Speaker
Description
Cyclotron Radiation Emission Spectroscopy (CRES) determines an electron's kinetic energy from the frequency of its cyclotron radiation in a magnetic field. Project 8 developed CRES to make a direct kinematic measurement of the neutrino mass using tritium beta decay with a multi-phase approach toward 40 meV neutrino mass sensitivity. The first two phases demonstrated the principle of CRES (Phase I) and produced the first CRES spectrum of the tritium beta-decay endpoint (Phase II). In Phase II, we did not observe any background events beyond the tritium endpoint in 82 days of data taking and demonstrated an energy resolution of 1.66 ± 0.19 eV with ^{83m}Kr conversion electrons.
The Cavity CRES Apparatus (CCA), currently being commissioned at the University of Washington, is a resonant-cavity implementation of CRES. The CCA is designed to demonstrate sub-eV energy resolution and other technologies required to scale CRES to larger detection volumes while preserving its intrinsically low-background character. The resonant microwave cavity enhances the signal-to-noise ratio (SNR) of the extremely weak (~fW) 26 GHz cyclotron radiation signal and makes the detection of the sideband structure associated with the electron's axial motion possible. Improved understanding of the electron trajectory will allow correction for variations in the magnetic field sampled by individual electrons and, therefore, will lead to more precise energy reconstruction. We present the design and commissioning status of the CCA and progress on developing precision calibration methods.