UA3 experiment

{{SppbarS}}{{Short description|Particle physics experiment at CERN}}

The Underground Area 3 (UA3) 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 1978 to 1988 with the objective of searching for magnetic monopoles.{{Cite web |title=Greybook |url=https://greybook.cern.ch/experiment/detail?id=UA3 |access-date=2023-08-03 |website=greybook.cern.ch}} No evidence for magnetic monopoles was found by the UA3 experiment.{{Cite journal |last=Dowell |first=John D |date=1985 |title=Proton antiproton physics |url=http://cds.cern.ch/record/880961 |journal=CERN |language=en |doi=10.5170/CERN-1985-011.1}}

File:UA3_detector.jpg

The experiment shares the same intersection region used as the UA1 colliding experiment, and looked for expected high ionisation of magnetic monopole in plastic detectors.{{Citation |last=Price |first=Michael J. |title=Experimental Searches for Magnetic Monopoles at Particle Colliders |date=1984 |url=https://doi.org/10.1007/978-1-4757-0375-7_61 |work=Monopole ’83 |pages=621–624 |editor-last=Stone |editor-first=James L. |access-date=2023-08-03 |series=NATO ASI Series |volume=111 |place=Boston, MA |publisher=Springer US |language=en |doi=10.1007/978-1-4757-0375-7_61 |isbn=978-1-4757-0375-7|url-access=subscription }} The beam pipe was a stainless steel corrugated cylinder, with 0.2 mm thickness.{{Cite journal |last1=Aubert |first1=B. |last2=Musset |first2=P. |last3=Price |first3=M. |last4=Vialle |first4=J.P. |date=12 Oct 1982 |title=Search for magnetic monopoles in proton-antiproton interactions at 540 GeV cm energy |url=https://linkinghub.elsevier.com/retrieve/pii/0370269383904884 |journal=Physics Letters B |language=en |volume=120 |issue=4–6 |pages=465–467 |doi=10.1016/0370-2693(83)90488-4}}

Plastic detectors were used as they are best suited to the chemically etched tracks left by the ionising particles, and they resist high temperatures during baking.{{Cite journal |last1=Aubert |first1=B |last2=Musset |first2=P |last3=Price |first3=M |last4=Vialle |first4=J P |date=2 Feb 1978 |title=Search for Magnetic Monopoles |url=https://cds.cern.ch/record/596854/files/CM-P00045655.pdf |journal=Proposal to the SPSC}} The plastic detectors used were 125μm thick kapton foils. The foils were placed inside of the vacuum chamber and around the central track detector for the UA1.{{Cite journal |last=Dowell |first=J D |date=1983 |title=Physics Results from the CERN Proton-Antiproton Collider |url=https://inis.iaea.org/collection/NCLCollectionStore/_Public/14/801/14801411.pdf |journal=Department of Physics, University of Birmingham, England}} Three cylindrical and four transverse layers of detectors were placed between three chambers: two forward chambers and a central chamber. This covered the maximum solid angle possible.

Holes etched along a monopole track were determined using diffusion of a gas or dye through the holes, followed by a chemical reaction. The ionisation rates of magnetic monopoles were predicted to be very high due to their short range.