed by the atomic nuclei. The [alpha,proton] process produces protons of a defined energy which are detected. Sodium, magnesium, silicon, aluminium and sulfur can be detected by this method. This method was only used in the Mars Pathfinder APXS. For the Mars Exploration Rovers the proton detector was replaced by a second alpha particle sensor. So it is also called alpha particle X-ray spectrometer.
X-ray
The alpha particles are also able to eject electrons from the inner shell (K- and L-shell) of an atom. These vacancies are filled by electrons from outer shells, which results in the emission of a characteristic X-ray. This process is termed particle-induced X-ray emission and is relatively easy to detect and has its best sensitivity and resolution for the heavier elements.
Specific instruments
Alpha-X, for DAS lander on Phobos 1 and Phobos 2.[6][11]
ALPHA, for Mars 96 landers. Collaboration between Germany, Russia, and USA.[12]
Alpha Particle X-ray Spectrometer, for Curiosity (MSL). The principal investigator for Curiosity's APXS is Ralf Gellert, a physicist at the University of Guelph in Ontario, Canada. It was developed and funded by the Canadian Space Agency, with operations also supported by Guelph and United States' space administration.[16]
^ Economou, T.E.; Turkevich, A.L.; Sowinski, K.P.; Patterson, J.H.; Franzgrote, E.J. (1970). "The Alpha-Scattering Technique of Chemical Analysis". Journal of Geophysical Research. 75 (32): 6514. Bibcode:1970JGR....75.6514E. doi:10.1029/JB075i032p06514.
^ Patterson, J.H.; Franzgrote, E.J.; Turkevich, A.L.; Anderson, W.A.; Economou, T.E.; Griffin, H.E.; Grotch, S.L.; Sowinski, K.P. (1969). "Alpha-scattering experiment on Surveyor 7 – Comparison with Surveyors 5 and 6". Journal of Geophysical Research. 74 (25): 6120–48. Bibcode:1969JGR....74.6120P. doi:10.1029/JB074i025p06120.
^ R. Rieder; H. Wänke; T. Economou; A. Turkevich (1997). "Determination of the chemical composition of Martian soil and rocks:The alpha proton X ray spectrometer". Journal of Geophysical Research. 102 (E2): 4027–4044. Bibcode:1997JGR...102.4027R. doi:10.1029/96JE03918.
^ Rieder, R.; Wanke, H.; Economou, T. (1997). "An Alpha Proton X-Ray Spectrometer for Mars-96 and Mars Pathfinder". American Astronomical Society. 28: 1062. Bibcode:1996DPS....28.0221R.
^ R. Rieder; R. Gellert; J. Brückner; G. Klingelhöfer; G. Dreibus; A. Yen; S. W. Squyres (2003). "The new Athena alpha particle X-ray spectrometer for the Mars Exploration Rovers". Journal of Geophysical Research. 108 (E12): 8066. Bibcode:2003JGRE..108.8066R. doi:10.1029/2003JE002150.
^ ab Hovestadt, D.; Andreichikov, B.; Bruckner, J.; Economou, T.; Klecker, B.; Kunneth, E.; Laeverenz, P.; Mukhin, L.; et al. (1988). "In-Situ Measurement of the Surface Composition of the Mars Moon Phobos: The Alpha-X Experiment on the Phobos Mission". Abstracts of the Lunar and Planetary Science Conference. 19: 511. Bibcode:1988LPI....19..511H.
^ abhttp://www.uni-mainz.de/, Johannes Gutenberg Universität Mainz, Alpha particle x-ray spectrometer developed in Mainz to be used on comet Churyumov–Gerasimenko, 10 April 2014
Media related to Alpha particle X-ray spectrometer (APXS) at Wikimedia Commons
H. Wänke; J. Brückner; G. Dreibus; R. Rieder; I. Ryabchikov (2001). "Chemical Composition of Rocks and Soils at the Pathfinder Site". Space Science Reviews. 96 (1/4): 317–330. doi:10.1023/A:1011961725645.
August 22, 2023
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APXS is also an abbreviation for APache eXtenSion tool an extension for Apache web servers An alpha particle X ray spectrometer APXS is a spectrometer that analyses the chemical element composition of a sample from scattered alpha particles and fluorescent X rays after a sample is irradiated with alpha particles and X rays from radioactive sources 1 This method of analysing the elemental composition of a sample is most often used on space missions which require low weight small size and minimal power consumption Other methods e g mass spectrometry are faster and do not require the use of radioactive materials but require larger equipment with greater power requirements A variation is the alpha proton X ray spectrometer such as on the Pathfinder mission which also detects protons Alpha particle X ray spectrometer top left APXS at the back of the Mars Pathfinder Sojourner rover top right MSL Curiosity s alpha particle X ray spectrometer with a ruler bottom Over the years several modified versions of this type of instrument such as APS without X ray spectrometer or APXS have been flown Surveyor 5 7 2 Mars Pathfinder 3 Mars 96 4 Mars Exploration Rover 5 Phobos 6 Mars Science Laboratory and the Philae comet lander 7 8 APS APXS devices will be included on several upcoming missions including the Chandrayaan 2 lunar rover 9 Contents 1 Sources 2 Alpha particles 3 Protons 4 X ray 5 Specific instruments 6 Gallery 7 References 8 External linksSources EditSeveral forms of radiation are used in APXS They include alpha particles protons and X rays Alpha particles protons and X rays are emitted during the radioactive decay of unstable atoms A common source of alpha particles is curium 244 It emits particles with an energy of 5 8 MeV X rays of 14 and 18 keV are emitted in the decay of plutonium 240 The Mars Exploration Rovers Athena payload uses curium 244 with a source strength of approximately 30 millicuries 1 1 GBq 10 Alpha particles Edit Sojourner takes its APXS measurement of the Yogi Rock Some of the alpha particles of a defined energy are backscattered to the detector if they collide with an atomic nucleus The physical laws for Rutherford backscattering in an angle close to 180 are conservation of energy and conservation of linear momentum This makes it possible to calculate the mass of the nucleus hit by the alpha particle Light elements absorb more energy of the alpha particle while alpha particles are reflected by heavy nuclei nearly with the same energy The energy spectrum of the scattered alpha particle shows peaks from 25 up to nearly 100 of the initial alpha particles This spectrum makes it possible to determine the composition of the sample especially for the lighter elements The low backscattering rate makes prolonged irradiation necessary approximately 10 hours Protons EditSome of the alpha particles are absorbed by the atomic nuclei The alpha proton process produces protons of a defined energy which are detected Sodium magnesium silicon aluminium and sulfur can be detected by this method This method was only used in the Mars Pathfinder APXS For the Mars Exploration Rovers the proton detector was replaced by a second alpha particle sensor So it is also called alpha particle X ray spectrometer X ray EditThe alpha particles are also able to eject electrons from the inner shell K and L shell of an atom These vacancies are filled by electrons from outer shells which results in the emission of a characteristic X ray This process is termed particle induced X ray emission and is relatively easy to detect and has its best sensitivity and resolution for the heavier elements Specific instruments EditAlpha X for DAS lander on Phobos 1 and Phobos 2 6 11 ALPHA for Mars 96 landers Collaboration between Germany Russia and USA 12 Alpha Proton X Ray Spectrometer for Mars Pathfinder by the Max Planck Institute and the University of Chicago 13 Alpha Particle X ray Spectrometer for Spirit MER A and Opportunity MER B Mars Exploration Rovers 14 15 Alpha Particle X ray Spectrometer for Curiosity MSL The principal investigator for Curiosity s APXS is Ralf Gellert a physicist at the University of Guelph in Ontario Canada It was developed and funded by the Canadian Space Agency with operations also supported by Guelph and United States space administration 16 Alpha Particle X ray Spectrometer for Philae the European Space Agency s lander attached to Rosetta to study the comet 67P Churyumov Gerasimenko 7 Gallery Edit Bonanza King rock on Mars cleaned with Dust Removal Tool 17 August 2014 Bonanza King rock on Mars dusted and initially drilled 11 September 2014 Bonanza King rock on Mars drilling stopped due to loose rock 11 September 2014 Bonanza King rock on Mars APXS analysis Curiosity rover 11 September 2014 References Edit Economou T E Turkevich A L Sowinski K P Patterson J H Franzgrote E J 1970 The Alpha Scattering Technique of Chemical Analysis Journal of Geophysical Research 75 32 6514 Bibcode 1970JGR 75 6514E doi 10 1029 JB075i032p06514 Patterson J H Franzgrote E J Turkevich A L Anderson W A Economou T E Griffin H E Grotch S L Sowinski K P 1969 Alpha scattering experiment on Surveyor 7 Comparison with Surveyors 5 and 6 Journal of Geophysical Research 74 25 6120 48 Bibcode 1969JGR 74 6120P doi 10 1029 JB074i025p06120 R Rieder H Wanke T Economou A Turkevich 1997 Determination of the chemical composition of Martian soil and rocks The alpha proton X ray spectrometer Journal of Geophysical Research 102 E2 4027 4044 Bibcode 1997JGR 102 4027R doi 10 1029 96JE03918 Rieder R Wanke H Economou T 1997 An Alpha Proton X Ray Spectrometer for Mars 96 and Mars Pathfinder American Astronomical Society 28 1062 Bibcode 1996DPS 28 0221R R Rieder R Gellert J Bruckner G Klingelhofer G Dreibus A Yen S W Squyres 2003 The new Athena alpha particle X ray spectrometer for the Mars Exploration Rovers Journal of Geophysical Research 108 E12 8066 Bibcode 2003JGRE 108 8066R doi 10 1029 2003JE002150 a b Hovestadt D Andreichikov B Bruckner J Economou T Klecker B Kunneth E Laeverenz P Mukhin L et al 1988 In Situ Measurement of the Surface Composition of the Mars Moon Phobos The Alpha X Experiment on the Phobos Mission Abstracts of the Lunar and Planetary Science Conference 19 511 Bibcode 1988LPI 19 511H a b http www uni mainz de Johannes Gutenberg Universitat Mainz Alpha particle x ray spectrometer developed in Mainz to be used on comet Churyumov Gerasimenko 10 April 2014 Alpha Proton X ray Spectrometer APXS Mission Name Philae NASA 26 August 2014 Payloads for Chandrayaan 2 Mission Finalised isro gov in Indian Space Research Organisation 30 August 2010 Archived from the original on 15 October 2012 Retrieved 7 August 2012 unknown Alpha Particle X Ray Spectrometer APXS 2 pages PDF JPL QuickLook Phobos 1 2 SMALL AUTONOMOUS STATIONS Mars 96 Mars Pathfinder Instrument Descriptions NASA ATHENA Cornell University Mars Exploration Rovers Spacecraft Surface Operations Instruments Alpha Particle X Ray Spectrometer APXS NASA JPL NASA Alpha Particle X ray Spectrometer APXS External links Edit Look up APXS in Wiktionary the free dictionary Media related to Alpha particle X ray spectrometer APXS at Wikimedia Commons H Wanke J Bruckner G Dreibus R Rieder I Ryabchikov 2001 Chemical Composition of Rocks and Soils at the Pathfinder Site Space Science Reviews 96 1 4 317 330 doi 10 1023 A 1011961725645 Retrieved from https en wikipedia org w index php title Alpha particle X ray spectrometer amp oldid 1122496181, wikipedia, wiki, book, books, library,
