Gamma Count Rates

Been spending a bunch of time in Gamma Town.  It's nice, you don't have to interact with anybody*.  Shown below is comparing results to simulated values from the total interactions. 

Source of all errors

Alright, so not perfect. But hey, I'm gonna take it.  It explains a lot of the problems we have been having; doubling the distance about doubles the counts.   I think at the father distances photons bouncing around off the table and the lab might also be a little bit an issue. It is also unsettling how the simulated and calculated cross each other.  Now the problem is going to make sure that we can have a repeatable geometry; so maybe we want to place it around 6" away, where 1/2" in each direction only changes the count rate by 12%.  At 1/4", moving the sample by 1/4" changes the counts by 30%.

*Groan worthy, but I'm proud of it.  Gamma's are photons, and are characterized by a probability of interaction, not like electrons which are always experiencing E&M fields.

100 uCi Co60 Source

A while ago I talked about the design of a 100 uCi Co60 source holder.  Budget constraints happened, so the eventual design was just to throw a bunch of lead bricks around it with some HDPE on top.  The white on top is the 4" high of HDPE (plastic - check out the milling detail around the center pipe), while below it to the gray base are 4 4"x8"x2" lead bricks and 4 4"x4"x2" lead bricks (about 150 lbs of lead total).

The lid is solid steel, as is the source holder on the front left corner (I got to use a milling machine! - there pretty nifty, POLK needs one).  The interior pipe is 1/4" thick steel as well.

The best though, is my awesome paint job.

We should get the source for it before Christmas.