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K2K experiment

December 15, 2023

The K2K experiment (KEK to Kamioka) was a neutrino experiment that ran from June 1999 to November 2004. It used muon neutrinos from a well-controlled and well-understood beam to verify the oscillations previously observed by Super-Kamiokande using atmospheric neutrinos. This was the first positive measurement of neutrino oscillations in which both the source and detector were fully under experimenters' control.[1][2] Previous experiments relied on neutrinos from the Sun or from cosmic sources. The experiment found oscillation parameters which were consistent with those measured by Super-Kamiokande.

Experimental design edit

K2K is a neutrino experiment which directed a beam of muon neutrinos (
ν
μ) from the 12 GeV proton synchrotron at the KEK, located in Tsukuba, Ibaraki, to the Kamioka Observatory, located in Kamioka, Gifu, about 250 km away.[3] The muon neutrinos travelled through Earth, which allowed them to oscillate (change) into other flavours of neutrinos, namely into electron neutrinos (
ν
e) and tau neutrinos (
ν
τ). K2K however, focused only on
ν
μ →
ν
τ oscillations.[4]

The proton beam from the synchrotron was directed onto an aluminium target, and the resulting collisions produced a copious amount of pions. These pions were then focused into a 200 m decay pipe, where they would decay into muons and muon neutrinos.[3] The muons were stopped at the end of the pipe, leaving a beam of muon neutrinos. The exact composition of the beam contained over 97% muon neutrinos, with the other 3% being made of electron neutrinos (
ν
e), electron antineutrinos (
ν
e) and muon antineutrinos (
ν
μ).[4]

After they exited the pipe, the neutrinos went through a 1-kiloton water Cherenkov neutrino detector ("near detector") located at about 300 m from the aluminium target to determine the neutrino beam characteristics. This 1-kiloton "near detector" was a scaled-down version of the 50-kiloton Super-Kamiokande "far detector" located at the Kamioka Observatory, which allowed scientists to eliminate certain systematic uncertainties that would be present if two different detector types were used.[5] This dual-detector configuration allowed the comparison of the neutrino beam at the near detector with the neutrino beam at the far detector to determine if neutrinos had oscillated or not.[6]

Collaboration edit

The K2K collaboration consisted of roughly 130 physicists from 27 universities and research institutes from all over the world, listed below.[7] The full list of scientists and their countries of origin is available on the K2K website.

Results edit

The final K2K results found that at 99.9985% confidence (4.3 σ) there had been a disappearance of muon neutrinos. Fitting the data under the oscillation hypothesis, the best fit for the square of the mass difference between muon neutrinos and tau neutrinos was Δm2 = 2.8×10−3 eV2.[4] This result is in good agreement with the previous Super-Kamiokande result,[8] and the later MINOS result.[9]

See also edit

References edit

  1. ^ "Synthetic neutrinos appear to disappear". CERN Courier. 40 (7). 18 August 2000.
  2. ^ N. Nosengo (2006). "Neutrinos make a splash in Italy". Nature. 443 (7108): 126. Bibcode:2006Natur.443..126N. doi:10.1038/443126a. PMID 16971911.
  3. ^ a b "Long Baseline neutrino oscillation experiment, from KEK to Kamioka (K2K)". High Energy Accelerator Research Organization. 13 June 2002. Retrieved 3 September 2010.
  4. ^ a b c M. H. Ahn; et al. (K2K Collaboration) (2006). "Measurement of Neutrino Oscillation by the K2K Experiment". Physical Review D. 74 (7): 072003. arXiv:hep-ex/0606032. Bibcode:2006PhRvD..74g2003A. doi:10.1103/PhysRevD.74.072003. S2CID 22053653.
  5. ^ "K2K: Near Detector". [Stony Brook Super-Kamiokande/K2K group]. 19 June 1999. Retrieved 3 September 2010.
  6. ^ "K2K: Introduction". [Stony Brook Super-Kamiokande/K2K group]. 20 June 1999. Retrieved 3 September 2010.
  7. ^ "K2K Member Institutes". High Energy Accelerator Research Organization. 20 January 2004. Retrieved 3 September 2010.
  8. ^ Y. Fukuda; et al. (Super-K Collaboration) (1998). "Measurements of the Solar Neutrino Flux from Super-Kamiokande's First 300 Days". Physical Review Letters. 81 (6): 1158–1162. arXiv:hep-ex/9805021. Bibcode:1998PhRvL..81.1158F. doi:10.1103/PhysRevLett.81.1158. S2CID 14217731. and erratum "Erratum: Measurements of the Solar Neutrino Flux from Super-Kamiokande's First 300 Days". Physical Review Letters. 81 (19): 4279. 1998. Bibcode:1998PhRvL..81.4279F. doi:10.1103/PhysRevLett.81.4279.
  9. ^ D.G. Michael; et al. (MINOS Collaboration) (2006). "Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam". Physical Review Letters. 97 (19): 191801. arXiv:hep-ex/0607088. Bibcode:2006PhRvL..97s1801M. doi:10.1103/PhysRevLett.97.191801. PMID 17155614. S2CID 119458915.

External links edit

  • K2K official website
  • K2K publications

December 15, 2023
experiment, kamioka, neutrino, experiment, that, from, june, 1999, november, 2004, used, muon, neutrinos, from, well, controlled, well, understood, beam, verify, oscillations, previously, observed, super, kamiokande, using, atmospheric, neutrinos, this, first,. The K2K experiment KEK to Kamioka was a neutrino experiment that ran from June 1999 to November 2004 It used muon neutrinos from a well controlled and well understood beam to verify the oscillations previously observed by Super Kamiokande using atmospheric neutrinos This was the first positive measurement of neutrino oscillations in which both the source and detector were fully under experimenters control 1 2 Previous experiments relied on neutrinos from the Sun or from cosmic sources The experiment found oscillation parameters which were consistent with those measured by Super Kamiokande Contents 1 Experimental design 2 Collaboration 3 Results 4 See also 5 References 6 External linksExperimental design editK2K is a neutrino experiment which directed a beam of muon neutrinos nm from the 12 GeV proton synchrotron at the KEK located in Tsukuba Ibaraki to the Kamioka Observatory located in Kamioka Gifu about 250 km away 3 The muon neutrinos travelled through Earth which allowed them to oscillate change into other flavours of neutrinos namely into electron neutrinos ne and tau neutrinos nt K2K however focused only on nm nt oscillations 4 The proton beam from the synchrotron was directed onto an aluminium target and the resulting collisions produced a copious amount of pions These pions were then focused into a 200 m decay pipe where they would decay into muons and muon neutrinos 3 The muons were stopped at the end of the pipe leaving a beam of muon neutrinos The exact composition of the beam contained over 97 muon neutrinos with the other 3 being made of electron neutrinos ne electron antineutrinos n e and muon antineutrinos n m 4 After they exited the pipe the neutrinos went through a 1 kiloton water Cherenkov neutrino detector near detector located at about 300 m from the aluminium target to determine the neutrino beam characteristics This 1 kiloton near detector was a scaled down version of the 50 kiloton Super Kamiokande far detector located at the Kamioka Observatory which allowed scientists to eliminate certain systematic uncertainties that would be present if two different detector types were used 5 This dual detector configuration allowed the comparison of the neutrino beam at the near detector with the neutrino beam at the far detector to determine if neutrinos had oscillated or not 6 Collaboration editThe K2K collaboration consisted of roughly 130 physicists from 27 universities and research institutes from all over the world listed below 7 The full list of scientists and their countries of origin is available on the K2K website Boston University Chonnam National University CEA Saclay DSM DAPNIA Dongshin University High Energy Accelerator Research Organization Hiroshima University Institute for Cosmic Ray Research Institute for Nuclear Research Kobe University Korea University Kyoto University Massachusetts Institute of Technology Niigata University Okayama University Sapienza University of Rome Seoul National University State University of New York at Stony Brook Tokyo University of Science Tohoku University Autonomous University of Barcelona IFAE University of California Irvine University of Geneva University of Hawaii University of Tokyo University of Valencia University of Warsaw University of WashingtonResults editThe final K2K results found that at 99 9985 confidence 4 3 s there had been a disappearance of muon neutrinos Fitting the data under the oscillation hypothesis the best fit for the square of the mass difference between muon neutrinos and tau neutrinos was Dm2 2 8 10 3 eV2 4 This result is in good agreement with the previous Super Kamiokande result 8 and the later MINOS result 9 See also editT2K experiment the successor of the K2K experimentReferences edit Synthetic neutrinos appear to disappear CERN Courier 40 7 18 August 2000 N Nosengo 2006 Neutrinos make a splash in Italy Nature 443 7108 126 Bibcode 2006Natur 443 126N doi 10 1038 443126a PMID 16971911 a b Long Baseline neutrino oscillation experiment from KEK to Kamioka K2K High Energy Accelerator Research Organization 13 June 2002 Retrieved 3 September 2010 a b c M H Ahn et al K2K Collaboration 2006 Measurement of Neutrino Oscillation by the K2K Experiment Physical Review D 74 7 072003 arXiv hep ex 0606032 Bibcode 2006PhRvD 74g2003A doi 10 1103 PhysRevD 74 072003 S2CID 22053653 K2K Near Detector Stony Brook Super Kamiokande K2K group 19 June 1999 Retrieved 3 September 2010 K2K Introduction Stony Brook Super Kamiokande K2K group 20 June 1999 Retrieved 3 September 2010 K2K Member Institutes High Energy Accelerator Research Organization 20 January 2004 Retrieved 3 September 2010 Y Fukuda et al Super K Collaboration 1998 Measurements of the Solar Neutrino Flux from Super Kamiokande s First 300 Days Physical Review Letters 81 6 1158 1162 arXiv hep ex 9805021 Bibcode 1998PhRvL 81 1158F doi 10 1103 PhysRevLett 81 1158 S2CID 14217731 and erratum Erratum Measurements of the Solar Neutrino Flux from Super Kamiokande s First 300 Days Physical Review Letters 81 19 4279 1998 Bibcode 1998PhRvL 81 4279F doi 10 1103 PhysRevLett 81 4279 D G Michael et al MINOS Collaboration 2006 Observation of muon neutrino disappearance with the MINOS detectors in the NuMI neutrino beam Physical Review Letters 97 19 191801 arXiv hep ex 0607088 Bibcode 2006PhRvL 97s1801M doi 10 1103 PhysRevLett 97 191801 PMID 17155614 S2CID 119458915 External links editK2K official website K2K publications Retrieved from https en wikipedia org w index php title K2K experiment amp oldid 1183908949, wikipedia, wiki, book, books, library,

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