[Tpe] [Fwd: TAR_TPE_eg5a.pdf]

[Larry Weinstein]

Dear Dave,

We have done all our simulations with a 6 cm diameter target cell.  The 
beam is well contained within that diameter, but there is some tail.  We 
might be able to reduce the diameter by 0.5 cm or at most 1 cm.  We can 
look into that.

Beam currents will be 100 pA each of e+ and e- incident on the target 
windows.  This translates to a dose of about 0.1 MG.
10^-10 A * 3*10^6 s = 3*10^-4 C
3*10^-4 C * 2 MJ/(g/cm^2) = 600 J/(g/cm^2)
The beam is spread out over at least 10 cm^2 --> 60 J/g = 60 kJ/kg = 
0.06 MGy
Double this to account for the two beams to get 0.1 MGy.

Radiation damage to the target endcaps is not a problem.

- Larry

David Kashy wrote:
> Hi All,
> Attached is a concept drawing that I'm starting to analyze for the new
> TPE target cell.
> The material is chosen to be .005" Kapton  for the cylinder and the
> upstream and downstream caps. The ring with the ports is Torlon (also a
> polyimide) like Kapton. the feed tubes are aluminum as used in all other
> targets.
>
> Please take a look and comment ASAP.
>
> Questions:
>
> 1) what is the expected beam spot size at the target?
> 2) is there any need to go bigger or smaller OD?  (Smaller is better
> since there is less flammable gas but not mandatory)
> 3) What is the dose expected for the end caps. (Kapton shows a 24% drop
> in ultimate strength and a 5% drop in elongation at 77K when exposed to
> 35MGy radiation dose. At 119 MGy the drop in strength is 38% amd
> elongation is  35%)
>
> Thanks
> Dave
>    

-- 
				Sincerely,
				Larry

-----------------------------------------------------------
Lawrence Weinstein
University Professor
Physics Department
Old Dominion University
Norfolk, VA 23529
757 683 5803
757 683 3038 (fax)
weinstein at odu.edu
http://www.lions.odu.edu/~lweinste/