Prometheus: An Open-Source Neutrino Telescope Simulation

TL;DR

Prometheus delivers an open-source, detector-agnostic simulation framework for neutrino telescopes in ice and water, integrating injection, particle propagation, light yield, and photon transport into a parquet-output workflow that supports arbitrary geometries via geo files and Earth models. By combining LeptonInjector, PROPOSAL, fennel, PPC, Hyperion, and a Parquet-based data format, Prometheus enables cross-experiment studies and rapid analysis, while its modular design allows injection extensibility and event weighting to physical fluxes. The paper demonstrates practical usage through ice- and water-based examples, analyzes performance where photon propagation dominates runtime, and validates the approach with comparisons to published effective areas, underscoring its potential as a community resource. The work aims to foster collaboration, data sharing, and development of reconstruction techniques that can be transferred across detectors, supported by documented configuration, testing plans, and future enhancements.

Abstract

Neutrino telescopes are gigaton-scale neutrino detectors comprised of individual light-detection units. Though constructed from simple building blocks, they have opened a new window to the Universe and are able to probe center-of-mass energies that are comparable to those of collider experiments. \prometheus{} is a new, open-source simulation tailored for this kind of detector. Our package, which is written in a combination of \texttt{C++} and \texttt{Python} provides a balance of ease of use and performance and allows the user to simulate a neutrino telescope with arbitrary geometry deployed in ice or water. \prometheus{} simulates the neutrino interactions in the volume surrounding the detector, computes the light yield of the hadronic shower and the out-going lepton, propagates the photons in the medium, and records their arrival times and position in user-defined regions. Finally, \prometheus{} events are serialized into a \texttt{parquet} file, which is a compact and interoperational file format that allows prompt access to the events for further analysis.

Figures (16)

• Figure 1: Schematic showing the physical processes Prometheus models. (1), Prometheus selects an interaction vertex within simulation volume, depicted here by the lighter-colored region. (2), the final states of this interaction are then propagated, accounting for energy losses and any daughter particles which may be produced. (3), these losses are then converted to a number of photons. (4), finally, these photons are then propagated until they either are absorbed or reach an optical module.
• Figure 2: Event views for various detector geometries. This shows the events created by either $\nu_{\mu}$ charged-current or $\nu_{e}$ charged-current interactions in a variety of geometries of current and proposed neutrino telescopes. Each black dot is an OM, while each colored dot indicates the average time at which photons arrived at the OM; black indicates an earlier arrival, orange indicates a later arrival, and purple an arrival in between. Furthermore, the size of the colored spheres is proportional to the number of photons that arrived at the OM. Detectors which appear against lighter blue backgrounds---the top row---are ice-based, while those against the darker blue backgrounds are water-based.
• Figure 3: Output format for default Prometheusparquet files. The solid lines indicate that information is stored in fields, while the dashed line indicates that information is stored in the metadata. We delay detailed discussion until Ex. \ref{['ex:output']}, where we explain each field and compute basic quantities of interest. Fields with an asterisk can be renamed by the user to be compatible with legacy conventions.
• Figure 4: Summary of packages used for different stages in the code. The boxes outlined in white are the default packages used, while boxes outlined in black have optional interfaces. Event weighting has a dashed outline to denote that this step is optional. The default behavior of the light yield calculation and the photon propagation depends on the medium, as is shown by the light shaded regions.
• Figure 5: Comparison between GEANT4 and fennel longitudinal profiles. Top: Shown are the differential track lengths for three particle showers each with a different energies. Note, the shift of the maximum depending on energy. Bottom: The ratio of the differential track lengths. For most of the shower's development, the differences between GEANT4 and fennel are below 20%.