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Physics/photon interaction


2 part question:

Consider propagation of 200KeV photon beam through a water target.
1. What fraction of photons would survive if the target was .1 cm, .2 cm, 10 cm, and 20 cm long?

2. Estimate up to what distances the absorbed fraction will be linearly depend on the length, L, of the target (with accuracy better than 20%). Use the taylor expansion to obtain the analytic result treating ÁL as a small parameter.

Hello Michael,

I'm sorry to have to say that this is outside my area of expertise. I searched for information that might help you and I'd like to offer this site:

I hope this will help,


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Steve Johnson


I would be delighted to help with questions up through the first year of college Physics. Particularly Electricity, Electronics and Newtonian Mechanics (motion, acceleration etc.). I decline questions on relativity and Atomic Physics. I also could discuss the Space Shuttle and space flight in general.


I have a BS in Physics and an MS in Electrical Engineering. I am retired now. My professional career was in Electrical Engineering with considerable time spent working with accelerometers, gyroscopes and flight dynamics (Physics related topics) while working on the Space Shuttle. I gave formal classroom lessons to technical co-workers periodically over a several year period.

BS Physics, North Dakota State University
MS Electrical Engineering, North Dakota State University

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