sPHENIX is a new detector at RHIC.

[EdwardOBrien <eobrien AT bnl.gov>]

    Hi Gunther,
     We agree with each other. It is now clear to me what you
    are suggesting. The configuration that  you propose of
    ITS inner + TPC+ EMCal+ IHCal+OHCal is a good set to simulate.
    I like the idea where we show the effect of cuts to each of the
    major subsystems. The buy back order of the cuts will be a
    valuable thing to agree to and write down for Berndt, DOE
    and especially the collaboration. I am confident that other funds will come in
    to restore our scope. As many have written, the physics program is
     the reason that so many will work so hard to make this experiment succeed.
    However, we need to be prepared to live with our minimal descoped
    configuration while we're out generating additional funds, which may take some time.
     I see your point about the urgency to get started with the simulations.
    I hope that you, Dave and I can find the time to talk with Berndt this week.

     Ed

On 4/27/2016 4:37 PM, Gunther M Roland wrote:

Hi Ed et al,

To make sure there is no misunderstanding: There is complete agreement that we will answer the charge directly and produce "best worst case" configurations that fit into the $75M envelope. We will show that we have considered cuts to each of the major subsystems and discuss the impact of each individual change with qualitative arguments or simple performance simulations. We will then define 1 or 2 "best worst case" configurations of descoped subsystems that deliver the most overall physics for the three main physics drivers, based on more detailed simulations. Finally, we will discuss considerations to which extend for each of the subsystems scope can be bought back, if additional funds become available (with different timing considerations for different systems). 

But to quantify the impact (and to convince ourselves we know what we're doing in these rapid studies), we need to compare to a configuration that demonstrably does the physics. If at all possible, that would be a configuration that could be realized if additional funding becomes available. Additional funds would probably first buy back the lost scope (e.g., EMCal readout to quote some example) and then enhance the tracker compared to whatever minimal solution is in the $75M configurations, although it is possible that our studies show that enhancing the tracker is more important than regaining scope lost e.g. in calorimetry.

We will discuss the outline of the document and the status of the studies with Berndt regularly (next meeting is in a week from today), but we need to start with simulations before then.

Best,

Gunther

 

On Apr 27, 2016, at 2:05 PM, Frawley, Anthony <afrawley AT fsu.edu> wrote:

Hello Ed,

I think I understand the purpose of the exercise. I am not treating it as an opportunity to increase the cost of sPHENIX, I am pointing out the unpleasant fact that increasing the cost of the tracking is the only option that has a chance of delivering the physics program.

I do understand that, in the absence of extra money, increasingthe tracking cost is a big deal and makes the needed cuts to the rest of the detector much worse. But I do not see how we can tell Berndt that we can build a tracker that will work for the money that is presently in the budget. I don't see how that would serve anyone's best interest - ours or the lab's. 

Tony

From: EdwardOBrien <eobrien AT bnl.gov> Sent: Wednesday, April 27, 2016 3:54 PM
To: Frawley, Anthony; Lajoie, John G [PHYSA]; sphenix-l AT lists.bnl.gov Cc: eobrien AT bnl.gov Subject: Re: [Sphenix-l] [Response to ADL charge] Continuing detector scenario discussion

 

    Dear Tony and John,
     The descoping exercise that Berndt has requested should not be
    seen as an opportunity to increase the cost of sPHENIX. I would
     have been ecstatic if Berndt had told us to plan for a $90M or $100M
     project, but his guidance is clear. We must respond to his charge
    with a real cost reduction that the Project team agrees is real and
     not just a low-ball estimate to satisfy management.  If we agree
    to stay with the $5M+40% Tracker number then we need to cut an
    additional $4-4.5M + contingency from the project cost in order to      meet the cost target. That will be painful. What ever we agree to do, 
    the Project and the Collaboration should bring the proposal to Berndt      before we start the simulations effort
    so that we give BNL Management what they want or at least they'll know
    what to expect. 
    Ed

On 4/27/2016 3:22 PM, Frawley, Anthony wrote:

Hello Ed and All,

I think it is time for us to make clear to Berndt that our original scenario of reusing the PHENIX pixels in sPHENIX has become increasingly unattractive as we learn about it and evaluate it with more realism. This process has now reached the point where those who are familiar with the likely performance do not consider this to be a real option - it would kill most of the physics program.

That is where we are, and where we have to start from.  We can not start from a baseline design that we now believe will not deliver most of the physics program.

I think it is very reasonable for us to start by considering a tracker that we know will a) work and b) deliver the physics, and measure the performance of all of our proposed tracking solutions relative to that. A 7 layer MAPS tracker serves that function well. This does not mean that we think we can afford to buy one within our $75M limit.

There is now no question in my mind that any realistic tracking solution we adopt will cost more than what we presented in the cost and schedule review. The cheapest solution is a TPC and an inner barrel for displaced vertex measurements. The only thing that makes sense for the inner barrel at this stage is a MAPS tracker following the design of the ALICE ITS upgrade. In that cheapest tracking scenario, we replace a "free" inner barrel with one costing $3-4M (maybe less, if we consider only 2 layers).
But it also should be clear to everyone that the TPC solution has not yet reached the point where we can say it will work, or that it will work without being backed up by intermediate tracking layers such as are used in STAR and ALICE. Having to add supporting tracking layers would mean that the effective TPC cost is underestimated and will need to be increased. One of our goals in the next month is to try to have a first look at that.

Therefore it would be remiss of us to not look at the cheapest alternatives we can come up with, and evaluate them. When we discuss outer MAPS layers or other silicon options that is really what is being suggested. 
Finally, a comment on your comment:
" Here is my proposal:
    1) Agree that whatever Tracker solution we adopt will be
    cost neutral, i.e $5M AY in material cost + 40% contingency.  That is what we should     tell Berndt. Whatever solution we choose will be cost neutral."
I think that this is the last thing we should tell Berndt. What I have said above is that I do not believe that it is possible for us to build a tracker that will deliver a large part of the physics program for $5M AY material cost and 40% contingency, since that is our estimate for a TPC alone. If there is disagreement about that we should hash it out, but we need to do that before we promise that we can deliver our physics program for a price that is just not possible.
Best regards Tony

From: sphenix-l-bounces AT lists.bnl.gov <sphenix-l-bounces AT lists.bnl.gov> on behalf of Lajoie, John G [PHYSA] <lajoie AT iastate.edu> Sent: Wednesday, April 27, 2016 2:40 PM
To: EdwardOBrien; sphenix-l AT lists.bnl.gov Subject: Re: [Sphenix-l] [Response to ADL charge] Continuing detector scenario discussion

 

Hi Ed, 

    Is it possible to separate these two issues (what we simulate and what we build)? 

    As you say, for the cost exercise we will just have to adopt a budget that it will have to fit into - as you suggest $5M AY + 40%.  That's fine.      However, for the simulations we have to choose something. I would think that a MAPS tracker would be more straightforward to implement in the simulations, and is less difficult to justify (in terms of the "reality" of the simulations) than an "ideal" TPC.  (I am more than happy to be shown to be incorrect.) The statement then becomes for the reference design that we ultimately want performance *similar to what was used in the simulations*. It doesn't say that it is the exact implementation that is in the simulations.      You can argue that this implementation is unrealistic for budgetary reasons, but I don't think either option passes the laugh (or smell) test at this point.  So let's decouple the simulations from the tracking choice and give both options time to evolve.    In this way I don't think we violate dramatically what we have told BNL, and we can decouple the choice of the tracker from the need to get simulations going now.  John

On 4/27/2016 1:09 PM, EdwardOBrien wrote:

    Dear Gunther,
      I have a very strong opinion on the issue of the baseline detector.
    The Project team has been telling Berndt for months
    that the sPHENIX baseline design is a the EMCal and HCal as      specified in the pCDR plus the reused pixels and compact TPC.

     Why? Because the project has been given a very strict guideline on
    total cost. The TPC cost including manpower that we'd have to pay for     has been looked at carefully and we believe that this is the cheapest option     by far unless there is outside money, such as JSPS money, to build
    something else. 
    If the collaboration wants to propose that the baseline is changed to 5-6     layers of MAPS as the Tracker then you better bring that to Berndt
    before you do anything. Unfortunately, it won't pass the laugh test.
    On cost alone the 7 layer ALICE ITS is estimated at $30M with a low contingency     and standard US accounting. 
    In addition the November Cost and Schedule review committee concluded that       cost aside, the collaboration had neither the schedule nor expertise to     pull off a MAPS pixel detector. Despite the hard work of one person
    at LANL there has been little progress on the MAPS option since November      beyond his effort. I'd also like to point out that nothing beyond
    the inner 3 layers of the ITS was discussed in the plenary session of the     Santa Fe workshop. Now some are proposing 5 layers minimum.

    Here is my proposal:
    1) Agree that whatever Tracker solution we adopt will be
    cost neutral, i.e $5M AY in material cost + 40% contingency.  That is what we should
    tell Berndt. Whatever solution we choose will be cost neutral.

    2) Independently complete that Cost and Schedule exercise on MAPS that was started     at the Santa Fe workshop. Mike McCumber has started on it. We have a standard approach to
     this that has been applied to all the subsystems, except the si strip Tracker option,
     and it needs to be applied to MAPS.
    3) Recommend a cost reduction of $4-4.5M plus contingency and simulate that      before the May deadline.

    These 3 suggestions imply that no reduction will be taken from the $5M     set aside for the Tracker. 
    I suggest that you and I run this by Berndt before we go to a lot of effort and find
     that he wants something else. Thanks.
    Ed

On 4/27/2016 11:31 AM, Gunther M Roland wrote:

On Apr 27, 2016, at 9:06 AM, Lajoie, John G [PHYSA] <lajoie AT iastate.edu> wrote:

(2) Project/Collaboration management just make a (damn) decision. The choice of a tracker for a reference design at this point does not need to imply or bias a final decision and neither side should take it as such. It is a necessary expedient at this time. 

Now let me go out on a limb and anger part of the collaboration. Given (2) I would choose to simulate a MAPS (full ALICE ITS) tracker option at this time as opposed to an "ideal TPC". As we will be investing a lot of effort in these simulations I think they would have a longer useful lifetime for future reviews, etc., if we use a more realistic simulation.  If we use an "ideal TPC" I think that opens us up to potential criticism we don't need.  Just my $0.02. 

We can argue about this ad infinitum. Neither option is fully developed and we will revisit this situation again. I've expressed a preference, but my main point is that the pain of making a decision is outweighed by the danger of dragging this on too long. 

Hi John,

Thanks for your comments, and thanks for being frank! We should make the decision very soon (24h?). I hope more people will weigh in shortly. We are talking to the simulations gurus to make sure that we don't decide on a reference configuration that we are not actually ready to simulate right away. 

Gunther

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Iowa State University

 

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