{{SppbarS}}[[File:UA6_experiment.jpg|thumb|UA6 experiment at CERN]] The '''Underground Area 6''' ('''UA6'''), also referred to as PHOTONS, experiment was a [[high-energy physics]] experiment at the [[Proton-Antiproton Collider]] ('''Sp{{overline|p}}S'''), a modification of the [[Super Proton Synchrotron]] ('''SPS'''), at [[CERN]]. The experiment ran from 1984 to 1990, with the purpose of studying inclusive [[Electromagnetism|electromagnetic]] final states and [[Lambda baryon|lambda]] production in proton-[[antiproton]] and [[proton]]-proton interactions.<ref>{{Cite web |title=Greybook |url=https://greybook.cern.ch/experiment/detail?id=UA6 |access-date=2023-08-04 |website=greybook.cern.ch}}</ref><ref name=":0">{{Cite book |last=Snow |first=Gregory R. |editor-last1=Para |editor-first1=Adam |editor-last2=Anderson |editor-first2=D. F. |editor-last3=Derrick |editor-first3=M. |editor-last4=Fisk |editor-first4=H. E. |editor-last5=Sazama |editor-first5=Cynthia |chapter-url=https://books.google.com/books?id=6ocvDwAAQBAJ&dq=UA6+experiment&pg=PA251 |chapter=A novel triggering system for the UA6 electromagnetic calorimeter |title=Calorimetry in High Energy Physics - Proceedings of the International Conference |date=1991-08-08 |publisher=#N/A |isbn=978-981-4556-54-5 |language=en}}</ref> Towards the end of its run it focused more on direct-[[photon]] and [[J/psi meson|J/ψ]] production.<ref name=":1">{{Cite journal |date=31 Mar 1992 |title=Experimental Studies of Elementary Particle Interactions at High Energy |url=https://inis.iaea.org/collection/NCLCollectionStore/_Public/27/032/27032831.pdf |journal=The Rockefeller University}}</ref> The experiment is complementary to the [[UA1 experiment|UA1]], [[UA2 experiment|UA2]] and [[Collider Detector at Fermilab|CDF]] experiments.<ref name=":2">{{Cite book |last=Snow |first=Gregory R. |date=16 Nov 1988 |chapter=Direct Photon Physics From CERN Experiment UA6 |chapter-url=https://cds.cern.ch/record/192866/files/198812057.pdf |title=VIIth Topical Workshop on Proton–Antiproton Collider Physics, Fermilab, Batavia, Ill., USA, 2–24 June 1988}}</ref> [[File:UA6_diagram.png|thumb|Schematic diagram of the UA6 experiment]] UA6 is a [[Fixed-target experiment|fixed target experiment]] in which an internal [[Hydrogen|H<sub>2</sub>]] cluster [[Jet (particle physics)|jet]] is sent through the [[collider]] beams. The [[luminosity]] is measured with four [[silicon detector]] that count the recoil protons from the [[scattering]].<ref name=":3">{{Cite journal |last1=Morel |first1=C. |last2=Bernasconi |first2=A. |last3=Breedon |first3=R.E. |last4=Camilleri |first4=L. |last5=Cool |first5=R.L. |last6=Cox |first6=P.T. |last7=Cushman |first7=P.|author7-link=Priscilla Cushman |last8=Dick |first8=L. |last9=Dukes |first9=E.C. |last10=Gabioud |first10=B. |last11=Gaille |first11=F. |last12=Giacomelli |first12=P. |last13=Jeanneret |first13=J.B. |last14=Joseph |first14=C. |last15=Kubischta |first15=W. |date=Dec 1990 |title=Measurement of the inclusive J/ψ production cross sections in and pp collisions at √s = 24.3 GeV |url=https://linkinghub.elsevier.com/retrieve/pii/037026939090579U |journal=Physics Letters B |language=en |volume=252 |issue=3 |pages=505–510 |doi=10.1016/0370-2693(90)90579-U}}</ref> This is followed by a double-arm [[spectrometer]], with each arm consisting of five multiword [[Proportional Chamber|proportional chambers]] (PCs) spaced behind and in front of a [[dipole magnet]], an [[Ionization chamber|ionisation chamber]], a [[transition radiation detector]], and an [[electromagnetic calorimeter]]. The spectrometer is placed on the other side of the jet target for pp collisions.<ref name=":2" /> The signals for the [[Trigger (particle physics)|trigger]] decisions are provided by the calorimeter and a hodoscope of seven [[Scintillation counter|scintillation counters]] between the first two modules of the calorimeter.<ref name=":3" /><ref>{{Cite journal |last1=Dobinson |first1=Robert W |last2=Pages |first2=J L |last3=Vermeulen |first3=J C |date=1991 |title=Transputers in particle physics experiments |url=https://cds.cern.ch/record/233995/files/part.world.2.2.39-45.pdf |journal=Particle World |volume=2 |issue=2 |pages=39–45}}</ref>
[[File:UA6_computer_room.jpg|thumb|Computer room for the UA6 experiment]]Throughout the running of UA6 the detector setup was progressively upgraded, resulting in increased available antiproton luminosity, minimised background interactions, and improved trigger logic.<ref name=":1" />
Preliminary results of the experiment showed clear peaks in the data from the two-photon decays of the [[Pion|π<sup>0</sup>]] and η mesons.<ref>{{Cite journal |last=Dukes |first=Craig |date=1986 |title=PRELIMINARY RESULTS FROM EXPERIMENT UA6 ON INCLUSIVE pi0, eta AND GAMMA PRODUCTION FROM p anti-p COLLISIONS AT S**1/2 = 24-GeV |url=https://inspirehep.net/files/05c925c76f56a1a822871122d1fbf24b |journal=Strong Interactions and Gauge Theories.}}</ref> Results from the experiment was used to publish cross sections for π<sup>0</sup> and η production, [[direct photon]] production, [[elastic scattering]], and J/ψ production.<ref name=":0" /><ref>{{Cite book |last=Camilleri |first=Leslie |chapter=Comparison of direct γγ production in {{overline|p}}p and pp reactions at √s = 24.3 GeV |chapter-url=https://cds.cern.ch/record/2119955/files/c90-08-02-p1436.pdf |title=High-energy physics. Proceedings, 25th International Conference, Singapore, August 2-8, 1990. |volume=2 |year=1991 |pages=1436–1438 }}</ref><ref>{{Cite journal |last=Duclos |first=Jean |date=1989-06-19 |title=Experiments with internal targets in electron storage rings |url=https://dx.doi.org/10.1016/0375-9474%2889%2990456-9 |journal=Nuclear Physics A |language=en |volume=497 |pages=77–90 |doi=10.1016/0375-9474(89)90456-9 |bibcode=1989NuPhA.497...77D |issn=0375-9474|url-access=subscription }}</ref><ref>{{Cite journal |last1=Breedon |first1=R. E. |last2=Chapin |first2=T. J. |last3=Cool |first3=R. L. |last4=Cox |first4=P. T. |last5=Goulianos |first5=K. |last6=Petersen |first6=P. C. |last7=Rusack |first7=R. W. |last8=Snow |first8=G. R. |last9=Vacghi |first9=A. |last10=White |first10=S. N. |last11=Camilleri |first11=L. |last12=Dick |first12=L. |last13=Jeanneret |first13=J. B. |last14=Kubischra |first14=W. |last15=Von Dardel |first15=G. |date=1989-01-12 |title=Precise comparison of antiproton-proton and proton-proton forward elastic scattering at √s = 24.3 GeV |url=https://dx.doi.org/10.1016/0370-2693%2889%2991150-7 |journal=Physics Letters B |language=en |volume=216 |issue=3 |pages=459–465 |doi=10.1016/0370-2693(89)91150-7 |bibcode=1989PhLB..216..459B |issn=0370-2693|url-access=subscription }}</ref><ref name=":3" />
== See also ==
* [[UA2 experiment]] * [[List of Super Proton Synchrotron experiments]]
== External links ==
* [https://greybook.cern.ch/experiment/detail?id=UA6 CERN Greybook for UA6]
== References == <references /> {{SPS experiments}} [[Category:CERN experiments]] [[Category:Particle experiments]]