Low Energy Antiproton Ring - Revision history

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	~~{{Short description\|Former CERN infrastructure}}~~		The '''Low Energy Anti-Proton Ring''' ('''LEAR''') was a particle accelerator at [[CERN]] which operated from 1982 until 1996.<ref name=":0">{{Cite web\|title=The Low Energy Antiproton Ring\|url=https://home.cern/science/accelerators/low-energy-antiproton-ring\|access-date=2021-08-17\|website=CERN\|language=en}}</ref> The ring was designed to decelerate and store antiprotons, to study the properties of antimatter and to create atoms of antihydrogen.<ref>{{Cite web\|date=2001-02-22\|title=The History of Antimatter - The Accelerator Era\|url=http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html\|access-date=2021-08-17\|archive-url=https://web.archive.org/web/20010222023926/http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html\|archive-date=2001-02-22}}</ref> Antiprotons for the ring were created by the CERN [[Proton Synchrotron]] via the [[Antiproton Collector]] and the [[Antiproton Accumulator]] (AA). The creation of at least nine atoms of antihydrogen were confirmed by the [[PS210\|PS210 experiment]] in 1995.
	~~{{Redirect\|LEAR\|the historic Mexican communist organization\|Liga de Escritores y Artistas Revolucionarios}}~~
	~~[[File:LEAR_experiment.jpg\|thumb\|The Low Energy Antiproton Ring (LEAR) at CERN]]~~
	~~{{Antimatter_facilities}}~~
	The '''Low Energy Anti-Proton Ring''' ('''LEAR''') was a [[particle accelerator]] at [[CERN]] which operated from 1982 until 1996.<ref name=":0">{{Cite web\|title=The Low Energy Antiproton Ring\|url=https://home.cern/science/accelerators/low-energy-antiproton-ring\|access-date=2021-08-17\|website=CERN\|language=en}}</ref> The ring was designed to decelerate and store ~~[[antiproton]]s~~, to study the properties of [[antimatter]] and to create atoms of [[antihydrogen]].<ref>{{Cite web\|date=2001-02-22\|title=The History of Antimatter - The Accelerator Era\|url=http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html\|access-date=2021-08-17\|archive-url=https://web.archive.org/web/20010222023926/http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html\|archive-date=2001-02-22}}</ref> Antiprotons for the ring were created by the CERN [[Proton Synchrotron]] via the [[Antiproton Collector]] and the [[Antiproton Accumulator]] (AA). The creation of at least nine atoms of antihydrogen were confirmed by the [[PS210 experiment]] in 1995.

	== Experimental setup ==		== Experimental setup ==
	LEAR is a multipurpose [[storage ring]] located in the South Hall of the [[Proton Synchrotron]] (PS), with a circumference of 78.5 m.<ref name=":1">{{Cite journal \|last=Plass \|first=Gunther \|date=16 May 1980 \|title=Design study of a facility for experiments with low energy antiprotons (LEAR) \|url=https://cds.cern.ch/record/124681/files/198009172.pdf \|journal=Cern/Ps/Dl 80-7}}</ref><ref name=":2">{{Citation \|last1=Lefèvre \|first1=P. \|title=The CERN Low Energy Antiproton Ring (LEAR) Project \|date=1980 \|url=https://doi.org/10.1007/978-3-0348-5540-2_119 \|work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 \|pages=819–824 \|editor-last=Newman \|editor-first=W. S. \|access-date=2023-08-07 \|series=Experientia Supplementum \|place=Basel \|publisher=Birkhäuser \|language=en \|doi=10.1007/978-3-0348-5540-2_119 \|isbn=978-3-0348-5540-2 \|last2=Möhl \|first2=D. \|last3=Plass \|first3=G.\|volume=40 \|url-access=subscription }}</ref> Four straight sections are alternated with compact 90° [[bending magnets]], along with eight [[quadrupole]] doublets. The straight sections each consist of an 8m long section, where equipment such as apparatus for internal beams and [[electron cooling]] can be stored, and two short sections of 1m.<ref name=":2" /> The C-type (bending) magnets used are open to the outside of the ring for injection and ejection.<ref name=":3">{{Cite journal \|last1=Koziol \|first1=H. \|last2=Möhl \|first2=D. \|date=2004-12-01 \|title=The CERN low-energy antiproton programme: the synchrotrons \|url=https://www.sciencedirect.com/science/article/pii/S0370157304003618 \|journal=Physics Reports \|language=en \|volume=403-404 \|pages=271–280 \|doi=10.1016/j.physrep.2004.09.003 \|bibcode=2004PhR...403..271K \|issn=0370-1573\|url-access=subscription }}</ref> The [[vacuum system]] used for LEAR is designed for baking at 300 °C.<ref name=":1" />		LEAR is a multipurpose storage ring located in the South Hall of the [[Proton Synchrotron]] (PS), with a circumference of 78.5 m.<ref name=":1">{{Cite journal \|last=Plass \|first=Gunther \|date=16 May 1980 \|title=Design study of a facility for experiments with low energy antiprotons (LEAR) \|url=https://cds.cern.ch/record/124681/files/198009172.pdf \|journal=Cern/Ps/Dl 80-7}}</ref><ref name=":2">{{Citation \|last1=Lefèvre \|first1=P. \|title=The CERN Low Energy Antiproton Ring (LEAR) Project \|date=1980 \|url=https://doi.org/10.1007/978-3-0348-5540-2_119 \|work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 \|pages=819–824 \|editor-last=Newman \|editor-first=W. S. \|access-date=2023-08-07 \|series=Experientia Supplementum \|place=Basel \|publisher=Birkhäuser \|language=en \|doi=10.1007/978-3-0348-5540-2_119 \|isbn=978-3-0348-5540-2 \|last2=Möhl \|first2=D. \|last3=Plass \|first3=G.\|volume=40 \|url-access=subscription }}</ref> Four straight sections are alternated with compact 90° bending magnets, along with eight quadrupole doublets. The straight sections each consist of an 8m long section, where equipment such as apparatus for internal beams and electron cooling can be stored, and two short sections of 1m.<ref name=":2" /> The C-type (bending) magnets used are open to the outside of the ring for injection and ejection.<ref name=":3">{{Cite journal \|last1=Koziol \|first1=H. \|last2=Möhl \|first2=D. \|date=2004-12-01 \|title=The CERN low-energy antiproton programme: the synchrotrons \|url=https://www.sciencedirect.com/science/article/pii/S0370157304003618 \|journal=Physics Reports \|language=en \|volume=403-404 \|pages=271–280 \|doi=10.1016/j.physrep.2004.09.003 \|bibcode=2004PhR...403..271K \|issn=0370-1573\|url-access=subscription }}</ref> The vacuum system used for LEAR is designed for baking at 300 °C.<ref name=":1" />

	Bunches of usually a few 10<sup>9</sup> antiprotons are skimmed off the AA and then decelerated by the PS from 3.5 GeV/c to 0.6 GeV/c.<ref name=":3" /><ref>{{Cite journal \|last=Klapisch \|first=R \|date=1983-01-01 \|title=The LEAR Project and Physics with Low Energy Antiprotons at CERN (A Summary) \|url=https://iopscience.iop.org/article/10.1088/0031-8949/1983/T5/023 \|journal=Physica Scripta \|volume=T5 \|pages=140–142 \|doi=10.1088/0031-8949/1983/T5/023 \|bibcode=1983PhST....5..140K \|s2cid=250785310 \|issn=0031-8949\|url-access=subscription }}</ref> The bunch was transferred to LEAR where it could be decelerated to a minimum 100 MeV/c or accelerated to generally 1000 MeV/c.<ref name=":3" /> For most experiments, a "beam stretcher mode" was used, where an ultra-slow extraction provided a high-~~[[Duty cycle\|~~duty]] (continuous) amount of antiprotons.<ref name=":3" /> Another mode, "internal target", kept a beam circulating for hours, or even days, until most particles were consumed by a gas jet target.<ref>{{Citation \|last1=Kilian \|first1=K. \|title=Internal Targets for LEAR \|date=1984 \|url=https://doi.org/10.1007/978-1-4684-8727-5_64 \|work=Physics at LEAR with Low-Energy Cooled Antiprotons \|pages=677–690 \|editor-last=Gastaldi \|editor-first=Ugo \|access-date=2023-08-07 \|series=Ettore Majorana International Science Series \|place=Boston, MA \|publisher=Springer New York \|language=en \|doi=10.1007/978-1-4684-8727-5_64 \|isbn=978-1-4684-8727-5 \|last2=Möhl \|first2=D. \|last3=Gspann \|first3=J. \|last4=Poth \|first4=H. \|editor2-last=Klapisch \|editor2-first=Robert\|url-access=subscription }}</ref><ref name=":3" />		Bunches of usually a few 10<sup>9</sup> antiprotons are skimmed off the AA and then decelerated by the PS from 3.5 GeV/c to 0.6 GeV/c.<ref name=":3" /><ref>{{Cite journal \|last=Klapisch \|first=R \|date=1983-01-01 \|title=The LEAR Project and Physics with Low Energy Antiprotons at CERN (A Summary) \|url=https://iopscience.iop.org/article/10.1088/0031-8949/1983/T5/023 \|journal=Physica Scripta \|volume=T5 \|pages=140–142 \|doi=10.1088/0031-8949/1983/T5/023 \|bibcode=1983PhST....5..140K \|s2cid=250785310 \|issn=0031-8949\|url-access=subscription }}</ref> The bunch was transferred to LEAR where it could be decelerated to a minimum 100 MeV/c or accelerated to generally 1000 MeV/c.<ref name=":3" /> For most experiments, a "beam stretcher mode" was used, where an ultra-slow extraction provided a high-duty (continuous) amount of antiprotons.<ref name=":3" /> Another mode, "internal target", kept a beam circulating for hours, or even days, until most particles were consumed by a gas jet target.<ref>{{Citation \|last1=Kilian \|first1=K. \|title=Internal Targets for LEAR \|date=1984 \|url=https://doi.org/10.1007/978-1-4684-8727-5_64 \|work=Physics at LEAR with Low-Energy Cooled Antiprotons \|pages=677–690 \|editor-last=Gastaldi \|editor-first=Ugo \|access-date=2023-08-07 \|series=Ettore Majorana International Science Series \|place=Boston, MA \|publisher=Springer New York \|language=en \|doi=10.1007/978-1-4684-8727-5_64 \|isbn=978-1-4684-8727-5 \|last2=Möhl \|first2=D. \|last3=Gspann \|first3=J. \|last4=Poth \|first4=H. \|editor2-last=Klapisch \|editor2-first=Robert\|url-access=subscription }}</ref><ref name=":3" />
	~~[[File:LEAR_magnet.jpg\|thumb\|LEAR bending magnet quadrant]]~~
	[[Stochastic cooling]] is implemented at several stages of the LEAR experimental setup, at different momenta.<ref name=":3" /> The focus of stochastic cooling is to restrict the motion of particles in the beam and control their energies close to a certain value. From 1987, the setup included electron cooling, using the electron cooler from the Initial Cooling Experiment (ICE) to complement the stochastic cooling.<ref>{{Cite journal \|last1=Poth \|first1=H. \|last2=Schwab \|first2=W. \|last3=Seligmann \|first3=B. \|last4=Wörtge \|first4=M. \|last5=Wolf \|first5=A. \|last6=Baird \|first6=S. \|last7=Bosser \|first7=J. \|last8=Chanel \|first8=M. \|last9=Haseroth \|first9=H. \|last10=Hill \|first10=C. E. \|last11=Ley \|first11=R. \|last12=Manglunki \|first12=D. \|last13=Möhl \|first13=D. \|last14=Tranquille \|first14=G. \|last15=Vallet \|first15=J. L. \|date=1990-02-01 \|title=Further results and evaluation of electron cooling experiments at LEAR \|url=https://dx.doi.org/10.1016/0168-9002%2890%2991818-V \|journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment \|language=en \|volume=287 \|issue=1 \|pages=328–332 \|doi=10.1016/0168-9002(90)91818-V \|bibcode=1990NIMPA.287..328P \|issn=0168-9002\|url-access=subscription }}</ref><ref>{{Citation \|last=Krienen \|first=F. \|title=Initial Cooling Experiments (ICE) at CERN \|date=1980 \|url=https://doi.org/10.1007/978-3-0348-5540-2_115 \|work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 \|pages=781–793 \|editor-last=Newman \|editor-first=W. S. \|access-date=2023-08-07 \|series=Experientia Supplementum \|volume=40 \|place=Basel \|publisher=Birkhäuser \|language=en \|doi=10.1007/978-3-0348-5540-2_115 \|isbn=978-3-0348-5540-2\|url-access=subscription }}</ref> Using cooling, high quality beams at low energies and low emittances could be produced.<ref name=":3" />		Stochastic cooling is implemented at several stages of the LEAR experimental setup, at different momenta.<ref name=":3" /> The focus of stochastic cooling is to restrict the motion of particles in the beam and control their energies close to a certain value. From 1987, the setup included electron cooling, using the electron cooler from the Initial Cooling Experiment (ICE) to complement the stochastic cooling.<ref>{{Cite journal \|last1=Poth \|first1=H. \|last2=Schwab \|first2=W. \|last3=Seligmann \|first3=B. \|last4=Wörtge \|first4=M. \|last5=Wolf \|first5=A. \|last6=Baird \|first6=S. \|last7=Bosser \|first7=J. \|last8=Chanel \|first8=M. \|last9=Haseroth \|first9=H. \|last10=Hill \|first10=C. E. \|last11=Ley \|first11=R. \|last12=Manglunki \|first12=D. \|last13=Möhl \|first13=D. \|last14=Tranquille \|first14=G. \|last15=Vallet \|first15=J. L. \|date=1990-02-01 \|title=Further results and evaluation of electron cooling experiments at LEAR \|url=https://dx.doi.org/10.1016/0168-9002%2890%2991818-V \|journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment \|language=en \|volume=287 \|issue=1 \|pages=328–332 \|doi=10.1016/0168-9002(90)91818-V \|bibcode=1990NIMPA.287..328P \|issn=0168-9002\|url-access=subscription }}</ref><ref>{{Citation \|last=Krienen \|first=F. \|title=Initial Cooling Experiments (ICE) at CERN \|date=1980 \|url=https://doi.org/10.1007/978-3-0348-5540-2_115 \|work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 \|pages=781–793 \|editor-last=Newman \|editor-first=W. S. \|access-date=2023-08-07 \|series=Experientia Supplementum \|volume=40 \|place=Basel \|publisher=Birkhäuser \|language=en \|doi=10.1007/978-3-0348-5540-2_115 \|isbn=978-3-0348-5540-2\|url-access=subscription }}</ref> Using cooling, high quality beams at low energies and low emittances could be produced.<ref name=":3" />

	== Results ==		== Results ==
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	== Conversion to LEIR ==		== Conversion to LEIR ==
	In 1996, LEAR was converted into the [[Low Energy Ion Ring]], which has since been used in the [[lead~~]] [[~~ion]] injection process for the [[Large Hadron Collider]].<ref name=":0" /><ref>{{Cite journal\|last=Katarina Anthony\|date=2012\|title=LEAR: a machine ahead of its time\|url=https://cds.cern.ch/record/1454240?ln=en\|journal=CERN Bulletin\|language=en}}</ref> Low energy antiproton research continues at CERN using the [[Antiproton Decelerator]]. It was built as a successor for LEAR and started operation in 2000.<ref>{{Cite web\|title=The Antiproton Decelerator\|url=https://home.cern/science/accelerators/antiproton-decelerator\|access-date=2021-08-17\|website=CERN\|language=en}}</ref>		In 1996, LEAR was converted into the [[Low Energy Ion Ring]], which has since been used in the lead ion injection process for the [[Large Hadron Collider]].<ref name=":0" /><ref>{{Cite journal\|last=Katarina Anthony\|date=2012\|title=LEAR: a machine ahead of its time\|url=https://cds.cern.ch/record/1454240?ln=en\|journal=CERN Bulletin\|language=en}}</ref> Low energy antiproton research continues at CERN using the [[Antiproton Decelerator]]. It was built as a successor for LEAR and started operation in 2000.<ref>{{Cite web\|title=The Antiproton Decelerator\|url=https://home.cern/science/accelerators/antiproton-decelerator\|access-date=2021-08-17\|website=CERN\|language=en}}</ref>

	== References ==		== References ==
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	{{CERN}}		{{CERN}}
			[[Category:Decommissioned CERN particle accelerators]]
	[[Category:CERN accelerators]]
	~~[[Category:Particle accelerators]]~~
	~~[[Category:CERN facilities]]~~
	~~[[Category:Particle physics facilities~~]]

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{{Short description|Former CERN infrastructure}}
{{Redirect|LEAR|the historic Mexican communist organization|Liga de Escritores y Artistas Revolucionarios}}
[[File:LEAR_experiment.jpg|thumb|The Low Energy Antiproton Ring (LEAR) at CERN]]
{{Antimatter_facilities}}
The '''Low Energy Anti-Proton Ring''' ('''LEAR''') was a [[particle accelerator]] at [[CERN]] which operated from 1982 until 1996.<ref name=":0">{{Cite web|title=The Low Energy Antiproton Ring|url=https://home.cern/science/accelerators/low-energy-antiproton-ring|access-date=2021-08-17|website=CERN|language=en}}</ref> The ring was designed to decelerate and store [[antiproton]]s, to study the properties of [[antimatter]] and to create atoms of [[antihydrogen]].<ref>{{Cite web|date=2001-02-22|title=The History of Antimatter - The Accelerator Era|url=http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html|access-date=2021-08-17|archive-url=https://web.archive.org/web/20010222023926/http://livefromcern.web.cern.ch/livefromcern/antimatter/history/AM-history02-c.html|archive-date=2001-02-22}}</ref> Antiprotons for the ring were created by the CERN [[Proton Synchrotron]] via the [[Antiproton Collector]] and the [[Antiproton Accumulator]] (AA). The creation of at least nine atoms of antihydrogen were confirmed by the [[PS210 experiment]] in 1995.

== Experimental setup ==
LEAR is a multipurpose [[storage ring]] located in the South Hall of the [[Proton Synchrotron]] (PS), with a circumference of 78.5 m.<ref name=":1">{{Cite journal |last=Plass |first=Gunther |date=16 May 1980 |title=Design study of a facility for experiments with low energy antiprotons (LEAR) |url=https://cds.cern.ch/record/124681/files/198009172.pdf |journal=Cern/Ps/Dl 80-7}}</ref><ref name=":2">{{Citation |last1=Lefèvre |first1=P. |title=The CERN Low Energy Antiproton Ring (LEAR) Project |date=1980 |url=https://doi.org/10.1007/978-3-0348-5540-2_119 |work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 |pages=819–824 |editor-last=Newman |editor-first=W. S. |access-date=2023-08-07 |series=Experientia Supplementum |place=Basel |publisher=Birkhäuser |language=en |doi=10.1007/978-3-0348-5540-2_119 |isbn=978-3-0348-5540-2 |last2=Möhl |first2=D. |last3=Plass |first3=G.|volume=40 |url-access=subscription }}</ref> Four straight sections are alternated with compact 90° [[bending magnets]], along with eight [[quadrupole]] doublets. The straight sections each consist of an 8m long section, where equipment such as apparatus for internal beams and [[electron cooling]] can be stored, and two short sections of 1m.<ref name=":2" /> The C-type (bending) magnets used are open to the outside of the ring for injection and ejection.<ref name=":3">{{Cite journal |last1=Koziol |first1=H. |last2=Möhl |first2=D. |date=2004-12-01 |title=The CERN low-energy antiproton programme: the synchrotrons |url=https://www.sciencedirect.com/science/article/pii/S0370157304003618 |journal=Physics Reports |language=en |volume=403-404 |pages=271–280 |doi=10.1016/j.physrep.2004.09.003 |bibcode=2004PhR...403..271K |issn=0370-1573|url-access=subscription }}</ref> The [[vacuum system]] used for LEAR is designed for baking at 300 °C.<ref name=":1" />

Bunches of usually a few 10<sup>9</sup> antiprotons are skimmed off the AA and then decelerated by the PS from 3.5 GeV/c to 0.6 GeV/c.<ref name=":3" /><ref>{{Cite journal |last=Klapisch |first=R |date=1983-01-01 |title=The LEAR Project and Physics with Low Energy Antiprotons at CERN (A Summary) |url=https://iopscience.iop.org/article/10.1088/0031-8949/1983/T5/023 |journal=Physica Scripta |volume=T5 |pages=140–142 |doi=10.1088/0031-8949/1983/T5/023 |bibcode=1983PhST....5..140K |s2cid=250785310 |issn=0031-8949|url-access=subscription }}</ref> The bunch was transferred to LEAR where it could be decelerated to a minimum 100 MeV/c or accelerated to generally 1000 MeV/c.<ref name=":3" /> For most experiments, a "beam stretcher mode" was used, where an ultra-slow extraction provided a high-[[Duty cycle|duty]] (continuous) amount of antiprotons.<ref name=":3" /> Another mode, "internal target", kept a beam circulating for hours, or even days, until most particles were consumed by a gas jet target.<ref>{{Citation |last1=Kilian |first1=K. |title=Internal Targets for LEAR |date=1984 |url=https://doi.org/10.1007/978-1-4684-8727-5_64 |work=Physics at LEAR with Low-Energy Cooled Antiprotons |pages=677–690 |editor-last=Gastaldi |editor-first=Ugo |access-date=2023-08-07 |series=Ettore Majorana International Science Series |place=Boston, MA |publisher=Springer New York |language=en |doi=10.1007/978-1-4684-8727-5_64 |isbn=978-1-4684-8727-5 |last2=Möhl |first2=D. |last3=Gspann |first3=J. |last4=Poth |first4=H. |editor2-last=Klapisch |editor2-first=Robert|url-access=subscription }}</ref><ref name=":3" />
[[File:LEAR_magnet.jpg|thumb|LEAR bending magnet quadrant]]
[[Stochastic cooling]] is implemented at several stages of the LEAR experimental setup, at different momenta.<ref name=":3" /> The focus of stochastic cooling is to restrict the motion of particles in the beam and control their energies close to a certain value. From 1987, the setup included electron cooling, using the electron cooler from the Initial Cooling Experiment (ICE) to complement the stochastic cooling.<ref>{{Cite journal |last1=Poth |first1=H. |last2=Schwab |first2=W. |last3=Seligmann |first3=B. |last4=Wörtge |first4=M. |last5=Wolf |first5=A. |last6=Baird |first6=S. |last7=Bosser |first7=J. |last8=Chanel |first8=M. |last9=Haseroth |first9=H. |last10=Hill |first10=C. E. |last11=Ley |first11=R. |last12=Manglunki |first12=D. |last13=Möhl |first13=D. |last14=Tranquille |first14=G. |last15=Vallet |first15=J. L. |date=1990-02-01 |title=Further results and evaluation of electron cooling experiments at LEAR |url=https://dx.doi.org/10.1016/0168-9002%2890%2991818-V |journal=Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment |language=en |volume=287 |issue=1 |pages=328–332 |doi=10.1016/0168-9002(90)91818-V |bibcode=1990NIMPA.287..328P |issn=0168-9002|url-access=subscription }}</ref><ref>{{Citation |last=Krienen |first=F. |title=Initial Cooling Experiments (ICE) at CERN |date=1980 |url=https://doi.org/10.1007/978-3-0348-5540-2_115 |work=11th International Conference on High-Energy Accelerators: Geneva, Switzerland, July 7–11, 1980 |pages=781–793 |editor-last=Newman |editor-first=W. S. |access-date=2023-08-07 |series=Experientia Supplementum |volume=40 |place=Basel |publisher=Birkhäuser |language=en |doi=10.1007/978-3-0348-5540-2_115 |isbn=978-3-0348-5540-2|url-access=subscription }}</ref> Using cooling, high quality beams at low energies and low emittances could be produced.<ref name=":3" />

== Results ==
There was a total of 27 experiments performed during LEAR's 14 years of running.<ref name=":4">{{Cite web |last=Bloch |first=Philippe |date=11 Jun 2012 |title=LEAR'S PHYSICS LEGACY |url=https://cdsweb.cern.ch/journal/CERNBulletin/2012/24/News%20Articles/1454683?ln=en |website=CERN Bulletin}}</ref> Several meson spectroscopy experiments were set up at LEAR to analyse the rare meson resonances produced in nucleon-antiproton annilhilation.<ref>{{Cite journal |last=Gianotti |first=P. |date=2005 |title=From LEAR to HESR: past, present and future of meson spectroscopy with antiprotons |url=https://doi.org/10.1063/1.1932911 |journal=AIP Conference Proceedings |volume=768 |pages=204–208 |publisher=AIP |doi=10.1063/1.1932911|bibcode=2005AIPC..768..204G |url-access=subscription }}</ref> These included the Crystal Barrel, OBELIX and JETSET experiments.<ref name=":4" /> Furthermore, matter-antimatter symmetry was investigated by studying specific proton-antiproton interactions, resulting in detailed measurements of CP violation.<ref>{{Cite journal |last1=Kounnas |first1=C. |last2=Lahanas |first2=A. B. |last3=Pavlopoulos |first3=P. |date=1983-08-04 |title=Limitations on CP-violating effects in strange particle decays |url=https://dx.doi.org/10.1016/0370-2693%2883%2991022-5 |journal=Physics Letters B |language=en |volume=127 |issue=5 |pages=381–383 |doi=10.1016/0370-2693(83)91022-5 |bibcode=1983PhLB..127..381K |issn=0370-2693}}</ref> The mass difference between the proton and antiproton was also studied at LEAR with an accuracy in 1 part in 10<sup>10</sup>.<ref>{{Cite journal |last1=Gabrielse |first1=G. |last2=Fei |first2=X. |last3=Orozco |first3=L. |last4=Tjoelker |first4=R. |last5=Haas |first5=J. |last6=Kalinowsky |first6=H. |last7=Trainor |first7=T. |last8=Kells |first8=W. |date=Sep 1990 |title=Thousandfold improvement in the measured antiproton mass |url=https://link.aps.org/doi/10.1103/PhysRevLett.65.1317 |journal=Physical Review Letters |language=en |volume=65 |issue=11 |pages=1317–1320 |doi=10.1103/PhysRevLett.65.1317 |pmid=10042233 |bibcode=1990PhRvL..65.1317G |issn=0031-9007}}</ref><ref name=":4" />

== Conversion to LEIR ==
In 1996, LEAR was converted into the [[Low Energy Ion Ring]], which has since been used in the [[lead]] [[ion]] injection process for the [[Large Hadron Collider]].<ref name=":0" /><ref>{{Cite journal|last=Katarina Anthony|date=2012|title=LEAR: a machine ahead of its time|url=https://cds.cern.ch/record/1454240?ln=en|journal=CERN Bulletin|language=en}}</ref> Low energy antiproton research continues at CERN using the [[Antiproton Decelerator]]. It was built as a successor for LEAR and started operation in 2000.<ref>{{Cite web|title=The Antiproton Decelerator|url=https://home.cern/science/accelerators/antiproton-decelerator|access-date=2021-08-17|website=CERN|language=en}}</ref>

== References ==
{{Reflist}}

{{CERN}}

[[Category:CERN accelerators]]
[[Category:Particle accelerators]]
[[Category:CERN facilities]]
[[Category:Particle physics facilities]]