[Isotope-prod] Optimization question

[Pavel Degtiarenko]

I'd like to revisit one optimization question that was standing from the 
very beginning.

We assume presently that minimizing volume of the isotopically pure 
target is paramount in this problem and we have to design windows, 
radiators, and targets that would survive extremely high power 
densities, to the limits of impossible. But there might be an optimal 
overall solution, in which the target volume is few times larger than 
the absolute minimum. The target itself, and the Cu67 separation process 
would be more expensive (most likely less than linearly). But the cost 
increase would be compensated by avoiding risky and therefore expensive 
engineering solutions. So may be the optimum solution would be using 
larger diameter targets and windows that could be cooled easier. I would 
suggest to consider for the proposal finding the beam diameter that we 
know could be run safely, base all estimates on that, and include 
further optimization as one of the goals of the proposal.

One of the solutions to consider could be a circular beam rastering when 
beam position at the target goes in circles at a constant radius. The 
target does not fill the whole cylinder volume, but is placed in a 
cylindrical layer, say, 5-10 mm thick, with the core of the cell made of 
the same material as the whole cell. The Ga/Zn target volume then goes 
linearly (not quadratically) with increasing radius, so that might be a 
comfortable variant for the optimization.

Best regards,
Pavel