Geant4 Gamma Monte Carlo Simulation of U/Th Contamination

Tobias Bruch - Run 123 Gamma Background

We aim to measure background contamination by tracing the sources of contamination within elements surrounding the detector towers. Primarily, this contamination is located within the six copper temperature shielding cans surrounding the detector towers. There is also contamination from the copper elements in the towers themselves, as well as the Inner layers of Poly and Lead surrounding the cans. This study was performed for Run 123 by Tobias Bruch, and is now being revised for the c58 geometry. Unlike the run 123 analysis, each temperature can is treated as an independent source. The sources by name are as follows: OVCCan, LiquidNCan, IVCCan, StillCan, ColdCan, BaseCan, T1, T2, T3, T4, T5, InnerPoly, and InnerLead.

The contamination of each Can and Tower assumed Th232 (Ac228, Bi212, Pb212, Tl208), U238 (Bi214, Pb214), Co60, and K40. The Inner Poly assumed Th232 and U238, while the Inner Lead assumed only Bi210. To generate particles, a function was constructed that treats each source as three parts: a top lid, a hollow middle, and a bottom lid. From this, each part can be modeled as a cylinder with some inner and outer radius. By specifying the inner radius, change in radius, lowest height, and change in height of each part, and assigning a probability of being located in each part based on volume, the function randomly generates a particle within the source. To account for various gaps within any of these parts, the function checks the material at the randomly generated point to ensure it matches the correct material for the source being simulated (Copper, Poly, or Lead).

This folder contains the following scripts

• load_D3.m
  • Creates a .mat file for Deposited Energy from Run 130 Data
  • Items to be individually modified before running
    • input_dir
    • output_dir

• peaks.m
  • Locates peak energy deposition values for each element from BaseCan source (for best statistics)
  • Items to be individually modified before running (* - not vital to operation)
    • input_dir
    • total_peaks*
    • bins*

• plotting.m
  • Creates graphs of energy deposition values for each element from each source
  • Items to be individually modified before running (* - not vital to operation)
    • input_dir
    • output_dir
    • colors*

• ratios.m
  • Specifies the efficiency of recorded detections for each element from each source
  • Items to be individually modified before running
    • input_dir

• src/DetectorConstruction.cc
  • Modification of visualization attributes for confirming proper generation of particles

• src/ParticleSource.cc & include/ParticleSource.hh
  • Creates the particles within the specified volumes of each temperature shielding can
  • Functions created
    • SetRandomPosInCan
    • FromOVCCan
    • FromLiquidNCan
    • FromIVCCan
    • FromStillCan
    • FromColdCan
    • FromBaseCan
    • FromTower

• src/ParticleSourceMessenger.cc
  • Enables selection of source type within program execution

can_dimensions.xls