View source for Physics:SAGE (Soviet–American Gallium Experiment)

'''SAGE''' ('''Soviet–American Gallium Experiment''', or sometimes '''Russian-American Gallium Experiment''') is a collaborative experiment devised by several prominent physicists to measure the [[Astronomy:Solar neutrino|solar neutrino]] [[Physics:Flux|flux]].
==The Experiment==
'''SAGE''' was devised to measure the [[Chemistry:Radiochemistry|radio-chemical]] solar neutrino flux based on the [[Physics:Inverse beta decay|inverse beta decay]] [[Physics:Nuclear reaction|reaction]], <sup>71</sup>Ga<math> + \nu_e \rightarrow e^{-}+ </math><sup>71</sup>Ge. The target for the reaction was 50-57 tonnes of liquid [[Chemistry:Gallium|gallium]] metal stored deep (2100 meters) underground at the [[Astronomy:Baksan Neutrino Observatory|Baksan Neutrino Observatory]] in the Caucasus mountains in {{wipe|Russia}}. The laboratory containing the SAGE-experiment is called '''gallium-germanium neutrino telescope''' ('''GGNT''') laboratory, GGNT being the name of the SAGE experimental apparatus. About once a month, the neutrino induced [[Chemistry:Germanium|Ge]] is extracted from the [[Chemistry:Gallium|Ga]]. <sup>71</sup>Ge is unstable with respect to [[Physics:Electron capture|electron capture]] (<math>t_{1/2}=11.43</math> days) and, therefore, the amount of extracted [[Chemistry:Germanium|germanium]] can be determined from its activity as measured in small [[Physics:Proportional counter|proportional counter]]s.

The experiment had begun to measure the solar neutrino capture rate with a target of gallium metal in December 1989 and continued to run in August 2011 with only a few brief interruptions in the timespan. As of 2013 is the experiment was described as "being continued"<ref>{{Cite journal | doi=10.1134/S106377881309007X| title=Contribution of gallium experiments to the understanding of solar physics and neutrino physics| journal=Physics of Atomic Nuclei| volume=76| issue=10| pages=1238–1243| date=October 2013| last1=Gavrin| first1=V. N.| bibcode=2013PAN....76.1238G| s2cid=122656176}}</ref> with the latest published data from August 2011. As of 2014 it was stated that the SAGE experiment continues the once-a-month extractions.<ref>{{Cite web |url=https://www.snolab.ca/sites/default/files/Chen3_EvidenceOsc.pdf |title=Archived copy |access-date=2018-12-15 |archive-date=2020-10-25 |archive-url=https://web.archive.org/web/20201025024021/https://www.snolab.ca/sites/default/files/Chen3_EvidenceOsc.pdf |url-status=dead }}</ref> The SAGE experiment continued in 2016.<ref>{{Cite web |url=http://www.hephy.at/user/mjeitler/TALKS/Baksan_Hephy5.pdf |title=Archived copy |access-date=2019-05-31 |archive-date=2019-05-31 |archive-url=https://web.archive.org/web/20190531142549/http://www.hephy.at/user/mjeitler/TALKS/Baksan_Hephy5.pdf |url-status=dead }}</ref> As of 2017, the SAGE-experiment continues.<ref>{{Cite web | url=https://cerncourier.com/baksan-scales-new-neutrino-heights/ | title=Baksan scales new neutrino heights – CERN Courier| date=19 May 2017}}</ref>

The experiment has measured the solar neutrino flux in 168 extractions between January 1990 and December 2007. The result of the experiment based on the whole 1990-2007 set of data is {{val|65.4|3.1|-3.0}} (stat.) {{su|p=+2.6|b=&minus;2.8}} (syst.) [[Physics:Solar neutrino unit|SNU]]. This represents only 56%-60% of the capture rate predicted by different Standard Solar Models, which predict 138 SNU. The difference is in agreement with neutrino oscillations.

The collaboration has used a 518 k[[Physics:Curie (unit)|Ci]] <sup>51</sup>[[Chemistry:Chromium|Cr]] neutrino source to test the experimental operation. The energy of these neutrinos is similar to the solar <sup>7</sup>[[Chemistry:Beryllium|Be]] neutrinos and thus makes an ideal check on the experimental procedure. The extractions for the [[Chemistry:Chromium|Cr]] experiment took place between January and May 1995 and the counting of the samples lasted until fall. The result, expressed in terms of a ratio of the measured production rate to the expected production rate, is {{val|1.0|0.15}}. This indicates that the discrepancy between the solar model predictions and the SAGE flux measurement cannot be an experimental artifact. Also calibrations with a <sup>37</sup>Ar neutrino source had been performed.

== Baksan Experiment on Sterile Transitions (BEST) ==
In 2014, the SAGE-experiment's GGNT-apparatus (gallium-germanium neutrino telescope) was upgraded to perform a very-short-baseline neutrino oscillation experiment '''BEST''' ('''Baksan Experiment on Sterile Transitions''') with an intense artificial neutrino source based on <sup>51</sup>[[Chemistry:Chromium|Cr]].<ref>{{Cite journal | doi=10.1134/S1063779615020100|bibcode = 2015PPN....46..131G|title = Current status of new SAGE project with <SUP>51</SUP>Cr neutrino source| journal=Physics of Particles and Nuclei| volume=46| issue=2| pages=131|last1 = Gavrin|first1 = V.| last2=Cleveland| first2=B.| last3=Danshin| first3=S.| last4=Elliott| first4=S.| last5=Gorbachev| first5=V.| last6=Ibragimova| first6=T.| last7=Kalikhov| first7=A.| last8=Knodel| first8=T.| last9=Kozlova| first9=Yu.| last10=Malyshkin| first10=Yu.| last11=Matveev| first11=V.| last12=Mirmov| first12=I.| last13=Nico| first13=J.| last14=Robertson| first14=R. G. H.| last15=Shikhin| first15=A.| last16=Sinclair| first16=D.| last17=Veretenkin| first17=E.| last18=Wilkerson| first18=J.| year=2015|osti = 1440431|url = https://www.osti.gov/biblio/1440431}}</ref> In 2017, the BEST apparatus was completed, but the artificial neutrino source was missing.<ref>{{Cite web | url=https://cerncourier.com/baksan-scales-new-neutrino-heights/ | title=Baksan scales new neutrino heights – CERN Courier| date=19 May 2017}}</ref> As of 2018, the BEST experiment was underway.<ref>{{Cite news | url=https://www.nytimes.com/2018/07/16/science/neutrinos-baksan.html | title=The Neutrino Trappers| newspaper=The New York Times| date=2018-07-16| last1=Babenko| first1=Maxim| last2=Overbye| first2=Dennis}}</ref> As of 2018, a follow-up experiment BEST-2 where the source would be changed to <sup>65</sup>[[Chemistry:Zinc|Zn]] was under consideration.<ref>{{Cite arXiv |eprint = 1807.02977|title = On the gallium experiment BEST-2 with a <sup>65</sup>Zn source to search for neutrino oscillations on a short baseline|last1 = Gavrin|first1 = V. N.|last2 = Gorbachev|first2 = V. V.|last3 = Ibragimova|first3 = T. V.|last4 = Kornoukhov|first4 = V. N.|last5 = Dzhanelidze|first5 = A. A.|last6 = Zlokazov|first6 = S. B.|last7 = Kotelnikov|first7 = N. A.|last8 = Izhutov|first8 = A. L.|last9 = Mainskov|first9 = S. V.|last10 = Pimenov|first10 = V. V.|last11 = Borisenko|first11 = V. P.|last12 = Kiselev|first12 = K. B.|last13 = Tsevelev|first13 = M. P.|year = 2018|class = physics.ins-det}}</ref> In June 2022, the BEST experiment released two papers observing a 20-24% deficit in the production the isotope germanium expected from the reaction  <sup>71</sup>Ga<math> + \nu_e \rightarrow e^{-}+ </math><sup>71</sup>Ge, summing evidence for the so called "Gallium anomaly" pointing out that a [[Physics:Sterile neutrino|sterile neutrino]] explanation can be consistent with the data.<ref>{{Cite web |last=Laboratory |first=Los Alamos National |date=2022-06-18 |title=Deep Underground Experiment Results Confirm Anomaly: Possible New Fundamental Physics |url=https://scitechdaily.com/deep-underground-experiment-results-confirm-anomaly-possible-new-fundamental-physics/ |access-date=2022-06-22 |website=SciTechDaily |language=en-us}}</ref><ref>{{Cite journal |last1=Barinov |first1=V. V. |last2=Cleveland |first2=B. T. |last3=Danshin |first3=S. N. |last4=Ejiri |first4=H. |last5=Elliott |first5=S. R. |last6=Frekers |first6=D. |last7=Gavrin |first7=V. N. |last8=Gorbachev |first8=V. V. |last9=Gorbunov |first9=D. S. |last10=Haxton |first10=W. C. |last11=Ibragimova |first11=T. V. |date=2022-06-09 |title=Results from the Baksan Experiment on Sterile Transitions (BEST) |url=https://link.aps.org/doi/10.1103/PhysRevLett.128.232501 |journal=Physical Review Letters |volume=128 |issue=23 |pages=232501 |doi=10.1103/PhysRevLett.128.232501|pmid=35749172 |arxiv=2109.11482 |bibcode=2022PhRvL.128w2501B |s2cid=237605431 }}</ref><ref>{{Cite journal |last1=Barinov |first1=V. V. |last2=Danshin |first2=S. N. |last3=Gavrin |first3=V. N. |last4=Gorbachev |first4=V. V. |last5=Gorbunov |first5=D. S. |last6=Ibragimova |first6=T. V. |last7=Kozlova |first7=Yu. P. |last8=Kravchuk |first8=L. V. |last9=Kuzminov |first9=V. V. |last10=Lubsandorzhiev |first10=B. K. |last11=Malyshkin |first11=Yu. M. |date=2022-06-09 |title=Search for electron-neutrino transitions to sterile states in the BEST experiment |url=https://link.aps.org/doi/10.1103/PhysRevC.105.065502 |journal=Physical Review C |volume=105 |issue=6 |pages=065502 |doi=10.1103/PhysRevC.105.065502|arxiv=2201.07364 |bibcode=2022PhRvC.105f5502B |s2cid=246035834 }}</ref>

==Members of SAGE==
SAGE is led by the following physicists:

*Vladimir Gavrin (leader of the experiment as of 2017)
*[[Biography:Georgiy Zatsepin|Georgiy Zatsepin]] ([[Organization:Joint Institute for Nuclear Research|Joint Institute for Nuclear Research]], Russia)
*Thomas J. Bowles ([[Organization:Los Alamos National Laboratory|Los Alamos]])

==See also==
* [[Astronomy:GALLEX|GALLEX]]/GNO was the second (of two) large gallium-germanium radiochemical experiment. It was running in 1991-2003.
*[[Biography:Hans Bethe|Hans Bethe]] was the architect of the [[Theory|theory]] of [[Physics:Nuclear fusion|nuclear fusion]] reactions in [[Astronomy:Star|star]]s.
*The [[Organization:University of Washington|University of Washington]] is playing a major role in the statistical analysis of the SAGE data and in the determination of systematic uncertainties. They are very active in the remaining analysis of the Cr experiment data as well as the solar neutrino data.

==References==
<references />

==Literature==
* {{cite journal |last1=Abdurashitov|first1=J. N.|last2=Gavrin|first2=V. N.|last3=Gorbachev|first3=V. V.|last4=Gurkina|first4=P. P.|last5=Ibragimova|first5=T. V.|last6=Kalikhov|first6=A. V.|last7=Khairnasov|first7=N. G.|last8=Knodel|first8=T. V.|last9=Mirmov|first9=I. N.|last10=Shikhin|first10=A. A.|last11=Veretenkin|first11=E. P.|last12=Yants|first12=V. E.|last13=Zatsepin|first13=G. T.|last14=Bowles|first14=T. J.|last15=Elliott|first15=S. R.|last16=Teasdale|first16=W. A.|last17=Nico|first17=J. S.|last18=Cleveland|first18=B. T.|last19=Wilkerson|first19=J. F. |display-authors=1 |title=Measurement of the solar neutrino capture rate with gallium metal. III. Results for the 2002–2007 data-taking period |journal=[[Physics:Physical Review C|Physical Review C]] |volume=80 |issue=1|pages=015807 |year=2009 |arxiv=0901.2200 |bibcode=2009PhRvC..80a5807A |doi=10.1103/PhysRevC.80.015807|s2cid=118782386}}

==External links==
* [http://ewi.npl.washington.edu/sage The web page of the experiment] in the [[Organization:University of Washington|University of Washington]]
*[http://cat.inist.fr/?aModele=afficheN&cpsidt=4077673 Old page (1994) with results of the experiments]
* [https://web.archive.org/web/20120323094245/http://www.inr.ru/rus/ins_sotr/sl78r.html Some results (2001)] {{in lang|ru}}
*[http://www.webofstories.com/people/hans.bethe/151 Hans Bethe talking about SAGE] (video)
*[https://inspirehep.net/experiments/1109179 SAGE experiment] record on [[Physics:INSPIRE-HEP|INSPIRE-HEP]]

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[[Category:Particle experiments]]

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