Elena Rocco Nikhef, The Netherlands On behalf of the ALICE Utrecht-Nikhef group Jamboree – Utrecht December 2012

2 E. Rocco - Jamboree, Utrecht December Proton-Lead: -Saturation/Color Glass Condensate effects -Direct  spectra at forward   -hadron/jet correlations (fwd-mid and fwd-fwd) -  0 spectra  0 -  0 correlation (fwd-mid and fwd- fwd) 2. Proton-Proton: - reference measurements: constrain PDFs with ,  0 -  0 (?) 3. Lead-Lead: -Extend acceptance for  -hadron/jet correlations;  0 R AA at forward rapidity  0 -  0 correlations

E. Rocco - Jamboree, Utrecht December Two options: z= 3.6 m, 2.5< η <4.5 z= 8 m, 3.3< η <5.3 Small Moliere radius (W!) Extreme granularity (~ 1 mm 2 ) Unique at LHC! (not only!) High-granularity electromagnetic calorimeter for photons and π 0 detection FULL MAPS PROTOTYPE BUILT AS PROOF-OF-PRINCIPLE Detector with MAPS should allow: Gamma/  0 discrimination 3D shower shape analysis for PID Particle flow Energy measurement by particle counting: requires high granularity due to high density particle (10 3 mm 2 ) Very small distance between the 2 photons  0 → 2 γ

E. Rocco - Jamboree, Utrecht December different energy ranges Minimum two-gamma separation ~ 100 GeV → Need high granularity/separation power

E. Rocco - Jamboree, Utrecht December 2012 Since E= p t cosh( η ) for p t =4 GeV/c and η =4 we obtain E =109 GeV!!  0 efficiency of ~90% should be reachable with 1 mm granularity (100<E<200 GeV) 5 4 GeV/c <p t <10 GeV/c

E. Rocco - Jamboree, Utrecht December z, Beam direction y, direction x, direction MIMOSA 23 W absorber W blocks, 3.0 mm (<X 0 ) Extra W block 20 mm 116 mm - 24 modules high granularity (MAPS) - 4 chips (MIMOSA) per module - 96 chips, ~39M pixels mm Bonding at Nikhef!!! Monolithic Active Pixel Sensor

7 © Marc Winter (IPHC) Working principle E. Rocco - Jamboree, Utrecht December 2012 Integrated circuit with 640 x 640 pixels Pixel pitch = 30 µm Possibility to thin down to 50 µm On-chip digitisation: chip level threshold setting, 1 bit per pixel Sequential chip readout (“rolling shutter”) → chip r/o time: 640 µs (1 µs per row)

E. Rocco - Jamboree, Utrecht December Full module Connecting cables W spacer 0.3 mm W plate 1.5 mm MIMOSA Mounting PCBs

E. Rocco - Jamboree, Utrecht December One half r/o system!! ~39 Mpixel to be read every 640 µs → buffering required!!! VIRTEX FPGA 2 GB BUFFER SPARTAN FPGA CHIPS SYNC SPARTAN FPGA CHIPS SYNC Data transfer to DAQ PC Demuxing data at the DAQ PC

E. Rocco - Jamboree, Utrecht December Setup mounted at the PS/SPS test beam facilities at CERN in 2012 beam detector Scintillators: Back, Front, Horizontal, Vertical, Present PV HFB B F beam B H P Central trigger selection (coincidence of HVF signals) for a full developed shower (the detector is 3.5 R M wide)

Rolling shutter continuous reading out Frame: is the sequence of the 640 rows read out and the pixels integrate the hits between to consecutive readouts Each trigger “covers” one frame All rows in this window might contain data from this trigger A new trigger in this window might make a row have data from multiple triggers Past-future protection required Frame N N+1 N+2 N+3 N+4 N+5 End of frame N End of frame N+1 End of frame N+2 End of frame N+3 End of triggered data Trigger happens here time End of frame N+3 Start of frame N+4 N + 4 N + 3 E. Rocco - Jamboree, Utrecht December

E. Rocco - Jamboree, Utrecht December Facility BEAM ENERGIES (Gev) TOTAL # OF FRAMES TOTAL # OF TRIGGERS DESY 2, 518GB~88k PS 2, 3, 5, 6, 838GB~1100k SPS 30, 50, 100, 150, 200, GB~290k

E. Rocco - Jamboree, Utrecht December GeV Signal Pedestal Detector response scales ~ with energy S/N> 2 at 2 GeV Detector response ~ 150 pixels/GeV 5 GeV Signal Pedestal Raw data!

E. Rocco - Jamboree, Utrecht December Shower profile: average number of hits per layer for electromagnetic showers generated by a single electron. Not working layer Shower Profile at 5 GeV Gamma function fit Raw data!

15 2 GeV E. Rocco - Jamboree, Utrecht December GeV 200 GeV Sum of all layers I dot = 1 pixel pitch = 30 µm!

E. Rocco - Jamboree, Utrecht December Hadronic shower Sum of all detector layers 1 dot = group of 100 pixels Low noise level: <5 pixel firing per chip/frame (1 chip is ~0.4 Mpixels) Electromagnetic shower Track

-Beam tests with prototype have demonstrated feasibility of digital calorimetry. A lot of data collected: analysis on going - Developments towards useable MAPS in Strasbourg, CERN and Nikhef (Nikhef electronics team): faster, data compression - Letter of Intent (LoI) due begin 2013; simulations on physics performance on going E. Rocco - Jamboree, Utrecht December