Re: PS target issues (fwd)

["Hrachya.Hakobyan" <hakopian@mail.yerphi.am>]

Richard,

You are right, I've proposed the use of two inserts for needs of PS 
optimal functioning. Quantitatively I may answer few days after.
The structure and costs of inserts for the  changeable converter 
and microstrip  detector are different and I believe they have to be
constucted independently, not to be a universal single, that  will 
complicate device.  I didn't understand the problem of Hall D 
schedule disruption with case of two independent converters.
I can't do a  correct evaluations for JLAB, you have a 
better knowledge of course.  But I  may  imagine that the standard vacuum 
pipes,vacuum flanges and cross-like inserta are available in catalogs.

Hrachya


On Thu, 11 Sep 2008, Richard Jones wrote:

> Hrachya,
>
> Are you proposing that we move the position of the converter from its current 
> position ~2m upsteam of the PS magnet, and then envision a second converter 
> somewhere else when we get around to designing the polarimeter?  We should 
> consider this possibility, but I am skeptical that it makes much difference. 
> Can you tell us quantitatively what gain we get in final energy resolution by 
> moving the converter downstream a couple of meters from its present position? 
> At least at its present position it is possible to think about doing 
> polarimetry with the same converter.  We are never going to find anything 
> like 19 m of space for doing polarimetry in the way we did at YERPHI.  To use 
> that system, we would need to scale that distance up by another factor to 
> account for the higher energies involved.  Whatever we do (and I have some 
> ideas) we will need to do within a few meters space that we have between the 
> second sweeping magnet and the PS.
>
> If we move the converter to the entrance of the PS magnet, we probably double 
> the cost of adding a polarimeter at some point in the future, and certainly 
> make installing it much more disruptive to the running schedule of the hall. 
> We could do that, but we need a compelling reason for it.
>
> Richard Jones
>