The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future
High Purity Germanium Detectors have excellent energy resolution; the best among the technologies used in double beta decay. Since neutrino-less double beta decay hinges on the search for a rare peak upon a background continuum, this strength has enabled the technology to consistently provide leadin...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2019-02-01
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| Series: | Frontiers in Physics |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fphy.2019.00006/full |
| _version_ | 1818067802592903168 |
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| author | Frank T. Avignone III Steven R. Elliott |
| author_facet | Frank T. Avignone III Steven R. Elliott |
| author_sort | Frank T. Avignone III |
| collection | DOAJ |
| description | High Purity Germanium Detectors have excellent energy resolution; the best among the technologies used in double beta decay. Since neutrino-less double beta decay hinges on the search for a rare peak upon a background continuum, this strength has enabled the technology to consistently provide leading results. The Ge crystals at the heart of these experiments are very pure; they have no measurable U or Th contamination. The added efforts to reduce the background associated with electronics, cryogenic cooling, and shielding have been very successful, leading to the longevity of productivity. The first experiment published in 1967 by the Milan group of Fiorini, established the benchmark half-life limit >3 × 1020 yr. This bound was improved with the early work of the USC-PNNL, UCSB, and Milan groups yielding limits above 1023 yr. The Heidelberg-Moscow and USC-PNNL collaborations pioneered the use of enriched Ge for detector fabrication. Both groups also initiated techniques of analyzing pulse waveforms to reject γ-ray background. These steps extended the limits to just over 1025 yr. In 2000, a subset of the Heidelberg-Moscow collaboration claimed the observation of double beta decay. More recently, the MAJORANA and GERDA collaborations have developed new detector technologies that optimize the pulse waveform analysis. As a result, the GERDA collaboration refuted the claim of observation with a revolutionary approach to shielding by immersing the detectors directly in radio-pure liquid argon. In 2018, the MAJORANA collaboration, using a classic vacuum cryostat and high-Z shielding, achieved a background level near that of GERDA by developing very pure materials for use nearby the detectors. Together, GERDA and MAJORANA have provided limits approaching 1026 yr. In this article, we elaborate on the historical use of Ge detectors for double beta decay addressing the strengths and weaknesses. We also summarize the status and future as many MAJORANA and GERDA collaborators have joined with scientists from other efforts to give birth to the LEGEND collaboration. LEGEND will exploit the best features of both experiments to extend the half-life limit beyond 1028 yr with a ton-scale experiment. |
| first_indexed | 2024-12-10T15:29:28Z |
| format | Article |
| id | doaj.art-1527981799234918a228082de73dfc75 |
| institution | Directory Open Access Journal |
| issn | 2296-424X |
| language | English |
| last_indexed | 2024-12-10T15:29:28Z |
| publishDate | 2019-02-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Physics |
| spelling | doaj.art-1527981799234918a228082de73dfc752022-12-22T01:43:25ZengFrontiers Media S.A.Frontiers in Physics2296-424X2019-02-01710.3389/fphy.2019.00006434515The Search for Double Beta Decay With Germanium Detectors: Past, Present, and FutureFrank T. Avignone III0Steven R. Elliott1Department of Physics, University of South Carolina, Columbia, SC, United StatesLos Alamos National Laboratory, Physics Division, Los Alamos, NM, United StatesHigh Purity Germanium Detectors have excellent energy resolution; the best among the technologies used in double beta decay. Since neutrino-less double beta decay hinges on the search for a rare peak upon a background continuum, this strength has enabled the technology to consistently provide leading results. The Ge crystals at the heart of these experiments are very pure; they have no measurable U or Th contamination. The added efforts to reduce the background associated with electronics, cryogenic cooling, and shielding have been very successful, leading to the longevity of productivity. The first experiment published in 1967 by the Milan group of Fiorini, established the benchmark half-life limit >3 × 1020 yr. This bound was improved with the early work of the USC-PNNL, UCSB, and Milan groups yielding limits above 1023 yr. The Heidelberg-Moscow and USC-PNNL collaborations pioneered the use of enriched Ge for detector fabrication. Both groups also initiated techniques of analyzing pulse waveforms to reject γ-ray background. These steps extended the limits to just over 1025 yr. In 2000, a subset of the Heidelberg-Moscow collaboration claimed the observation of double beta decay. More recently, the MAJORANA and GERDA collaborations have developed new detector technologies that optimize the pulse waveform analysis. As a result, the GERDA collaboration refuted the claim of observation with a revolutionary approach to shielding by immersing the detectors directly in radio-pure liquid argon. In 2018, the MAJORANA collaboration, using a classic vacuum cryostat and high-Z shielding, achieved a background level near that of GERDA by developing very pure materials for use nearby the detectors. Together, GERDA and MAJORANA have provided limits approaching 1026 yr. In this article, we elaborate on the historical use of Ge detectors for double beta decay addressing the strengths and weaknesses. We also summarize the status and future as many MAJORANA and GERDA collaborators have joined with scientists from other efforts to give birth to the LEGEND collaboration. LEGEND will exploit the best features of both experiments to extend the half-life limit beyond 1028 yr with a ton-scale experiment.https://www.frontiersin.org/article/10.3389/fphy.2019.00006/fulldouble beta decayneutrinoGe detectorsMajoranaDirac |
| spellingShingle | Frank T. Avignone III Steven R. Elliott The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future Frontiers in Physics double beta decay neutrino Ge detectors Majorana Dirac |
| title | The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future |
| title_full | The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future |
| title_fullStr | The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future |
| title_full_unstemmed | The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future |
| title_short | The Search for Double Beta Decay With Germanium Detectors: Past, Present, and Future |
| title_sort | search for double beta decay with germanium detectors past present and future |
| topic | double beta decay neutrino Ge detectors Majorana Dirac |
| url | https://www.frontiersin.org/article/10.3389/fphy.2019.00006/full |
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