Proton induced radiation damage studies on plastic scintillators for the Tile calorimeter of the atlas detector

4
 
Experimental details 
4.1.
 
Overview of radiation damage methods 
The 6 MV EN Tandem accelerator of iThemba LABS in Gauteng was used to 
irradiate samples with 6 MeV protons. To ensure that the study simulated a 
similar type of particle-scintillator interaction as observed in the Ti le 
Calorimeter, protons were required to pass through the samples whilst imparting 
energy primarily through electronic energy loss due to electronic excitation and 
ionisation interactions.
The stopping range of 6 MeV protons and their energy deposited within the 
scintillator material was determined using the SRIM software package. Samples 
were then prepared using a cutting and polishing procedure based on standard 
metallographic techniques. Samples were irradiated with doses of approximately 
0.8 MGy, 8 MGy, 25 MGy and 80 MGy and their damage anal ysed using several 
techniques. 
4.1.1.
 
SRIM simulations 
SRIM (the Stopping and Range of Ions in Matter) [26], is a program that 
simulates the interaction of ions in matter . It takes into account the screened 
Coulomb collision between ions and target atoms as well as the exchange and 
correlation interactions between the overlapping electron shells, in order to 
calculate the stopping and range of ions into matter.
SRIM contains an additional program called TRIM (the Transport of Ions in 
Matter) which is a Monte-Carlo program that calculates the interaction of ions 
within a target. It establishes the collision details between ions and target atoms 
by inputting a random number for the impact parameter and distance to the next 
colliding atom to create a probability distribution that is dependent on the target 
density [26].

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For these simulations, preset PVT and PS based scintillator materials from the 
SRIM database were used and adjusted to accommodate for the Carbon to 
Hydrogen (CH) ratio and density of the plastics as indicated by the manufacturer. 
The following figure shows the TRIM simulation for 6 MeV protons (hydrogen 
ions) through a PVT based target.