diff --git a/libra_toolbox/neutronics/__init__.py b/libra_toolbox/neutronics/__init__.py
index 7755235..a15de0b 100644
--- a/libra_toolbox/neutronics/__init__.py
+++ b/libra_toolbox/neutronics/__init__.py
@@ -1,3 +1,4 @@
 from .neutron_source import *
 from .vault import *
+from .baby1l import *
 from . import materials
diff --git a/libra_toolbox/neutronics/baby1l.py b/libra_toolbox/neutronics/baby1l.py
new file mode 100644
index 0000000..283b447
--- /dev/null
+++ b/libra_toolbox/neutronics/baby1l.py
@@ -0,0 +1,342 @@
+import openmc
+from libra_toolbox.neutronics.materials import *
+
+
+def baby_geometry(x_c: float, y_c: float, z_c: float):
+    """Returns the geometry for the BABY experiment.
+
+    Args:
+        x_c: x-coordinate of the center of the BABY experiment (cm)
+        y_c: y-coordinate of the center of the BABY experiment (cm)
+        z_c: z-coordinate of the center of the BABY experiment (cm)
+
+    Returns:
+        the sphere, cllif cell, and cells
+    """
+
+    epoxy_thickness = 2.54  # 1 inch
+    alumina_compressed_thickness = 2.54  # 1 inch
+    base_thickness = 0.786
+    alumina_thickness = 0.635
+    he_thickness = 0.6
+    inconel_thickness = 0.3
+    heater_gap = 0.878
+    cllif_thickness = 6.388 + 0.13022  # without heater: 0.1081
+    gap_thickness = 4.605
+    cap = 1.422
+    firebrick_thickness = 15.24
+    high = 21.093
+    cover = 2.392
+    z_tab = 28.00
+    lead_height = 4.00
+    lead_width = 8.00
+    lead_length = 16.00
+    heater_r = 0.439
+    heater_h = 25.40
+    heater_z = (
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + inconel_thickness
+        + heater_gap
+        + z_c
+    )
+
+    cllif_radius = 7.00
+    inconel_radius = 7.3
+    he_radius = 9.144
+    firebrick_radius = 12.002
+    vessel_radius = 12.853
+    external_radius = 13.272
+
+    source_h = 50.00
+    source_x = x_c - 13.50
+    source_z = z_c - 5.635
+    source_external_r = 5.00
+    source_internal_r = 4.75
+
+    ######## Surfaces #################
+    z_plane_1 = openmc.ZPlane(0.0 + z_c)
+    z_plane_2 = openmc.ZPlane(epoxy_thickness + z_c)
+    z_plane_3 = openmc.ZPlane(epoxy_thickness + alumina_compressed_thickness + z_c)
+    z_plane_4 = openmc.ZPlane(
+        epoxy_thickness + alumina_compressed_thickness + base_thickness + z_c
+    )
+    z_plane_5 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + z_c
+    )
+    z_plane_6 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + z_c
+    )
+    z_plane_7 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + inconel_thickness
+        + z_c
+    )
+    z_plane_8 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + inconel_thickness
+        + cllif_thickness
+        + z_c
+    )
+    z_plane_9 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + inconel_thickness
+        + cllif_thickness
+        + gap_thickness
+        + z_c
+    )
+    z_plane_10 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + he_thickness
+        + inconel_thickness
+        + cllif_thickness
+        + gap_thickness
+        + cap
+        + z_c
+    )
+    z_plane_11 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + alumina_thickness
+        + firebrick_thickness
+        + z_c
+    )
+    z_plane_12 = openmc.ZPlane(
+        epoxy_thickness + alumina_compressed_thickness + base_thickness + high + z_c
+    )
+    z_plane_13 = openmc.ZPlane(
+        epoxy_thickness
+        + alumina_compressed_thickness
+        + base_thickness
+        + high
+        + cover
+        + z_c
+    )
+    z_plane_14 = openmc.ZPlane(z_c - z_tab)
+    z_plane_15 = openmc.ZPlane(z_c - z_tab - epoxy_thickness)
+
+    ######## Cylinder #################
+    z_cyl_1 = openmc.ZCylinder(x0=x_c, y0=y_c, r=cllif_radius)
+    z_cyl_2 = openmc.ZCylinder(x0=x_c, y0=y_c, r=inconel_radius)
+    z_cyl_3 = openmc.ZCylinder(x0=x_c, y0=y_c, r=he_radius)
+    z_cyl_4 = openmc.ZCylinder(x0=x_c, y0=y_c, r=firebrick_radius)
+    z_cyl_5 = openmc.ZCylinder(x0=x_c, y0=y_c, r=vessel_radius)
+    z_cyl_6 = openmc.ZCylinder(x0=x_c, y0=y_c, r=external_radius)
+
+    right_cyl = openmc.model.RightCircularCylinder(
+        (x_c, y_c, heater_z), heater_h, heater_r, axis="z"
+    )
+    ext_cyl_source = openmc.model.RightCircularCylinder(
+        (source_x, y_c, source_z), source_h, source_external_r, axis="x"
+    )
+    source_region = openmc.model.RightCircularCylinder(
+        (source_x + 0.25, y_c, source_z), source_h - 0.50, source_internal_r, axis="x"
+    )
+
+    ######## Sphere #################
+    sphere = openmc.Sphere(x0=x_c, y0=y_c, z0=z_c, r=50.00)  # before r=50.00
+
+    ######## Lead bricks positioned under the source #################
+    lead_positions = [
+        (x_c - 13.50, y_c, z_c - z_tab),
+        (x_c - 2.96, y_c, z_c - z_tab),
+        (x_c + 36.50, y_c, z_c - z_tab),
+        (x_c + 25.96, y_c, z_c - z_tab),
+    ]
+
+    lead_blocks = []
+    for position in lead_positions:
+        lead_block_region = openmc.model.RectangularParallelepiped(
+            position[0] - lead_width / 2,
+            position[0] + lead_width / 2,
+            position[1] - lead_length / 2,
+            position[1] + lead_length / 2,
+            position[2],
+            position[2] + lead_height,
+        )
+        lead_blocks.append(lead_block_region)
+
+    src_supp_length = 40.00
+    src_supp_height = 20.00
+    src_supp_width = 2.54
+    src_supp_position = [
+        (x_c - 13.50 + lead_width / 2, y_c, z_c - z_tab),
+        (x_c + 25.96 + lead_width / 2, y_c, z_c - z_tab),
+    ]
+    src_supports = []
+    for position in src_supp_position:
+        source_support = openmc.model.RectangularParallelepiped(
+            position[0],
+            position[0] + src_supp_width,
+            position[1] - src_supp_length / 2,
+            position[1] + src_supp_length / 2,
+            position[2],
+            position[2] + src_supp_height,
+        )
+        src_supports.append(source_support)
+
+    # regions
+    source_wall_region = -ext_cyl_source & +source_region
+    source_region = -source_region
+    epoxy_region = +z_plane_1 & -z_plane_2 & -sphere
+    alumina_compressed_region = +z_plane_2 & -z_plane_3 & -sphere
+    bottom_vessel = +z_plane_3 & -z_plane_4 & -z_cyl_6
+    top_vessel = +z_plane_12 & -z_plane_13 & -z_cyl_6 & +right_cyl
+    cylinder_vessel = +z_plane_4 & -z_plane_12 & +z_cyl_5 & -z_cyl_6
+    vessel_region = bottom_vessel | cylinder_vessel | top_vessel
+    alumina_region = +z_plane_4 & -z_plane_5 & -z_cyl_5
+    bottom_cap = +z_plane_6 & -z_plane_7 & -z_cyl_2 & +right_cyl
+    cylinder_cap = +z_plane_7 & -z_plane_9 & +z_cyl_1 & -z_cyl_2 & +right_cyl
+    top_cap = +z_plane_9 & -z_plane_10 & -z_cyl_2 & +right_cyl
+    cap_region = bottom_cap | cylinder_cap | top_cap
+    cllif_region = +z_plane_7 & -z_plane_8 & -z_cyl_1 & +right_cyl
+    gap_region = +z_plane_8 & -z_plane_9 & -z_cyl_1 & +right_cyl
+    firebrick_region = +z_plane_5 & -z_plane_11 & +z_cyl_3 & -z_cyl_4
+    heater_region = -right_cyl
+    table_under_source_region = +z_plane_15 & -z_plane_14 & -sphere
+    lead_block_1_region = -lead_blocks[0]
+    lead_block_2_region = -lead_blocks[1]
+    lead_block_3_region = -lead_blocks[2]
+    lead_block_4_region = -lead_blocks[3]
+    src_supp_1_region = -src_supports[0] & ~source_wall_region & ~source_region
+    src_supp_2_region = -src_supports[1] & ~source_wall_region & ~source_region
+    he_region = (
+        +z_plane_5
+        & -z_plane_12
+        & -z_cyl_5
+        & ~source_region
+        & ~epoxy_region
+        & ~alumina_compressed_region
+        & ~alumina_region
+        & ~cllif_region
+        & ~gap_region
+        & ~firebrick_region
+        & ~vessel_region
+        & ~cap_region
+        & ~heater_region
+        & ~table_under_source_region
+        & ~lead_block_1_region
+        & ~lead_block_2_region
+        & ~lead_block_3_region
+        & ~lead_block_4_region
+        & ~src_supp_1_region
+        & ~src_supp_2_region
+    )
+    sphere_region = (
+        -sphere
+        & ~source_wall_region
+        & ~source_region
+        & ~epoxy_region
+        & ~alumina_compressed_region
+        & ~alumina_region
+        & ~cllif_region
+        & ~gap_region
+        & ~firebrick_region
+        & ~he_region
+        & ~vessel_region
+        & ~cap_region
+        & ~heater_region
+        & ~table_under_source_region
+        & ~lead_block_1_region
+        & ~lead_block_2_region
+        & ~lead_block_3_region
+        & ~lead_block_4_region
+        & ~src_supp_1_region
+        & ~src_supp_2_region
+    )
+
+    # cells
+    source_wall_cell_1 = openmc.Cell(region=source_wall_region)
+    source_wall_cell_1.fill = SS304
+    source_region = openmc.Cell(region=source_region)
+    source_region.fill = None
+    epoxy_cell = openmc.Cell(region=epoxy_region)
+    epoxy_cell.fill = Epoxy
+    alumina_compressed_cell = openmc.Cell(region=alumina_compressed_region)
+    alumina_compressed_cell.fill = Alumina
+    vessel_cell = openmc.Cell(region=vessel_region)
+    vessel_cell.fill = Inconel625
+    alumina_cell = openmc.Cell(region=alumina_region)
+    alumina_cell.fill = Alumina
+    cllif_cell = openmc.Cell(region=cllif_region)
+    cllif_cell.fill = Cllif  # Cllif or lithium_lead
+    gap_cell = openmc.Cell(region=gap_region)
+    gap_cell.fill = Helium
+    cap_cell = openmc.Cell(region=cap_region)
+    cap_cell.fill = Inconel625
+    firebrick_cell = openmc.Cell(region=firebrick_region)
+    firebrick_cell.fill = Firebrick
+    heater_cell = openmc.Cell(region=heater_region)
+    heater_cell.fill = Heater_mat
+    table_cell = openmc.Cell(region=table_under_source_region)
+    table_cell.fill = Epoxy
+    sphere_cell = openmc.Cell(region=sphere_region)
+    sphere_cell.fill = Air
+    he_cell = openmc.Cell(region=he_region)
+    he_cell.fill = Helium
+    lead_block_1_cell = openmc.Cell(region=lead_block_1_region)
+    lead_block_1_cell.fill = Lead
+    lead_block_2_cell = openmc.Cell(region=lead_block_2_region)
+    lead_block_2_cell.fill = Lead
+    lead_block_3_cell = openmc.Cell(region=lead_block_3_region)
+    lead_block_3_cell.fill = Lead
+    lead_block_4_cell = openmc.Cell(region=lead_block_4_region)
+    lead_block_4_cell.fill = Lead
+    src_supp_1_cell = openmc.Cell(region=src_supp_1_region)
+    src_supp_1_cell.fill = HDPE
+    src_supp_2_cell = openmc.Cell(region=src_supp_2_region)
+    src_supp_2_cell.fill = HDPE
+
+    cells = [
+        source_wall_cell_1,
+        source_region,
+        epoxy_cell,
+        alumina_compressed_cell,
+        vessel_cell,
+        alumina_cell,
+        cap_cell,
+        cllif_cell,
+        gap_cell,
+        firebrick_cell,
+        heater_cell,
+        he_cell,
+        sphere_cell,
+        table_cell,
+        lead_block_1_cell,
+        lead_block_2_cell,
+        lead_block_3_cell,
+        lead_block_4_cell,
+        src_supp_1_cell,
+        src_supp_2_cell,
+    ]
+
+    return sphere, cllif_cell, cells
+
diff --git a/test/neutronics/test_baby.py b/test/neutronics/test_baby.py
new file mode 100644
index 0000000..4773ec2
--- /dev/null
+++ b/test/neutronics/test_baby.py
@@ -0,0 +1,70 @@
+from libra_toolbox.neutronics import vault
+from libra_toolbox.neutronics.baby1l import baby_geometry
+from libra_toolbox.neutronics.neutron_source import A325_generator_diamond
+from libra_toolbox.neutronics.materials import *
+
+import pytest
+
+
+def test_baby_model():
+    """Test that the baby_geometry model can be created and run without errors inside the vault"""
+    try:
+        import openmc
+    except ImportError:
+        pytest.skip("OpenMC is not installed")
+
+    materials = [
+        Inconel625,
+        Cllif,
+        SS304,
+        Heater_mat,
+        Firebrick,
+        Alumina,
+        Lead,
+        Air,
+        Epoxy,
+        Helium,
+        HDPE,
+    ]
+
+    # BABY coordinates
+    x_c = 587  # cm
+    y_c = 60  # cm
+    z_c = 100  # cm
+    sphere, cllif_cell, cells = baby_geometry(x_c, y_c, z_c)
+
+    ############################################################################
+    # Define Settings
+
+    settings = openmc.Settings()
+
+    src = A325_generator_diamond((x_c, y_c, z_c - 5.635), (1, 0, 0))
+    settings.source = src
+    settings.batches = 3
+    settings.inactive = 0
+    settings.run_mode = "fixed source"
+    settings.particles = int(100)
+    settings.output = {"tallies": False}
+    settings.photon_transport = False
+
+    ############################################################################
+    overall_exclusion_region = -sphere
+
+    ############################################################################
+    # Specify Tallies
+    tallies = openmc.Tallies()
+
+    tbr_tally = openmc.Tally(name="TBR")
+    tbr_tally.scores = ["(n,Xt)"]
+    tbr_tally.filters = [openmc.CellFilter(cllif_cell)]
+    tallies.append(tbr_tally)
+
+    model = vault.build_vault_model(
+        settings=settings,
+        tallies=tallies,
+        added_cells=cells,
+        added_materials=materials,
+        overall_exclusion_region=overall_exclusion_region,
+    )
+
+    model.run()
\ No newline at end of file