Preliminary Scan in x Shahab Khan

Scan in x procedure Placed Sr 90 radiation source 6mm from the edge of the left most cell moved across along the center axis in 1mm steps Ended 6mm from the edge of the right cell 6mm Start 6mm End

Results

Discussion There were flaws in this experiment: The thickness of the paint on the three cells scanned were different, making it difficult to pinpoint the edges In order to prevent damaging the fibers, the scanning height was increased to the point where the area of radiation was too large

Experiment improvements Either choose cells which have nearly the same response (As per the cell-response data, taken earlier) or normalize the cell response relative to each other by comparing each cell’s central response With a newly engineered case, flip over the cells so that the fibers are on the underside; repeat with scanning height almost zero

Black vs White measurements to determine cross-talk Shahab Khan

Procedure, step 1 Remove all cells except cell in the center Record the mean of 500 measurements of the current from the center cell

Procedure, step 2 Replace all the cells Repeat: record the mean of 500 measurements of the current at the same x-y-z location of the source

Effect By removing all the surrounding cells, the optical photons that exit from the sides of the central cell will not be read by the PMT In the usual setup, with all cells: The optical photons that exit from the sides of the central cell will enter the surrounding cells and most of the radiation will be read by the PMT- This is the cross-talk from the 6 sides

Preliminary Results 2 sets of measurements were made so far, one of black cells and one of white cells Cross-talk % was calculated as: ((all-center)/center)*100%

Future These results show that the difference between white and black is not much at all There is always the variation in thickness of the paint on the sides of cells Will make further measurements with the other array of cells