View source for Physics:CERN Neutrinos to Gran Sasso

[[File:Underground structures at CERN.png|right|thumb|200px|alt=CERN Neutrinos to Gran Sasso Underground Structures|CERN Neutrinos to Gran Sasso Underground Structures]]
<!-- Deleted image removed: [[File:OPERA.png|right|thumb|400px|alt=Result of the OPERA experiment|Result of the OPERA experiment: The left plot shows δt as a function of the energy for νμ CC internal events, where δt (low-energy: <span style="text-decoration: overline">13.9</span> GeV) = (53.1 ± 18.8 (stat.) ± 7.4 (sys.)) ns and δt (high-energy: <span style="text-decoration: overline">42.9</span> GeV) = (67.1 ± 18.2 (stat.) ± 7.4 (sys.)) ns. The right plot shows the global result of the analysis including both internal and external events (for the latter the energy cannot be measured), where δt (average-energy: <span style="text-decoration: overline">17</span> GeV) = (60.7 ± 6.9 (stat.) ± 7.4 (sys.)) ns.]] -->
The '''CERN Neutrinos to Gran Sasso''' ('''CNGS''') project was a physics project of the [[Organization:CERN|European Organization for Nuclear Research]] (CERN). The aim of the project was to analyse the hypothesis of [[Physics:Neutrino oscillation|neutrino oscillation]] by directing a [[Physics:Accelerator neutrino|beam]] of [[Physics:Neutrino|neutrino]]s from CERN's facilities to the detector of the [[Physics:OPERA experiment|OPERA experiment]] at the [[Organization:Laboratori Nazionali del Gran Sasso|Gran Sasso National Laboratory]] (LNGS), located in the Gran Sasso mountain in Italy. The CNGS facility was housed in a tunnel which diverged from one of the SPS–LHC transfer tunnels, at the {{wipe|France}}–{{wipe|Switzerland}} border near [[Place:Geneva|Geneva]].<ref name="cngsdgve">{{cite web|url=http://proj-cngs.web.cern.ch/proj-cngs/Download/CNGSDGVE/cngsdgve.pdf|title=General Description of the CERN Project for a Neutrino Beam}}</ref> It used the [[Physics:Super Proton Synchrotron|Super Proton Synchrotron]] (SPS) accelerator as a source of high-energy [[Physics:Proton|proton]]s.

==History==
[[File:CNGS_tunnel.jpg|thumb|The magnetic horn being installed in the CNGS target chamber]]
Approval for the CNGS project was signed by the CERN Council in December 1999,<ref>{{cite web |url=http://proj-cngs.web.cern.ch/proj-cngs/ProjetOverview/projetoverview2002.htm |title=CNGS project Overview}}</ref> with civil engineering on the project starting the following September.<ref>{{cite web |url=http://proj-cngs.web.cern.ch/proj-cngs/PDF_files/IEEE06_CNGS.pdf |title=CERN Neutrinos to Gran Sasso (CNGS): First Beam}}</ref> Construction of the tunnels and service caverns was completed in mid-2004, with equipment installation completed in summer 2005 and commissioning being carried out throughout spring 2006. The first proton beam was sent to the target on 11 July 2006, with the CNGS facility being approved for physics operations on 18 August 2006. CNGS ceased operation in 2012. The tunnel was then repurposed for the [[Physics:AWAKE|AWAKE]] experiment, which became operational in 2016.

==Function==
A [[Physics:Proton|proton]] beam was taken from the SPS at {{val|400|ul=GeV}} and is made to collide with a [[Chemistry:Graphite|graphite]] target within the CNGS tunnel. The resulting particles, most importantly kaons and pions among many other particles, were then focused by [[Physics:Magnetic lens|magnetic lens]]ing and travelled {{convert|1|km}} down the CNGS tunnel in a vacuum tube. These particles are naturally unstable, and their decay products include [[Physics:Muon|muon]]s and [[Physics:Muon neutrino|muon neutrino]]s. All particles except neutrinos (protons, muons, pion, kaon...) stop near the end of the tunnel. The neutrinos continue their flight unaffected, as they rarely interact with matter. The number of muons was measured at this point, which gave an indication of the beam's profile and intensity. This beam then passed {{convert|732|km}} through the [[Earth:Crust (geology)|crust]] of the [[Astronomy:Earth|Earth]] and it is expected that during flight some of the muon neutrinos convert into other neutrino types such as [[Physics:Tau neutrino|tau neutrino]]s.<ref name="cngsdgve"/> Once the beam arrived at Gran Sasso, the [[Physics:OPERA experiment|OPERA]] and ICARUS experiments were used to detect the neutrinos.

==Results==
The first candidates for neutrino oscillation to tau neutrinos were announced in May 2010 by the OPERA experiment.<ref>{{cite web|url=http://www.lngs.infn.it/lngs_infn/contents/lngs_en/public/educational/physics/NEWS_docs/OPERA_press_rel_May_2010.pdf|title=Tau Neutrino embargo|access-date=2011-09-23|archive-date=2011-10-26|archive-url=https://web.archive.org/web/20111026201535/http://www.lngs.infn.it/lngs_infn/contents/lngs_en/public/educational/physics/NEWS_docs/OPERA_press_rel_May_2010.pdf|url-status=dead}}</ref> In total five tau neutrinos were observed,<ref>{{cite web |last=O'Luanaigh|first=C. |date=6 October 2015 |title=OPERA detects its fifth tau neutrino |url=https://home.cern/about/updates/2015/06/opera-detects-its-fifth-tau-neutrino |access-date=2017-02-08}}</ref> consistent with the expectations from the theory of [[Physics:Neutrino oscillation|neutrino oscillation]].

On 22 September 2011, the OPERA collaboration garnered international attention when they released a [[Preprint|preprint]]<ref>{{cite journal|arxiv=1109.4897|title=Measurement of the neutrino velocity with the OPERA detector in the CNGS beam|date=22 September 2011|author=T. Adam ''et al.'' (OPERA Collaboration)|doi=10.1007/JHEP10(2012)093|volume=2012|issue=10|pages=93|journal=Journal of High Energy Physics|bibcode = 2012JHEP...10..093A |s2cid=17652398}}</ref> reporting the [[Physics:Faster-than-light neutrino anomaly|Faster-than-light neutrino anomaly]], wherein neutrinos were measured to be travelling, on average, at [[Physics:Faster-than-light|faster-than-light]] speed.<ref>{{cite news|title=Speed-of-light experiments give baffling result at Cern|url=https://www.bbc.co.uk/news/science-environment-15017484|publisher=BBC|date=22 September 2011}}</ref>  On 24 February 2012, the team said they had discovered two problems with their previous test, muddying the validity of the previous result.<ref>{{cite news| url=https://www.bbc.co.uk/news/science-environment-17139635 | work=BBC News | title=Faster-than-light neutrinos could be down to bad wiring | date=23 February 2012}}</ref> The preprint has been modified to account for these facts, and indeed the measurement of the neutrino speed, there reported, agrees with the velocity of the light.

==References==
{{reflist}}

==External links==
* [http://www.cern.ch/proj-cngs Official CNGS project website]
* [https://archive.today/20120713232158/http://operaweb.lngs.infn.it/ Official OPERA experiment website]
* [http://www.lngs.infn.it/lngs_infn/contents/lngs_en/public/educational/physics/experiments/current/icarus/index.htm Official ICARUS experiment website] {{Webarchive|url=https://web.archive.org/web/20120328083910/http://www.lngs.infn.it/lngs_infn/contents/lngs_en/public/educational/physics/experiments/current/icarus/index.htm |date=2012-03-28 }}

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