Gamma source-dose rate

I have a rectangular prism shaped detector like this (Radiation detection moduleC12137). I made a design like this, I’m not sure about its accuracy. Then I want to calculate the distance dependent dose by putting the source at different distances. I couldn’t find an example like this can you help me?

import numpy as np
import matplotlib.pyplot as plt
import openmc
import pandas as pd
import os

cesium_iodide = openmc.Material()
cesium_iodide.add_element(‘Cs’, 1)
cesium_iodide.add_element(‘I’, 1)
cesium_iodide.set_density(‘g/cm3’, 4.51)
materials = openmc.Materials([cesium_iodide])
materials.cross_section=‘C:/Users/Gokcenur/endfb71_hdf5/cross_sections.xml’
materials.export_to_xml()
materials = openmc.Materials()
materials +=[cesium_iodide]
isinstance(materials, list)

xmin=openmc.XPlane(x0=11,boundary_type=“periodic”)

xmax = openmc.XPlane(x0=-11,boundary_type=“periodic”)

ymin = openmc.YPlane(y0=5,boundary_type=“periodic”)

ymax = openmc.YPlane (y0=-5,boundary_type=“periodic”)
xmax.periodic_surface = xmin
ymin.periodic_surface = ymax

zmin = openmc.ZPlane(z0=2,boundary_type=“periodic”)

zmax = openmc.ZPlane(z0=-2,boundary_type=“periodic”)
zmax.periodic_surface=zmin
mats = openmc.Materials((cesium_iodide,))
region = +xmax &- xmin & +ymax &-ymin & +zmax &-zmin
cube = openmc.Cell(region=region)
cube.fill = cesium_iodide

universe = openmc.Universe(
cells=[cube])
universe.plot(width = (30.0,30.0),basis = ‘xz’)

geometry = openmc.Geometry(universe)
geometry.export_to_xml()
universe = openmc.Universe(cells=[cube])

settings = openmc.Settings()
settings.run_mode = ‘fixed source’
settings.source = source
settings.batches = 6
settings.particles = 100000
settings.export_to_xml()
number_bins = 101
bins_both = np.linspace(0, 1e6, number_bins)

tallies = openmc.Tallies()

cell_filter = openmc.CellFilter(cube)
energy_filter = openmc.EnergyFilter(bins_both)

tally = openmc.Tally(name=‘flux’)
tally.filters = [cell_filter, energy_filter]
tally.scores = [‘flux’]
tallies.append(tally)

model = openmc.model.Model(geometry, materials, settings, tallies)

results_filename = model.run()