Ideas for Super LHC tracking upgrades 3/11/04 Marc Weber

We have been thinking and meeting to discuss SLHC tracking R&D for a while…

Agenda Introduction: SLHC and opportunities for tracking R&D at PPD/RAL (Marc)

Plans of ID: MAPS, electronics, other (Markus, Renato) MAPS and SLHC: next steps (Giulio)

Discussion

What is SLHC ? Large Hadron Collider Upgrade

phase 0: x 2.3 luminosity increase phase 1: x 10 luminosity increase (L = 10^35 cm-2 s-1) phase 2: energy increase

SLHC start: 2013 / 2014 How to achieve the luminosity increase ? Not yet known ! reduced bunch crossing: 25 ns -> 12.5 ns

or superbunches which are 75 m long

many good reasons to assume SLHC will be built (if technically feasible): increased physics reach for “little money”; break down of current LHC detectors due to radiation; without SLHC, it takes 8 years of LHC running to halve errors; there is no other big CERN project; LC still far away.

Tracking at SLHC arguably biggest challenges

despite uncertainties in machine parameters, the following is known:

particle fluences increased by factor 10 (=> radiation damage);

much more channels to fight occupancy => more power; readout speed (=> more power )

LHC SLHC

s 14 TeV 14 TeVLuminosity 1034 1035

Bunch spacing t 25 ns 12.5/25 ns

pp (inelastic) ~ 80 mb ~ 80 mbN. interactions/x-ing ~ 20 ~ 100/200(N=L pp t) dNch/d per x-ing ~ 150 ~ 750/1500<ET> charg. particles ~ 450 MeV ~ 450 MeV

Tracker occupancy 1 5/10Pile-up noise in calo 1 ~3Dose central region 1 10

Challenges depend strongly on location

Inner region: pixels; fluences up to 10^16 p/cm^2; very challenging

Middle region: pixels/short strips; fluences up to 10^15 p/cm^2

Outer region (is straw tracker now): pixels/smart pixels MAPS)/strips ?

fluences comparable to SCT region

Disclaimer:

the 3 regions are not well defined as yet, there might be 2 regions only, etc.

assume fluence ~ 1/r1.6

Why do are we looking at MAPS option ?

Cost: commercial 0.25 um technology (IBM/TSMC…) vs high resistivity silicon (Hamamatsu)

price difference of factor 3-10 in favour of commercial technology

example: ~$250K/m^2 of strip silicon and a 40 m^2 system gives $10 M

Power: high resistivity silicon strips are operated at 100/300 V with leakage currents of 100 nA/10 mA before and after irradiation (10^14 n/cm^2)

standard RO chips use <0.5 W/128 channels

=> irradiated strip module is: < 3 + 2 W

MAPS “sensor power” is much less (factor 50-100) for same area

(since depletion voltage is ~2 V and leak current is ~ to depletion volume)

MAPS “electronics” design dependent but probably also much reduced…

What could be first steps ?What is the effort and what would it cost ?

Radiation hardness is key to use of MAPS at sLHC and a likely show stopper => test this early on

Establish validity of ISECAD simulations at high radiation doses Build a simple structure that works even at high doses Ignore readout speed and position resolution requirements

too much layout work, too dependent on particular use of MAPS)

for smart pixel, position resolution is less important and pixel size could be large

make sure device is easy to test (charge injection, buffer to connect external low noise preamp, but also digital output)

later S/N must be improved !!