HRRL Simulations
This document describes the simulations performed to estimate the radiological background in the event that a 1 nA electron current from the HRRL enters the experimental cell.
Radiation monitors: Ludlum Model 45-8.
Low energy gamma cutoff = 60 keV
Tungsten SImulation
I created a world volume filled with Air to represent the experimental cell.
I created a 2mm thick tungsten target that is 30 cm x 30 cm in area.
The image below shows several electrons hitting the tungsten foil, then scattering in air. The red lines are electrons and the green ones are photons.
Run 1
I then ran 1 million events in which an incident 7 MeV electron hit the 2 mm thick Tungsten with the physics processes
if (particleName == "gamma") {
// gamma
pmanager->AddDiscreteProcess(new G4PhotoElectricEffect);
pmanager->AddDiscreteProcess(new G4ComptonScattering);
pmanager->AddDiscreteProcess(new G4GammaConversion);
} else if (particleName == "e-") {
//electron
pmanager->AddProcess(new G4MultipleScattering,-1, 1,1);
pmanager->AddProcess(new G4eIonisation, -1, 2,2);
pmanager->AddProcess(new G4eBremsstrahlung, -1, 3,3);
I only kept event in which had a momentum component towards the ceiling
The energy distribution (in MeV) of the gammas headed towards the roof is shown below. Of the 1 million electrons incident on the 2 mm thick Tungsten target, only 70,000 gammas were headed towards the cieling. This does not mean that they hit it, they could have hit the wall.
If I sum the above distribution I see a total energy of 43,987 MeV going up from the 1 million 7 MeV electrons hitting the 2mm Tungsten target.
1 Rad = = the amount of energy absorbed per 100 kg of material
To calculate the worst possible case lets assume all of the radiation is absorbed by a person (there is no concrete ceiling).
Converting the energy from MeV to Joules
In terms of the energy per beam current charge we would have
I we ran the HRRL for 1 hour at the maximum beam current of 80 mA per 100 ns pulse and 1 kHz rep rate then the dose to the ceiling would be
The total photon radiation hitting the upper half of the experimental cell is predicted to be 1.4 krad/hr. To determine the dose on a radiation detector you just need to scale by the solid angle.
Run 2: Floor Penetration
A 6 inch concrete floor is assumed to exist on the top of the experimental cell which will block radiation from penetrating to the offices above the cell.
Stopping power from NIST
Composition of CONCRETE, PORTLAND: Density (g/cm3) = 2.30000E+00 Mean Excitation Energy (eV) = 135.200000
COMPOSITION: Atomic number Fraction by weight 1 0.010000 6 0.001000 8 0.529107 11 0.016000 12 0.002000 13 0.033872 14 0.337021 19 0.013000 20 0.044000 26 0.014000
(required) Kinetic Energy (MeV) Stopping Power (MeV cm2/g) CSDA Range (g/cm2) Radiation Yield Density Effect Parameter
Collision Radiative Total 1.000E-02 1.804E+01 5.754E-03 1.805E+01 3.207E-04 1.710E-04 0.000E+00 1.250E-02 1.526E+01 5.864E-03 1.526E+01 4.720E-04 2.072E-04 0.000E+00 1.500E-02 1.330E+01 5.942E-03 1.330E+01 6.480E-04 2.419E-04 0.000E+00 1.750E-02 1.184E+01 5.999E-03 1.184E+01 8.476E-04 2.755E-04 0.000E+00 2.000E-02 1.070E+01 6.044E-03 1.071E+01 1.070E-03 3.080E-04 0.000E+00 2.500E-02 9.049E+00 6.107E-03 9.056E+00 1.580E-03 3.704E-04 0.000E+00 3.000E-02 7.899E+00 6.153E-03 7.905E+00 2.173E-03 4.298E-04 0.000E+00 3.500E-02 7.049E+00 6.189E-03 7.055E+00 2.844E-03 4.867E-04 0.000E+00 4.000E-02 6.393E+00 6.220E-03 6.400E+00 3.589E-03 5.415E-04 0.000E+00 4.500E-02 5.872E+00 6.249E-03 5.878E+00 4.405E-03 5.944E-04 0.000E+00 5.000E-02 5.446E+00 6.276E-03 5.453E+00 5.289E-03 6.457E-04 0.000E+00 5.500E-02 5.092E+00 6.302E-03 5.099E+00 6.238E-03 6.955E-04 0.000E+00 6.000E-02 4.793E+00 6.328E-03 4.799E+00 7.250E-03 7.440E-04 0.000E+00 7.000E-02 4.315E+00 6.381E-03 4.321E+00 9.450E-03 8.375E-04 0.000E+00 8.000E-02 3.948E+00 6.437E-03 3.955E+00 1.187E-02 9.269E-04 0.000E+00 9.000E-02 3.659E+00 6.497E-03 3.665E+00 1.450E-02 1.013E-03 0.000E+00 1.000E-01 3.425E+00 6.560E-03 3.431E+00 1.732E-02 1.096E-03 0.000E+00 1.250E-01 2.996E+00 6.733E-03 3.003E+00 2.514E-02 1.292E-03 0.000E+00 1.500E-01 2.706E+00 6.925E-03 2.713E+00 3.393E-02 1.477E-03 0.000E+00 1.750E-01 2.498E+00 7.134E-03 2.505E+00 4.353E-02 1.652E-03 0.000E+00 2.000E-01 2.341E+00 7.357E-03 2.349E+00 5.385E-02 1.819E-03 0.000E+00 2.500E-01 2.124E+00 7.843E-03 2.132E+00 7.627E-02 2.137E-03 0.000E+00 3.000E-01 1.982E+00 8.377E-03 1.990E+00 1.006E-01 2.438E-03 0.000E+00 3.500E-01 1.883E+00 8.952E-03 1.892E+00 1.264E-01 2.728E-03 8.781E-04 4.000E-01 1.811E+00 9.563E-03 1.820E+00 1.534E-01 3.011E-03 1.827E-02 4.500E-01 1.756E+00 1.021E-02 1.766E+00 1.813E-01 3.290E-03 3.821E-02 5.000E-01 1.714E+00 1.088E-02 1.725E+00 2.099E-01 3.565E-03 5.986E-02 5.500E-01 1.681E+00 1.159E-02 1.693E+00 2.392E-01 3.839E-03 8.276E-02 6.000E-01 1.655E+00 1.231E-02 1.668E+00 2.690E-01 4.112E-03 1.066E-01 7.000E-01 1.618E+00 1.383E-02 1.632E+00 3.296E-01 4.657E-03 1.562E-01 8.000E-01 1.593E+00 1.543E-02 1.609E+00 3.914E-01 5.204E-03 2.072E-01 9.000E-01 1.577E+00 1.709E-02 1.594E+00 4.539E-01 5.754E-03 2.587E-01 1.000E+00 1.566E+00 1.882E-02 1.585E+00 5.168E-01 6.308E-03 3.102E-01 1.250E+00 1.553E+00 2.339E-02 1.577E+00 6.751E-01 7.716E-03 4.363E-01 1.500E+00 1.551E+00 2.828E-02 1.580E+00 8.335E-01 9.157E-03 5.566E-01 1.750E+00 1.555E+00 3.342E-02 1.588E+00 9.914E-01 1.063E-02 6.704E-01 2.000E+00 1.560E+00 3.876E-02 1.599E+00 1.148E+00 1.213E-02 7.777E-01 2.500E+00 1.575E+00 4.998E-02 1.625E+00 1.459E+00 1.520E-02 9.746E-01 3.000E+00 1.590E+00 6.176E-02 1.651E+00 1.764E+00 1.835E-02 1.152E+00 3.500E+00 1.604E+00 7.400E-02 1.678E+00 2.064E+00 2.155E-02 1.312E+00 4.000E+00 1.617E+00 8.662E-02 1.704E+00 2.360E+00 2.479E-02 1.459E+00 4.500E+00 1.630E+00 9.956E-02 1.729E+00 2.651E+00 2.805E-02 1.595E+00 5.000E+00 1.641E+00 1.128E-01 1.754E+00 2.938E+00 3.134E-02 1.721E+00 5.500E+00 1.651E+00 1.263E-01 1.778E+00 3.221E+00 3.465E-02 1.839E+00 6.000E+00 1.661E+00 1.400E-01 1.801E+00 3.501E+00 3.796E-02 1.949E+00 7.000E+00 1.678E+00 1.680E-01 1.846E+00 4.049E+00 4.459E-02 2.152E+00 8.000E+00 1.693E+00 1.968E-01 1.890E+00 4.584E+00 5.122E-02 2.334E+00 9.000E+00 1.706E+00 2.261E-01 1.932E+00 5.108E+00 5.781E-02 2.500E+00 1.000E+01 1.718E+00 2.558E-01 1.973E+00 5.620E+00 6.437E-02 2.652E+00 1.250E+01 1.742E+00 3.320E-01 2.074E+00 6.855E+00 8.050E-02 2.984E+00 1.500E+01 1.761E+00 4.102E-01 2.171E+00 8.033E+00 9.619E-02 3.267E+00 1.750E+01 1.777E+00 4.899E-01 2.267E+00 9.160E+00 1.114E-01 3.513E+00 2.000E+01 1.791E+00 5.707E-01 2.362E+00 1.024E+01 1.261E-01 3.731E+00 2.500E+01 1.813E+00 7.350E-01 2.548E+00 1.228E+01 1.540E-01 4.106E+00 3.000E+01 1.831E+00 9.020E-01 2.733E+00 1.417E+01 1.799E-01 4.422E+00 3.500E+01 1.845E+00 1.071E+00 2.916E+00 1.594E+01 2.041E-01 4.694E+00 4.000E+01 1.857E+00 1.241E+00 3.099E+00 1.761E+01 2.266E-01 4.934E+00 4.500E+01 1.868E+00 1.413E+00 3.281E+00 1.917E+01 2.476E-01 5.148E+00 5.000E+01 1.877E+00 1.586E+00 3.463E+00 2.066E+01 2.673E-01 5.342E+00 5.500E+01 1.886E+00 1.760E+00 3.646E+00 2.206E+01 2.858E-01 5.519E+00 6.000E+01 1.893E+00 1.934E+00 3.828E+00 2.340E+01 3.032E-01 5.681E+00 7.000E+01 1.906E+00 2.286E+00 4.192E+00 2.590E+01 3.350E-01 5.971E+00 8.000E+01 1.918E+00 2.639E+00 4.557E+00 2.819E+01 3.634E-01 6.225E+00 9.000E+01 1.928E+00 2.994E+00 4.922E+00 3.030E+01 3.891E-01 6.451E+00 1.000E+02 1.936E+00 3.351E+00 5.288E+00 3.226E+01 4.123E-01 6.654E+00 1.250E+02 1.954E+00 4.248E+00 6.203E+00 3.662E+01 4.620E-01 7.087E+00 1.500E+02 1.969E+00 5.151E+00 7.120E+00 4.038E+01 5.025E-01 7.443E+00 1.750E+02 1.981E+00 6.059E+00 8.040E+00 4.368E+01 5.363E-01 7.746E+00 2.000E+02 1.992E+00 6.969E+00 8.961E+00 4.662E+01 5.650E-01 8.010E+00 2.500E+02 2.010E+00 8.797E+00 1.081E+01 5.170E+01 6.114E-01 8.451E+00 3.000E+02 2.024E+00 1.063E+01 1.266E+01 5.597E+01 6.474E-01 8.813E+00 3.500E+02 2.036E+00 1.247E+01 1.451E+01 5.965E+01 6.764E-01 9.119E+00 4.000E+02 2.046E+00 1.432E+01 1.636E+01 6.290E+01 7.003E-01 9.385E+00 4.500E+02 2.055E+00 1.616E+01 1.822E+01 6.579E+01 7.204E-01 9.620E+00 5.000E+02 2.064E+00 1.801E+01 2.008E+01 6.841E+01 7.376E-01 9.830E+00 5.500E+02 2.071E+00 1.986E+01 2.194E+01 7.079E+01 7.525E-01 1.002E+01 6.000E+02 2.078E+00 2.172E+01 2.379E+01 7.298E+01 7.656E-01 1.019E+01 7.000E+02 2.090E+00 2.543E+01 2.752E+01 7.688E+01 7.874E-01 1.050E+01 8.000E+02 2.100E+00 2.914E+01 3.124E+01 8.029E+01 8.051E-01 1.077E+01 9.000E+02 2.109E+00 3.286E+01 3.497E+01 8.331E+01 8.197E-01 1.100E+01 1.000E+03 2.117E+00 3.658E+01 3.870E+01 8.603E+01 8.320E-01 1.121E+01