Mainz 2026 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 63: Precision Spectroscopy of Atoms and Ions V (joint session A/Q)
Q 63.6: Vortrag
Donnerstag, 5. März 2026, 15:45–16:00, N 3
Tungsten Emissivity Modeling and Temperature Diagnostics for the Project 8 Atomic Beam Source — •Brunilda Mucogllava1, Martin Fertl1, and Marco Röllig2 for the KAMATE collaboration — 1Johannes Gutenberg University Mainz — 2Tritium Laboratory Karlsruhe
To achieve a neutrino-mass sensitivity of 40 meV/c2, the Project 8 experiment aims to employ cyclotron radiation emission spectroscopy to measure the energies of beta-decay electrons from an atomic tritium source. The JGU Mainz atomic test stand uses a Hydrogen Atom Beam Source (HABS) in which molecular hydrogen flows through a 1-mm-diameter tungsten capillary radiatively heated to ~2200 K. The dissociation efficiency of the source depends on the hydrogen flow rate and on the capillary surface temperature. Because the source operates under ultra-high-vacuum conditions, where access is limited and direct-contact sensors risk damaging the capillary, minimally invasive diagnostics, such as optical analysis of its thermal radiation, are preferred. Accurate temperature determination requires reliable knowledge of the tungsten surface emissivity, its evolution over repeated thermal cycles, and the consequent impact on the achievable maximum temperatures. To address these challenges, a dedicated calibration setup was developed at the Tritium Laboratory Karlsruhe to measure tungsten emissivity using a near-infrared spectrometer and a single-wavelength pyrometer. This talk will present new results on tungsten-emissivity modeling and HABS temperature diagnostics, addressing challenges in calibration, temperature stability, and source aging.
Keywords: neutrino physics; atomic hydrogen beam; temperature measurement; infrared spectroscopy; tungsten emissivity