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Summer 2004 RHIC IR Vacuum Upgrade Plans
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Meeting Notes
Tuesday, April 13, 2004
(limited participation)
PHOBOS Proposal: Postpone 10 o'clock Be beam pipe NEG coating until
next year unless it can be demonstrated beam induced vacuum problems at PHOBOS
limit pp luminosity. The argument is inspired by the great luminosity
delivered during the Au-Au run and the potential to lose the PHOBOS experiment
if its Be pipes are damaged.
The present plan is to ship the PHOBOS Be pipes to CERN this summer for NEG
coating.
This will be discussed at the 14 April RHIC Machine/detector Planning
Meeting and will likely require a decision by T. Kirk within the next couple of
weeks.
Phil
Tuesday, April 6, 2004
The
vacuum group: Started test coating of an insert. They are also looking into
the packaging of the pipes for transportation. CERN is committed to coat our
pipes. Most probably during July - August time frame.
A plausible time
frame for PHOBOS as an example:
End of run
prepare the pipes and ship to CERN
End of July:
coating and transportation to BNL.
August: 3 weeks
to re install pipes and bake to activate the NEG coating
1 month for
PHOBOS to reinstall and re commission the detector.
STAR: Agreement
not to wrap a solenoidal field around the spool pieces.
PHOBOS: Dropped
the option to coat the outer pipes only. The group will discuss the option of
coating all three pipes and provide us with an answer within a week. Tests
with helium showed no leaks in the PHOBOS pipes.
PHENIX: No
coating this year. Coating next shutdown if time allows.
Roser: Stressed
that we should look ahead when all pipes are to be coated to attain high
luminousities and 112 bunches. This implies in house coating capability. Also
STAR to redesign (upgrades) to allow for coating and baking which now is
impeded by the FTPCs and the SVT. We should keep in mind that the NEG coating
requires periodic rejuvenation.
Yousef for Phil
Tuesday, March 30, 2004
The Fischer/Hseuh tentative plan for each experiment follows:
BRAHMS:
Plan:
Al sleeves of 3m (#1 side) and 2.5m (#2 side), NEG on Al sleeves will be
partially activated @150C, lower SEY, ESD & pumping.
Schedule:
install coated sleeves, bake and activate in June
STAR:
Plan:
Al sleeves 3.3m x 2, NEG on Al sleeves will not be activated @ <100C but still
have lower SEY, ESD.
Schedule: install coated sleeves in late Sept, assemble, bake by Oct.
PHENIX (may be delayed to 05 shutdown?)
Plan:
Al sleeves of 1.1m (#8 side) and 2.5m (#7 side) or coat the whole 5.5m central
pipe in 2005. “Big effort” to remove, re-install and bake all Phenix IR pipes.
Schedule: remove pipes, coat and install sleeves in Sept?
PHOBOS
Plan:
Coat three 4m Be beam pipes --
Option 1: by BNL after successful development effort (by June?)
Option 2: by CERN at LHC NEG coating facility
CERN is interested, need to work out all the logistics, activation level (?),
cost ~ $25K, schedule (RHIC & LHC), need to weight the risk of shipping vs.
development effort and Vacuum Group work load
Schedule:
Coat the Be pipes in July – Aug. (BNL or CERN?)
Experiments comments or altenatives to Fischer/Hseuh plan:
BRAHMS: OK with proposed plan
STAR:
(1) Agree with proposal to NEG coat the Stainless Steel “spool” pipe pieces.
(2) Agree with proposal to wrap these “spool” pieces with electrical conductor
to generate weak solenoidal B field (BUT NOT NEEDED).
(3) Do not want to install proposed “inserts” into the central beampipe at STAR
at this time. Propose to modify “spool” pieces as proposed and then empirically
determine if there is a vacuum constraint on the RHIC beam intensity with this
new setup next year. Recall that there is a 5,000 G solenoidal field over the
length of the STAR central beampipe.
PHOBOS: - three options in order of preference:
(1) Do Nothing (with experiment accepting background and RHIC accepting HI
luminosity limitation)
(2) NEG coat only outer Be pipes. This leaves most of the Si for PHOBOS intact
thereby considerably reducing the risk to the experiment and time required for
reassembly. This will provide reduced SEY and ESD and improved pumping and may
result in no vacuum issues for PHOBOS in Run 5.
(3) Carry-out the plan as described above. Most risky...this will likely cause
about a month delay in RHIC startup since up to about 2 months will be required
to reinstall Si once the Be pipes are in place and baked out.
PHENIX:
Proposes we do nothing this year. The central pipe is fully baked, is shorter
than the other IR's and the Be section is connected to stainless steel pipes,
and is emersed in a magnetic field -- i.e. PHENIX is not likely to become the
next "PHOBOS", at least in RUN 5.
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