Project 8 (physics experiment)

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Project 8 is an international collaboration of physicists intending to measure the absolute mass of the neutrino [1] with a sensitivity of approximately 40 meV. [2] [3] [4] [5]

The experiment measures the beta decay of tritium. The energy spectrum of beta-decay electrons depends on the mass of the electron antineutrino. A non-zero neutrino mass will distort the shape of the highest-energy part of the energy spectrum. [6] Project 8 relies on cyclotron radiation from single electrons produced in beta decay in order to measure their energy, a method dubbed CRES (Cyclotron Radiation Emission Spectroscopy). The cyclotron radiation is captured using a microwave waveguide (as in the first demonstration) or a resonant cavity (as considered for future phases [7] ). This method was successfully demonstrated in Phase I of Project 8, marking the first measurement of cyclotron radiation from a single electron. [8]

The beta decay source for the 40 meV experiment is planned to be atomic tritium. This provides higher precision than molecular tritium since an isolated atom has no rotational or vibrational states that can take up some of the decay's energy. [9]

Tritium beta decay has been used by a number of previous experiments, the current generation of which is KATRIN. its design uses a large spectrometer which would need to be enlarged to implausible proportions to materially improve its sensitivity. CRES is therefore a more promising method for a tritium-based next-generation direct neutrino-mass experiment. [10] Project 8 was mentioned in The 2023 Long Range Plan for Nuclear Science from the Nuclear Science Advisory Committee (NSAC) of the United States Department of Energy, which described the status of the field as follows: [11]

Any experiment that follows KATRIN will need two new technologies: (1) a scalable electron spectroscopy technique to measure the tritium decay spectrum and (2) a tritium source consisting of atoms rather than the more natural molecular form of this hydrogen isotope.

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References

  1. ↑ More specifically, the electron-weighted neutrino mass; see the page on Neutrinos - Flavor, mass, and their mixing for details.
  2. ↑ Kwon, Diana (2015-05-20). "Small teams, big dreams | symmetry magazine". www.symmetrymagazine.org. Retrieved 2024-11-18.
  3. ↑ "Циклотронное излучение открывает новые возможности для измерения массы нейтрино • Новости науки". «Элементы» (in Russian). Retrieved 2024-11-18.
  4. ↑ Overgaard, Elise (2023-01-24). "Ways to weigh a neutrino | symmetry magazine". www.symmetrymagazine.org. Retrieved 2024-11-18.
  5. ↑ Huber, Patrick (2015-04-20). "Cyclotron Radiation from One Electron". Physics. 8: 36. doi:10.1103/PhysRevLett.114.162501.
  6. ↑ "Neutrino Mass Experiment - About". www.project8.org. Retrieved 2024-11-18.
  7. ↑ Project 8 Collaboration; et al. (Project 8 Collaboration) (2022-03-14). "The Project 8 Neutrino Mass Experiment". arXiv: 2203.07349 [physics.ins-det].{{cite arXiv}}: CS1 maint: numeric names: authors list (link)
  8. ↑ Asner, D. M.; Bradley, R. F.; de Viveiros, L.; Doe, P. J.; Fernandes, J. L.; Fertl, M.; Finn, E. C.; Formaggio, J. A.; Furse, D.; Jones, A. M.; Kofron, J. N.; LaRoque, B. H.; Leber, M.; McBride, E. L.; Miller, M. L. (2015-04-20). "Single-Electron Detection and Spectroscopy via Relativistic Cyclotron Radiation". Physical Review Letters. 114 (16): 162501. arXiv: 1408.5362 . Bibcode:2015PhRvL.114p2501A. doi:10.1103/PhysRevLett.114.162501. ISSN   0031-9007. PMID   25955048.
  9. ↑ Bodine, L. I.; Parno, D. S.; Robertson, R. G. H. (27 March 2015). "Assessment of molecular effects on neutrino mass measurements from tritium β decay". Physical Review C. 91 (3): 035505. arXiv: 1502.03497 . Bibcode:2015PhRvC..91c5505B. doi:10.1103/PhysRevC.91.035505.
  10. ↑ Formaggio, Joseph A.; de Gouvêa, André Luiz C.; Robertson, R. G. Hamish (3 June 2021). "Direct measurements of neutrino mass". Physics Reports. 914: 1–54. arXiv: 2102.00594 . Bibcode:2021PhR...914....1F. doi:10.1016/j.physrep.2021.02.002.
  11. ↑ None, None (1 October 2023). "A New Era of Discovery: The 2023 Long Range Plan for Nuclear Science". doi:10.2172/2280968. OSTI   2280968.{{cite journal}}: Cite journal requires |journal= (help)
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