.. Copyright Celeritas contributors: see top-level COPYRIGHT file for details
.. SPDX-License-Identifier: CC-BY-4.0

.. _release_v0.6.0:

Version 0.6.0
-------------
*Released 2025/04/23*

Version 0.6.0 is a major update to Celeritas featuring:

- High-level integration utilities for Geant4 applications
- Optical physics implementation including volumetric physics
- Advanced field mapping capabilities with 3D cylindrical and cartesian field maps and volume-specific uniform fields
- Extended geometry conversion and optimization-oriented features for ORANGE
- Support for VecGeom 2.0
- Spline interpolation for cross-section calculations and energy loss

A few minor features are noteworthy:

- Improved debugging utilities for diagnosing stuck/errored tracks
- Support for sensitive detectors in replica/parameterized volumes
- Better handling of tracks that fail or get stuck during simulation

Notable bug fixes include:

- Fixed navigation and mapping of reflecting volumes for VecGeom
- Resolved crashes related to process construction and memory access
- Fixed issues with GDML file loading and SD hit scoring
- Fixed Urban MSC scattering distribution (backported to v0.5.3)

Some interfaces have been removed:

- Obsolete demonstration apps and celer-dump-data
- Macro setup from celer-g4
- The ability to run on the default stream

Known deficiencies:

- Surface optical physics (reflection, refraction) is not yet implemented
- ORANGE performance is significantly degraded compared to v0.5

Changes since v0.5.0, excluding those released in v0.5.3, follow.

New features
------------

* Add optical "locate vacancies" and pre-step actions *(@amandalund, #1441)*
* Extend debug utilities for stuck/errored tracks *(@sethrj, #1451)*
* Add CELER_NONFATAL_FLUSH to cleanly kill stuck tracks *(@sethrj, #1455)*
* Add optical absorption model with imported data *(@hhollenb, #1440)*
* Add multilevel "volume instance"  *(@sethrj, #1461)*
* Reconstruct Geant4 navigation history from stack *(@sethrj, #1466)*
* Add "cut" for individual track steps *(@sethrj, #1467)*
* Improve error checking and diagnostic output for managing GPU *(@sethrj, #1464)*
* Add distance-to-bbox function *(@elliottbiondo, #1446)*
* Add multi-level state to detector step result *(@sethrj, #1471)*
* Override and save Geant4 dataset variables at configure time *(@pcanal, #1475)*
* Implement spline interpolation for cross-section calculation *(@lebuller, #1444)*
* Implement optical Rayleigh model *(@hhollenb, #1469)*
* Allow core and optical loops to have different numbers of track slots *(@amandalund, #1491)*
* Add muon decay interactor *(@stognini, #1456)*
* Add option to use spline-interpolated energy loss *(@lebuller, #1496)*
* Add an Optical WLS *(@whokion, #1507)*
* Add muon pair production *(@amandalund, #1518)*
* Extend BIH capabilities for intersection operations *(@elliottbiondo, #1479)*
* Add along-step and tracking cut optical executors *(@sethrj, #1540)*
* Enable optical stepping loop *(@sethrj, #1546)*
* Simplify UnitProto after building a CsgUnit *(@esseivaju, #1415)*
* Implement device bitset *(@esseivaju, #1547)*
* Reduce ``celer-sim`` memory usage and improve its ``CELER_LOG`` transport output *(@stognini, #1550)*
* Support sense caching for future lazy evaluation *(@esseivaju, #1539)*
* Support building infix logic representation *(@esseivaju, #1530)*
* Import and use muon+hadron EM physics parameters *(@amandalund, #1581)*
* Extend Coulomb scattering to support additional particle types *(@amandalund, #1574)*
* Add optical model importer and refactor imported optical materials *(@hhollenb, #1520)*
* Add global Celeritas input definition *(@sethrj, #1562)*
* Always select at-rest process for stopped tracks *(@amandalund, #1592)*
* Use BIH to accelerate background_intersect *(@elliottbiondo, #1599)*
* Add ultra-simple tracking manager integration *(@sethrj, #1609)*
* Implement cubic spline interpolation *(@amandalund, #1607)*
* Add a calculator to integrate range from energy loss *(@amandalund, #1544)*
* Add G4Ellipsoid without bottom/top cuts *(@elliottbiondo, #1617)*
* Add safety visualization tool *(@sethrj, #1614)*
* Remove pointers from Geant4 labels *(@sethrj, #1620)*
* Add high-level user/fast sim integration helpers *(@sethrj, #1615)*
* Support spline interpolation on a nonuniform grid *(@amandalund, #1625)*
* Prune primaries that start outside the world volume *(@sethrj, #1624)*
* Add support for Z cuts when converting G4Solids *(@elliottbiondo, #1638)*
* Support sensitive detectors in replica/parameterized volumes *(@sethrj, #1649)*
* Add an option to enable status checker through celer-sim *(@sethrj, #1650)*
* Add support for elliptical cylinders and elliptical cones in orange and g4org *(@elliottbiondo, #1642)*
* Support post-step touchable location and step status *(@sethrj, #1653)*
* Support surface-based VecGeom 2.x navigator *(@mrguilima, #1422)*
* Approximate G4Torus using inner/outer bounding cylinders *(@elliottbiondo, #1654)*
* Support volume-specific uniform field *(@amandalund, #1659)*
* Implement discrete optical physics *(@hhollenb, #1604)*
* Add an example user action for gathering statistics on GPU *(@sethrj, #1664)*
* Add quantity support to FindInterp and template Turn *(@sethrj, #1675)*
* Support VecGeom 2.0 *(@sethrj, #1674)*
* Add 3D Cylindrical field map *(@esseivaju, #1662)*
* Make SB energy limit configurable and partially fix failures when using a single brems model *(@amandalund, #1686)*
* Add timers to accel integration classes *(@amandalund, #1693)*
* Use float for field interpolation *(@esseivaju, #1684)*
* Allow some "required" SetupOptions to be set via Geant4 UI *(@sethrj, #1697)*
* Support counter with NVTX *(@esseivaju, #1702)*
* Use programmatic optical counters instead of absurdly verbose printout *(@sethrj, #1707)*
* Allow G4 applications to query celeritas offload mode *(@sethrj, #1711)*
* Reduce logging verbosity during Geant4 runs *(@sethrj, #1705)*
* Improve messages when multiple tracks fail in flight *(@sethrj, #1715)*
* Estimate scintillation wavelength distribution parameters from tabulated values when only the latter is provided *(@amandalund, #1722)*
* Add utilities to stabilize downstream use of ORANGE *(@sethrj, #1736)*
* Expand support for spline interpolation *(@amandalund, #1633)*
* Add cartesian magnetic field using Covfie *(@esseivaju, #1744)*

Bug fixes
---------

* Define a "unique event ID" different from event counter *(@sethrj, #1447)*
* Fix optical import when unused materials are defined *(@sethrj, #1449)*
* Remove trackid counter from primary *(@sethrj, #1448)*
* Improve single-event mode in ``accel`` *(@sethrj, #1452)*
* Fix GDML export messages and geometry-only use case *(@sethrj, #1454)*
* Fix tracking cut message *(@sethrj, #1458)*
* Anchor vtables to fix broken dynamic cast in tests *(@sethrj, #1474)*
* Fix documentation *(@sethrj, #1502)*
* Fix clang-tidy weekly cron *(@esseivaju, #1541)*
* Fix multiple ``release()`` calls to ensure nullptr is not used in process construction *(@amandalund, #1612)*
* Support different grid spacings for cross section data *(@amandalund, #1622)*
* Fix crash in multithreaded celer-g4 *(@amandalund, #1627)*
* Fix loading of GDML files with reflection *(@sethrj, #1626)*
* Fix navigation and mapping of reflecting volumes *(@sethrj, #1629)*
* Fix reading and writing HepMC3 events *(@amandalund, #1635)*
* Initialize MPI in high-level integration classes *(@sethrj, #1672)*
* Fix bremsstrahlung process construction when using only a single model *(@amandalund, #1677)*
* Lazily fetch volumes for UniformAlongStepFactory  *(@rahmans1, #1666)*
* Fix BoundingZone floating point issue *(@elliottbiondo, #1681)*
* Fix out-of-bounds memory access in ``CylMapField`` *(@amandalund, #1689)*
* Fix Geant4 SD hit scoring *(@amandalund, #1708)*
* Fix field map usage from accel *(@sethrj, #1724)*
* Fix failures when integral approach is disabled *(@amandalund, #1727)*

Documentation improvements
--------------------------

* Improve XSCalculator documentation and tests *(@sethrj, #1450)*
* Require clang-tidy in CI *(@esseivaju, #1524)*
* Tidy headers *(@esseivaju, #1534)*
* Run clang-tidy on modified files only *(@esseivaju, #1531)*
* Build VecGeom in weekly clang-tidy cron *(@esseivaju, #1551)*
* Document and slightly refactor Bethe-Heitler interactor *(@sethrj, #1553)*
* Update copyrights *(@sethrj, #1560)*
* Enable more dependencies in clang-tidy checks *(@esseivaju, #1561)*
* Fix Doxygen member group formatting *(@amandalund, #1567)*
* Improve and fix documentation *(@sethrj, #1588)*
* Add generic geometry test interface to reduce duplication *(@sethrj, #1623)*
* Improve testing and documentation for VecGeom *(@sethrj, #1639)*
* Fix rendering of README *(@dalg24, #1640)*
* Add ORCID to citation *(@esseivaju, #1645)*
* Improve geometry testing *(@sethrj, #1652)*
* Move offload template into a celeritas::example namespace *(@sethrj, #1663)*
* Enable optical GPU tests *(@amandalund, #1682)*
* Update ROOT data and tests with Geant4 version 11.3.0 *(@amandalund, #1687)*
* Split EM physics and Geant4 interface into sub-files *(@sethrj, #1698)*
* Improve doc generation and brems-related documentation *(@sethrj, #1701)*
* Update Geant4 version to 11.3 in CI build *(@amandalund, #1712)*
* Add histogram helper class to simplify distribution tests *(@amandalund, #1717)*
* Add string simplifier helper class for testing *(@sethrj, #1719)*
* Improve MSC test code coverage *(@sethrj, #1723)*
* Add quick-start documentation for integrating *(@sethrj, #1725)*
* Fix pedantic warning in tests *(@elliottbiondo, #1730)*
* Add authorship guidelines *(@sethrj, #1747)*
* Support testing nested container equivalence and tweak ``Histogram`` class *(@amandalund, #1753)*

Minor internal changes
----------------------

* Give priority to existing environment variables for G4 data location *(@pcanal, #1457)*
* Define ``id_cast`` helper function *(@sethrj, #1459)*
* Simplify geometry "volume" interface *(@sethrj, #1460)*
* Refactor step storage to use aux state *(@sethrj, #1465)*
* Refactor pinned allocator to reduce need for templates *(@sethrj, #1468)*
* Tweak Perfetto integration *(@sethrj, #1470)*
* Escape semicolons in exported CMake variables *(@drbenmorgan, #1472)*
* Require ``CELERITAS_DEBUG`` be on to enable ``CELERITAS_DEVICE_DEBUG`` *(@amandalund, #1476)*
* Use kernel launchers instead of macros *(@sethrj, #1477)*
* Fix missing brace and refactor #1475 *(@sethrj, #1480)*
* Fix build with latest Geant4 develop *(@pcanal, #1484)*
* Refactor "touchable updater" that uses a navigator *(@sethrj, #1483)*
* Store edge bounding boxes on BIH and refactor for upcoming intersection capabilities *(@elliottbiondo, #1478)*
* Add FourVector helper functions *(@sethrj, #1510)*
* Define hypotenuse function using fma *(@sethrj, #1513)*
* Add a helper class for inverse transform sampling *(@amandalund, #1525)*
* Rename Cerenkov to Cherenkov *(@amandalund, #1533)*
* Clean up optical mock test data *(@hhollenb, #1519)*
* Store a single process-integrated energy loss and range table per particle *(@amandalund, #1536)*
* Add piecewise integrator and CDF utilities *(@sethrj, #1537)*
* Define precision-agnostic Constant class *(@sethrj, #1549)*
* Adapt bitset word size *(@esseivaju, #1554)*
* Add 'LogicalTrue' functor *(@sethrj, #1564)*
* Fix unnecessary use of inline constexpr *(@sethrj, #1568)*
* Replace "volid" with "vol_id" throughout ORANGE *(@elliottbiondo, #1486)*
* Compose caching functionality of LazySenseCalculator *(@esseivaju, #1569)*
* Use lazy sense calculator *(@esseivaju, #1576)*
* Change PrimaryGeneratorAction to be a wrapper  *(@sethrj, #1593)*
* Refactor primary generator using new ``inp`` *(@sethrj, #1583)*
* Add postfix to infix conversion utility *(@esseivaju, #1582)*
* Move physics lists out of details and rename tracking offload *(@sethrj, #1603)*
* Add TrackingManagerConstructor and SharedParams::GetMode *(@sethrj, #1606)*
* Move ``PolyEvaluator`` to corecel/math *(@amandalund, #1610)*
* Rename fast simulation offload *(@sethrj, #1613)*
* Rename ``Generic`` grid to ``Nonuniform`` *(@amandalund, #1616)*
* Require VecGeom 1.2.10 for CUDA RDC support *(@pcanal, #1628)*
* Construct CoreParams from new problem input in celer-sim *(@sethrj, #1601)*
* Move Geant4 SD integration into celeritas/ext *(@sethrj, #1631)*
* Refactor log handlers for better reuse *(@sethrj, #1636)*
* Rename ``CoreTrackView`` methods *(@amandalund, #1658)*
* Refactor geometry tests into common file *(@sethrj, #1656)*
* Use extern static data for versions, configuration *(@sethrj, #1657)*
* Use CLI11 for front end command line parsing *(@sethrj, #1660)*
* Hide Thrust from .cc code *(@sethrj, #1670)*
* Remove G4EmExtraPhysics from FtfpBertPhysicsList *(@whokion, #1644)*
* Define dependency helper targets and reorganize CMakeLists *(@sethrj, #1673)*
* Change default field substeps in accel *(@esseivaju, #1690)*
* Update and fix G4VG external integration *(@sethrj, #1700)*
* Use ``inp`` to build ``accel`` core params *(@sethrj, #1632)*
* Move random to corecel *(@sethrj, #1716)*
* Remove dependency of orange test on celeritas *(@sethrj, #1718)*
* Simplify Geant4 user application interface *(@sethrj, #1729)*
* Replace ``ImportPhysicsVector`` with ``inp::Grid`` *(@amandalund, #1735)*
* Add ExtThrust for more explicit dependencies *(@sethrj, #1694)*
* Rename field integration interfaces: Stepper→Integrators, Driver→Substepper *(@sethrj, #1737)*
* Add uniform grid input and continue to simplify grid construction *(@amandalund, #1739)*
* Rename material ID types *(@sethrj, #1742)*
* Simplify grid construction in a few more places *(@amandalund, #1743)*
* Fix ROCTX find: hip not cuda *(@sethrj, #1755)*
* Move types around to fix ROOT error *(@sethrj, #1757)*
* Simplify MSC angular sampling *(@sethrj, #1714)*

Deprecation and removal
-----------------------

* Delete obsolete demonstration apps *(@sethrj, #1463)*
* Remove 'default_stream' option *(@sethrj, #1667)*
* Remove deprecations for v0.6 *(@sethrj, #1691)*
* Remove macro setup from celer-g4 *(@sethrj, #1710)*
* Remove per-process switch for integral cross section method *(@amandalund, #1734)*
* Remove celer-dump-data app *(@amandalund, #1740)*

Reviewers
---------

* Seth R. Johnson *(@sethrj)*: 89
* Amanda Lund *(@amandalund)*: 68
* Philippe Canal *(@pcanal)*: 22
* Stefano Tognini *(@stognini)*: 10
* Guilherme Lima *(@mrguilima)*: 9
* Julien Esseiva *(@esseivaju)*: 7
* Elliott Biondo *(@elliottbiondo)*: 5
* Soon Yung Jun *(@whokion)*: 3

**Full Changelog**: https://github.com/celeritas-project/celeritas/compare/v0.5.0...v0.6.0