sPHENIX is a new detector at RHIC.

[David Morrison <morrison AT bnl.gov>]

Dear Collaborators,

As you're likely aware, the project and the collaboration have been
asked by BNL ALD Berndt Mueller to provide by early October a scope for
the sPHENIX baseline detector which fits within $32M.  The current cost
estimate is about $38M.  The ALD anticipates meeting with DOE ONP in
late October to present the current scope and cost and discuss with the
them paths forward to realize the detector.

Everyone should anticipate that scenarios that address the cost cap set
by the ALD will decrease the physics capability of the detector to some
degree.  At the same time, we remain strongly committed to building the
complete detector and carrying out the full sPHENIX physics program.
Approaches for dealing with the tension between scope and funding as we
move forward include working with our collaborators to see about
opportunities for non-DOE contributions and by working to preserve
contingency funds to "buy back" as much capability as possible.

Between the executive council and the biweekly general meetings, we've
had a number of very constructive discussions about how best to respond
to this request – what scenarios should we study, what risks do we face,
what plots should we aim for?

We think the best strategy for addressing the ALD's $32M cost cap is to
focus on straightforward alterations of the current $38M detector.  The
menu of such changes identified so far include:

- no iHCal (just a non-detector support structure to hold up the EMCal)

- non-instrumented stainless steel iHCal

- non-instrumented aluminum iHCal

- limited pseudorapidity acceptance of EMCal (fewer W/SciFi blocks and
corresponding electronics)

- limited pseudorapidity acceptance of the oHCal (same steel structure,
but with fewer scintillator tiles and corresponding electronics)

Our current "default" scenario is no iHCal, coupled with limiting the
acceptance of the EMCal and oHCal until the $32M cap is met.  We think
this provides a clear path to restoring the full capabilities and also a
clear target for possible non-DOE contributions.

While we study the physics impacts of possible changes, the project is
working with the L2 managers to "scrub" costs and look for any savings
that can be readily justified.  If savings are identified, they would
lower the current $38M estimate and reduce the need for any descoping.
The current expectation is that this scrubbing exercise might identify a
few x $100k.

In thinking about all this, it's useful to keep in mind a key conclusion
of the August Director's review of the baseline detector, "The committee
believes that sPHENIX should be positioned for a successful CD-1 review
in the spring of 2018 if continued progress is made in development of
the technical, management and cost/schedule aspects of the project."
This is a really encouraging statement made by a panel of very
experienced people.  The date by which we get CD-1 approval has a big
effect on sPHENIX.  Subsequent steps in the project, including the year
in which sPHENIX would be ready to take data, follow rather directly
from that date.  Radical reimaginings of the detector or overly
optimistic cost scrubbing will likely delay the scheduling of the
official CD-1 review and generate a corresponding delay first physics.

Regards,
Dave and Gunther

-- 
David Morrison  Brookhaven National Laboratory  phone: 631-344-5840
                Physics Department, Bldg 510 C    fax: 631-344-3253
                          Upton, NY 11973-5000  email: dave AT bnl.gov