Weighing the Solar Axion

Axion helioscopes search for solar axions and axion-like particles via inverse Primakoff conversion in strong laboratory magnets pointed at the Sun. While helioscopes can always measure the axion coupling to photons, the conversion signal is independent of the mass for axions lighter than around 0.02 eV. Masses above this value on the other hand have suppressed signals due to axion-photon oscillations which destroy the coherence of the conversion along the magnet. However, the spectral oscillations present in the axion conversion signal between these two regimes are highly dependent on the axion mass. We show that these oscillations are observable given realistic energy resolutions and can be used to determine the axion mass to within percent level accuracies. Using projections for the upcoming helioscope IAXO, we demonstrate that $>3\sigma$ sensitivity to a non-zero axion mass is possible between $3 \times 10^{-3}$ and $10^{-1}$ eV for both the Primakoff and axion-electron solar fluxes.Comment: 13 pages, 7 figures, matches published version, code available at http://cajohare.github.io/IAXOmas

PandaX-III: Searching for neutrinoless double beta decay with high pressure136^{136}Xe gas time projection chambers

International audienceSearching for the neutrinoless double beta decay (NLDBD) is now regarded as the topmost promising technique to explore the nature of neutrinos after the discovery of neutrino masses in oscillation experiments. PandaX-III (particle and astrophysical xenon experiment III) will search for the NLDBD of$^{136}$Xe at the China Jin Ping Underground Laboratory (CJPL). In the first phase of the experiment, a high pressure gas Time Projection Chamber (TPC) will contain 200 kg, 90%$^{136}$Xe enriched gas operated at 10 bar. Fine pitch micro-pattern gas detector (Microbulk Micromegas) will be used at both ends of the TPC for the charge readout with a cathode in the middle. Charge signals can be used to reconstruct the electron tracks of the NLDBD events and provide good energy and spatial resolution. The detector will be immersed in a large water tank to ensure ~5 m of water shielding in all directions. The second phase, a ton-scale experiment, will consist of five TPCs in the same water tank, with improved energy resolution and better control over backgrounds