Geometry Work Plan for 2026

Version 1.2

NOTE: Any dates assigned to items are to be considered just indicative.
- Items marked with refer to new developments.
- Items marked with will involve new man-power or contribution from external sources.
- Items marked with will require coordination with more than one Working Group.
- Items marked with (*) may or may not be achieved.

  1. Navigation & optimisation:
    • Use of multi-threading to speed up overlap checking for complex setups - (1)

      Plan to parallelise over candidate volumes, using tasks and/or threads. Goal is to enable increased statistics for overlap checks.

    • Improvements to parallel geometry initialisation for complex volumes- (1)/(2)

      Apply parallelisation over axis order to tackle mother volumes with many daughters; reintroduce memory management for optimisation structures.

    • Generate full geometry path for a given volume name - (1)/(2)

      Descend the geometry tree and create list of touchables of a physical volume (given by name); for use by GPS generator for distributions, also requested previously by Geant4 users.

  2. Field transport:
    • Introduce strict(er) default accuracy for field propagation - (2)

      Adapt default values for HEP tracking detectors.

  3. Solids modelling:
    • Improve robustness and performance of selected Geant4 solids - (1)/(2)

      Review implementation of selected solids in Geant4 for LHC and FCC production use.

  4. VecGeom:
    • Enhancements to deliver higher GPU navigation performance, and restructure it for consistent behavior across CPU and GPU with a maintainable, portable code base (CUDA/HIP) - (2)

      - Simplify and standardise the navigation interface (including boundary behavior).
      - Improve GPU navigation performance with new locality-aware accelerator.
      - Replace recursion with iteration (esp. for Boolean solids).
      - Remove vector constructs to simplify code and improve scalar performance.
      - Add portability layer and refactor device code to POD + explicit dispatch (no device virtuals).

  • Routine activities
    • Review of user documentation

(1) First semester
(2) Second semester

Created: 15 January 2026
Modified: 16 January 2026