def get_pmt_surface():
data = np.genfromtxt('config/qe_curve.dat', delimiter=',')
wavelength = data[:, 0]
efficiency = data[:, 1]
r8486_pmt = Surface('R8486 PMT')
r8486_pmt.set('detect', efficiency, wavelength)
return r8486_pmt
def get_mirror_surface():
data = np.genfromtxt('config/gold_reflectivity.dat', delimiter=',')
wavelength = data[:, 0]
reflectivity = data[:, 1] / 100
specular_percent = 0.995 #This is the % of reflectance that is specular
diffuse_percent = 1 - specular_percent
gold_mirror = Surface('EO mirror')
gold_mirror.set('absorb', 1 - reflectivity, wavelength)
gold_mirror.set('reflect_specular', specular_percent * reflectivity,
wavelength)
gold_mirror.set('reflect_diffuse', diffuse_percent * reflectivity,
wavelength)
return gold_mirror
def make_glass_surface():
# mostly fake numbers based on http://www.shimadzu.com/an/uv/support/uv/ap/measuring_solar2.html
# glass mostly absorbs until 300 nm, then gradually transmits. reflected light assumed diffuse
glass_surface = Surface("glass_surface")
glass_surface.set(
'reflect_diffuse',
np.array([(100, 0.0), (280.0, 0.0), (350.0, 0.5), (1000.0, 0.5)]))
glass_surface.set(
'reflect_specular',
np.array([(100, 0.0), (280.0, 0.0), (350.0, 0.5), (1000.0, 0.5)]))
glass_surface.set(
'absorb',
np.array([(100, 1.0), (280.0, 1.0), (350.0, 0.0), (1000.0, 0.0)]))
glass_surface.set('detect', 0.0)
glass_surface.set('reemit', 0.0)
glass_surface.transmissive = 1
return glass_surface
def make_titanium_surface():
titanium_surface = Surface("titanium_surface")
titanium_surface.set('reflect_diffuse', 0.125)
titanium_surface.set('reflect_specular', 0.125)
titanium_surface.set('detect', 0.0)
titanium_surface.set('absorb', 0.75)
titanium_surface.set('reemit', 0.0)
titanium_surface.transmissive = 0
return titanium_surface
def make_steel_surface():
steel_surface = Surface("steel_surface")
steel_surface.set('reflect_diffuse', 0.25)
steel_surface.set('reflect_specular', 0.0)
steel_surface.set('detect', 0.0)
steel_surface.set('absorb', 0.75)
steel_surface.set('reemit', 0.0)
steel_surface.transmissive = 0
# eta and kappa not set
return steel_surface
def make_absorbing_surface(name="absorbing_surface"):
# mostly fake numbers based on http://www.shimadzu.com/an/uv/support/uv/ap/measuring_solar2.html
# glass mostly absorbs until 300 nm, then gradually transmits. reflected light assumed diffuse
black_surface = Surface(name)
black_surface.set('reflect_diffuse', 0.0)
black_surface.set('reflect_specular', 0.0)
black_surface.set('absorb', 1.0)
black_surface.set('detect', 0.0)
black_surface.set('reemit', 0.0)
black_surface.transmissive = 0
return black_surface
import numpy as np
from chroma.geometry import Material, Surface
vacuum = Material('vacuum')
vacuum.set('refractive_index', 1.0)
vacuum.set('absorption_length', 1e6)
vacuum.set('scattering_length', 1e6)
lambertian_surface = Surface('lambertian_surface')
lambertian_surface.set('reflect_diffuse', 1)
black_surface = Surface('black_surface')
black_surface.set('absorb', 1)
shiny_surface = Surface('shiny_surface')
shiny_surface.set('reflect_specular', 1)
glossy_surface = Surface('glossy_surface')
glossy_surface.set('reflect_diffuse', 0.5)
glossy_surface.set('reflect_specular', 0.5)
red_absorb_surface = Surface('red_absorb')
red_absorb_surface.set('absorb', [0.0, 0.0, 1.0], [465, 545, 685])
red_absorb_surface.set('reflect_diffuse', [1.0, 1.0, 0.0], [465, 545, 685])
# r7081hqe photocathode material surface
# source: hamamatsu supplied datasheet for r7081hqe pmt serial number zd0062
r7081hqe_photocathode = Surface('r7081hqe_photocathode')
r7081hqe_photocathode.detect = \
np.array([(260.0, 0.00),
(270.0, 0.04), (280.0, 0.07), (290.0, 0.77), (300.0, 4.57),
lensmat.set('refractive_index', lensmat_refractive_index)
lensmat.set('absorption_length', 1e8)
lensmat.set('scattering_length', 1e8)
lensmat_ohara = Material('lensmat_ohara')
lensmat_ohara.set('refractive_index', lensmat_ohara_refractive_index)
lensmat_ohara.set('absorption_length', 1e8)
lensmat_ohara.set('scattering_length', 1e8)
blackhole = Material('blackhole')
blackhole.set('refractive_index', 1.0)
blackhole.set('absorption_length', 1e-15)
blackhole.set('scattering_length', 1e8)
#creates a surface with complete detection-- used on pmt
fulldetect = Surface('fulldetect')
fulldetect.set('detect', 1.0)
#creates a surface with complete absorption-- used on volume boundary (previously flat pmt detecting surface)
fullabsorb = Surface('fullabsorb')
fullabsorb.set('absorb', 1.0)
noreflect = Surface('noreflect')
#noreflect.transmissive = 1.0
noreflect.model = 2
mirror = Surface('mirror')
mirror.set('reflect_specular', 1.0)
# myglass = Material('glass')
# myglass.set('refractive_index', 1.49)
bulk_absorb = IntCol()
surface_detect = IntCol()
surface_absorb = IntCol()
surface_reemit = IntCol()
def reset(self):
self.reflect_diffuse = 0
self.reflect_specular = 0
self.bulk_scatter = 0
self.bulk_absorb = 0
self.surface_detect = 0
self.surface_absorb = 0
self.surface_reemit = 0
uboone_wireplane = Surface('uboone_wireplane')
uboone_wireplane.nplanes = 3.0
uboone_wireplane.wire_pitch = 0.3
uboone_wireplane.wire_diameter = 0.015
uboone_wireplane.transmissive = 1
uboone_wireplane.model = Surface.SURFACE_WIREPLANE
def add_wireplane_surface(solid):
# function detector class will use to add a wireplane surface to the geometry
# set surface for triangles on x=-1281.0 plane
for n, triangle in enumerate(solid.mesh.triangles):
nxplane = 0
for ivert in triangle:
if solid.mesh.vertices[ivert, 0] == -1281.0:
nxplane += 1
def get_sipm_surface():
wavelength = np.arange(100, 600, 0.5)
hamamatsu_sipm = Surface('Hamamatsu SiPM')
hamamatsu_sipm.set('detect', np.ones(len(wavelength)), wavelength)
return hamamatsu_sipm
def surfacesdict(self):
# Steel/LAr
steel_surface = Surface("steel_surface")
steel_surface.set('reflect_diffuse', 0.25)
steel_surface.set('reflect_specular', 0.0)
steel_surface.set('detect', 0.0)
steel_surface.set('absorb', 0.75)
steel_surface.set('reemit', 0.0)
steel_surface.transmissive = 0
# Titanium/LAr
titanium_surface = Surface("titanium_surface")
titanium_surface.set('reflect_diffuse', 0.125)
titanium_surface.set('reflect_specular', 0.125)
titanium_surface.set('detect', 0.0)
titanium_surface.set('absorb', 0.75)
titanium_surface.set('reemit', 0.0)
titanium_surface.transmissive = 0
# Glass/LAr
glass_surface = Surface("glass_surface")
glass_surface.set(
'reflect_diffuse',
np.array([(100, 0.0), (280.0, 0.0), (350.0, 0.5), (1000.0, 0.5)]))
glass_surface.set(
'reflect_specular',
np.array([(100, 0.0), (280.0, 0.0), (350.0, 0.5), (1000.0, 0.5)]))
glass_surface.set(
'absorb',
np.array([(100, 1.0), (280.0, 1.0), (350.0, 0.0), (1000.0, 0.0)]))
glass_surface.set('detect', 0.0)
glass_surface.set('reemit', 0.0)
glass_surface.transmissive = 1
# Acrylic: detecting surface
acrylic_surface = Surface("acrylic_surface_detector")
acrylic_surface.set('reflect_diffuse', 0.0)
acrylic_surface.set('reflect_specular', 0.0)
acrylic_surface.set('detect', 1.0)
acrylic_surface.set('absorb', 0.0)
acrylic_surface.set('reemit', 0.0)
acrylic_surface.transmissive = 0
# Acrylic: wavelength shifting
#acrylic_surface_wls = Surface("acrylic_surface_wls")
#acrylic_surface_wls.set('reflect_diffuse', 0.0)
#acrylic_surface_wls.set('reflect_specular',0.0)
#acrylic_surface_wls.set('detect',0.0)
#acrylic_surface_wls.set('absorb',0.0)
#acrylic_surface_wls.set('reemit', load_hist_data( os.path.dirname(__file__)+"/raw_tpb_emission.dat", 350, 640 ) ) # 100% reemission. Actually, should be 120%!! Need to think about this.
#acrylic_surface_wls.transmissive = 1
# G10
g10_surface = Surface("g10_surface")
g10_surface.set('reflect_diffuse', 0.5)
g10_surface.set('reflect_specular', 0.0)
g10_surface.set('detect', 0.0)
g10_surface.set('absorb', 0.5)
g10_surface.set('reemit', 0.0)
g10_surface.transmissive = 0
# Black surface
black_surface = Surface("black_surface")
black_surface.set('reflect_diffuse', 0.0)
black_surface.set('reflect_specular', 0.0)
black_surface.set('absorb', 1.0)
black_surface.set('detect', 0.0)
black_surface.set('reemit', 0.0)
black_surface.transmissive = 0
#boundary_surfaces = { ("STEEL_STAINLESS_Fe7Cr2Ni", "LAr"):black_surface,
# ("Titanium", "LAr"):black_surface,
# ("Acrylic", "LAr"):acrylic_surface,
# ("G10", "LAr"):black_surface,
# ("Glass", "LAr"):black_surface,
# ("Glass", "STEEL_STAINLESS_Fe7Cr2Ni"):black_surface,
# ("Glass","Vacuum"):black_surface, }
boundary_surfaces = {
("STEEL_STAINLESS_Fe7Cr2Ni", "LAr"): steel_surface,
("Titanium", "LAr"): titanium_surface,
("Acrylic", "LAr"): acrylic_surface,
("G10", "LAr"): g10_surface,
("Glass", "LAr"): glass_surface,
("Glass", "STEEL_STAINLESS_Fe7Cr2Ni"): steel_surface,
("Glass", "Vacuum"): black_surface,
}
return boundary_surfaces
import numpy as np
from chroma.geometry import Material, Surface
from chroma.demo.optics import vacuum, r7081hqe_photocathode
import math
glass = Material('glass')
glass.set('refractive_index', 1.49)
glass.absorption_length = \
np.array([(200, 0.1e-6), (300, 1000), (330, 1000.0), (500, 2000.0), (600, 1000.0), (770, 500.0), (800, 0.1e-6)])
glass.set('scattering_length', 1e6)
silica = np.array([(180, .9), (200, .93), (220,.94), (240, .95), (260, .95), (280, .95), (800,.95)])
gel = np.array([(180, 0.0), (260, 0.0),(280, .09),(300.,.4), (320, .83), (365,.98), (404.7,0.99), (480,1.0), (800,1.0)])
mirror = np.array([(180, 0), (220, 0), (240,.0), (260, .1), (280, .4), (300, .7), (340,.88), (360, .95), (400, .97), (550, .97), (600, .95), (700, .92), (800, .87)])
mcp_boro_photocathode = Surface('mcp_boro_photocathode')
mcp_silica_photocathode = Surface('mcp_silica_photocathode')
'''
mcp_boro_photocathode.detect = \
np.array([(240.0, 0.00), (250.0, 0.04), (260.0, 2),
(270.0, 8.77), (280.0, 24), (290.0, 26), (300.0, 27),
(310.0, 28.00), (320.0, 28.8), (330.0, 29.7), (340.0, 30.1),
(350.0, 30.52), (360.0, 31.0), (370.0, 31.30), (380.0, 31.20),
(390.0, 31.00), (400.0, 30.90), (410.0, 30.50), (420.0, 30.16),
(430.0, 29.24), (440.0, 28.31), (450.0, 27.41), (460.0, 26.25),
(470.0, 24.90), (480.0, 23.05), (490.0, 21.58), (500.0, 19.94),
(510.0, 18.48), (520.0, 17.01), (530.0, 15.34), (540.0, 12.93),
(550.0, 10.17), (560.0, 7.86), (570.0, 6.23), (580.0, 5.07),
(590.0, 4.03), (600.0, 3.18), (610.0, 2.38), (620.0, 1.72),
(630.0, 0.95), (640.0, 0.71), (650.0, 0.44), (660.0, 0.25),
Transmission = []
for ii,angle in enumerate(Angles):
reflect = np.tile(Refl[ii], len(chroma.geometry.standard_wavelengths))
reflect = np.array(list(zip(chroma.geometry.standard_wavelengths, reflect)), dtype=np.float32)
Reflection.append(reflect)
transmit = np.tile(Transm[ii], len(chroma.geometry.standard_wavelengths))
transmit = np.array(list(zip(chroma.geometry.standard_wavelengths, transmit)), dtype=np.float32)
Transmission.append(transmit)
angledep = chroma.geometry.DichroicProps(Angles, Reflection, Transmission)
Surface.dichroic_props = angledep
return Surface
# fulldetect.set('reflect_diffuse', ApplyReflectivityData(fulldetect))
# fulldetect.set('reflect_specular', ApplyReflectivityData(fulldetect))
reflective = Surface('reflective')
refl = angledep('reflective')
reflective = refl.SetSurface('reflective')
#fulldetect.set('detect', 1)
sipm = Surface('sipm')
sipm.set('detect', 1)
#FullAbsorb surface for sipm
fullAbsorb = Surface('fullAbsorb')
fullAbsorb.set('absorb', 1.0)
fullAbsorb.set('eta', 1)
#***************************************************************************
CuSurface = Surface('CuSurface') # tailored to the real parameters of copper at this temperature/wavelength light
CuSurface.cuAbsorption = 0.95 #the most likely value is 35.8% ref for copper. Source: #cu absorp-0.95
CuSurface.cuSpecReflect =0.05 #refractiveindex.info/?shelf=main&book=Cu&page=Werner #originally 0.5, CuSurface.cuSpecReflect = rp.CuSpecRef #0.05
CuSurface.cuDiffuseReflect= 0
def make_acrylic_surface_detectmode():
"""
this version of acrylic surface detects photons and acts as our counting unit.
"""
acrylic_surface = Surface("acrylic_surface_detector")
acrylic_surface.set('reflect_diffuse', 0.0)
acrylic_surface.set('reflect_specular', 0.0)
acrylic_surface.set('detect', 1.0)
acrylic_surface.set('absorb', 0.0)
acrylic_surface.set('reemit', 0.0)
acrylic_surface.transmissive = 0
return acrylic_surface
def make_opticalsurface(self, dsurf, debug=False):
"""
:param dsurf: G4DAE surface
:return: Chroma surface
* name
* model ? defaults to 0
G4DAE Optical Surface properties
* REFLECTIVITY (the only property to be widely defined)
* RINDEX (seems odd for a surface, looks to always be zero)
* SPECULARLOBECONSTANT (set to 0.85 for a few surface)
* BACKSCATTERCONSTANT,SPECULARSPIKECONSTANT (often present, always zero)
`chroma/geometry_types.h`::
enum { SURFACE_DEFAULT, SURFACE_COMPLEX, SURFACE_WLS };
Potentially wavelength dependent props all default to zero.
Having values for these is necessary to get SURFACE_DETECT, SURFACE_ABSORB
* detect
* absorb
* reflect_diffuse
* reflect_specular
* reemit
* eta
* k
* reemission_cdf
`chroma/cuda/photon.h`::
701 __device__ int
702 propagate_at_surface(Photon &p, State &s, curandState &rng, Geometry *geometry,
703 bool use_weights=false)
704 {
705 Surface *surface = geometry->surfaces[s.surface_index];
706
707 if (surface->model == SURFACE_COMPLEX)
708 return propagate_complex(p, s, rng, surface, use_weights);
709 else if (surface->model == SURFACE_WLS)
710 return propagate_at_wls(p, s, rng, surface, use_weights);
711 else
712 {
713 // use default surface model: do a combination of specular and
714 // diffuse reflection, detection, and absorption based on relative
715 // probabilties
716
717 // since the surface properties are interpolated linearly, we are
718 // guaranteed that they still sum to 1.0.
719 float detect = interp_property(surface, p.wavelength, surface->detect);
720 float absorb = interp_property(surface, p.wavelength, surface->absorb);
721 float reflect_diffuse = interp_property(surface, p.wavelength, surface->reflect_diffuse);
722 float reflect_specular = interp_property(surface, p.wavelength, surface->reflect_specular);
723
"""
if debug:
print "%-75s %s " % (dsurf.name, dsurf)
surface = Surface(dsurf.name)
finish_map = {
OpticalSurfaceFinish.polished: 'reflect_specular',
OpticalSurfaceFinish.ground: 'reflect_diffuse',
}
if 'EFFICIENCY' in dsurf.properties:
EFFICIENCY = dsurf.properties.get('EFFICIENCY', None)
surface.set('detect',
EFFICIENCY[:, 1],
wavelengths=EFFICIENCY[:, 0])
pass
elif 'REFLECTIVITY' in dsurf.properties:
REFLECTIVITY = dsurf.properties.get('REFLECTIVITY', None)
key = finish_map.get(int(dsurf.finish), None)
if key is None or REFLECTIVITY is None:
log.warn(
"miss REFLECTIVITY key : not setting REFLECTIVITY for %s "
% surface.name)
else:
log.debug("setting prop %s for surface %s " %
(key, surface.name))
surface.set(key,
REFLECTIVITY[:, 1],
wavelengths=REFLECTIVITY[:, 0])
pass
else:
log.warn(" no REFLECTIVITY/EFFICIENCY in dsurf.properties %s " %
repr(dsurf.properties))
pass
return surface
def make_acrylic_surface_wlsmode():
"""
this version of acrylic surface wavelength shifts reemitted light
"""
acrylic_surface = Surface("acrylic_surface_detector")
acrylic_surface.set('reflect_diffuse', 0.0)
acrylic_surface.set('reflect_specular', 0.0)
acrylic_surface.set('detect', 0.0)
acrylic_surface.set('absorb', 0.0)
acrylic_surface.set(
'reemit',
datatools.load_hist_data(
os.path.dirname(__file__) + "/raw_tpb_emission.dat", 350, 640)
) # 100% reemission. Actually, should be 120%!! Need to think about this.
acrylic_surface.transmissive = 1
return acrylic_surface
eventid = IntCol()
id = IntCol()
NTDC = IntCol()
NS_PER_TDC = FloatCol()
adc = FloatArrayCol(GPUDaqUBooNE.NTDC)
q = FloatCol()
t = FloatCol()
class OpMap(TreeModel):
opid = IntCol()
x = FloatCol()
y = FloatCol()
z = FloatCol()
lar1nd_wireplane = Surface('lar1nd_wireplane')
lar1nd_wireplane.nplanes = 3.0
lar1nd_wireplane.wire_pitch = 0.3
lar1nd_wireplane.wire_diameter = 0.015
lar1nd_wireplane.transmissive = 1
lar1nd_wireplane.model = Surface.SURFACE_WIREPLANE
def add_wireplane_surface(solid):
# function detector class will use to add a wireplane surface to the geometry
# LAr1ND has two drift regions, so we need two planes
# set surface for triangles on x=-2023.25 and x=2023.25 planes
for n, triangle in enumerate(solid.mesh.triangles):
#print [ solid.mesh.vertices[x] for x in triangle ] # for debug
nxplane = 0
import numpy as np
from chroma.geometry import Material, Surface
vacuum = Material('vacuum')
vacuum.set('refractive_index', 1.0)
vacuum.set('absorption_length', 1e6)
vacuum.set('scattering_length', 1e6)
lambertian_surface = Surface('lambertian_surface')
lambertian_surface.set('reflect_diffuse', 1)
black_surface = Surface('black_surface')
black_surface.set('absorb', 1)
shiny_surface = Surface('shiny_surface')
shiny_surface.set('reflect_specular', 1)
glossy_surface = Surface('glossy_surface')
glossy_surface.set('reflect_diffuse', 0.5)
glossy_surface.set('reflect_specular', 0.5)
red_absorb_surface = Surface('red_absorb')
red_absorb_surface.set('absorb', [0.0, 0.0, 1.0], [465, 545, 685])
red_absorb_surface.set('reflect_diffuse', [1.0, 1.0, 0.0], [465, 545, 685])
# r7081hqe photocathode material surface
# source: hamamatsu supplied datasheet for r7081hqe pmt serial number zd0062
r7081hqe_photocathode = Surface('r7081hqe_photocathode')
r7081hqe_photocathode.detect = \
np.array([(260.0, 0.00),
(270.0, 0.04), (280.0, 0.07), (290.0, 0.77), (300.0, 4.57),
def make_G10_surface():
g10_surface = Surface("g10_surface")
g10_surface.set('reflect_diffuse', 0.5)
g10_surface.set('reflect_specular', 0.0)
g10_surface.set('detect', 0.0)
g10_surface.set('absorb', 0.5)
g10_surface.set('reemit', 0.0)
g10_surface.transmissive = 0
return g10_surface
def testBulkReemission(self):
'''Test bulk reemission
Start a bunch of monoenergetic photons at the center of a wavelength-
shifting sphere, forcing reemission, and check that the final
wavelength distribution matches the wls spectrum.
'''
import scipy.stats
nphotons = 1e5
# set up detector -- a sphere of 'scintillator' surrounded by a
# detecting sphere
scint = Material('scint')
scint.set('refractive_index', 1)
scint.set('absorption_length', 1.0)
scint.set('scattering_length', 1e7)
scint.set('reemission_prob', 1)
x = np.arange(0,1000,10)
norm = scipy.stats.norm(scale=50, loc=600)
pdf = 10 * norm.pdf(x)
cdf = norm.cdf(x)
scint.reemission_cdf = np.array(zip(x, cdf))
detector = Surface('detector')
detector.set('detect', 1)
world = Geometry(vacuum)
world.add_solid(Solid(sphere(1000), vacuum, vacuum, surface=detector))
world.add_solid(Solid(sphere(500), scint, vacuum))
w = create_geometry_from_obj(world, update_bvh_cache=False)
sim = Simulation(w, geant4_processes=0)
# initial photons -- isotropic 250 nm at the origin
pos = np.tile([0,0,0], (nphotons,1)).astype(np.float32)
dir = np.random.rand(nphotons, 3).astype(np.float32) * 2 - 1
dir /= np.sqrt(dir[:,0]**2 + dir[:,1]**2 + dir[:,2]**2)[:,np.newaxis]
pol = np.zeros_like(pos)
t = np.zeros(nphotons, dtype=np.float32)
wavelengths = np.ones(nphotons).astype(np.float32) * 250
photons = Photons(pos=pos, dir=dir, pol=pol, t=t, wavelengths=wavelengths)
# run simulation and extract final wavelengths
event = sim.simulate([photons], keep_photons_end=True).next()
mask = (event.photons_end.flags & SURFACE_DETECT) > 0
final_wavelengths = event.photons_end.wavelengths[mask]
# compare wavelength distribution to scintillator's reemission pdf
hist, edges = np.histogram(final_wavelengths, bins=x)
print 'detected', hist.sum(), 'of', nphotons, 'photons'
hist_norm = 1.0 * hist / (1.0 * hist.sum() / 1000)
pdf /= (1.0 * pdf.sum() / 1000)
chi2 = scipy.stats.chisquare(hist_norm, pdf[:-1])[1]
print 'chi2 =', chi2
# show histogram comparison
#plt.figure(1)
#width = edges[1] - edges[0]
#plt.bar(left=edges, height=pdf, width=width, color='red')
#plt.bar(left=edges[:-1], height=hist_norm, width=width)
#plt.show()
self.assertTrue(chi2 > 0.75)
import os, sys
from chroma.importgeo import UserVG4DEAGeo, load_hist_data
from chroma.geometry import Surface
import numpy as np
wireplane = Surface('wireplane')
wireplane.nplanes = 3.0
wireplane.wire_pitch = 0.3
wireplane.wire_diameter = 0.015
wireplane.transmissive = 1
wireplane.model = Surface.SURFACE_WIREPLANE
class SBND(UserVG4DEAGeo):
def __init__(self):
super(SBND,
self).__init__("SBND",
"dae/lar1nd_lightguides_nowires_chroma.dae")
def surfacesdict(self):
# Steel/LAr
steel_surface = Surface("steel_surface")
steel_surface.set('reflect_diffuse', 0.25)
steel_surface.set('reflect_specular', 0.0)
steel_surface.set('detect', 0.0)
steel_surface.set('absorb', 0.75)
steel_surface.set('reemit', 0.0)
steel_surface.transmissive = 0
# Titanium/LAr
titanium_surface = Surface("titanium_surface")
titanium_surface.set('reflect_diffuse', 0.125)