https://doi.org/10.1140/epjc/s10052-024-13392-3
Regular Article
CYG
S: detecting solar neutrinos with directional gas time projection chambers
1
ARC Centre of Excellence for Dark Matter Particle Physics, School of Physics, The University of Sydney, 2006, Camperdown, NSW, Australia
2
Department of Astroparticle Physics, Gran Sasso Science Institute, 67100, L’Aquila, Italy
3
Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Gran Sasso, 67100, Assergi, Italy
4
ARC Centre of Excellence for Dark Matter Particle Physics, Research School of Physics, Australian National University, 2601, Canberra, ACT, Australia
5
Department of Physics and Astronomy, University of Hawaii, 2505 Correa Road, 96822, Honolulu, HI, USA
6
ARC Centre of Excellence for Dark Matter Particle Physics, School of Physics, The University of Melbourne, 3010, Parkville, VIC, Australia
Received:
14
May
2024
Accepted:
17
September
2024
Published online:
8
October
2024
Cygnus is a proposed global network of large-scale gas time projection chambers (TPCs) with the capability of directionally detecting nuclear and electron recoils at 
keV energies. The primary focus of Cygnus so far has been the detection of dark matter, with directional sensitivity providing a means of circumventing the so-called “neutrino fog”. However, the excellent background rejection and electron/nuclear recoil discrimination provided by the 3-dimensional reconstruction of ionisation tracks could turn the solar neutrino background into an interesting signal in its own right. For example, directionality would facilitate the simultaneous spectroscopy of multiple different flux sources. Here, we evaluate the possibility of measuring solar neutrinos using the same network of gas TPCs built from 10 m
-scale modules operating under conditions that enable simultaneous sensitivity to both dark matter and neutrinos. We focus in particular on electron recoils, which provide access to low-energy neutrino fluxes like pp, pep, 
Be, and CNO. An appreciable event rate is already detectable in experiments consisting of a single 10 m module, assuming standard fill gases such as CF
mixed with helium at atmospheric pressure. With total volumes around 1000 m or higher, the TPC network could be complementary to dedicated neutrino observatories, whilst entering the dark-matter neutrino fog via the nuclear recoil channel. We evaluate the required directional performance and background conditions to observe, discriminate, and perform spectroscopy on neutrino events. We find that, under reasonable projections for planned technology that will enable 10–30-degree angular resolution and 
% fractional energy resolution, Cygnus could be a competitive directional neutrino experiment.
© The Author(s) 2024
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Funded by SCOAP3.
