sPHENIX HCal discussion

[EdwardOBrien <eobrien AT bnl.gov>]

    Hi John, John and Edward,
     I agree that we need to have someone, presumably a
    collaborator from a Russian institution, visit Uniplast
    regularly during all future production, even the next
    prototype round.

    Can someone answer whether Uniplast can correct the thickness
    problems prior to completing the the high eta tile production?

    We should spend some effort to qualify a second tile vendor. Is
    there any chance that we can do this in time for the Inner HCal 
prototype
    to be used in April? If not then I suggest we use a second vendor 
for a part
    of the high eta tiles, both Inner and Outer. Since we have ordered 
the full high eta tile
    complement from Uniplast, the tiles from a second vendor will result
    in us having spares in the end. We are already pursuing
    different production options for the EMCal towers, and will also
    look at a variety of vendors for the Outer HCal steel and Inner
    HCal stainless steel. We should do the same for the tiles.

    Ed

On 1/6/2016 11:12 AM, John Haggerty wrote:
> As I said, I'll summarize my e-conversation with Edward about the tile
> thickness.  I forgot that to make these tiles, they had to make some
> changes to their extruder in order to make wide enough tiles.
>
> > picture gets a bit cleaner with UNIPLAST. In summary - this is my fault, I 
> > was too certain that 2013 production is a good predictor for what we’ll get 
> > in 2015. Ignored the fact that UNIPLAST essentially crossed the line - they 
> > switched from 19cm wide band extrusion to 25cm wide extrusion. Lot of 
> > hardware modifications and no other consumers except us.
> > - large tiles are relatively uniform but with excess thickness of ~0.4mm. 0.2 
> > mm are due to coating (I expected 0.1mm or 0.05mm per layer), 0.2mm is due to 
> > excess thickness at the edges (temperature regime which is undercompensated 
> > by the slit shape);
> > - small tiles are from tune-up cycles - wide bands but small loads;
> > - not much care of wrap quality on short tiles (large one were made after my 
> > visit - wrap quality was probably improved but sill not strictly enforced.
> >
> > There is no problem to bring tiles to the spec (we need to decide if we want 
> > 7mm or 7.2mm (coated) thickness.
> > We will also need to decide on wrapping materials - they will set the final 
> > tile thickness.
> > PS. If any measurements on tiles are still going - please add the corner to 
> > corner dimensions at the inner and at the outer edges of the tile (cylinder 
> > radii) in finished state.
> So I would say the lesson is that we probably have to have someone at
> Uniplast at least periodically during fabrication who can assess the
> production before we ship them to BNL or wherever we decide to send them
> first.  We also need to finalize the wrapping, Edward is still
> interested in Tedlar, although I think we'll have to assess the
> thickness that we'll end up with before we buy a lot of it.
>
> There will be more on measurements later today, I think, from Kenny by
> way of Abhisek and Megan that will help us understand how to proceed.