gsf flux 2comp for IT (#81)

* add 2 component GSF version for IceTop systematic data sets

* Update and minor fixes

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

* add GSF2Comp to tests and drop _IT suffix

* add h4a 2 component

* Update _fluxes.py

clearify the description for the GSF 2 component model

* make test_fluxes executable

not sure how it wasnt

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Kevin Meagher <11620178+kjmeagher@users.noreply.github.com>

Author: 3 people

src/simweights/__init__.py

@@ -22,6 +22,7 @@
     "FixedFractionFlux",
     "GaisserH3a",
     "GaisserH4a",
+    "GaisserH4a2Comp",
     "GaisserH4a_IT",
     "GaisserHillas",
     "GenerationSurface",
@@ -31,6 +32,7 @@
     "GlobalFitGST4Comp",
     "GlobalFitGST_IT",
     "GlobalSplineFit",
+    "GlobalSplineFit2Comp",
     "GlobalSplineFit5Comp",
     "GlobalSplineFit_IT",
     "Hoerandel",
@@ -55,12 +57,14 @@
     FixedFractionFlux,
     GaisserH3a,
     GaisserH4a,
+    GaisserH4a2Comp,
     GaisserH4a_IT,
     GaisserHillas,
     GlobalFitGST,
     GlobalFitGST4Comp,
     GlobalFitGST_IT,
     GlobalSplineFit,
+    GlobalSplineFit2Comp,
     GlobalSplineFit5Comp,
     GlobalSplineFit_IT,
     Hoerandel,

src/simweights/_fluxes.py

@@ -31,6 +31,7 @@
 
     from numpy.typing import ArrayLike, NDArray
 
+PDGID_2COMP = (PDGCode.PPlus, PDGCode.Fe56Nucleus)
 PDGID_4COMP = (PDGCode.PPlus, PDGCode.He4Nucleus, PDGCode.O16Nucleus, PDGCode.Fe56Nucleus)
 PDGID_5COMP = (PDGCode.PPlus, PDGCode.He4Nucleus, PDGCode.N14Nucleus, PDGCode.Al27Nucleus, PDGCode.Fe56Nucleus)
 PDGID_ALL = (
@@ -231,6 +232,32 @@ class GaisserH4a(CosmicRayFlux):
     )
 
 
+class GaisserH4a2Comp(CosmicRayFlux):
+    r"""Variation of Gaisser's H4a flux using only two components.
+
+    *This is not a very physical flux*: The light group is the sum of H4a's proton and helium groups. Heavy group is the rest.
+    """
+
+    pdgids = PDGID_2COMP
+    _funcs = (
+        lambda E: (
+            0.7860 * E**-2.66 * exp(-E / (4e6 * 1))
+            + 0.0020 * E**-2.4 * exp(-E / (3e7 * 1))
+            + 0.0200 * E**-2.6 * exp(-E / 6e10)
+            + 0.3550 * E**-2.58 * exp(-E / (4e6 * 2))
+            + 0.0020 * E**-2.4 * exp(-E / (3e7 * 2))
+        ),
+        lambda E: (
+            0.2200 * E**-2.63 * exp(-E / (4e6 * 7))
+            + 0.00134 * E**-2.4 * exp(-E / (3e7 * 7))
+            + 0.1430 * E**-2.67 * exp(-E / (4e6 * 13))
+            + 0.00134 * E**-2.4 * exp(-E / (3e7 * 13))
+            + 0.2120 * E**-2.63 * exp(-E / (4e6 * 26))
+            + 0.00134 * E**-2.4 * exp(-E / (3e7 * 26))
+        ),
+    )
+
+
 class GaisserH4a_IT(CosmicRayFlux):
     r"""Variation of Gaisser's H4a flux using only four components.
 
@@ -435,6 +462,20 @@ def __init__(self: GlobalSplineFit_IT) -> None:
         super().__init__()
 
 
+class GlobalSplineFit2Comp(GlobalSplineFitBase):
+    r"""Sum of the flux of the GSF model for a 2-component dataset injected by IceCube.
+
+    [(H, He),  (Li, Be, B, C, N, O, F, Ne, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni)]
+    GSF is a Data-driven spline fit of the cosmic ray spectrum by Dembinski et. al. \ [#GSFDembinski]_.
+    """
+
+    pdgids = PDGID_2COMP
+    groups = ((1, 2), (3, 28))
+
+    def __init__(self: GlobalSplineFit2Comp) -> None:
+        super().__init__()
+
+
 class FixedFractionFlux(CosmicRayFlux):
     """Total energy per particle flux flux split among mass groups with a constant fraction.
 

tests/test_fluxes.py

@@ -20,13 +20,15 @@
     simweights.GaisserHillas(),
     simweights.GaisserH3a(),
     simweights.GaisserH4a(),
+    simweights.GaisserH4a2Comp(),
     simweights.GaisserH4a_IT(),
     simweights.Honda2004(),
     simweights.TIG1996(),
     simweights.GlobalFitGST(),
     simweights.GlobalFitGST_IT(),
     simweights.GlobalFitGST4Comp(),
     simweights.GlobalSplineFit(),
+    simweights.GlobalSplineFit2Comp(),
     simweights.GlobalSplineFit5Comp(),
     simweights.GlobalSplineFit_IT(),
     simweights.FixedFractionFlux({2212: 0.1, 1000020040: 0.2, 1000080160: 0.3, 1000260560: 0.4}),
@@ -43,6 +45,7 @@ def test_flux_model(flux, ndarrays_regression):
 
 gsfmodels = [
     simweights.GlobalSplineFit(),
+    simweights.GlobalSplineFit2Comp(),
     simweights.GlobalSplineFit5Comp(),
     simweights.GlobalSplineFit_IT(),
 ]