Search for Majorana neutrinos with the first two years of EXO-200 data

doi:10.1038/nature13432

Search for Majorana neutrinos with the first two years of EXO-200 data

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Abstract

Many extensions of the standardmodel of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult to confirm. Observation of neutrinoless double-b decay (0nbb), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with ⁷⁶Ge (the GERDA experiment) and ¹³⁶Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 10²⁵ years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Herewereport newresults fromEXO-200 basedon a large ¹³⁶Xeexposure that representsan almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9x10²⁵ years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0nbb decay and set a half-life limit of 1.1x10 ²⁵ years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0nbb decay searches with an improved Xe-based experiment, nEXO.

Original language	English
Pages (from-to)	229-234
Number of pages	6
Journal	Nature
Volume	510
Issue number	7504
DOIs	https://doi.org/10.1038/nature13432
State	Published - Jun 1 2014

Bibliographical note

Funding Information:
Acknowledgements EXO-200 is supported by the DOE and NSF in the United States, NSERC in Canada, SNF in Switzerland, NRF in Korea, RFBR (12-02-12145) in Russia and the DFG Cluster of Excellence ‘Universe’ in Germany. EXO-200 data analysis and simulation used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. The EXO-200 collaboration acknowledges the WIPP for their hospitality.

Funding

Acknowledgements EXO-200 is supported by the DOE and NSF in the United States, NSERC in Canada, SNF in Switzerland, NRF in Korea, RFBR (12-02-12145) in Russia and the DFG Cluster of Excellence ‘Universe’ in Germany. EXO-200 data analysis and simulation used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. The EXO-200 collaboration acknowledges the WIPP for their hospitality.

Funders	Funder number
DFG Research Center/Cluster of Excellence	EXO-200
Office of Science of the US DOE	DE-AC02-05CH11231
National Science Foundation Arctic Social Science Program	1307362, 1205977
National Science Foundation Arctic Social Science Program
U.S. Department of Energy EPSCoR
Natural Sciences and Engineering Research Council of Canada
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung
Russian Foundation for Basic Research	12-02-12145, 14-02-00675
Russian Foundation for Basic Research
National Research Foundation of Korea

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10.1038/nature13432

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@article{779459e27fc14f55a20dc5dcfb51a6e0,

title = "Search for Majorana neutrinos with the first two years of EXO-200 data",

abstract = "Many extensions of the standardmodel of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult to confirm. Observation of neutrinoless double-b decay (0nbb), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with 76Ge (the GERDA experiment) and 136Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 1025 years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Herewereport newresults fromEXO-200 basedon a large 136Xeexposure that representsan almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9x1025 years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0nbb decay and set a half-life limit of 1.1x10 25 years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0nbb decay searches with an improved Xe-based experiment, nEXO.",

author = "Albert, {J. B.} and Auty, {D. J.} and Barbeau, {P. S.} and E. Beauchamp and D. Beck and V. Belov and C. Benitez-Medina and J. Bonatt and M. Breidenbach and T. Brunner and A. Burenkov and Cao, {G. F.} and C. Chambers and J. Chaves and B. Cleveland and M. Coon and A. Craycraft and T. Daniels and M. Danilov and Daugherty, {S. J.} and Davis, {C. G.} and J. Davis and R. DeVoe and S. Delaquis and T. Didberidze and A. Dolgolenko and Dolinski, {M. J.} and M. Dunford and W. Fairbank and J. Farine and W. Feldmeier and P. Fierlinger and D. Fudenberg and G. Giroux and R. Gornea and K. Graham and G. Gratta and C. Hall and S. Herrin and M. Hughes and Jewell, {M. J.} and Jiang, {X. S.} and A. Johnson and Johnson, {T. N.} and S. Johnston and A. Karelin and Kaufman, {L. J.} and R. Killick and T. Koffas and R. MacLellan",

note = "Funding Information: Acknowledgements EXO-200 is supported by the DOE and NSF in the United States, NSERC in Canada, SNF in Switzerland, NRF in Korea, RFBR (12-02-12145) in Russia and the DFG Cluster of Excellence {\textquoteleft}Universe{\textquoteright} in Germany. EXO-200 data analysis and simulation used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. The EXO-200 collaboration acknowledges the WIPP for their hospitality.",

year = "2014",

month = jun,

day = "1",

doi = "10.1038/nature13432",

language = "English",

volume = "510",

pages = "229--234",

number = "7504",

}

TY - JOUR

T1 - Search for Majorana neutrinos with the first two years of EXO-200 data

AU - Albert, J. B.

AU - Auty, D. J.

AU - Barbeau, P. S.

AU - Beauchamp, E.

AU - Beck, D.

AU - Belov, V.

AU - Benitez-Medina, C.

AU - Bonatt, J.

AU - Breidenbach, M.

AU - Brunner, T.

AU - Burenkov, A.

AU - Cao, G. F.

AU - Chambers, C.

AU - Chaves, J.

AU - Cleveland, B.

AU - Coon, M.

AU - Craycraft, A.

AU - Daniels, T.

AU - Danilov, M.

AU - Daugherty, S. J.

AU - Davis, C. G.

AU - Davis, J.

AU - DeVoe, R.

AU - Delaquis, S.

AU - Didberidze, T.

AU - Dolgolenko, A.

AU - Dolinski, M. J.

AU - Dunford, M.

AU - Fairbank, W.

AU - Farine, J.

AU - Feldmeier, W.

AU - Fierlinger, P.

AU - Fudenberg, D.

AU - Giroux, G.

AU - Gornea, R.

AU - Graham, K.

AU - Gratta, G.

AU - Hall, C.

AU - Herrin, S.

AU - Hughes, M.

AU - Jewell, M. J.

AU - Jiang, X. S.

AU - Johnson, A.

AU - Johnson, T. N.

AU - Johnston, S.

AU - Karelin, A.

AU - Kaufman, L. J.

AU - Killick, R.

AU - Koffas, T.

AU - MacLellan, R.

N1 - Funding Information: Acknowledgements EXO-200 is supported by the DOE and NSF in the United States, NSERC in Canada, SNF in Switzerland, NRF in Korea, RFBR (12-02-12145) in Russia and the DFG Cluster of Excellence ‘Universe’ in Germany. EXO-200 data analysis and simulation used resources of the National Energy Research Scientific Computing Center (NERSC), which is supported by the Office of Science of the US DOE under contract no. DE-AC02-05CH11231. The EXO-200 collaboration acknowledges the WIPP for their hospitality.

PY - 2014/6/1

Y1 - 2014/6/1

N2 - Many extensions of the standardmodel of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult to confirm. Observation of neutrinoless double-b decay (0nbb), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with 76Ge (the GERDA experiment) and 136Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 1025 years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Herewereport newresults fromEXO-200 basedon a large 136Xeexposure that representsan almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9x1025 years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0nbb decay and set a half-life limit of 1.1x10 25 years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0nbb decay searches with an improved Xe-based experiment, nEXO.

AB - Many extensions of the standardmodel of particle physics suggest that neutrinos should be Majorana-type fermions-that is, that neutrinos are their own anti-particles-but this assumption is difficult to confirm. Observation of neutrinoless double-b decay (0nbb), a spontaneous transition that may occur in several candidate nuclei, would verify the Majorana nature of the neutrino and constrain the absolute scale of the neutrino mass spectrum. Recent searches carried out with 76Ge (the GERDA experiment) and 136Xe (the KamLAND-Zen and EXO (Enriched Xenon Observatory)-200 experiments) have established the lifetime of this decay to be longer than 1025 years, corresponding to a limit on the neutrino mass of 0.2-0.4 electronvolts. Herewereport newresults fromEXO-200 basedon a large 136Xeexposure that representsan almost fourfold increase from our earlier published data sets. We have improved the detector resolution and revised the data analysis. The half-life sensitivity we obtain is 1.9x1025 years, an improvement by a factor of 2.7 on previous EXO-200 results. We find no statistically significant evidence for 0nbb decay and set a half-life limit of 1.1x10 25 years at the 90 per cent confidence level. The high sensitivity holds promise for further running of the EXO-200 detector and future 0nbb decay searches with an improved Xe-based experiment, nEXO.

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U2 - 10.1038/nature13432

DO - 10.1038/nature13432

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JO - Nature

JF - Nature

IS - 7504

ER -

Search for Majorana neutrinos with the first two years of EXO-200 data

Abstract

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