Editing CERN Axion Solar Telescope (section)

== Detectors ==
The CAST focuses on the solar axions using a [[helioscope]], which is a 9.2&nbsp;m superconducting [[Large Hadron Collider|LHC]] prototype dipole magnet. The superconductive magnet is maintained by constantly keeping it at 1.8 Kelvin using [[superfluid helium]]. There are two magnetic bores of 43&nbsp;mm diameter and 9.2&nbsp;6m length with X-ray detectors placed at all ends. These detectors are sensitive to photons from [[Primakoff effect|inverse Primakoff conversion]] of solar axions. The two X-ray telescopes of CAST measures both signal and background simultaneously with the same detector and reduces the systematic uncertainties.<ref name=":4">{{cite journal | last1=Álvarez Melcón | first1=A. | last2=Arguedas Cuendis | first2=S. | last3=Baier | first3=J. | last4=Barth | first4=K. | last5=Bräuninger | first5=H. | last6=Calatroni | first6=S. | last7=Cantatore | first7=G. | last8=Caspers | first8=F. | last9=Castel | first9=J. F. | last10=Cetin | first10=S. A. | last11=Cogollos | first11=C. | last12=Dafni | first12=T. | last13=Davenport | first13=M. | last14=Dermenev | first14=A. | last15=Desch | first15=K. | last16=Díaz-Morcillo | first16=A. | last17=Döbrich | first17=B. | last18=Fischer | first18=H. | last19=Funk | first19=W. | last20=Gallego | first20=J. D. | last21=García Barceló | first21=J. M. | last22=Gardikiotis | first22=A. | last23=Garza | first23=J. G. | last24=Gimeno | first24=B. | last25=Gninenko | first25=S. | last26=Golm | first26=J. | last27=Hasinoff | first27=M. D. | last28=Hoffmann | first28=D. H. H. | last29=Irastorza | first29=I. G. | last30=Jakovčić | first30=K. | last31=Kaminski | first31=J. | last32=Karuza | first32=M. | last33=Lakić | first33=B. | last34=Laurent | first34=J. M. | last35=Lozano-Guerrero | first35=A. J. | last36=Luzón | first36=G. | last37=Malbrunot | first37=C. | last38=Maroudas | first38=M. | last39=Miralda-Escudé | first39=J. | last40=Mirallas | first40=H. | last41=Miceli | first41=L. | last42=Navarro | first42=P. | last43=Ozbey | first43=A. | last44=Özbozduman | first44=K. | last45=Peña Garay | first45=C. | last46=Pivovaroff | first46=M. J. | last47=Redondo | first47=J. | last48=Ruz | first48=J. | last49=Ruiz Chóliz | first49=E. | last50=Schmidt | first50=S. | last51=Schumann | first51=M. | last52=Semertzidis | first52=Y. K. | last53=Solanki | first53=S. K. | last54=Stewart | first54=L. | last55=Tsagris | first55=I. | last56=Vafeiadis | first56=T. | last57=Vogel | first57=J. K. | last58=Widmann | first58=E. | last59=Wuensch | first59=W. | last60=Zioutas | first60=K. | title=First results of the CAST-RADES haloscope search for axions at 34.67 μeV | journal=Journal of High Energy Physics | publisher=Springer Science and Business Media LLC | volume=2021 | issue=10 | year=2021 | page=75 | issn=1029-8479 | doi=10.1007/jhep10(2021)075 |bibcode=2021JHEP...10..075A|s2cid=233423635|arxiv=2104.13798|display-authors=3}}</ref><ref name=":2">{{Cite web|title=CAST in Time – The Quest for Axions and Chameleons|url=https://ep-news.web.cern.ch/content/cast-time-quest-axions-and-chameleons|access-date=2021-06-14|website=EP News|language=en}}</ref>

From 2003 to 2013, the following three detectors were attached to ends of the dipole magnet, all based on the inverse Primakoff effect, to detect the photons converted from the solar axions.<ref name=":3">{{cite journal | last1=Kuster | first1=M | last2=Bräuninger | first2=H | last3=Cebrián | first3=S | last4=Davenport | first4=M | last5=Eleftheriadis | first5=C | last6=Englhauser | first6=J | last7=Fischer | first7=H | last8=Franz | first8=J | last9=Friedrich | first9=P | last10=Hartmann | first10=R | last11=Heinsius | first11=F H | last12=Hoffmann | first12=D H H | last13=Hoffmeister | first13=G | last14=Joux | first14=J N | last15=Kang | first15=D | last16=Königsmann | first16=K | last17=Kotthaus | first17=R | last18=Papaevangelou | first18=T | last19=Lasseur | first19=C | last20=Lippitsch | first20=A | last21=Lutz | first21=G | last22=Morales | first22=J | last23=Rodríguez | first23=A | last24=Strüder | first24=L | last25=Vogel | first25=J | title=The x-ray telescope of CAST | journal=New Journal of Physics | publisher=IOP Publishing | volume=9 | issue=6 | date=2007-06-22 | issn=1367-2630 | doi=10.1088/1367-2630/9/6/169 | pages=169 |arxiv=physics/0702188 | bibcode=2007NJPh....9..169K | s2cid=92986351 | display-authors=3}}</ref>

# Conventional [[time projection chamber]] detectors (TPC).
# MICROMEsh GAseous Structure detectors (MICROMEGAS).
# X-ray telescope with a [[Charge-coupled device|charged couple device]] (CCD).

After 2013 several new detectors such as the RADES, GridPix, and KWISP were installed, with modified goals and newly enhanced technologies.<ref name=":0">{{cite journal | last1=Abbon | first1=P | last2=Andriamonje | first2=S | last3=Aune | first3=S | last4=Dafni | first4=T | last5=Davenport | first5=M | last6=Delagnes | first6=E | last7=Oliveira | first7=R de | last8=Fanourakis | first8=G | last9=Ribas | first9=E Ferrer | last10=Franz | first10=J | last11=Geralis | first11=T | last12=Giganon | first12=A | last13=Gros | first13=M | last14=Giomataris | first14=Y | last15=Irastorza | first15=I G | last16=Kousouris | first16=K | last17=Morales | first17=J | last18=Papaevangelou | first18=T | last19=Ruz | first19=J | last20=Zachariadou | first20=K | last21=Zioutas | first21=K | title=The Micromegas detector of the CAST experiment | journal=New Journal of Physics | publisher=IOP Publishing | volume=9 | issue=6 | date=2007-06-22 | issn=1367-2630 | doi=10.1088/1367-2630/9/6/170 | pages=170 |display-authors=3 |doi-access=free |arxiv=physics/0702190 |bibcode=2007NJPh....9..170A}}</ref>

=== Conventional time projection chamber detectors (TPC) ===
TPC is a gas-filled drift chambers type of detector, designed to detect the low-intensity X-ray signals at CAST. The interactions in this detector take place in a very large gaseous chamber and produce ionizing electrons. These electrons travel towards the [[multiwire proportional chamber]] (MWPC), where the signal is then amplified through the avalanche process.<ref>{{Cite journal|last1=Autiero|first1=D.|last2=Beltrán|first2=B.|last3=Carmona|first3=J. M.|last4=Cebrián|first4=S.|last5=Chesi|first5=E.|last6=Davenport|first6=M.|last7=Delattre|first7=M.|last8=Lella|first8=L. Di|last9=Formenti|first9=F.|last10=Irastorza|first10=I. G.|last11=Gómez|first11=H.|date=June 2007|title=The CAST time projection chamber|journal=New Journal of Physics|language=en|volume=9|issue=6|pages=171|doi=10.1088/1367-2630/9/6/171|arxiv=physics/0702189|bibcode=2007NJPh....9..171A|s2cid=16525428|issn=1367-2630}}</ref>

=== MICROMEsh GAseous Structure detectors (MICROMEGAS) ===
This detector operated during the period of 2002 to 2004. It is a gaseous detector and was primarily employed for to detect X-rays in the energy range of 1–10 KeV. The detector itself was made up of low radioactive materials. The choice of material was mainly based on reducing the background noise, and Micromegas achieved a significantly low background rejection of {{val|6|e=-7|u=counts·keV<sup>−1</sup>·cm<sup>−2</sup>·s<sup>−1</sup>}} without any shielding.<ref name=":0" /><ref name=":1">{{Cite web|title=CAST opens a new window into dark energy and dark matter after 11 years of operation and continuous renewal.|url=https://ep-news.web.cern.ch/content/cast-opens-new-window-dark-energy-and-dark-matter-after-11-years-operation-and-continuous|access-date=2021-06-14|website=EP News|language=en}}</ref>

=== X-ray telescope with a charged couple device (CCD) ===
This detector has a pn-CCD chip located at the focal plane of the X-ray telescope. The X-ray telescope is based on the popular Wolter-I mirror optics concept. This technique is widely used in almost all [[X-ray astronomy]] telescopes. Its mirror is made up of 27 gold-coated nickel shells. These parabolic and hyperbolic shells are [[Confocal paraboloidal coordinates|confocally]] arranged to optimize the resolution. The largest shell is 163&nbsp;mm in diameter, while the smallest is 76&nbsp;mm. The overall mirror system has a focal length of 1.6&nbsp;m.<ref name=":3" /><ref>{{Cite thesis|title=Search for Solar Axions with the CCD Detector and X-ray Telescope at CAST Experiment|url=https://cds.cern.ch/record/2023683?ln=en|publisher=TUPrints ULB|date=2015|place=Darmstadt, Germany|first=Madalin Mihai|last=Rosu}}</ref> This detector achieved a remarkably good signal to noise ratio by focusing the axions created inside the magnetic field chamber onto small, about few <math>mm^2</math> area.<ref name=":1" />

=== GridPix detector ===
In 2016, The GridPix detector was installed to detect the [[soft X-rays]] (energy range of 200&nbsp;eV to 10&nbsp;KeV) generated by [[Chameleon particle|solar chameleons]] through the primakoff effect. During the search period of 2014 to 2015 the detected signal-to-noise ratio was below the required levels.<ref name=":6">{{cite journal | last1=Anastassopoulos | first1=V. | last2=Aune | first2=S. | last3=Barth | first3=K. | last4=Belov | first4=A. | last5=Bräuninger | first5=H. | last6=Cantatore | first6=G. | last7=Carmona | first7=J.M. | last8=Castel | first8=J.F. | last9=Cetin | first9=S.A. | last10=Christensen | first10=F. | last11=Dafni | first11=T. | last12=Davenport | first12=M. | last13=Dermenev | first13=A. | last14=Desch | first14=K. | last15=Döbrich | first15=B. | last16=Eleftheriadis | first16=C. | last17=Fanourakis | first17=G. | last18=Ferrer-Ribas | first18=E. | last19=Fischer | first19=H. | last20=Funk | first20=W. | last21=Garc𝚤a | first21=J.A. | last22=Gardikiotis | first22=A. | last23=Garza | first23=J.G. | last24=Gazis | first24=E.N. | last25=Geralis | first25=T. | last26=Giomataris | first26=I. | last27=Gninenko | first27=S. | last28=Hailey | first28=C.J. | last29=Hasinoff | first29=M.D. | last30=Hoffmann | first30=D.H.H. | last31=Iguaz | first31=F.J. | last32=Irastorza | first32=I.G. | last33=Jakobsen | first33=A. | last34=Jacoby | first34=J. | last35=Jakovčić | first35=K. | last36=Kaminski | first36=J. | last37=Karuza | first37=M. | last38=Kostoglou | first38=S. | last39=Kralj | first39=N. | last40=Krčmar | first40=M. | last41=Krieger | first41=C. | last42=Lakić | first42=B. | last43=Laurent | first43=J. M. | last44=Liolios | first44=A. | last45=Ljubičić | first45=A. | last46=Luzón | first46=G. | last47=Maroudas | first47=M. | last48=Miceli | first48=L. | last49=Neff | first49=S. | last50=Ortega | first50=I. | last51=Papaevangelou | first51=T. | last52=Paraschou | first52=K. | last53=Pivovaroff | first53=M.J. | last54=Raffelt | first54=G. | last55=Rosu | first55=M. | last56=Ruz | first56=J. | last57=Chóliz | first57=E. Ruiz | last58=Savvidis | first58=I. | last59=Schmidt | first59=S. | last60=Semertzidis | first60=Y.K. | last61=Solanki | first61=S.K. | last62=Stewart | first62=L. | last63=Vafeiadis | first63=T. | last64=Vogel | first64=J.K. | last65=Vretenar | first65=M. | last66=Wuensch | first66=W. | last67=Yildiz | first67=S.C. | last68=Zioutas | first68=K. | last69=Brax | first69=P. | title=Improved search for solar chameleons with a GridPix detector at CAST | journal=Journal of Cosmology and Astroparticle Physics | publisher=IOP Publishing | volume=2019 | issue=1 | date=2019-01-16 | issn=1475-7516 | doi=10.1088/1475-7516/2019/01/032 | pages=032 |display-authors=3 |arxiv=1808.00066|bibcode=2019JCAP...01..032A|s2cid=54052079}}</ref>

=== InGrid Based X-ray detector ===
The sole aim of this detector is to enhance the sensitivity of CAST to energy thresholds around 1 KeV range. This is an improved sensitive detector set up in 2014 behind the X-ray telescope, for the search of solar chameleons which have low threshold energies. The InGrid detector and its granular Timepix pad readout with low energy threshold of 0.1 KeV for photon detection hunts the solar chameleons in this range.<ref name=":2" /><ref>{{cite journal | last1=Krieger | first1=Christoph | last2=Desch | first2=Klaus | last3=Kaminski | first3=Jochen | last4=Lupberger | first4=Michael | title=Operation of an InGrid based X-ray detector at the CAST experiment | journal=EPJ Web of Conferences | publisher=EDP Sciences | volume=174 | year=2018 | issn=2100-014X | doi=10.1051/epjconf/201817402008 | page=02008|bibcode=2018EPJWC.17402008K|doi-access=free}}</ref>
[[File:Cast3.jpg|thumb|391x391px|A CAST experiment member working at the RADES detector]]

=== Relic Axion Dark Matter Exploratory Setup (RADES) ===
The RADES started searching for axion-like dark matter in 2018, and the first results from this detector were published in early 2021. Although no significant axion signal was detected above the noise background during the 2018 to 2021 period, RADES became the first detector to search for axions above <math>30 \mu eV</math>. CAST helioscope (looks at sun) was made a haloscope (looks at galactic halo) in late 2017.<ref name=":4" />  RADES detector attached to this haloscope has a 1&nbsp;m long alternating-irises stainless-steel cavity able to search for dark matter axions around <math>34 \mu eV</math>. Further prospects of improving the detector system with enhancements such as superconductive cavities and [[Ferromagnetism|ferro-magnetic]] tunings are being looked into.<ref>{{Cite web|title=CAST: from Solar to Dark Matter Axions searches|url=https://ep-news.web.cern.ch/content/cast-solar-dark-matter-axions-searches|access-date=2021-06-15|website=EP News|language=en}}</ref><ref name=":4" />

=== KWISP detector ===
KWISP at CAST is designed to detect the coupling of solar chameleons with matter particles. It uses a very sensitive [[Optomechanics|optomechanical]] force sensor, capable of detecting a displacement in a thin membrane caused by the mechanical effects from the solar chameleon interactions.<ref name=":7">{{cite journal | last1=Arguedas Cuendis | first1=S. | last2=Baier | first2=J. | last3=Barth | first3=K. | last4=Baum | first4=S. | last5=Bayirli | first5=A. | last6=Belov | first6=A. | last7=Bräuninger | first7=H. | last8=Cantatore | first8=G. | last9=Carmona | first9=J.M. | last10=Castel | first10=J.F. | last11=Cetin | first11=S.A. | last12=Dafni | first12=T. | last13=Davenport | first13=M. | last14=Dermenev | first14=A. | last15=Desch | first15=K. | last16=Döbrich | first16=B. | last17=Fischer | first17=H. | last18=Funk | first18=W. | last19=García | first19=J.A. | last20=Gardikiotis | first20=A. | last21=Garza | first21=J.G. | last22=Gninenko | first22=S. | last23=Hasinoff | first23=M.D. | last24=Hoffmann | first24=D.H.H. | last25=Iguaz | first25=F.J. | last26=Irastorza | first26=I.G. | last27=Jakovčić | first27=K. | last28=Kaminski | first28=J. | last29=Karuza | first29=M. | last30=Krieger | first30=C. | last31=Lakić | first31=B. | last32=Laurent | first32=J.M. | last33=Luzón | first33=G. | last34=Maroudas | first34=M. | last35=Miceli | first35=L. | last36=Neff | first36=S. | last37=Ortega | first37=I. | last38=Ozbey | first38=A. | last39=Pivovaroff | first39=M.J. | last40=Rosu | first40=M. | last41=Ruz | first41=J. | last42=Chóliz | first42=E. Ruiz | last43=Schmidt | first43=S. | last44=Schumann | first44=M. | last45=Semertzidis | first45=Y.K. | last46=Solanki | first46=S.K. | last47=Stewart | first47=L. | last48=Tsagris | first48=I. | last49=Vafeiadis | first49=T. | last50=Vogel | first50=J.K. | last51=Vretenar | first51=M. | last52=Yildiz | first52=S.C. | last53=Zioutas | first53=K. | title=First results on the search for chameleons with the KWISP detector at CAST | journal=Physics of the Dark Universe | publisher=Elsevier BV | volume=26 | year=2019 | issn=2212-6864 | doi=10.1016/j.dark.2019.100367 | page=100367 |arxiv=1906.01084|bibcode=2019PDU....2600367A|s2cid=174798025 |display-authors=3}}</ref><ref>{{cite journal | last1=Karuza | first1=M. | last2=Cantatore | first2=G. | last3=Gardikiotis | first3=A. | last4=Hoffmann | first4=D.H.H. | last5=Semertzidis | first5=Y.K. | last6=Zioutas | first6=K. | title=KWISP: An ultra-sensitive force sensor for the Dark Energy sector | journal=Physics of the Dark Universe | publisher=Elsevier BV | volume=12 | year=2016 | issn=2212-6864 | doi=10.1016/j.dark.2016.02.004 | pages=100–104|arxiv=1509.04499|bibcode=2016PDU....12..100K|s2cid=119255228}}</ref><ref name=":2" />

=== CAST-CAPP ===
This detector has a delicate tuning mechanism, made of 2 parallel sapphire plates and activated by a [[piezoelectric motor]]. The maximum tuning corresponds to axions masses between 21–23&nbsp;μeV. CAST-CAPP detector is also sensitive to dark matter axion tidal or cosmological streams and to the theorized axion mini-clusters. A newer and better version of CAPP is being developed at CAPP, South Korea.<ref>{{Cite web|date=2021-03-04|title=In search of WISPs|url=https://cerncourier.com/a/in-search-of-wisps/|access-date=2021-06-15|website=CERN Courier|language=en-GB}}</ref><ref name=":2" /><ref>{{cite journal | last1=Adair | first1=C. M. | last2=Altenmüller | first2=K. | last3=Anastassopoulos | first3=V. | last4=Arguedas Cuendis | first4=S. | last5=Baier | first5=J. | last6=Barth | first6=K. | last7=Belov | first7=A. | last8=Bozicevic | first8=D. | last9=Bräuninger | first9=H. | last10=Cantatore | first10=G. | last11=Caspers | first11=F. | last12=Castel | first12=J. F. | last13=Çetin | first13=S. A. | last14=Chung | first14=W. | last15=Choi | first15=H. | last16=Choi | first16=J. | last17=Dafni | first17=T. | last18=Davenport | first18=M. | last19=Dermenev | first19=A. | last20=Desch | first20=K. | last21=Döbrich | first21=B. | last22=Fischer | first22=H. | last23=Funk | first23=W. | last24=Galan | first24=J. | last25=Gardikiotis | first25=A. | last26=Gninenko | first26=S. | last27=Golm | first27=J. | last28=Hasinoff | first28=M. D. | last29=Hoffmann | first29=D. H. H. | last30=Díez Ibáñez | first30=D. | last31=Irastorza | first31=I. G. | last32=Jakovčić | first32=K. | last33=Kaminski | first33=J. | last34=Karuza | first34=M. | last35=Krieger | first35=C. | last36=Kutlu | first36=Ç. | last37=Lakić | first37=B. | last38=Laurent | first38=J. M. | last39=Lee | first39=J. | last40=Lee | first40=S. | last41=Luzón | first41=G. | last42=Malbrunot | first42=C. | last43=Margalejo | first43=C. | last44=Maroudas | first44=M. | last45=Miceli | first45=L. | last46=Mirallas | first46=H. | last47=Obis | first47=L. | last48=Özbey | first48=A. | last49=Özbozduman | first49=K. | last50=Pivovaroff | first50=M. J. | last51=Rosu | first51=M. | last52=Ruz | first52=J. | last53=Ruiz-Chóliz | first53=E. | last54=Schmidt | first54=S. | last55=Schumann | first55=M. | last56=Semertzidis | first56=Y. K. | last57=Solanki | first57=S. K. | last58=Stewart | first58=L. | last59=Tsagris | first59=I. | last60=Vafeiadis | first60=T. | last61=Vogel | first61=J. K. | last62=Vretenar | first62=M. | last63=Youn | first63=S. | last64=Zioutas | first64=K. | title=Search for Dark Matter Axions with CAST-CAPP | journal=Nature Communications | publisher=Springer Science and Business Media LLC | volume=13 | issue=1 | date=2022-10-19 | page=6180 | issn=2041-1723 | doi=10.1038/s41467-022-33913-6 | pmid=36261453 | pmc=9581938 | arxiv=2211.02902 | bibcode=2022NatCo..13.6180A | s2cid=252973014 | display-authors=3}}</ref>