add some basic documentation

docs/source/index.rst

@@ -1,10 +1,39 @@
 Welcome to legendhpges's documentation!
-==========================================
+=======================================
 
-Table of Contents
------------------
+Python package of Germanium detector geometries for radiation transport simulations.
+
+Getting started
+---------------
+
+legendhpges can be installed with pip.
+
+.. code-block:: console
+
+   $ git pull [email protected]:legend-exp/legend-pygeom-hpges.git
+   $ cd legend-pygeom-hpges
+   $ pip install .
+
+
+Next steps
+----------
+
+.. toctree::
+   :maxdepth: 1
+
+   User Manual <manual>
 
 .. toctree::
    :maxdepth: 1
 
    Package API reference <api/modules>
+
+See also
+--------
+
+ - `remage <https://remage.readthedocs.io/en/stable/>`_: Modern *Geant4* application for HPGe and LAr experiments,
+ - `reboost <https://github.com/legend-exp/reboost>`_: Post processing of remage simulations in python.
+ - `pyg4ometry <https://pyg4ometry.readthedocs.io/en/stable/>`_: Package to create simulation geometry in python,
+ - `legend-pygeom-optics <https://legend-pygeom-optics.readthedocs.io/en/stable/>`_: Package to handle optical properties in python,
+ - `legend-pygeom-l200 <https://github.com/legend-exp/legend-pygeom-l200>`_: Implementation of the LEGEND-200 experiment (**private**),
+ - `pyvertexgen <https://github.com/tdixon97/pyvertexgen/>`_: Generation of vertices for simulations.

docs/source/manual.rst

@@ -0,0 +1,140 @@
+Basic User Manual
+=================
+
+This package implements a ``HPGe`` which describes the detector geometry and can be used for:
+
+- visualisation with `pyg4ometry <https://pyg4ometry.readthedocs.io/en/stable/>`_
+- exporting to GDML for Geant4 simulations (again with pyg4ometry),
+- computing detector properties.
+
+Metadata specification
+----------------------
+
+The detector geometry is constructed based on the LEGEND metadata specification `(metadata-docs) <https://github.com/legend-exp/legend-detectors/tree/main/germanium/diodes>`_.
+This consists of a JSON file (or python dictionary) describing the geometry for example:
+
+.. code-block:: python
+
+    metadata = {
+        "name": "B00000B",
+        "type": "bege",
+        "production": {
+            "enrichment": {"val": 0.9, "unc": 0.003},
+            "mass_in_g": 697.0,
+        },
+        "geometry": {
+            "height_in_mm": 29.46,
+            "radius_in_mm": 36.98,
+            "groove": {"depth_in_mm": 2.0, "radius_in_mm": {"outer": 10.5, "inner": 7.5}},
+            "pp_contact": {"radius_in_mm": 7.5, "depth_in_mm": 0},
+            "taper": {
+                "top": {"angle_in_deg": 0.0, "height_in_mm": 0.0},
+                "bottom": {"angle_in_deg": 0.0, "height_in_mm": 0.0},
+            },
+        },
+    }
+
+.. note::
+    Currently bege, icpc, ppc and coax geometries are implemented as well as a few LEGEND detectors with special geometries.
+    Different geometries can be implemented as subclasses deriving from ``legendhpges.base.HPGe``.
+
+The different keys of the dictionary describe the different aspects of the geometry.
+Some are self explanatory, for others:
+
+- "production": gives information on the detector production, we need the "enrichment" to define the detector material,
+- "geometry"  : gives the detector geometry in particular, "groove" and "pp_contact" describe the contacts of detector.
+
+Other fields can be added to describe different geometry features (more details in the legend metadata documentation).
+
+Constructing the HPGe object
+----------------------------
+
+The HPGe object can be constructed from the metadata with:
+
+.. code-block:: python
+
+    from legendhpges import make_hpge
+    import pyg4ometry as pg4
+
+    reg = pg4.geant4.Registry()
+    hpge = make_hpge(metadata, name="det_L")
+
+The metadata can either be passed as a python dictionary or a path to a JSON file.
+
+
+Detector properties
+-------------------
+
+Most detectors are described by a ``G4GenericPolycone`` (:class:`pyg4ometry.geant4.solid.GenericPolycone`)
+This describes the solid by a series of (r,z) pairs rotated around the z axis.
+
+There are methods to plot the (r,z) profile of the detector, in addition this is able to label the contact type (p+,n+ or passivated) each surface
+corresponds to (based on the metadata).
+
+.. code-block:: python
+
+    from legendhpges import draw
+
+    draw.plot_profile(hpge, split_by_type=True)
+
+.. image:: images/bege_profile.png
+
+We can also directly extract the r,z profile and the surface types and surface area of each.
+
+.. code-block:: python
+
+    r, z = hpge.get_profile()
+    surfaces = hpge.surfaces
+    area = hpge.surface_area()
+    print(f"total area {sum(area)}")
+
+.. code-block:: console
+
+    total area 13775.325839135963 mm²
+
+Here the surfaces correspond to the line from :math:`r_i` to :math:`r_{i+1}` and :math:`z_i` to :math:`z_{i+1}`.
+
+We can also easily extract the detector mass and volume:
+
+.. code-block:: python
+
+    print(f"mass   {hpge.mass}")
+    print(f"volume {hpge.volume}")
+
+.. code-block:: text
+
+    mass   700.5770262065953 g
+    volume 126226.52555880952 mm³
+
+Finally we can compute the distance of a set of points to the electrodes and check whether a point is inside the detector.
+mm
+
+
+Use in a Geant4 simulation
+--------------------------
+
+The HPGe object derives from :class:`pyg4ometry.geant4.LogicalVolume` and can be used to visualise the detector in 3D, or to run Geant4 simulations.
+
+For example to visualise a detector we can use:
+
+.. code-block:: python
+
+    # create a world volume
+    world_s = pg4.geant4.solid.Orb("World_s", 20, registry=reg, lunit="cm")
+    world_l = pg4.geant4.LogicalVolume(world_s, "G4_Galactic", "World", registry=reg)
+    reg.setWorld(world_l)
+
+    # place the detector
+    pg4.geant4.PhysicalVolume(
+        [0, 0, 0], [0, 0, 0, "cm"], hpge, "det", world_l, registry=reg
+    )
+
+    viewer = pg4.visualisation.VtkViewerColoured()
+    viewer.addLogicalVolume(reg.getWorldVolume())
+    viewer.view()
+
+.. image:: images/bege.png
+
+The `(remage-tutorial) <https://remage.readthedocs.io/en/stable/>`_ gives a more complete example of using legendhpges to run a simulation.
+
+This class is also the basis of the *legend-pygeom-l200* implementation of the LEGEND-200 experiment `(legend-pygeom-l200 docs) <https://github.com/legend-exp/legend-pygeom-l200>`_ (**private**),