legend-geom-optics¶

This package contains a collection of optical properties of materials used in the LEGEND experiment.

As a common interface, each optical property gets its own defining function in the material’s module. Those functions can be used directly to just retrieve the value(s) of the property. Most property definitions contain unit information via the pint package. For a full list of defined properties see the API reference.

To ease the use in Geant4-based simulations, every module defines one or more functions prefixed with pyg4_attach_. Those functions are to be used with pyg4ometry and will attach the listed properties to a material or surface instance.

Features¶

High-level helpers to attach optical properties to Geant4/pyg4ometry materials and optical surfaces (RINDEX, ABSLENGTH, RAYLEIGH, WLS*, SCINTILLATION*).
Pluggable property store to override or swap implementations at runtime without forking your code.
Unit-safe data handling using pint, including wavelength/energy conversion contexts for correct conversions.
Data-driven spectra with a simple file format and interpolation utilities.
Ready-made properties for many materials (LAr, PEN, TPB, scintillating fibers, reflectors like Tyvek/Tetratex/VM2000, metals/semiconductors/glass, water, nylon, Ultem, PMTs).
CLI utility to write G4GeneralParticleSource emission spectra from built-in WLS/scintillation spectra.
Sphinx plotting helpers to render optical property plots in the docs.

See the User Guide for a short walkthrough of these features.

Installation¶

You can install this package from PyPI or conda-forge:

PyPI (pip):
```
pip install legend-pygeom-optics
```

conda-forge (conda):

conda install -c conda-forge legend-pygeom-optics

Usage example¶

This example demonstrates how to use the pygeomoptics.lar submodule to add important optical properties to a pyg4ometry.geant4.Material instance using pygeomoptics.lar.pyg4_lar_attach_rindex(), pygeomoptics.lar.pyg4_lar_attach_attenuation(), and pygeomoptics.lar.pyg4_lar_attach_scintillation():

import pygeomoptics.lar
import pint
import pyg4ometry.geant4 as g4

g4_registry = g4.Registry()

_liquidargon = g4.Material(
    name="LiquidArgon",
    state="liquid",
    # [...]
    registry=g4_registry,
)

u = pint.get_application_registry().get()
pygeomoptics.lar.pyg4_lar_attach_rindex(
    _liquidargon,
    g4_registry,
)
pygeomoptics.lar.pyg4_lar_attach_attenuation(
    _liquidargon,
    g4_registry,
)
pygeomoptics.lar.pyg4_lar_attach_scintillation(
    _liquidargon,
    g4_registry,
    triplet_lifetime_method="legend200-llama",
)

Each property can be used separately:

import pygeomoptics.lar

lifetimes = pygeomoptics.lar.lar_lifetimes(triplet_lifetime_method="legend200-llama")
print(lifetimes.triplet)