Editing CERN Axion Solar Telescope (section)

=== Constraints on axions ===
During the initial years, axion detection was the primary goal of CAST. Although the CAST experiment did not yet observe axions directly, it has constraint the search parameters. Mass and the [[coupling constant]] of an axion are primary aspects of its detectability.  Over almost 20 years of the operation period, CAST has added very significant details and limitations to the properties of solar axions and axion-like particles.<ref>{{Cite journal|last1=Irastorza|first1=Igor G.|last2=Redondo|first2=Javier|date=September 2018|title=New experimental approaches in the search for axion-like particles|journal=Progress in Particle and Nuclear Physics|volume=102|pages=89–159|doi=10.1016/j.ppnp.2018.05.003|arxiv=1801.08127|bibcode=2018PrPNP.102...89I|s2cid=119471148}}</ref><ref>{{Cite web|date=2018-08-31|title=Search for WISPs gains momentum|url=https://cerncourier.com/a/search-for-wisps-gains-momentum/|access-date=2021-06-23|website=CERN Courier|language=en-GB}}</ref> In the initial run period, the first three CAST detectors put an upper limit of <math>\mathrm{8.8 \times 10^{-11} GeV^{-1}} </math> on <math>g_{a\gamma}</math> (parameter for axion-photon coupling) with a 95% [[Confidence interval|confidence limit]] (CL) for axion mass-  <math>\mathrm{m_{a}\lesssim 0.02 eV} </math>.<ref>{{Cite journal|last=CAST Collaboration|date=2007-04-17|title=An improved limit on the axion-photon coupling from the CAST experiment|journal=Journal of Cosmology and Astroparticle Physics|volume=2007|issue=4|pages=010|doi=10.1088/1475-7516/2007/04/010|arxiv=hep-ex/0702006|bibcode=2007JCAP...04..010A|s2cid=119067481 |issn=1475-7516}}</ref>  For axion mass range between  <math> \mathrm{34.6771 \mu eV}</math> and <math> \mathrm{34.6738 \mu eV}</math>,  RADES constrained the axion-photon coupling constant <math>\mathrm{g_{a\gamma} \gtrsim 4 \times 10^{-13} GeV^{-1}}</math> with just about 5% error.<ref name=":4" /> The most recent results, in 2017 set an upper limit on  <math>g_{a\gamma}</math> <math>\mathrm{< 0.66 \times 10^{-10} GeV^{-1}}</math> (with 95% CL)  for all axions with masses below 0.02 eV.<ref name=":5" /><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=2021-06-23|website=EP News|language=en}}</ref> CAST has thus improved the previous astrophysical limits and has probed numerous relevant axion models of sub-electron-volt mass.<ref>{{Cite web|title=BabyIAXO submits for publication its Conceptual Design Report|url=https://ep-news.web.cern.ch/content/babyiaxo-submits-publication-its-conceptual-design-report|access-date=2021-06-23|website=EP News|language=en}}</ref>