sPHENIX tracking discussion

[Thomas K Hemmick <hemmick AT skipper.physics.sunysb.edu>]

Hi gang

I agree with both Abhay and Ed, the TPC would certainly be intended to be re-used.  

As Ed points out, a 10 cm radial envelope is possible for PID devices (e.g. DIRC or proximity-focus cherenkov) one needs to add to this a stay-clear zone in any realistic design.  Earlier this week in the TPC engineering mtg, we talked about what would be a proper addition and most agreed that 2 cm to each side (indicating an outer radius of 76 cm for the TPC *mechanical* extent) is likely the more correct value as compared to the 80-cm round number.

As for the inner radius, that one could be interesting.  Carlos is is actively refining the space charge calculations to the point that we will have strong confidence that they are right (significant improvements are already in hand).  After that, we can play with the parameters.  One intriguing idea would be to purposely move the inner field cage inward.  This might create a compensation space charge that would actually improve the response at r=30cm.  My guess is that it will, but the calculations will tell us the real cost/benefit of playing around with the inner radius.

So in my mind an outer mechanical extent of 76 cm seems like it is becoming realistic and the inner one would like to see more simulation effort.

Tom

On Fri, Feb 5, 2016 at 11:14 AM, EdwardOBrien <eobrien AT bnl.gov> wrote:

    Hi Abhay,
     For now I think it best that we keep a 10 cm wide radial space set aside
     for an undetermined PID detector between the Tracker and EMCal, in
     the EIC era. In addition we'll need a small stay clear region front and back
    to make installation possible and to take into account mechanical tolerances.

    Ed

On 2/5/2016 5:52 AM, Abhay Deshpande wrote:

Yes, true. But the TPC itself will serve us as a PID detector. We could further think of something thin beyond that if necessary. 

Cheers, Abhay

Sent from my iPhone

On Feb 4, 2016, at 6:51 PM, EdwardOBrien <eobrien AT bnl.gov> wrote:

    Dear all,
     The sPHENIX radial control envelop has a space beginning at 80 cm
    for an undefined future PID detector (EIC era). Presuming a stay-clear space
    between detectors of 2 cm that means the outer radius of
    the Tracker can reach to 78 cm, no further. The proposed design of the
    Si Tracker does not approach that radius but the TPC option would
    in principle reach that radius.

    Ed

On 1/29/2016 1:39 PM, Frawley, Anthony wrote:

The minutes of today's tracking meeting are below. The slides are posted at:

https://indico.bnl.gov/conferenceDisplay.py?confId=1719

Cheers

Tony

sphenix tracking meeting, January 29, 2016
---------------------------------------------------------

Itaru Nakagawa - strip tracker status:
-------------------------------------------------

Itaru reported on the status and future timeline of the strip tracker silicon R&D.

Ed: Can you send me a couple of slides outlining what you have done for R&D in last 6 months and what will happen in next 6 months. Useful to have this in hand if questions are asked.

Rachid: Can you send us the table of sensor characteristics so we can decide which ones are better? Helps to choose the testing order.

It will be early March for the next funding news - will learn then if we make the interview. Maybe April for the actual funding decision.

Rachid Nouicer - integration of the silicon pixels into sPHENIX:
----------------------------------------------------------------------------------

Slide 4: The outer tracking envelope is at 75 cm or 80 cm? Ed is still checking, will report later.

slide 6: How much do the sensors overlap in phi? We should start by using the same overlap as in the VTX, see slide 5 for the configuration.
Rachid will check that slide 7 has the same sensor overlap as the VTX. Mike: You may have to fiddle with radius to get the 12 sensors to fit nicely, but will need to check if the result satisfies all engineering stay clear boundaries.

What is the dead space at the end of each sensor? Rachid will check. Comment: the dead area around the edge depends on the chip.
Mike: There are two questions - we need both the intrinsic dead areas and the dead pixel map for simulations.
With the dead area that exists in the pixels already, it may not make sense to worry too much about gaps between sensors.

We need to know how the number of active pixels that overlap at each gap in sPHENIX affects the momentum measurement at low momentum. Mike said we could use the VTX simulations and scale the bend by the magnetic field ratio. Remember that at some point we are ruled by multiple scattering.

Action item: Rachid will get back to us by email with an overlap geometry for the pixels, we will then do some crude estimates  of where the momentum measurement is affected. Note that every other ladder is staggered in radius.
 
Mike: At some point we need the GEANT 3 geometry ported to GEANT 4, so we can simulate the actual proposed configuration.

Tom Hemmick - Brief TPC update:
----------------------------------------------

Slide 3: Ed: do you need help from BNL? Tom: yes, need professional engineering to discuss details of how to do the machinable foam. Ed: bring Niv to BNL, set up a meeting with BNL engineers and experts.

Tom: still trying to figure out which foam to buy. Four densities on the market, more expensive with density. Not sure if the lightest density foam will work. Ed: Mike Lenz has experience with foam.

Mike McCumber - MAPS layers for sPHENIX:
-----------------------------------------------------------
Mike made a verbal report, but uploaded a few slides after the meeting. He reported on three areas that are being pursued.

Slide 3: LANL LDRD funding: Mike outlined the path and timeline.

Slide 4: Exploring collaborations. Working hard on establishing ties with LBL now.

Slide 5: Santa Fe MAPS cost and schedule workshop. Three day workfest to produce cost and schedule document for the inner tracker, and a full tracker option.

Discussion:
Ming is working on when the needed experts are available. Will define the workfest schedule around the schedule of experts (Luciano Musa, Leo Greiner, ... ).
Dave: An earlier date would be better. Does the request for CD0 in April mean this should be before April? Ed: the CD0 does not address the scope, so they are in principle not coupled. Comment: won't DOE want to have an idea of the scope before awarding CD0?

Ed: What would the full tracker outer radius be? The outer radius with 1.5 T field would be 60 cm. With 1.4 Tesla it would increase to about 64 cm.
We were told by Luciano in his presentation that a CERN engineer thought the ALICE ladders would work without re-engineering at the increased radius. That opinion would need to be checked carefully.

Mike would like to get from Berkely the MAPS geometry in simulation, and hopes to do that when he visits LBL in two weeks.

Discussion of the review recommendation that we should focus on reusing the pixels. Ed commented that we do not have to follow the review, if we make a good case for not doing so.  In this case the response will be a document that outlines the MAPS plan and justification. The response would be needed by the time of the next review (probably next Fall?). We need to think about the time scale for preparing the document. The intended audience is Berndt Mueller and David Lissauer. 

Ed noted that there is a web page for review comments and responses.

Dave: When do you think you can settle on a date for the workfest? Mike said they will push hard to get it defined in the next week.

---

From: Frawley, Anthony
Sent: Thursday, January 28, 2016 10:44 AM
To: sphenix-tracking-l AT lists.bnl.gov
Cc: Frawley, Anthony
Subject: sPHENIX tracking meeting Friday January 29 at 9:00 am ET

 

Hi All,

We will have an sPHENIX tracking meeting tomorrow, Friday January 29, at 9:00 am ET. The agenda page is:

https://indico.bnl.gov/conferenceDisplay.py?confId=1719

At present we are expecting to hear from:

Rachid Nouicer - Update on reused pixels integration

Tom Hemmick - TPC progress

If anyone else would like to add an agenda item, please let me know.

Tony

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