Figure 4-3: Photographs of (a) the Buehler IsoMet cutting machine, (b) a front view of an
EJ260 bar being cut, (c) a side view of the EJ260 bar being cut.
The sample slices were then mounted within the 6 mm x 6 mm x 0.36 mm grove
machined into aluminium sample holders. The holders were designed to be
attached to the polishing machine. Several photographs of the aluminium holder
are shown in Figure 4-4.
Carbon tape was chosen as the mounting medium because it did not attack the
plastic scintillators like other typical mounting agents would and provided a firm
enough hold during polishing. Furthermore, removing the carbon tape entailed
soaking in an ultrasonic bath of ethanol as opposed to using a harsher alcohol
solvent which could damage the plastic material chemically.
Figure 4-4: Aluminium holders used to mount the samples onto before polishing.
27
The sample polishing was performed using a “Struers” metallographic polishing
machine. Samples were mounted onto a rotating polishing head, and a polishing
cloth was attached onto the spinning polishing wheel. A 2 Newton force pushed
down on the samples as they rotated along the polishing cloth using a
complimentary polishing direction.
The setup is indicated in Figure 4-5. Two polishing stages, medium and fine
polishing were employed. The medium polishing stage was carried out using a 6
µm diamond suspension on a “Struers MD-Dac” polishing cloth, which is a satin
woven acetate cloth. The fine polishing was carried out using a 1 µm diamond
suspension on a soft synthetic fibre cloth (Struers MD-Nap).
Figure 4-5: Photographs of the Struers polishing machine.
In the case of the Protvino samples, where a tile of 3 mm thickness was obtained
from the Tile Calorimeter, 5 x 5 mm
2
squares were cut directly from the tile and
rough polished down to 1 mm thicknesses before undergoing the medium and
fine polishing stages.
All samples were polished on their transverse surfaces. After polishing, samples
were soaked in the ultrasonic bath of ethanol for 30 minutes in order to remove
the carbon tape and cleaned using lukewarm soapy water. Samples were then
placed in brass holders in preparation for irradiation. In Figure 4-6, a final
polished sample is shown being mounted into a brass holder. The transparency
of the scintillator should be noted.
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