Simulation Model#

Introduction#

Simulation model parameters describe properties of all relevant elements of the observatory including site, telescopes, and calibration devices. The management, definition, derivation, verification, and validation of the simulation model is central to the functionality of simtools. Model parameters are centrally stored (in a database and repository) and described and defined by schema files.

Examples for model parameters are those describing atmospheric model (profile, transmission) or geomagnetic field characteristics for the site, descriptions of optical and mechanical properties of the telescope, and detector plan, trigger, and readout settings for the cameras (see model parameter schema files for all model parameters.)

For simplicity, the term parameter is used for values, (multi-dimensional) vectors of values (e.g., the mirror reflectivity vs wavelength and photon incident angle), functions, and algorithms (e.g., the telescope trigger algorithm). Parameters might be fixed in time (e.g., the number of mirrors on a certain telescope), or variable on different time scales (e.g., compare the degradation of the mirror reflectivity over several months with the nightly variability of the atmospheric parameters).

The major components to handle the simulation model in simtools are:

Model parameter databases: The simulation model is stored in mongoDB databases. The db_handler module provides reading and writing interfaces to the database.
Model parameter management: The model parameters module provides interfaces to manage the simulation model parameters.
A model of an array and its elements consists of the SiteModel and several TelescopeModel`and CalibrationModel instances.

Simtools includes applications to write new model parameters to the databases and the export or import model parameters from sim_telarray configuration files (see following sections).

Review and revision control of the simulation models uses the model parameters gitlab repository. Simtools provides applications to read, write, and update the databases from this repository.

Note

The simulation model is a central part of the CTAO Simulation Pipeline. The responsibility for the values and the correctness of the simulation model parameters is with the CTAO Simulation Team.

Description of model parameters#

Schema files define all simulation model parameters are part of simtools and can be found in simtools/schemas/model_parameters.

These files describe the simulation model parameters including (among others fields) name, type, format, units, applicable telescopes, and parameter description. They include information about setting and validation activities, data sources, and simulation software. The schema files and especially the model parameter descriptions are derived from (and planned to be synchronized with) the sim_telarray manual.

The schema files are in human readable yaml format and follow a fixed meta metaschema (see model_parameter_and_data_schema.metaschema.yml; found in simtools schema directory).

Example#

The following example is for a single parameter description.

%YAML 1.2
---
title: Schema for num_gains model parameter
version: 0.1.0
meta_schema: simpipe-schema
meta_schema_url: https://raw.githubusercontent.com/gammasim/simtools/main/simtools/schemas/model_parameter_and_data_schema.metaschema.yml
meta_schema_version: 0.1.0
name: num_gains
description: Number of different gains the input signal gets digitized.
data:
  - type: int
    unit: dimensionless
    default: 1
    allowed_range:
      min: 1
      max: 2
instrument:
  class: Camera
  type:
    - LSTN
    - LSTS
    - MSTN
    - MSTS
    - SSTS
    - SCTS
activity:
  setting:
    - SetParameterFromExternal
  validation:
    - ValidateParameterByExpert
source:
  - Initial instrument setup
simulation_software:
  - name: sim_telarray

Valid Keys#

Valid keys are described in detail in model_parameter_and_data_schema.metaschema.yml. The most important parameters are:

Header section#

title: Title of the schema file.
version: Version of this schema file.
meta_schema: Name of the base schema.
meta_schema_url: URL of the base schema.
meta_schema_version: Version of the base schema.

Parameter description#

name: Name of the parameter.
description: Description of the parameter.
short_description: Short description of the parameter (optional).

Parameter data#

The data field is used to describe the actual type, format, and allowed values of the parameter.

type: Data type of the parameter.
unit: Units of the parameter (compatible with astropy units).
default: Default value of the parameter.
allowed_range: Allowed range of the parameter.
allowed_values: Allowed values of the parameter. Use if values are not continuous and restricted to a small list of allowed values.

Tables of any dimensions can be described using the data_table field. Example:

data:
  - type: data_table
    table_columns:
      - name: wavelength
        description: Wavelength.
        required: true
        unit: nm
        type: double
        required_range:
          min: 300.0
          max: 700.0
        input_processing:
          - remove_duplicates
          - sort
      - name: photo_detection_efficiency
        description: Average quantum or photon detection efficiency.
        required: true
        unit: dimensionless
        type: double
        allowed_range:
          min: 0.0
          max: 1.0

Input processing in form of sorting, removing of duplicates, etc. can be specified using the input_processing field.

Warning

The data_table field is not yet implemented in the simtools schema and parameter files.

Instrument description#

class: Instrument class. Allow values are Camera, Site, Structure, Telescope
type: Instrument type following CTAO Naming.
site: CTAO site. Allowed values are North and South.

Activity description#

Describes setting and validation activities. Each activity corresponds to a workflow as described in the simtools workflows repository.

Warning

The implementation of activities and workflows is incomplete and in progress.

Data source description#

Describes the source of the data or parameter (e.g., Calibration)

Simulation software description#

Describes the simulation software (e.g., sim_telarray or corsika) the parameter is used for.

simulation_software:
  - name: corsika

Allowed is here to add the internal simulation software parameter naming (if different than the name used here in the schema). This is important to write correct and consistent CORSIKA or sim_telarray configuration files.

Example:

simulation_software:
  - name: sim_telarray
    internal_parameter_name: secondary_ref_radius

Data structure for model parameters#

The model parameters are stored in json-style in the model repository and database. A typical model parameter file looks like:

{
    "parameter": "num_gains",
    "instrument": "LSTN-01",
    "site": "North",
    "version": "2024-02-01",
    "value": 2,
    "unit": null,
    "type": "int64",
    "applicable": true,
    "file": false
}

Updating the model database#

Danger

This is for experts only and might impact the simulation model database for all users. Tests should be done using a sandbox database before applying this to the production databases.

Update a single model parameter#

New model parameter defined in the simtools database format (json file) can be uploaded to the database using the simtools-add-value-from-json-to-db application. New data files can be uploaded using simtools-add-file-to-db.

Upload a complete simulation model from model repository to model database#

The application db_add_model_parameters_from_repository_to_db.py allows to export the simulation model parameters from a model repository to the model database for a given model version. See the database section for implementation details on databases in simtools.

Example:

simtools-add_model-parameters-from-repository-to-db \
      --input_path /path/to/repository \
      --db_name new_db_name

This application loops over all subdirectories in input_path and uploads all json files to the database new_db_name (or updates an existing database with the same name):

subdirectories starting with OBS are uploaded to the sites collection
json files from the subdirectory configuration_sim_telarray are uploaded to the configuration_sim_telarray collection
Files are added to the files collection
all other json files are uploaded to collection defined in the array element description in simtools/schemas/array_elements.yml. Allowed values are e.g., telescopes, calibration_devices.

Import simulation model parameters#

Import Prod6 model parameters#

Prod6 model parameters can be extracted from sim_telarray using the following commands.

./sim_telarray/bin/sim_telarray \
   -c sim_telarray/cfg/CTA/CTA-PROD6-LaPalma.cfg \
   -C limits=no-internal -C initlist=no-internal \
   -C list=no-internal -C typelist=no-internal \
   -C maximum_telescopes=30 -DNSB_AUTOSCALE \
   -DNECTARCAM -DHYPER_LAYOUT -DNUM_TELESCOPES=30 \
   /dev/null 2>|/dev/null | grep '(@cfg)'  >| all_telescope_config_la_palma.cfg

./sim_telarray/bin/sim_telarray \
   -c sim_telarray/cfg/CTA/CTA-PROD6-Paranal.cfg \
   -C limits=no-internal -C initlist=no-internal \
   -C list=no-internal -C typelist=no-internal \
   -C maximum_telescopes=87 -DNSB_AUTOSCALE \
   -DNECTARCAM -DHYPER_LAYOUT -DNUM_TELESCOPES=87 \
   /dev/null 2>|/dev/null | grep '(@cfg)'  >| all_telescope_config_paranal.cfg

Import Prod5 model parameters#

Prod5 model parameters can be extracted from sim_telarray using the following commands.

./sim_telarray/bin/sim_telarray \
   -c sim_telarray/cfg/CTA/CTA-PROD5-LaPalma.cfg \
   -C limits=no-internal -C initlist=no-internal \
   -C list=no-internal -C typelist=no-internal \
   -C maximum_telescopes=85 -DNSB_AUTOSCALE \
   -DNECTARCAM -DHYPER_LAYOUT -DNUM_TELESCOPES=85 \
   /dev/null 2>|/dev/null | grep '(@cfg)'  >| all_telescope_config_la_palma_prod5.cfg

./sim_telarray/bin/sim_telarray \
   -c sim_telarray/cfg/CTA/CTA-PROD5-Paranal.cfg \
   -C limits=no-internal -C initlist=no-internal \
   -C list=no-internal -C typelist=no-internal \
   -C maximum_telescopes=120 -DNSB_AUTOSCALE \
   -DNECTARCAM -DHYPER_LAYOUT -DNUM_TELESCOPES=120 \
   /dev/null 2>|/dev/null | grep '(@cfg)'  >| all_telescope_config_paranal_prod5.cfg

Import telescope positions#

Positions of array elements like telescopes are provided by CTAO in form of tables (typically ecsv files). To import these positions into the model parameter repository, see the following example:

simtools-write-array-element-positions-to-repository \
    --input /path/to/positions.txt \
    --repository_path /path/to/repository \
    --model_version 1.0.0 \
    --coordinate_system ground \
    --site North

Simulation Model

Contents

Simulation Model#

Introduction#

Description of model parameters#

Example#

Valid Keys#

Header section#

Parameter description#

Parameter data#

Instrument description#

Activity description#

Data source description#

Simulation software description#

Data structure for model parameters#

Updating the model database#

Update a single model parameter#

Upload a complete simulation model from model repository to model database#

Import simulation model parameters#

Import Prod6 model parameters#

Import Prod5 model parameters#

Import telescope positions#