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from Geant4 import *
import g4py.ezgeom
import g4py.NISTmaterials
import g4py.ParticleGun
import pyublas
import numpy as np
import chroma.event as event
try:
import G4chroma
except:
# Try building the module
import subprocess
import sys, os
module_dir = os.path.split(os.path.realpath(__file__))[0]
print >>sys.stderr, 'Compiling G4chroma.so...'
retcode = subprocess.call('g++ -o \'%s/G4chroma.so\' -shared \'%s/G4chroma.cc\' -fPIC `geant4-config --cflags --libs` `python-config --cflags --libs --ldflags` -lboost_python' % (module_dir, module_dir), shell=True)
assert retcode == 0
import G4chroma
class G4Generator(object):
def __init__(self, material, seed=None):
'''Create generator to produce photons inside the specified material.
material: chroma.geometry.Material object with density,
composition dict and refractive_index.
composition dictionary should be
{ element_symbol : fraction_by_weight, ... }.
seed: Random number generator seed for HepRandom. If None,
generator is not seeded.
'''
if seed is not None:
HepRandom.setTheSeed(seed)
g4py.NISTmaterials.Construct()
g4py.ezgeom.Construct()
self.physics_list = G4chroma.ChromaPhysicsList()
gRunManager.SetUserInitialization(self.physics_list)
self.particle_gun = g4py.ParticleGun.Construct()
self.world_material = self.create_g4material(material)
g4py.ezgeom.SetWorldMaterial(self.world_material)
g4py.ezgeom.ResizeWorld(100*m, 100*m, 100*m)
self.world = g4py.ezgeom.G4EzVolume('world')
self.world.CreateBoxVolume(self.world_material, 100*m, 100*m, 100*m)
self.world.PlaceIt(G4ThreeVector(0,0,0))
self.tracking_action = G4chroma.PhotonTrackingAction()
gRunManager.SetUserAction(self.tracking_action)
gRunManager.Initialize()
#preinitialize the process by running a simple event
self.generate_photons(event.Event(event_id=0, particle_name='e-',
gen_position=(0,0,0),
gen_direction=(1,0,0),
gen_total_energy=1.0))
def create_g4material(self, material):
g4material = G4Material('world_material', material.density * g / cm3,
len(material.composition))
# Add elements
for element_name, element_frac_by_weight in material.composition.items():
g4material.AddElement(G4Element.GetElement(element_name, True),
element_frac_by_weight)
# Set index of refraction
prop_table = G4MaterialPropertiesTable()
# Reverse entries so they are in ascending energy order rather
# than wavelength
energy = list((2*pi*hbarc / (material.refractive_index[::-1,0] * nanometer)).astype(float))
values = list(material.refractive_index[::-1, 1].astype(float))
prop_table.AddProperty('RINDEX', energy, values)
# Load properties
g4material.SetMaterialPropertiesTable(prop_table)
return g4material
def _extract_photons_from_tracking_action(self):
n = self.tracking_action.GetNumPhotons()
pos = np.zeros(shape=(n,3), dtype=np.float32)
pos[:,0] = self.tracking_action.GetX()
pos[:,1] = self.tracking_action.GetY()
pos[:,2] = self.tracking_action.GetZ()
dir = np.zeros(shape=(n,3), dtype=np.float32)
dir[:,0] = self.tracking_action.GetDirX()
dir[:,1] = self.tracking_action.GetDirY()
dir[:,2] = self.tracking_action.GetDirZ()
pol = np.zeros(shape=(n,3), dtype=np.float32)
pol[:,0] = self.tracking_action.GetPolX()
pol[:,1] = self.tracking_action.GetPolY()
pol[:,2] = self.tracking_action.GetPolZ()
wavelengths = self.tracking_action.GetWavelength().astype(np.float32)
times = self.tracking_action.GetT0().astype(np.float32)
return event.Photons(positions=pos, directions=dir, polarizations=pol, times=times, wavelengths=wavelengths)
def generate_photons(self, ev):
'''Use GEANT4 to generate photons produced by the given particle.
ev: a generator.event.Event object with the particle
properties set. If it contains subtracks, those
will be used to create the photon vertices rather
than the main particle.
Returns an instance of event.Photons containing the
generated photon vertices for the primary particle or
all the subtracks, if present.
'''
photons = []
if ev.subtracks:
subtracks = ev.subtracks
else:
# Create temporary subtrack for single primary particle
subtracks = [event.Subtrack(particle_name=ev.particle_name,
position=ev.gen_position,
direction=ev.gen_direction,
start_time=0.0,
total_energy=ev.gen_total_energy)]
for subtrack in subtracks:
self.particle_gun.SetParticleByName(subtrack.particle_name)
self.particle_gun.SetParticleEnergy(subtrack.total_energy * MeV)
self.particle_gun.SetParticlePosition(G4ThreeVector(*subtrack.position)*m)
self.particle_gun.SetParticleMomentumDirection(G4ThreeVector(*subtrack.direction).unit())
self.tracking_action.Clear()
gRunManager.BeamOn(1)
photons.append(self._extract_photons_from_tracking_action())
# Merge all photon lists into one big list
return event.concatenate_photons(photons)
if __name__ == '__main__':
import time
import optics
gen = G4Generator(optics.water)
start = time.time()
n = 0
for i in xrange(100):
photons = gen.generate_photons(event.Event('mu-', (0,0,0), (1,0,0), 1.0))
n += len(photons.times)
print photons.positions[0].min(), photons.positions[0].max()
stop = time.time()
print stop - start, 'sec'
print n / (stop-start), 'photons/sec'
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