Ultra-high precision high voltage system for PTOLEMY

TL;DR

This paper demonstrates an ultra-high precision high voltage system using commercial references and field mill monitoring, achieving sub-ppm stability crucial for the PTOLEMY project's neutrino detection goals.

Contribution

It introduces a novel high voltage control system with unprecedented precision, combining commercial references and field mill technology for neutrino experiments.

Findings

Achieved voltage stability as low as 0.2 ppm per 1 kV board.

Potential for 0.05 ppm precision over 20 kV with noise extrapolation.

Demonstrated real-time monitoring capability for high voltage control.

Abstract

The PTOLEMY project is prototyping a novel electromagnetic filter for high-precision $\beta$ 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 $\beta$-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}.