1. Strawman module design

2. VELOPix module VELOPix: Pixel readout chip based on medipix/timepix
256 x 256 pixels 55 mm square. Chip is 3 side buttable
Small pixel cell means that single sided modules can be built
By using TSV (through silicon vias) dead side can be reduced to 0.8 mm in Medipix3
Analogue power consumption 6 mW per pixel.
4 bit equivalent ADC resolution provided via TOT
Upgrade being considered to 90 nm technology (power consumption and radiation hardness benefits)
14100
14100
800
Medipix3
Chip dimensions 2 2

3. U-shape VELOPix Module Layout
50 mm
Al ground plane
behind diamond
power tape
connector
inactive
part of chip
Region of 800x55 mm pixels
metallisation on diamond 3
windows in diamond for bonding
through to TSVs
guard rings 3

4. Cross section of central part of 2 chip assembly
window
in diamond
wire
bonds
power tape
200 mm diamond
50 mm Al ground plane
bump
bonds
glue
150 mm ASIC
interposer
150 mm silicon
55x55 mm pixels
800x55 mm pixels
under inactive part of chip
TSVs
Key points of design:
Full efficiency for first measured point
reduced resolution in 5% of active area
TSVs an essential feature
Diamond metallisation and laser cutting
has been achieved by other collaborations
but remains to be proven for LHCb
-edgeless technology would remove the 2%
remaining dead area between silicon pieces
- Semi tiled solution: minimise dead regions 4

5. readout Vacuum tank average particle rate per bx and
1.4
3.1
5.8
10.9
1.7
3.7
4.6
8.8
0.9
2.3
1.3
3.0
7 mm
LHC beam
average particle rate per bx and
average data rates (Gbit/s)
for the Velopix asics, at the highest luminosity (L=20*1032/cm2/s) and with an average cluster size=2
20 x Differential copper links ~ 2m
20 x optical links ~60m
vacuum feed-throughs
Electro-optical
Tell 40
Network interface
Vacuum tank

6. Many many other issues Optimal number of modules/stations
Sensor technology
Paddles
Base and movement system
RF foil
Material choices
Single sided -> CTE is very important
Gluing
Radiation hardness
Vacuum compatibility
Powering / biasing
Hybridisation / routing
And this is only the tip of the iceberg…..

8. z of first measured point (compared
Material Estimate:
150 mm silicon + ASIC ~ 0.3%
100 mm Aluminium ~ 0.2%
200 mm Diamond ~ 0.2%
TOTAL ~ % per station
(single layer)
- 8W per station
Simulating 21 stations as current VELO gives satisfactory hit distributions
z of first measured point (compared
to VELO with inner radius of 8 mm..)
Number of hits per track 8 8