SiD and L*
RDR: L* QD0=3.5m, L* QF1=9.5m
NOW: L* QD0=4.1m, L* QF1=9.1m
Tom Markiewicz/SLAC
SiD CM, SLAC
13 January 2015
What is L* and Why Did SiD Choose L*=3.5m
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L*=Distance between IP and front face of closest quad of final doublet
SiD (& predecessors) were always designed for the lowest L* allowed by the magnet
technology and the crossing angle θC to maximize Luminosity
– In 1995 with idealistic permanent magnet quads and θC=20mrad, L*=2m
– In 2005 with BNL compact direct wind SC quads and θC=14mrad, L*=3.5m
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Design algorithm:
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BeamCal is placed as close to QD0 and as far away from IP & Tracker as possible to minimize
backgrounds from e+e- pairs that splash on front face and backscatter
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but leave space on extraction line for the feedback BPM
Lumical offset 10cm from Endcap Ecal for solid angle coverage
Beam pipe between Lumical & beamcal shielded (or shielded+instrumented)
Disconnect valves and pumps on both input & extraction lines to allow push pull
Kicker on input beam line
In ~2007 optics developed to hold QF1 stationary at 9.5m on the lip of the tunnel and
allow for both L*=3.5m and L*=4.5m with QD0 residing in SiD/ILD & moving during
push/pull
Now Accelerator Design Team wants a common L* and realize that low QD0 L* with
large QF1 L* sub-optimal
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
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SiD 3.5/9.5m FD
92cm
Beampipe
Spider
Support
(Door Closed)
115cm
Movers
QF1
Valves/ L*=9.5m
LumiCal
Pumps
QD0
L*=3.5m
FB Kicker
W Mask
Beampipe
Bellows &
Flange
QD0 Service Pipe
FB BPM
BeamCal
PolyCarbonate
QF1
Cryostat
QD0 Cryostat
E
C
A
L
HCAL
2015.01.13 SiD L* @SiD SLAC CM
Door Yoke
T. Markiewicz/SLAC
PACMAN
3 of 15
SiD 3.5/9.5m FD
(Door Open 2.8m)
Beampipe
Spider
Support
Movers
QF1
Valves/ L*=9.5m
LumiCal
Pumps
QD0
L*=3.5m
Beampipe
FB Kicker
W Mask
Bellows &
Flange
QD0 Service Pipe
FB BPM
BeamCal
PolyCarbonate
QD0 Cryostat
E
C
A
L
2015.01.13 SiD L* @SiD SLAC CM
HCAL
T. Markiewicz/SLAC
QF1
Cryostat
Door Yoke
4 of 15
SiD 4.1/9.1m FD
(Door Closed)
78cm
Beampipe
Spider
Support
78cm
Movers
QF1
Valves/ L*=9.1m
LumiCal
FB
Kicker
Pumps
QD0
L*=4.1m
W Mask
Beampipe
Bellows &
Flange
QD0
Service
Pipe
BPMs
BeamCal
PolyCarbonate
QF1
Cryostat
QD0 Cryostat
E
C
A
L
HCAL
2015.01.13 SiD L* @SiD SLAC CM
Door Yoke
T. Markiewicz/SLAC
PACMAN
5 of 15
SiD 4.1/9.1m FD
78cm
(Door Open 2.8m)
78cm
Beampipe
Spider
Support
Movers
QF1
Valves/ L*=9.1m
LumiCal
FB
Kicker
Beampipe
Pumps
QD0
L*=4.1m
W Mask
Bellows &
Flange
QD0
Service
Pipe
BPMs
BeamCal
PolyCarbonate
QD0 Cryostat
E
C
A
L
2015.01.13 SiD L* @SiD SLAC CM
HCAL
T. Markiewicz/SLAC
QF1
Cryostat
Door Yoke
6 of 15
Granada LCWS’11 Engineering Model
Go from PPT Engineering to COTS parts
G. Anzalone/SLAC
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
7 of 15
Granada LCWS’11 Engineering Model
Go from PPT Engineering to COTS parts
G. Anzalone/SLAC
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
8 of 15
BNL Design of QD0
Support and Alignment System
• ANSYS analysis of QD0 outer can in either original 0.25” or suggested 1”
thickness shows unacceptable deformation of cold mass support structure
• BNL designed an external support tube and a compact mover system
Bolt Hole Rotation Pt.
Bill Sporre/BNL
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
9 of 15
Evolution of QD0-QF1 region
•Valve/Pump Out/RGA assemblies near QF1 end
•QD0 Service Line to 2K chiller extended maximally to rear
•Support tube behind QD0 extends to allow 2.8m door
opening transitioning to a half-cylinder for access
Front QD0
3283mm
Front QD0
9236mm
Door plates
Door Ring
5683mm
Wedge Alignment System
in Pockets in Door Ring
FB BPM
G. Anzalone/SLAC
2015.01.13 SiD L* @SiD SLAC CM
QD0 Service Line
Back end of QD0
6933mm
Back end of
Support Tube
550mm FB Kicker
8090mm from IP
T. Markiewicz/SLAC
Valve Assembly
10 of 15
Back End Services
All Vacuum Parts
from MDC Catalog
Four 1-1/2” Gate Valves
Support Tube
QD0 Service
Line
QF1
Formed
Bellows &
Disconnect
Flanges
63cm Assembly for
55cm Kicker
2015.01.13 SiD L* @SiD SLAC CM
Ion Pumps
68cm Pump & Valve Assembly
T. Markiewicz/SLAC
11 of 15
Plan & Elevation Views of Disconnect & Pumpout Valves
1-1/2” Gate Valves
Formed Bellows
& Disconnect
Flanges
2015.01.13 SiD L* @SiD SLAC CM
Angle Valve for Roughout Pump
Ion Pumps
All Vacuum Parts
from MDC Catalog
T. Markiewicz/SLAC
G. Anzalone/SLAC
12 of 15
Elevation View at 2.8m Door Opening
Kicker with Electrodes
Alignment Wedge
Support tube cut to semicylinder at rear
Semicircular plate and strut
at end of support tube
G. Anzalone/SLAC
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
13 of 15
Larger L* Issues
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More deflection of pairs from dipole component of solenoid
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Nominally compensated by “anti-DID”
Less backsplash from BeamCal to VXD & Tracker
Length and weight of W mask (currently 1.23m long) increase
Diameter of BeamCal likely increases
More space for LumiCal & BeamCal readout
More load on support tube from W and BeamCal
Probably more stress and vertical displacement of tip of support tube when
door opened to maximum of 2.8m (needs analysis)
More cantilever of QD0 when door in closed position (1.26m + increase in L*)
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
14 of 15
Summary
• SiD can accommodate a L* between 2.6-4.5m
– Minimum L* probably dictated by QD0
technology, not SiD
• Minimum and maximum L* in SiD are a function
of
– Z where endcap ECAL begins
– Length of QD0 cryostat
– L* of QF1 (9.5m) and space required for
disconnect valves, flanges, pump outs and the
feedback kicker
• More work needed to evaluate engineering
stresses and backgrounds if L* changes
2015.01.13 SiD L* @SiD SLAC CM
T. Markiewicz/SLAC
15 of 15