Outline

1. ALICE Upgrade Strategy L. Musa, ECB 11 May 2012 Outline • Motivations • Upgrade strategy • Detector and readout upgrade • Conclusions

2. The ALICE Detector ALICE Layout • Barrel Tracking • Pseudo-rapidity coverage |η| < 0.9 • Robust tracking for heavy ion environment • up to 150 points along the tracks • Wide transverse momentum range (100 MeV/c – 100 GeV/c) • Low material budget (13% X0 for ITS+TPC) • Large lever arm to guarantee good tracking resolution at high pt Max readout rate ~500 Hz • PID over a wide momentum range • Combined PID based on several techniques: dE/dx, TOF, transition and Cherenkov radiation • Rate capabilities • Interaction rates: Pb-Pb < 8kHz, p-p < 200 kHz (~30 events in the TPC) • Readout rates (Pb-Pb) • Pb-Pb minimum bias 520 Hz • pp ~2kHz

3. Beyond the ALICE approved physics programme • Progress on the characterization of QGP properties is made by studying • multi-differential observables: • Flavour, Centrality, Transverse momentum, Reaction plane, … • This requires high statistics (high luminosity) Centrality Reaction plane

4. Beyond the ALICE approved physics programme • ALICE physics plans focus on physics observables where ALICE unique features (PID, low material thickness, precise vertexing down to low pt, …), are essential • precision measurements of spectra, correlations and flow of heavy flavour hadrons and quarkonia at low transverse momenta • precision measurements of low-mass lepton pairs emitted from the QGP • energy loss and flavour tagging of partons in the QGP via g-jet and jet-jet with hadron PID • search for the existence of heavy nuclear states such as the H dibaryon or L-neutron bound states and systematic study of production of anti-matter •  This requires high statistics and precision measurements • Standard trigger strategy not applicable in most cases

5. ALICE Upgrade Strategy • “ALICE at High Rate” submitted to LHCC • A document has been prepared defining the physics goals and the experimental approach for a run of at least 10 nb-1 with PbPb • run ALICE at high rates, 50kHz Pb-Pb (i.e. L = 6x1027 cm-1s-1), with minimum bias (pipeline) readout ( max readout with present ALICE set-up ~500Hz) • Improve vertexing and tracking at low pt The Pb-Pb run would be complemented by p-Pb and pp running • It entails building • New beam pipe • New silicon tracker (improved tracking resolution and readout rate) • High-rate upgrade for the readout of TPC, TRD, TOF, CALs, Muons, DAQ/HLT • This will allow a readout architecture with minimum-bias readout and event selection done by software algorithms in the online systems (DAQ/HLT) • Targets LS2

6. ALICE at High Rate - Readout Architecture • 50 kHz Pb–Pb collisions inspected with the least possible bias • Possibility to perform online event selection, based on topological and PID criteria, is under study • HI run 2011: online cluster finding data compression factor of ~5 for TPC • min. bias event size ~20 MB  ~4 MB after data reduction • We assume for 2018 a bandwidth to mass storage ~ 20 GB/s. • Two HLT scenarios for the upgrade: • Partial event reconstruction (clustering and tracking): Factor of ~20 (ready for 2012 run)→ Rate to tape: 20 kHz • clusters (associated to tracks) information recorded on tape • Full event reconstruction: additional reduction factor ~3 → Rate to tape > 50 kHz • clusters (associated to tracks) information recorded on tape • If smaller bandwidth or higher interaction rate, matching between data throughput and bandwidth might be achieved with online event reconstruction and selection

7. Readout and Online Systems Architecture Readout scheme Fast Trigger Processor (FTP) Event Processors (EPN) L1 L2 L3 inter. L0 t0+10ms t0+ ~1s t0+ >10s t0 t0+ ~1ms Bandwidth to tape 20 Gbyte/s L0 FTP  Fast Trigger Processor FLP  First Level Processor EPN Event processor Node

8. ALICE Upgrade Strategy • Contextually, submitted to LHCC the CDR for the ITS upgrade which is an essential part of the General Strategy • Furthermore, three major proposals are under consideration to extend the scope of ALICE: VHMPID, MFT, and FOCAL (a decision will be taken by September) • New high momentum PID capabilities • b-tagging for low pt J/psi and low-mass di-muons at forward rapidities • Low-x physics with identified g/p0 VHMPID FOCAL MFT

9. ITS upgrade options • Two design options are being studied • 7 layers of pixel detectors • better standalone tracking efficiency and pt resolution • worse PID • 3 inner layers of pixel detectors and 4 outer layers of strip detectors • worse standalone tracking efficiency and momentum resolution • better PID 4 layers of strips Option B Option A 7 layers of pixels 3 layers of pixels • 685 krad/ 1013neq per year • Includes safety factor > 4 Pixels: O(20x20µm2 – 50 x 50µm2) Pixels: O( 20x20µm2 – 50 x 50µm2) Strips: 95 µm x 2 cm, double sided

10. ITS upgrade options • Several technologies are being considered for pixel detectors • Hybrid pixel detectors • Edgeless sensors (100mm) + front-end chip (50mm) in 130 nm CMOS • Monolithic pixel detectors • MIMOSA like in 180 nm CMOS • INMAPS in 180 nm CMOS • LePix in 130nm CMOS Hybrid dummy structures sensor 100mm FEE chip 50mm MISTRAL prototype circuit glass carrier INMAPS TPAC prototype 50 µm pixel - over 150 CMOS transistors

11. Conclusions • ALICE general upgrade strategy: • Minimum bias readout of all central detector at 50 kHZ • Factor ~3 improvement in secondary vertex resolution • Very high standalone tracking efficiency down to low pt(> 95% for pt> 200MeV/c) • Fast access (winter shutdown) to silicon tracker • It entails • Replacement of ITS • Major upgrade of the TPC (replace MWPC with GEM + new readout electronics) • Upgrade of readout electronics for TRD, TOF and Calorimeters. • Major upgrade of the Hardware Trigger and online systems (DAQ, HLT) • After a couple of years of studies, ALICE is confident that this ambitious proposal can be turned into a real detector to be ready for physics in 2019 • Strong support from the whole ALICE Collaboration and Funding Agencies for R&D phase