1. SVT Mechanics Baseline SuperB SVT configuration
Collected pictures from the BaBar SVT
Open issues & Strategy
SVT Mechanics, March 2011
Giuliana Rizzo – Filippo Bosi
Universita’ & INFN Pisa
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

2. The SuperB Silicon Vertex Tracker
BaBar SVT
5 Layers of double-sided Si strip sensor
Low-mass design. (Pt < 2.7 GeV)
Stand-alone tracking for slow particles.
97% reconstruction efficiency
Resolution ~15μm at normal incidence
40 cm
30 cm
20 cm
Layer0
old beam pipe
new beam pipe
SVT
SuperB SVT based on Babar SVT design for R>3cm. BUT:
Reduced beam energy asymmetry (7x4 GeV vs. 9x3.1 GeV) requires improved vertex resolution (~ factor 2 needed)
Layer0 very close to the IP (R~ 1.5 cm) with low material budget
Layer0 area 100 cm2
Background levels depends steeply on radius
 Layer0 needs to have fine granularity and radiation tolerance
Bp p decay mode, bg=0.28, beam pipe X/X0=0.42%, hit resolution =10 mm
Dt resolution (ps)
Layer0 subject to large background and needs to be extremely thin:
Track rate > 5MHz/cm2, > 3MRad/yr, < 1 %X0
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

3. SuperB SVT Layer 0 technology options
Striplets option: mature technology, not so robust against background occupancy.
Marginal with back. track rate higher than ~ 5 MHz/cm2
FE chip development & engineering of mod. design needed
Hybrid Pixel option: viable, although marginal.
Reduction of total material needed!
Reduction in the front-end pitch to 50x50 μm2, fast readout (developed for DNW MAPS)
 FE prototype chip (4k pixel, ST 130 nm) successfully tested with pixel sensor matrix connected.
CMOS MAPS option: new & challenging technology.
Sensor & readout in 50 μm thick chip!
Extensive R&D (SLIM5-Collaboration) on
Deep N-well devices 50x50μm2 with in-pixel sparsification.
Fast readout architecture with target hit rate O(100MHz/cm2)
CMOS MAPS (4k pixels) successfully tested with beams.
Thin pixels with Vertical Integration: reduction of material and improved performance.
Two options are being pursued (VIPIX-Collaboration)
DNW MAPS with 2 tiers
Hybrid Pixel: FE chip with 2 tiers + high resistivity sensor
Complexity
Sensor
Digital tier
Analog tier
Wafer bonding & electrical interconn.
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

4. SVT Mechanics Meeting – March, 9 2011
Layer0 Strategy
Plan
Start data taking (~ 2016) with striplets (baseline option for TDR):
Better physics performance (lower material ~0.5% vs 1% hybrid pixel, MAPS or thin hybrid pixel in between but not yet mature!)
Upgrade Layer0 to pixel (Hybrid or CMOS MAPS), more robust against background, for the full Luminosity (1-2 yrs after t0).
SVT Mechanics will be designed to allow a quick access/removal of Layer0
~10% better
~20% more Luminosity
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

5. SVT baseline configuration for TDR
Layer 0: Striplets modules
CDR design is being revised for TDR
Quite complex mechanical structure need to fit inside the L1 radius 3.3 cm
SuperB Interaction Region Schematic SVT superimposed
External Layers:
Similar to the present BaBar SVT: double sided silicon detectors 300 um thick
Assume same BaBar radii for the 5 layers (3-15 cm)
L1-L2-L3 barrel shape
L4-L5 arch shape
Extend coverage down to 300 mrad FW and BW
In BaBar it was 300 mrad FW and 520 mrad BW
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

6. Layer 0 striplets design
CDR design is being revised for TDR!
(Lab.) Geometrical acceptance: 300 mrad both in FW and BW
Distance from the i.p. : R=15 mm U V
12.9 mm
97.0 mm
Choosing an Octagonal shape:
- Module active area = 12.9 x 97.0 mm2
(includes 4% area overlap for alignment)
- double sided Si detector, 200 mm thick with striplets (45o w.r.t det. edges)
readout pitch 50 mm
- multi-layer fanout circuits (similar to SVT modules, z side) are glued on each sensor, connecting Si strips to Front End Electronics
(fanout extends twice wider than the detector, to allow a minimum of 50 mm between metal traces ~ 700 strip/readout side!).
In a module needed ~2 fanouts/side !
A new readout chip is needed to cope with the high background rate (up to 200 MHz/cm2)
Readout Right
Readout Left z
HDI
Si detector
1st fanout, 2nd fanout
r= 15 mm
Conceptual design module “flat”
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

7. SVT Mechanics Meeting – March, 9 2011
Already at the time of the CDR, it was clear that:
the striplet det’s required a fan-out circuit of some complexity to take out the
signals from so many strips (768).
not negligible X0 contribution (45um Si-eq/f.o. layer)
to fit the geometrical constraints, the L0 module must use the f.o.
extension to bend at a higher radius and to be connected with a transverse hybrid
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

8. For the SuperB SVT L1-L5 we start from the BaBar configuration
BaBar SVT
For the SuperB SVT L1-L5 we start from the BaBar configuration
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

9. The BaBar Silicon Vertex Tracker
5 Layers of double-sided, AC-coupled Silicon.
Custom rad-hard readout IC (the AToM chip).
Low-mass design. ( Pt < 2.7 GeV/c2 for B daughters)
Stand-alone tracking for slow particles.
Inner 3 layers for angle and impact parameter measurement.
Outer 2 layers for pattern recognition and low Pt tracking.
20 cm
30 cm
40 cm
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

10. Space Frame and Support Cones
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

11. SVT Mechanics Meeting – March, 9 2011
SVT Geometry
Layer Radius cm cm cm
to 12.7 cm
to 14.6 cm
Be Beam pipe
1.0 % X0
10 cm
(Arched wedge wafers not shown)
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

12. SVT Mechanical Features
Brass
cooling rings
Carbon fiber
Space Frame
22 cm
B1 dipole
permanent magnet
(inside support cone)
B1 dipole
permanent magnet
(inside support cone)
Carbon fiber
support cones
109 cm
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

13. SVT Mechanical Features
Silicon wafers
Carbon & Kevlar fiber support ribs
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

14. SVT Mechanics Meeting – March, 9 2011
BaBar SVT
SVT complete
half SVT
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

15. SVT BaBar Modules Number of Wafers Total Phi-Strip Length
Backward Forward
Layer
Z-Strip Length
5b cm 26.5 cm to 5.1 cm
5a cm 25.1 cm to 5.1 cm
4b cm 19.9 cm to 5.1 cm
4a cm 18.5 cm to 5.1 cm
cm cm cm
cm cm cm
cm cm cm
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

16. SVT SuperB Modules (first guess!)
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

17. SVT Mechanics Meeting – March, 9 2011
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

18. SVT Mechanics Meeting – March, 9 2011
Fanouts
Fanout circuits provide
electrical connections
between the detector
strip and the front-end
chip
Properties:
Cu (Cr and Au) layer on
an Upilex substrate
(50 mm thick, < 0.03%X0)
C = 0.52 pF/cm
R = 2 W/cm
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

19. SVT Mechanics Meeting – March, 9 2011
SVT Module / Layer:
L 1-2 : 6
L 3 :
L 4A+B:
L 5A+B:
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

20. L0/SVT mech. Specifications
Difficult at this stage to have an IR design frozen to perform a realistic mechanical design of L0 and SVT :
Anyway, now, there are some constraints that force the design : A) L0 and SVT design should allow a quick demounting from the IR. B) L0 must be mounted on the Be beam pipe to avoid any possible relative movement (low clearance from beam pipe). C) SVT is independent from beam pipe and supported on the QD0 criostat.
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

21. SVT Mechanics Meeting – March, 9 2011
L0/SVT specification
SVT demounting means to spilt it in two half near I.R., so SVT structure has to be very rigid to assure good stability and also it is necessary a mechanical equipments that is able to support the two SVT halves just beside of Be pipe and, also, able to reassemble them after L0 replacement .
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

22. SVT Mechanics Meeting – March, 9 2011
L0/SVT specification
Cooling system, cables and any system service of SVT has to be independent from any L0 component, allowing a complete independent demounting. If we assume a support structure with two semicone support, (BaBar like), we need a rigid space-frame structure to be redesigned
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

23. Mechanical Design Items
Current work in Pisa :
Central Be pipe and cooling
L0 Striplets module design and supports
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

24. Mechanical Design Items
Current work in Pisa:
L0 pixel module design and supports
IR solid modelling ( on M.Sullivan indications)
I.P.
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

25. Mechanical Design Items
Current work in Pisa:
Quick demounting of L0/SVT
SVT geometrical layout of layer 1-5 modules
13mm ?
300mrad
350mrad
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

26. Mechanical Design Item
Items not covered:
Layer1-5 detailed Module design
SVT semicone support Structure and HDI cooling design
Space Frame structure design
Mechanichal equipment for SVT split .
(Work on these items could start as soon as geometrical layout of layer 1-5 modules has been defined ).
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,

27. Engineering /Technical Man Power
Actually in Pisa:
0.7 fte senior mechanical engineer
0.7 fte draftman
Starting beginning of April:
1 fte young mechanical engineer
Technical staff:
H.T. labs facilities and expert technicians from High Technologies technical group for electronics and mechanical prototype preparations .
G. Rizzo-F. Bosi
SVT Mechanics Meeting – March,