Cherenkov light
A Geant4 electron track in water. Simulate its light, move around the chamber, and slow the event to a fraction of a nanosecond.
Physics, data, and rendering
The electron event comes from DORAEMON / LUCiD configuration 000006, event 123. Segment endpoints, initial directions, initial speeds, and event-relative times are preserved under a rigid rotation and translation, without changing their physical size. Secondary electron tracks are included. The straight-track reference is synthetic.
New photons are generated over 360–700 nm using the Frank–Tamm spectrum and the wavelength-dependent Cherenkov angle. The source uses the stored speed and direction at each segment's start, uniform emission along its chord, and constant speed within the segment. This is a reconstruction from exported steps, not a bitwise Geant4 replay. The original photon counts have an unconfirmed wavelength band and are not used to normalize this simulation.
Transport includes wavelength-dependent absorption, polarized Rayleigh scattering, and dispersive group delay. The chamber walls are absorbing diffuse observation screens; the camera looks through an open cutaway, with no glass window. The illustrative water model uses a Cauchy refractive index, a Rayleigh length of 80 m at 450 nm, and approximate absorption lengths. These are demonstration optics, not the source detector's calibration.
Every photon sample contributes to time-binned surface maps and a track-length estimate of scattered light, retaining polarization moments. The camera integrates a smoothed 36³ volume map; wall maps are 128² per face, with 0.25 ns time bins. Visible colors use Chroma's CIE 1964 matching tables. Camera attenuation uses three representative visible wavelengths after color integration. Volume gain separately increases the visibility of weak scattered light; set it to 1× for a common exposure. These are finite-resolution rendering approximations.
The pulse view shows simultaneous event-time slices of the scattering field. Screens accumulate arrivals up to the selected time. It is not a retarded-time movie from a physical high-speed camera. Increasing photon samples reduces noise; it does not increase event energy. At a fixed exposure, brightness scales with the estimated visible yield. The estimate assumes unit-charge electrons and the illustrative optical model.
Geant4 Cherenkov reference · Exported event data and provenance