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^{159}Dy Electron-Capture: A New Candidate for Neutrino Mass Determination
1Department of Physics, University of Jyväskylä, P.O. Box 35, FI-40014 Jyväskylä, Finland.
Physical Review Letters
|January 21, 2022
Summary
We precisely measured the electron-capture Q value of Dysprosium-159 using a Penning trap mass spectrometer. This opens new avenues for determining the electron-neutrino mass in the sub-eV range.
Area of Science:
- Nuclear Physics
- Atomic Physics
- Mass Spectrometry
Background:
- Precise measurement of electron-capture Q values is crucial for nuclear structure studies and fundamental physics, including neutrino mass determination.
- Dysprosium-159 (159Dy) electron-capture decay provides a potential pathway for sub-eV electron-neutrino mass measurements.
Purpose of the Study:
- To directly measure the ground-state to ground-state electron-capture Q value of 159Dy.
- To determine Q values for transitions to excited states in 159Terbium (159Tb).
- To assess the potential of 159Dy electron-capture for determining the electron-neutrino mass.
Main Methods:
- Utilized the double Penning trap mass spectrometer JYFLTRAP for high-precision measurements.
- Employed the phase-imaging ion-cyclotron resonance technique to measure cyclotron frequency ratios.
- Performed atomic many-body calculations to determine electron-capture probabilities.
Main Results:
- Measured the 159Dy ground-state to ground-state electron-capture Q value as 364.73(19) keV.
- Determined Q values for transitions to the 5/2- and 11/2+ states in 159Tb as 1.18(19) keV and 2.68(19) keV, respectively.
- Identified an enhancement in event rates for the 5/2- state transition, suggesting potential for neutrino mass studies.
Conclusions:
- The high-precision Q value for the 3/2- -> 5/2- transition is the lowest measured, aiding spectrum characterization.
- The 159Dy electron-capture decay to the 5/2- state in 159Tb is a promising candidate for sub-eV electron-neutrino mass determination.
- The transition to the 11/2+ state is suppressed and unsuitable for neutrino mass measurements.
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