Add detector architecture + isotropic detectors

src/pg_rad/configs/defaults.py

@@ -16,3 +16,10 @@ DEFAULT_MAX_TURN_ANGLE = 90.
 DEFAULT_FRICTION_COEFF = 0.7      # dry asphalt
 DEFAULT_GRAVITATIONAL_ACC = 9.81  # m/s^2
 DEFAULT_ALPHA = 100.
+
+# --- Detector efficiencies ---
+DETECTOR_EFFICIENCIES = {
+    "dummy": 1.0,
+    "NaIR": 0.0216,
+    "NaIF": 0.0254
+}

src/pg_rad/detector/builder.py

@@ -0,0 +1,20 @@
+from pg_rad.inputparser.specs import DetectorSpec
+
+from .detectors import IsotropicDetector, AngularDetector
+
+
+class DetectorBuilder:
+    def __init__(
+        self,
+        detector_spec: DetectorSpec,
+    ):
+        self.detector_spec = detector_spec
+
+    def build(self) -> IsotropicDetector | AngularDetector:
+        if self.detector_spec.is_isotropic:
+            return IsotropicDetector(
+                self.detector_spec.name,
+                self.detector_spec.eff
+            )
+        else:
+            raise NotImplementedError("Angular detector not supported yet.")

src/pg_rad/detector/detectors.py

@@ -0,0 +1,38 @@
+from abc import ABC
+
+
+class BaseDetector(ABC):
+    def __init__(
+        self,
+        name: str,
+        eff: float
+    ):
+        self.name = name
+        self.eff = eff
+
+    def get_efficiency(self):
+        pass
+
+
+class IsotropicDetector(BaseDetector):
+    def __init__(
+        self,
+        name: str,
+        eff: float | None = None
+    ):
+        super().__init__(name, eff)
+
+    def get_efficiency(self, energy):
+        return self.eff
+
+
+class AngularDetector(BaseDetector):
+    def __init__(
+        self,
+        name: str,
+        eff: float | None = None
+    ):
+        super().__init__(name, eff)
+
+    def get_efficiency(self, angle, energy):
+        pass

src/pg_rad/inputparser/parser.py

@@ -17,7 +17,8 @@ from .specs import (
     SourceSpec,
     AbsolutePointSourceSpec,
     RelativePointSourceSpec,
-    SimulationSpec,
+    DetectorSpec,
+    SimulationSpec
 )
 
 
@@ -31,7 +32,8 @@ class ConfigParser:
         "acquisition_time",
         "path",
         "sources",
-        "options",
+        "detector",
+        "options"
     }
 
     def __init__(self, config_source: str):
@@ -49,6 +51,7 @@ class ConfigParser:
         options = self._parse_options()
         path = self._parse_path()
         sources = self._parse_point_sources()
+        detector = self._parse_detector()
 
         return SimulationSpec(
             metadata=metadata,
@@ -56,6 +59,7 @@ class ConfigParser:
             options=options,
             path=path,
             point_sources=sources,
+            detector=detector
         )
 
     def _load_yaml(self, config_source: str) -> Dict[str, Any]:
@@ -285,6 +289,34 @@ class ConfigParser:
 
         return specs
 
+    def _parse_detector(self) -> DetectorSpec:
+        det_dict = self.config.get("detector", {})
+        required = {"name", "is_isotropic"}
+
+        missing = required - det_dict.keys()
+        if missing:
+            raise MissingConfigKeyError(missing)
+
+        name = det_dict.get("name")
+        is_isotropic = det_dict.get("is_isotropic")
+        eff = det_dict.get("efficiency")
+
+        default_detectors = defaults.DETECTOR_EFFICIENCIES
+
+        if eff is None and name in default_detectors.keys():
+            eff = default_detectors[name]
+        elif eff is not None:
+            pass
+        else:
+            raise ValueError(
+                f"The detector {name} is not in the library, and no "
+                "efficiency was defined. Either specify detector efficiency "
+                "or choose one from the following list: "
+                f"{default_detectors.keys()}"
+            )
+
+        return DetectorSpec(name=name, eff=eff, is_isotropic=is_isotropic)
+
     def _warn_unknown_keys(self, section: str, provided: set, allowed: set):
         unknown = provided - allowed
         if unknown:

src/pg_rad/inputparser/specs.py

@@ -63,6 +63,13 @@ class RelativePointSourceSpec(SourceSpec):
     z: float
 
 
+@dataclass
+class DetectorSpec:
+    name: str
+    eff: float | None
+    is_isotropic: bool
+
+
 @dataclass
 class SimulationSpec:
     metadata: MetadataSpec
@@ -70,3 +77,4 @@ class SimulationSpec:
     options: SimulationOptionsSpec
     path: PathSpec
     point_sources: list[SourceSpec]
+    detector: DetectorSpec

src/pg_rad/main.py

@@ -5,6 +5,7 @@ import sys
 from pandas.errors import ParserError
 from yaml import YAMLError
 
+from pg_rad.detector.builder import DetectorBuilder
 from pg_rad.exceptions.exceptions import (
     MissingConfigKeyError,
     OutOfBoundsError,
@@ -81,9 +82,10 @@ def main():
         try:
             cp = ConfigParser(args.config).parse()
             landscape = LandscapeDirector.build_from_config(cp)
-
+            detector = DetectorBuilder(cp.detector).build()
             output = SimulationEngine(
                 landscape=landscape,
+                detector=detector,
                 runtime_spec=cp.runtime,
                 sim_spec=cp.options
             ).simulate()

src/pg_rad/physics/fluence.py

@@ -2,6 +2,9 @@ from typing import Tuple, TYPE_CHECKING
 
 import numpy as np
 
+from pg_rad.detector.detectors import IsotropicDetector, AngularDetector
+
+
 if TYPE_CHECKING:
     from pg_rad.landscape.landscape import Landscape
 
@@ -12,6 +15,7 @@ def phi(
         branching_ratio: float,
         mu_mass_air: float,
         air_density: float,
+        eff: float
         ) -> float:
     """Compute the contribution of a single point source to the
     primary photon fluence rate phi at position (x,y,z).
@@ -34,6 +38,7 @@ def phi(
 
     phi_r = (
         activity
+        * eff
         * branching_ratio
         * np.exp(-mu_air * r)
         / (4 * np.pi * r**2)
@@ -42,12 +47,20 @@ def phi(
     return phi_r
 
 
-def calculate_fluence_at(landscape: "Landscape", pos: np.ndarray, scaling=1E6):
+def calculate_fluence_at(
+    landscape: "Landscape",
+    pos: np.ndarray,
+    detector: IsotropicDetector | AngularDetector,
+    tangent_vectors: np.ndarray,
+    scaling=1E6
+):
     """Compute fluence at an arbitrary position in the landscape.
 
     Args:
         landscape (Landscape): The landscape to compute.
         pos (np.ndarray): (N, 3) array of positions.
+        detector (IsotropicDetector | AngularDetector):
+            Detector object, needed to compute correct efficiency.
 
     Returns:
         total_phi (np.ndarray): (N,) array of fluences.
@@ -56,15 +69,30 @@ def calculate_fluence_at(landscape: "Landscape", pos: np.ndarray, scaling=1E6):
     total_phi = np.zeros(pos.shape[0])
 
     for source in landscape.point_sources:
-        r = np.linalg.norm(pos - np.array(source.pos), axis=1)
+        source_to_detector = pos - np.array(source.pos)
+        r = np.linalg.norm(source_to_detector, axis=1)
         r = np.maximum(r, 1E-3)  # enforce minimum distance of 1cm
 
+        if isinstance(detector, AngularDetector):
+            cos_theta = (
+                np.sum(tangent_vectors * source_to_detector, axis=1) / (
+                    np.linalg.norm(source_to_detector, axis=1) *
+                    np.linalg.norm(tangent_vectors, axis=1)
+                )
+            )
+            cos_theta = np.clip(cos_theta, -1, 1)
+            theta = np.arccos(cos_theta)
+            eff = detector.get_efficiency(theta, energy=source.isotope.E)
+        else:
+            eff = detector.get_efficiency(energy=source.isotope.E)
+
         phi_source = phi(
             r=r,
             activity=source.activity * scaling,
             branching_ratio=source.isotope.b,
             mu_mass_air=source.isotope.mu_mass_air,
-            air_density=landscape.air_density
+            air_density=landscape.air_density,
+            eff=eff
         )
 
         total_phi += phi_source
@@ -74,6 +102,7 @@ def calculate_fluence_at(landscape: "Landscape", pos: np.ndarray, scaling=1E6):
 
 def calculate_fluence_along_path(
     landscape: "Landscape",
+    detector: "IsotropicDetector | AngularDetector",
     points_per_segment: int = 10
 ) -> Tuple[np.ndarray, np.ndarray]:
     path = landscape.path
@@ -98,6 +127,17 @@ def calculate_fluence_along_path(
     z = np.full(xnew.shape, path.z)
     full_positions = np.c_[xnew, ynew, z]
 
-    phi_result = calculate_fluence_at(landscape, full_positions)
+    # to compute the angle between sources and the direction of travel, we
+    # compute tangent vectors along the path.
+    dx_ds = np.gradient(xnew, s)
+    dy_ds = np.gradient(ynew, s)
+    tangent_vectors = np.c_[dx_ds, dy_ds, np.zeros_like(dx_ds)]
+    tangent_vectors /= np.linalg.norm(tangent_vectors, axis=1, keepdims=True)
+
+    phi_result = calculate_fluence_at(
+        landscape,
+        full_positions,
+        detector,
+        tangent_vectors)
 
     return s, phi_result

src/pg_rad/simulator/engine.py

@@ -6,6 +6,7 @@ from pg_rad.simulator.outputs import (
     SimulationOutput,
     SourceOutput
 )
+from pg_rad.detector.detectors import IsotropicDetector, AngularDetector
 from pg_rad.physics.fluence import calculate_fluence_along_path
 from pg_rad.utils.projection import minimal_distance_to_path
 from pg_rad.inputparser.specs import RuntimeSpec, SimulationOptionsSpec
@@ -16,11 +17,13 @@ class SimulationEngine:
     def __init__(
         self,
         landscape: Landscape,
-        runtime_spec=RuntimeSpec,
-        sim_spec=SimulationOptionsSpec
+        detector: IsotropicDetector | AngularDetector,
+        runtime_spec: RuntimeSpec,
+        sim_spec: SimulationOptionsSpec,
     ):
 
         self.landscape = landscape
+        self.detector = detector
         self.runtime_spec = runtime_spec
         self.sim_spec = sim_spec
 
@@ -37,7 +40,10 @@ class SimulationEngine:
         )
 
     def _calculate_count_rate_along_path(self) -> CountRateOutput:
-        arc_length, phi = calculate_fluence_along_path(self.landscape)
+        arc_length, phi = calculate_fluence_along_path(
+            self.landscape,
+            self.detector
+        )
         return CountRateOutput(arc_length, phi)
 
     def _calculate_point_source_distance_to_path(self) -> List[SourceOutput]:

tests/test_fluence_rate.py

@@ -7,7 +7,13 @@ from pg_rad.physics import calculate_fluence_at
 
 
 @pytest.fixture
-def phi_ref(test_landscape):
+def isotropic_detector():
+    from pg_rad.detector.detectors import IsotropicDetector
+    return IsotropicDetector(name="test_detector", eff=1.0)
+
+
+@pytest.fixture
+def phi_ref(test_landscape, isotropic_detector):
     source = test_landscape.point_sources[0]
 
     r = np.linalg.norm(np.array([10, 10, 0]) - np.array(source.pos))
@@ -17,7 +23,8 @@ def phi_ref(test_landscape):
     mu_air = source.isotope.mu_mass_air * test_landscape.air_density
     mu_air *= 0.1
 
-    return A * b * np.exp(-mu_air * r) / (4 * np.pi * r**2)
+    eff = isotropic_detector.get_efficiency(source.isotope.E)
+    return A * eff * b * np.exp(-mu_air * r) / (4 * np.pi * r**2)
 
 
 @pytest.fixture
@@ -38,6 +45,10 @@ def test_landscape():
             activity_MBq: 100
             position: [0, 0, 0]
             isotope: CS137
+
+    detector:
+        name: dummy
+        is_isotropic: True
     """
 
     cp = ConfigParser(test_yaml).parse()
@@ -45,9 +56,11 @@ def test_landscape():
     return landscape
 
 
-def test_single_source_fluence(phi_ref, test_landscape):
+def test_single_source_fluence(phi_ref, test_landscape, isotropic_detector):
     phi = calculate_fluence_at(
         test_landscape,
         np.array([10, 10, 0]),
+        isotropic_detector,
+        tangent_vectors=None,
         )
     assert pytest.approx(phi[0], rel=1E-3) == phi_ref