Difference between revisions of "HRRL Simulations"
Line 89: | Line 89: | ||
=== Photon Energy -to- Dose === | === Photon Energy -to- Dose === | ||
{| border="1" |cellpadding="20" cellspacing="0 | {| border="1" |cellpadding="20" cellspacing="0 | ||
− | |||
− | |||
|- | |- | ||
|Photon Energy || Dose Conversion Coeff | |Photon Energy || Dose Conversion Coeff |
Revision as of 10:03, 20 July 2008
Mark Balzer: 282-5652
Brian Oborn: 282- 6243
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 gamma which had a momentum component towards the ceiling (p_y>0).
The energy distribution (in MeV) of the gammas headed towards the ceiling 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 materialTo 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.
Mark Balzer tells me that the ion chambers are cylinders of length 4 inches and 1 inch in diameter. The ion chamber's cylindrical axis is mounted parallel to the ceiling. We will be limited to running with beam current that generate 2 mRad/hr or less in a single ion chamber. As a first estimate I will treat the cylinder as having a rectangular surface area of 4 " x 1 " = 4 in^2 = 25.8 cm^2. The ion chamber is on the ceiling which is about 6 meters from the beam pipe. The solid angle is thus
- .
The predicted rate in an ion chamber would then be
- our max beam current for 1 mRad/hr would be = 5 mA peak
Or in terms of an average current
- average
Run 2: Ceiling Penetration
=Setup
The picture below shows the simulation World volume. A red electron beam enters the HRRL experimental cell from the left side and hits a 2 mm thick Tungsten target shown as the white vertical line inside the white inner box. The yellow box is a detector tracking cell. The roof is shown as 2 horizontal lines near the top of the World volume.
A few interesting events:
Photon Energy -to- Dose
Photon Energy | Dose Conversion Coeff |
(MeV) | Rad/MeV/hr |
0.01 | 3.96E-6 |
0.03 | 0.582E-6 |
0.05 | 0.290E-6 |
0.07 | 0.258E-6 |
0.1 | 0.283E-6 |
0.15 | 0.379E-6 |
0.2 | 0.501E-6 |
0.25 | 0.631E-6 |
0.3 | 0.759E-6 |
0.35 | 0.878E-6 |
0.4 | 0.985E-6 |
0.45 | 1.08E-6 |
0.5 | 1.17E-6 |
0.55 | 1.27E-6 |
0.6 | 1.36E-6 |
0.65 | 1.44E-6 |
0.7 | 1.52E-6 |
0.8 | 1.68E-6 |
1.0 | 1.98E-6 |
1.4 | 2.51E-6 |
1.8 | 2.99E-6 |
2.2 | 3.42E-6 |
2.6 | 3.82E-6 |
2.8 | 4.01E-6 |
3.25 | 4.41E-6 |
3.75 | 4.83E-6 |
4.25 | 5.23E-6 |
4.75 | 5.60E-6 |
5.0 | 5.80E-6 |
5.25 | 6.01E-6 |
5.75 | 6.37E-6 |
6.25 | 6.74E-6 |
6.75 | 7.11E-6 |
7.5 | 7.66E-6 |
9.0 | 8.77E-6 |
11.0 | 10.3E-6 |
13.0 | 11.8E-6 |
15.0 | 13.3E-6 |
Concrete Definition and Stopping Power
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) || RadiationYield || Density EffectParameter | |
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 |