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

Figure 4-1: TRIM simulation of 6 MeV protons in PVT target.
As highlighted in the purple box, about 99.93% of the energy loss is due to 
ionization imparted by the protons. Figure 4-2 shows the range of the ions over 
the PVT based and the PS based target. Most of the ions stop at around 476 μm 
in PVT and 466 μm in PS. Due to the requirement that protons pass through the 
samples and not stop within them, a thickness of ~350 μm was decided. This 
range is well before any stopping begins to occur in both sample base types. 
Thicknesses of less than 250 μm were ruled out as the machining of such samples 
induced stress related structural damage to them.

---

25 
Figure 4-2: Plot of the range over which protons stop within the PVT and PS targets. 
Simulations of 6 MeV protons through targets of 300 -400 μm thickness were then 
conducted in order to establish the energy of particles transmitted f rom the target. 
This was used in order to estimate the amount of energy deposited by a 6 MeV 
proton traversing the samples, which was a parameter needed for estimating the 
absorbed dose upon irradiation of the samples. For a 6 MeV proton traversing 
through a PVT based scintillator, the estimated amount of energy deposited is 
3.20 MeV through a 350 μm thick sample and 3.89 MeV through a 400 μm thick 
sample.
4.1.2.
 
Sample preparation 
Samples were prepared with targeted dimensions of 5 mm x 5 mm area and 350 
μm thickness. Since cutting the samples caused them to become rough and 
opaque, samples were polished to improve their transparency. A polishing 
procedure based on standard metallographic techniques [27] was employed.
A “Buehler IsoMet” low speed cut-off machine was used to section rectangular 
bars of 5 mm x 5 mm area and with varying lengths. The lengths depended on the 
dimensions of the sample blocks provided by the manufacturers. The bars were 
further cut along their cross-section into 1 mm thick slices.

---

26 
The cutting operation was carried out using a diamond finished blade with cutting 
fluid as a lubricant. Photographs of the Buehler IsoMet cutting machine are 
shown in Figure 4-3.