sPHENIX HCal discussion

["Lajoie, John G [PHYSA]" <lajoie AT iastate.edu>]

Hi Edward,

 

Forgive my  French, but that is complete bullshit.  Less than 48hrs ago we sat in a meeting at Uniplast and we both agreed on this course of action – recall how concerned Uniplast is about additional changes introducing errors. There is a very real potential for additional errors here as we go into production. 

 

We make decisions based on quantitative information, not subjective guesses about what might be better.  If you think this is critical then we should have MEPHI map an old and new B25 tile as soon as possible and compare them.

 

Regards,

John

 

From: BNL Mail <kistenev AT bnl.gov>
Sent: Thursday, June 13, 2019 11:52 PM
To: Lajoie, John G [PHYSA] <lajoie AT iastate.edu>; EdwardOBrien <eobrien AT bnl.gov>; Xiaochun He <xhe AT gsu.edu>; Richard Ruggiero <ruggiero AT bnl.gov>; Stefan Bathe <bathe AT bnl.gov>; John Haggerty <haggerty AT bnl.gov>
Cc: Stefan Bathe <bathe AT bnl.gov>; sphenix-hcal-l AT lists.bnl.gov
Subject: Re: [Sphenix-hcal-l] summary from production readiness meeting at Uniplast

 

John, Maybe we need to take few days make a step back and discuss this issue instead of stating that decision is already made. I happened to know that original pattern was developed not for no reasons- we tried to create fiber configuration symmetrical with respect to the central long axis in the tile in the hope to keep it as uniform as possible. This was made and this is still preserved everywhere except redesigned tile 25 (5). When I agreed to this modification I was left with impression that interference is between tile and comb which really exclude any chance for original design to stay. If Stefan and others do believe that relatively small extra work may result in returning to what we initially designed I will support this path wholeheartedly. 

It will make calorimeter a little better and will save all good work made at Uniplast and will keep our reserves of consumables (fibers, wrapping etc) untouched (will help IHCal) and in the end it will save money.

Edward

Sent from my iPhone

On 13 Jun 2019, at 19:31, Lajoie, John G [PHYSA] <lajoie AT iastate.edu> wrote:

Hi Stefan,

 

The overall decision is made. I appreciate everyone trying to be creative, but there is no need to spend tech time and modify all the steel sectors to accommodate a mistake in the scintillators that is more easily remedied by having Uniplast make what we actually ordered. I don’t see a compelling need – we have ample time to make the pre-production sectors.

 

We could consider modifying ONE sector as you described, which would allow us to get a start assembling one sector with the old B25 tiles if necessary, but we would replace it with the correct B25 tiles once they arrived. I’m still not sure that is worth the effort as we could still learn a lot by partially assembling a half-sector up to B25 and testing it.

 

Regards,
John

 

From: Stefan Bathe <bathe AT bnl.gov>
Sent: Thursday, June 13, 2019 7:20 PM
To: Lajoie, John G [PHYSA] <lajoie AT iastate.edu>
Cc: sphenix-hcal-l AT lists.bnl.gov
Subject: Re: [Sphenix-hcal-l] summary from production readiness meeting at Uniplast

 

Hi John,

 

There is an alternative to replacing the B25 tiles:  tap ten additional holes per sector to accommodate the tile clips for the B25 tiles we have on hand.  Richie, Carter, Aron, and I just discussed this.  We’d make a jig to make the drilling and tapping easier, and then it would take about two days of tech labor to tap the 60 holes for the six preproduction sectors.

The obvious advantage of this option is that we wouldn’t have to rely on the replacement tiles to get here in time.

We should make a decision which way we want to go.

 

Regards,

Stefan

-- 

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Stefan Bathe

Professor of Physics
Baruch College, CUNY

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On Jun 13, 2019, at 11:43 AM, Lajoie, John G [PHYSA] <lajoie AT iastate.edu> wrote:

 

Dear HCAL’ers: 

 

Xiaochun, Anthony, Edward toured Uniplast Wednesday and met with Victor Majatski to discuss the results from the pre-production and action items for the full HCAL tile production.  The notes from this meeting are attached for reference.

 

Something not listed in the notes is that for the pre-production tile B25 was manufactured to an older design, before the light guide was moved to accommodate the combs in the outer HCAL.  This happened because an operator was on vacation when the production switch was made to B25, and the wrong file was loaded into the CnC machine. Uniplast recognizes this mistake and will replace the B25 tiles – they have sufficient spare materials on hand to start immediately and expect to have the replacement tiles completed in two weeks. Ideally we will still get them in July for the sector assembly, and I have spoken with Anthony about fast-tracking testing.  We have reviewed the rest of the tile designs and they are OK; Megan plans a test fit of a complete set in an oHCAL gap soon to verify. 

 

Nobody wants things like to happen, but they do. If everything seemed perfect I would worry what we missed….

 

Regards,

John

John Lajoie

Professor of Physics

Iowa State University

 

(515) 294-6952

lajoie AT iastate.edu

 

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