Improve derivation of CORSIKA limits and allow to define a loss fraction per energy bin ('differential loss').

[GernotMaier]

A new config value allows to trigger a event loss fraction calculation per energy bin (e.g., --differential_loss_bins_per_decade=5). Energy bins are chosen as bins per decade, with bins aligned to the decades (e.g., lower limit to 100 GeV).

The limit chosen (at this point) is the max of the differential limit.

Motivation is to get a better handle on the impact of the power law used to select the energies in the simulations. Limits should also be independent of the power-law index chosen.

Improve the plotting and plot the differential limit in the 2D plots.

[Copilot]

Pull request overview

This PR extends the CORSIKA limit derivation workflow to optionally compute “differential” (per-energy-bin) loss limits and enhances plotting to display the resulting limit curves, aiming to make derived limits less sensitive to the simulation spectral index.

Changes:

• Add a new CLI/config option differential_loss_bins_per_decade and propagate it through the CORSIKA limits grid execution.
• Implement differential per-energy-bin limit computation and expose the resulting curves for plotting.
• Update event energy binning to use decade-aligned bins and adjust unit/integration tests accordingly.

Reviewed changes

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
src/simtools/production_configuration/derive_corsika_limits.py	Adds differential-limit computation path and per-energy-slice limit extraction utilities.
src/simtools/applications/production_derive_corsika_limits.py	Adds CLI argument for enabling/configuring differential loss binning.
src/simtools/sim_events/histograms.py	Changes energy bin edges to decade-aligned binning (10 bins/decade).
src/simtools/visualization/plot_simtel_event_histograms.py	Extends limit mapping and plotting to support drawing differential limit curves.
tests/unit_tests/production_configuration/test_derive_corsika_limits.py	Adds/updates unit tests for differential mode and argument propagation.
tests/unit_tests/sim_events/test_histograms.py	Updates expected energy bin structure for new decade-aligned binning.
tests/unit_tests/visualization/test_plot_simtel_event_histograms.py	Updates plotting tests for curve rendering and revised line behavior.
tests/integration_tests/config/production_derive_corsika_limits_hdf5_db_arrays.yml	Enables differential loss mode in an integration config.
docs/changes/2185.feature.md	Adds changelog fragment for the new capability.

[ctao-sonarqube]

Quality Gate passed

Issues
0 New issues
0 Fixed issues
0 Accepted issues

Measures
0 Security Hotspots
98.5% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube