Towards Low-Energy Electron High-Resolution Spectroscopy with Transition-Edge Sensors
Authors:
R. Ammendola,
A. Apponi,
G. Benato,
M. G. Betti,
R. Biondi,
P. Bos,
M. Cadeddu,
A. Casale,
O. Castellano,
G. Cavoto,
L. Cecchini,
E. Celasco,
M. Chirico,
W. Chung,
A. G. Cocco,
A. P. Colijn,
B. Corcione,
N. D'Ambrosio,
M. D'Incecco,
G. De Bellis,
M. De Deo,
N. de Groot,
A. Esposito,
M. Farino,
S. Farinon
, et al. (40 additional authors not shown)
Abstract:
We present a study of the energy resolution of transition-edge sensors (TESs) for the detection of electrons in the 100 eV kinetic energy range. The TES is a Ti-Au bilayer with an active area of $(60 \times 60)$ $μ\text{m}^2$ and a critical temperature of $\sim$ 80 mK. The electron source is based on vertically-aligned multiwall carbon nanotubes located inside the cryostat, with electrons generate…
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We present a study of the energy resolution of transition-edge sensors (TESs) for the detection of electrons in the 100 eV kinetic energy range. The TES is a Ti-Au bilayer with an active area of $(60 \times 60)$ $μ\text{m}^2$ and a critical temperature of $\sim$ 80 mK. The electron source is based on vertically-aligned multiwall carbon nanotubes located inside the cryostat, with electrons generated via field emission. For electrons in the (92 - 99) eV kinetic energy range, we obtain a Gaussian energy resolution for fully-absorbed electrons of (0.479 $\pm$ 0.041 $\pm$ 0.055) eV. When considering the full-width at half-maximum of the peak, the corresponding resolution is of (1.44 $\pm$ 0.17 $\pm$ 0.27) eV. The former represents an improvement of (46 - 60)% with respect to previous results, and is mainly attributed to the reduction in the TES active area. The latter is instead an improvement of over a factor of 20, and is mainly due to the reduction in the emitting area of the electron source, which significantly suppresses electron back-scattering in proximity of the TES. These results represent a major milestone toward high-precision spectroscopy on low-energy electrons, which is a key objective for the PTOLEMY experiment.
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Submitted 25 February, 2026;
originally announced February 2026.
Ultra-high precision high voltage system for PTOLEMY
Authors:
R. Ammendola,
A. Apponi,
G. Benato,
M. G. Betti,
R. Biondim,
P. Bos,
G. Cavoto,
M. Cadeddu,
A. Casale,
O. Castellano,
E. Celasco,
L. Cecchini,
M. Chirico,
W. Chung,
A. G. Cocco,
A. P. Colijn,
B. Corcione,
N. D'Ambrosio,
M. D'Incecco,
G. De Bellis,
M. De Deo,
N. de Groot,
A. Esposito,
M. Farino,
S. Farinon
, et al. (41 additional authors not shown)
Abstract:
The PTOLEMY project is prototyping a novel electromagnetic filter for high-precision $β$ spectroscopy, with the ultimate and ambitious long-term goal of detecting the cosmic neutrino background through electron capture on tritium bound to graphene. Intermediate small-scale prototypes can achieve competitive sensitivity to the effective neutrino mass, even with reduced energy resolution. To reach a…
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The PTOLEMY project is prototyping a novel electromagnetic filter for high-precision $β$ spectroscopy, with the ultimate and ambitious long-term goal of detecting the cosmic neutrino background through electron capture on tritium bound to graphene. Intermediate small-scale prototypes can achieve competitive sensitivity to the effective neutrino mass, even with reduced energy resolution. To reach an energy resolution better than \SI{500}{meV} at the tritium $β$-spectrum endpoint of \SI{18.6}{keV}, and accounting for all uncertainties in the filtering chain, the electrode voltage must be controlled at the level of a few parts per million and monitored in real time. In this work, we present the first results obtained in this effort, using a chain of commercial ultra-high-precision voltage references, read out by precision multimeters and a \emph{field mill} device. The currently available precision on high voltage is, in the conservative case, as low as \SI{0.2}{ppm} per \SI{1}{kV} single board and $\lesssim$ \SI{50}{mV} over the \SI{10}{kV} series, presently limited by field mill read-out noise. However, assuming uncorrelated Gaussian noise extrapolation, the real precision could in principle be as low as \SI{0.05}{ppm} over \SI{20}{kV}.
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Submitted 22 December, 2025;
originally announced December 2025.