Calorimetry for low-energy electrons using charge and light in liquid argon

Abstract

Precise calorimetric reconstruction of 5-50 MeV electrons in liquid argon time projection chambers (LArTPCs) will enable the study of astrophysical neutrinos in DUNE and could enhance the physics reach of oscillation analyses. Liquid argon scintillation light has the potential to improve energy reconstruction for low-energy electrons over charge-based measurements alone. Here we demonstrate light-augmented calorimetry for low-energy electrons in a single-phase LArTPC using a sample of Michel electrons from decays of stopping cosmic muons in the LArIAT experiment at Fermilab. Michel electron energy spectra are reconstructed using both a traditional charge-based approach as well as a more holistic approach that incorporates both charge and light. A maximum-likelihood fitter, using LArIAT's well-tuned simulation, is developed for combining these quantities to achieve optimal energy resolution. A sample of isolated electrons is simulated to better determine the energy resolution expected for astrophysical electron-neutrino charged-current interaction final states. In LArIAT, which has very low wire noise and an average light yield of 18 pe/MeV, an energy resolution of σ/E 9.3%/ √ E ⊕ 1.3% is achieved. Samples are then generated with varying wire noise levels and light yields to gauge the impact of light-augmented calorimetry in larger LArTPCs. At a chargereadout signal-to-noise of S/N 30, for example, the energy resolution for electrons below 40 MeV is improved by ≈ 10%, ≈ 20%, and ≈ 40% over charge-only calorimetry for average light yields of

LArQL: A phenomenological model for treating light and charge generation in liquid argon

“…2.5. The dashed black lines show 𝐿 for a recently proposed light-charge correlated model [9] which does not take escape electrons into account resulting in the same fixed estimate for 𝐿 at ℰ = 0 for any 𝑑𝐸/𝑑𝑥. Notice that LArQL predictions of 𝐿 differ from the correlated model for any 𝑑𝐸/𝑑𝑥 at lower values of ℰ giving estimates for 𝐿 consistent with available data (e.g.…”

Review of Liquid Argon Detector Technologies in the Neutrino Sector

“…The high statistics of data collected by LArIAT during its operation has allowed not only high precision characterisation of the detector itself (thereby providing valuable insights into the hardware and designs that were used), but also successful investigations of a number of charged particle LAr interactions as originally envisioned. These include the world first measurement of the π-Ar cross-section [42], high resolution calorimetric reconstruction of low-energy electrons [43] and identification and analysis of Michel electrons using only scintillation light-based triggering [44]. An example of an identified stopping muon and its associated Michel electron, as seen by the induction and collection wire planes, is shown in Figure 20.…”

A Demonstration of Light-Augmented Calorimetry For Low-Energy Electrons in Liquid Argon.

“…Extraction and reconstruction of the optical data values in MC is thus done in an idealized way that doesn't employ waveform corrections, hit-finding, or the integration techniques discussed in the previous section. Instead, simulated photoelectron arrival time distributions are used as proxy-waveforms and light yields are taken as the number of counts within the same integration regions applied to data (with smearing applied) [75].…”