{{Short description|Particle physics experiment at CERN}} {{Redirect-distinguish|COULOMB|Coulomb (disambiguation)}}{{SppbarS}}thumb|UA4 experimental setup, CERN, April 1982: The experiment measured elastic scattering and total cross-section at the Proton-Antiproton Collider.
thumb|Wire chamber roman-pot for experiment UA4, CERN, Jan 1980
'''UA4 experiment''' ('''COULOMB'''<ref name="greybook"/>) was a high-energy physics experiment at the Proton-Antiproton Collider at CERN. The UA4 collaboration consisted of physicists from Amsterdam, Genova, Napoli, Pisa, Roma, California and CERN.<ref name=Proposal/> UA4 was approved on 18 January 1979, and the first phase of data taking lasted until 17 June 1985. The spokesperson of UA4 was Giorgi Matthiae.<ref name="greybook">{{cite web |url=https://greybook.cern.ch/greybook/experiment/detail?id=UA4 |title=UA4/COULOMB |author=<!--Not stated--> |website=CERN Greybook |access-date=19 July 2017}}</ref>
UA4 was followed by UA4/2, a collaboration between Genova, Roma, Paris, Prague, Valencia and CERN.<ref name=UA42>{{cite journal |last1=Augier |display-authors=etal |date=1997 |title=The UA4/2 experiment at the CERN SppbarS Collider |journal=Nuclear Instruments and Methods in Physics Research |volume=389 |issue=1997 |pages=409–414|doi= 10.1016/S0168-9002(97)00330-6|bibcode= 1997NIMPA.389..409A}}</ref> The purpose of UA4/2 was to measure the ratio of real to the imaginary part of the forward elastic scattering amplitude.<ref name=UA42/> It was approved in July 1990, and recorded data throughout 1991.
The objective of the UA4 experiment was to measure the antiproton-proton cross-section, in order to show that cross-sections rising with energy are a characteristic of strong interaction.<ref name=Proposal>{{cite journal |last1=Battistion|display-authors=etal |date=6 October 1978 |title=Proposal: The Measurement of Elastic Scattering and of the Total Cross-section at the CERN proton-antiproton Collider |url=https://cds.cern.ch/record/301874/files/SC00000497.pdf |journal=SPSC |volume=78-105, P114 |access-date=19 July 2017}}</ref> One had previously measured proton-antiproton cross-sections at the Intersecting Storage Rings, but as the Proton-Antiproton Collider — a modification of the Super Proton Synchrotron — began operating, the measurements could be done in a new energy range: up to 540 GeV center-of-mass energy.
Elastic events were detected by high resolution wire chambers and scintillation-counter hodoscopes. A system of drift chamber telescopes and counter telescopes were placed on the left and the right side of the crossing region to detect inelastic events.<ref name=result>{{cite conference |url=https://books.google.com/books?id=fzxeGjvAZaUC |title=Results from the UA4 Collaboration |last1=Van Swol |first1=R. |date=31 August 1983 |publisher=Gif-sur-Yvette: Ed. Frontières |book-title=3rd International Conference on Physics in Collision |pages=53–65 |location=Como, Italy |isbn=9782863320259 |conference=3rd International Conference on Physics in Collision }}</ref>
After the period of data taking, the UA4 collaboration could conclude that proton-antiproton cross-section indeed rises with energy.<ref name=result/>
==See also== *List of Super Proton Synchrotron experiments *UA1 experiment *UA2 experiment
==References== {{Reflist|30em}}
==External links== *[https://cds.cern.ch/search?cc=Published+Articles&ln=en&jrec=11&p=UA4&f=experiment List of publications from the UA4 and UA4/2 Collaboration] *[https://inspirehep.net/experiments/1109580 CERN-UA-004 experiment record] on INSPIRE-HEP
{{CERN}} {{SPS experiments}}
Category:Particle experiments Category:CERN experiments