IR design update
MDI (and IR) Summary
M. Sullivan
SuperB General Meeting
Perugia, Italy
June 15-20, 2009
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SuperB Gen meeting
June 15-20, 2009
IR design update
Outline
• Presentations in the MDI session
–
–
–
–
–
IR beam pipe
SVT and beam pipe
Shielding and QD0/QF1
HOM
IFR backgrounds
Sullivan
Bosi
Paoloni
Novokhatski
Cibinetto
• IR topics this meeting
– SVT
• L0
• L1-4
– Cryostats and SVT Assembly
– Energy change
– Next IR design
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SuperB Gen meeting
June 15-20, 2009
IR design update
MDI presentations
• Sullivan presented the latest thoughts on the IR
beam pipe and Filippo Bosi presented an SVT
perspective on the IR beam pipe
– Magic flange – a vacuum connection that can be
disconnected that is between the cryostats
– After looking at all of the “magic flange” designs we realized
that these designs rely on the removal of one of the
cryostats first, i.e. one could get to the flange either with
long tools or with hand wrenches directly.
– The Cornell design is most like a true magic flange that can
be disconnected with the cryostat present – however the
design has o-rings
– Come back to this topic in the assembly discussion
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SuperB Gen meeting
June 15-20, 2009
IR design update
IP beam pipe
Plan view
Side view
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SuperB Gen meeting
June 15-20, 2009
IR design update
MDI presentations (cont.)
• Filippo presented current thinking on
the beam pipe from the SVT group
– Perhaps 300 um thick Be
– Au layer most likely on the inside (~4 um)
– Cooled at the ends or cooled with a very
thin layer of liquid
• How much power can we expect?
• PEP-II had to cool ~500 W after the extra
cooling was added to the bellows at each end
• Decided as a working assumption to design for
200 W
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SuperB Gen meeting
June 15-20, 2009
IR design update
HOM
• Sasha Novokhatski showed a work in
progress toward calculating the HOM
heating for the IR
– He observed that we are making cavities in
the region between 3 and 6 m
– We will want to install absorbers in this
area
– There will obviously be HOM power in the
IP region from the joining of the two beam
pipes to one
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SuperB Gen meeting
June 15-20, 2009
IR design update
The Present Design
300
DC
200
LER
HER
QD0
B0
B0
100
mm
-100
QF1
QF1
0
B0
B0
-200
300
mrad
-300
-7.5
7
5
-2.5
meters 0
BaBar
foreward
door
200
mrad
2.5
5
M. Sullivan
Feb. 12, 2009
SB_IT _ILC_P4_SR_7_5M
7.5
SuperB Gen meeting
June 15-20, 2009
IR design update
S. Novokhatski
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SuperB Gen meeting
June 15-20, 2009
IR design update
Shielding and backgrounds
• Eugenio showed the latest on QD0 and QF1 as well
as recent work on shielding the DCH from the beam
– The shielding became a point of discussion
– A large tungsten shield
• Weight
• Who or what has to hold up this weight
– SuperB is very different from PEP-II
• PEP-II had a shield around the beam pipe that was at least 10
cm of Fe thick (the permanent magnets)
• Eugenio has some first data runs of various
backgrounds
• Gianluigi Cibinetto presented concerns for neutron
backgrounds for the IFR and showed that the
neutron rate found for BaBar was already too high
for the new IFR detectors
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SuperB Gen meeting
June 15-20, 2009
IR design update
IR + SuperB Geant4 Model
•
•
IR P3 Modeled in Geant4:
beam pipe and magnetic fields
Preliminary look at Luminosity
backgrounds:
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–
–
–
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Beam strahlung from 1400
bunch crossing ( ~6.2 10-6 sec )
400k evt. pair production ( ~53
10-6 sec )
Neutron production included in
the sim.
Analysis of this data just
started
SuperB Gen meeting
June 15-20, 2009
IR design update
Future activities
•
Bigger sample production (including Touschek
and beam gas contributions):
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•
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Shielding thickness optimization (cost benefit
considerations)
Shielding external design optimization
Physics window beam pipe optimization
Study neutron production downstream QF1
Primary reflected
by the
Tungsten shielding
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SuperB Gen meeting
June 15-20, 2009
IR design update
Preliminary Suggested Shielding Scheme
Actual shield simulation is 3 cm thick
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SuperB Gen meeting
June 15-20, 2009
IR design update
IR topics
• SVT and L0
– L0 attached to the central chamber
– SVT mounts to the beam pipe that is part of the
cryostats
– Very similar to PEP-II
• SVT access
– Want access to the SVT on a week time scale
(instead of months)
• We are presently defining the 300 mrad line
as the treaty line between machine and
detector
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SuperB Gen meeting
June 15-20, 2009
IR design update
SVT and Cryostats
• Fast access to the SVT
– KEKB does this and if we plan for this up front we
can do this too
– We need to put the nearby beam components on
rails so we can easily move them out of the way
also get the components back into position
without having to survey them
– According to the previous discussion we do not
have an easy way of disconnecting the flanges
between the two cryostats
– So propose putting the SVT and cryostats
together outside of the detector and then sliding
the assembly into the detector
–
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SuperB Gen meeting
June 15-20, 2009
IR design update
How to do this?
Backward side
needs more
thought
• We have decided that the cryostats have to be
mounted on sturdy supports that mostly likely go
down to the floor
– There are large expulsion forces and we want minimize
vibrations
– Now there are also these tungsten sleeves that need to be
supported
– Propose mounting the W sleeves on the cryostat supports
and leave enough room inside the W sleeve for something
like rails or a trough that we can use to slide the SVT and
cryostat assembly in and out of the detector
– This gives us quick access to the SVT (1-4) and to L0 and to
the Be beam pipe and to the permanent magnets
– If this is planned carefully we disconnect nothing
– Needs plenty of thought and attention to details
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SuperB Gen meeting
June 15-20, 2009
IR design update
Energy change
• The quick access to the SVT gives us also
quick access to the permanent magnets
• This allows us to reconfigure the machine for
other energy running relatively quickly by
removing or altering the PMs
• It probably still takes a week to 10 days for a
complete turn around so we don’t want to do
this too often
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SuperB Gen meeting
June 15-20, 2009
IR design update
Next IR design
• Try to make QD0 as easy as we can without
changing too much
– This is one of the hardest magnets to build so we
should at least make it look better on paper
– Stay with our philosophy of using the most
aggressive design parameters
• 7x4 beam energies (larger energy asymmetries are
harder)
• Smallest beta*s
• Largest emittances
– Lengthen the cryostat some to cover more of the
detector solenoid field with compensating
solenoids – perhaps move QF1 out some more
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SuperB Gen meeting
June 15-20, 2009
IR design update
Summary
• Many good and detailed discussions about the
machine and detector interface
• Integrating plans are being hatched that look
interesting
– Quick access
– Tungsten shields
– Cryostat supports
• There will be many more issues to resolve as they
surface
• IR design work will continue to use aggressive
machine parameters in developing new iterations
• Good progress!
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SuperB Gen meeting
June 15-20, 2009