{{Short description|Synchrotron light sources}} '''Diffraction-limited storage rings''' (DLSR), or '''ultra-low emittance storage rings''', are synchrotron light sources where the emittance of the electron-beam in the storage ring is smaller or comparable to the emittance of the x-ray photon beam they produce at the end of their insertion devices. These facilities operate in the soft to hard x-ray range (100eV—100keV) with extremely high brilliance (in the order of 10<sup>21</sup>—10<sup>22</sup> photons/s/mm<sup>2</sup>/mrad<sup>2</sup>/0.1%BW)
Together with X-ray free-electron lasers, they constitute the fourth generation of light sources,<ref>{{cite journal|doi=10.1038/nphoton.2016.251|title=The next ten years of X-ray science|journal=Nature Photonics|volume=11|pages=12–14|year=2017|last1=Yabashi|first1=Makina|last2=Tanaka|first2=Hitoshi}}</ref> characterized by a relatively high coherent flux (in the order of 10<sup>14</sup>—10<sup>15</sup>photons/s/0.1%BW for DLSR) and enable extended physical and chemical characterizations at the nano-scale.
== Existing diffraction-limited storage rings == *MAX IV Laboratory, in Lund, Sweden. *Sirius, in Campinas, Brazil *European Synchrotron Radiation Facility, Extremely Brilliant Source ([http://ebs.esrf.fr/ ESRF-EBS]), in Grenoble, France
== DLSR upgrade or facilities under construction == *Advanced Photon Source Upgrade ([https://www.aps.anl.gov/APS-Upgrade APS-U]), in Argonne, Illinois, USA *Swiss Light Source 2, Upgrade (SLS 2.0<ref>{{cite journal|doi=10.1107/S1600577518002722 |doi-access=free|pmid=29714174|pmc=5929351|title=SLS-2 – the upgrade of the Swiss Light Source|journal=Journal of Synchrotron Radiation|volume=25|issue=3|pages=631–641|year=2018|last1=Streun|first1=Andreas|last2=Garvey|first2=Terence|last3=Rivkin|first3=Lenny|last4=Schlott|first4=Volker|last5=Schmidt|first5=Thomas|last6=Willmott|first6=Philip|last7=Wrulich|first7=Albin}}</ref>), in Villigen, Switzerland
== Planned or projected DLSR upgrades or new facilities == === Upgrades === *PETRA IV, Upgrade ([https://photon-science.desy.de/facilities/petra_iv_project/index_eng.html PETRA IV]), at DESY, Hamburg, Germany *Advanced Light Source, Upgrade ([https://als.lbl.gov/als-u/ ALS-U]), in Berkeley, California, USA *Diamond II ([https://www.diamond.ac.uk/Home/News/LatestNews/13-06-14.html Diamond II]), in Didcot, Oxfordshire, UK *ELETTRA 2.0 ([https://www.elettra.trieste.it/lightsources/elettra/elettra-2-0.html Elettra 2.0]), in Trieste, Italy *ALBA II, in Barcelona, Spain<ref>[https://www.albasynchrotron.es/en/media/news/alba-initiates-its-upgrade-process-to-become-a-4th-generation-facility Alba Initiates Its Upgrade Process To Become A 4th Generation Facility]</ref> * SOLEIL II, in Saint-Aubin, France<ref>''[https://www.synchrotron-soleil.fr/en/news/conceptual-design-report-soleil-upgrade Conceptual Design Report for SOLEIL Upgrade]'', accessed 24 April 2023.</ref>
=== New facilities === *High Energy Photon Source (HEPS), in Beijing, China<ref>{{Cite web |date=2019-08-15 |title=China's next big thing: a new fourth-generation synchrotron facility in Beijing |url=https://physicsworld.com/a/chinas-next-big-thing-a-new-fourth-generation-synchrotron-facility-in-beijing/ |access-date=2023-09-15 |website=Physics World |language=en-GB}}</ref><ref>{{Cite web |year=2019 |title=Groundbreaking Ceremony at the High Energy Photon Source in Beijing |url=https://www.tandfonline.com/doi/abs/10.1080/08940886.2019.1654833 |publisher=Synchrotron Radiation News |pages=32:5, 40-40}}</ref> * BESSY III, in Berlin, Germany<ref>BESSY III - The Materials Discovery Facility ''[https://www.helmholtz-berlin.de/forschung/quellen/bessy3/index_en.html]'' </ref>
== See also== *X-Ray Free Electron Lasers
== References == {{Reflist}}
Category:X-rays Category:Photons Category:Accelerator physics
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