1. Search for the Lost Information Through the Faces Shahab khan

2. Objective: Account for the Signal Quantify the amount of signal lost to the top and bottom faces of the cell Radiation Source Cross-talk To PMT Signal Lost through bottom face Signal Lost through top face

3. How can I find how much is lost? Stack Cells one on top of the other Record the signal from each cell separately Account for the signal due to beta particles crossing over to the other cells Put it all together

4. Complicated Theory X = amount of light from bottom surface S = new light from betas to bottom cell (Source) C = cross-talk Y = signal read from top cell alone d1,d2,d3 are paint thickness A, R, and T are Absorption, Reflection, and Transmission coefficients X Source betas S C Y d1 d2 d3

5. Equations & Simplifications T(d2)*X + R(d2)*X + A(d2)*X = X Measurement from bottom cell gives: S + T(d2)*X – X*C*T(d2)*X – f(X) Possible Simplification: A(d2)*X  A(d3)*X  0

6. Series of Tests Optical paper PMT Test 1 Test 2 Test 3 Test 4

7. The Data

8. Conclusion Not much is known to determine the exact amount of light lost More studies should be done to determine the T, R, and A properties of the paint However, it can be inferred that the light lost through the bottom face is enough to cause at least 40 nA, which is about 8 percent