DosiPix-N / Simulations

Generic simulation files can be downloaded on this page.
After a brief description of the simulated setup, features used both in MCNPX and Geant4 are given.

1. Setup

• Source
  • content
    • AmBe ISO neutron spectrum (see here, p.15) // uncertainty: +/- 4% (see here)
    • 4.438 MeV gamma at 0.575+/-4.8% photon per neutron (see here)
  • container: X3 capsule from AEA Technology wrapped in a 1 mm thick Pb shell
• Detector
  • sensor: mimosa5 front-illuminated (1 Mpix on 4 matrices)
    • matrix = 510*512 pix², pixel = 17*17 um²
    • layers' thickness = 5.7+/-0.8 um oxyde // 14.5+/-2 um epi // 300 um sub
  • neutron converter: CH₂ slab (0.94+/-0.01 gcc) doped or not with ¹⁰B, LiF, Li₂B₄O₇
  • support: 1.5 mm thick PCB (FR-4)
• Environment
  • free in air with or without walls, floor, ceiling (plain concrete or concrete with baryum)
  • optionally, a 7 inch CH₂ thermalization sphere (0.94+/-0.01 gcc) with or without a 1 mm thick Cd shell (thermal neutron cut)

2. MCNPX features

• Physics
  • LCPs
    • different energy loss models: CSDA, (Old) Vavilov (PHYS:h/a 4J -1|0|1 2J)
  • neutrons
    • libs: LA150N (.24c & .25c)
    • recoil proton activation (PHYS:N 6J 1)
    • thermal scattering treatment (S(alpha,beta) / POLY.60T)
• Outputs
  • usual tallies
    • F1:X (X=any particle) at the entrance of all layers of interest, at all angles to get the current of any particles (number of particles crossing a surface)
    • F4:Z x cell volume (Z=any LCP) inside all layers of interest, to get the range of any LCP
    • F8:Z / FT8 PHL / F6 (Z=any LCP) inside all layers of interest, to get the deposited energy by any LCP
    • F8:p inside all layers of interest, to get the photon deposited energy
  • extra tallies
    • dE/dF for photons and neutrons using h_p(10,0°) neutron fluence to neutron dose equivalent conversion function (ICRP74)
    • rectangular mesh tally for photons and neutrons (flux and dose)
    • pert card
  • ptrac file (see the last page of this)
• Issues
  • Energy loss for LCPs (Look for "dE/dx" in here or see here (..._mtrocme.pdf))
  • 14N(n,p) reaction not coded in MCNPX!
• Notes
  • (photo-)electron not generated (to be improved)
  • To get the histograms automatically, see here or here (..._mtrocme.pdf)
  • To run this example in multiprocessing mode, see here
  • [MCNPX_Workshop_IPHC My MCNP tutorial]
• Download
  • Here's my file!

3. Geant4 features

• Physics (see here section "3. Advices for Low Energy users")
  • LCPs
    • G4LowEnergy classes (ICRU49)
  • neutrons
    • LHEP_PRECO_HP
    • thermal scattering treatment (S(alpha,beta) / TS_H_of_Polyethylene)
• Outputs
  • ROOT tree coupled with a specific class (see here then here)
    • particle info: name, Z, A, ID, parent ID, creator process name
    • position, direction, kinetic energy, time and weight at the entrance of all the sensitive layers
    • energy deposited, dose, and range (projected or not wrt different directions) in all the sensitive layers
  • heprep.zip file (see here section "2.1.3. Visualization")
• Issues
  • Several NIST compounds should not be used with G4LowEnergy classes (see here).
  • From g4.9.3.b01 (june 2009), the G4LowEnergy* classes are not supported any more. For more information, please see here section "3.4. WARNING".
• Notes
  • Geant4/ROOT proper coupling
  • To run this example on the Grid, see here
  • My G4 tutorial
• Download
  • The core program is exactly the same as that one.
    Just the physics list (and the detector geometry) differ. Because of the above issues (physics list), no file is provided any more.
    As abovementioned, everything is explained here section "3. Advices for Low Energy users".

4. Misc

• Thanks for reporting me any blunders and sharing your simulation experience too.
• In order to fully illustrate CAD to Monte Carlo simulation code coupling, the next releases will start from the same CAD file.
• General simulation advices can be found here.
• If you use NEdit, please see here.