Rich Occupancies and Bandwidth in Minimal Upgrade Layout My Work so far... Robert Currie 12/04/2010

'... a stepping stone in development of the LHCb software...' Simulation Want to estimate the requirements of the electronics for the RICH detectors in the LHCb upgrade. Using events simulated using the Minimal Upgrade Layout (MUL without Aerogel) : https://twiki.cern.ch/twiki/bin/view/LHCb/MinimalUpgradeLayout '... a stepping stone in development of the LHCb software...' To measure the bandwidth required we need to know the Occupancy of modules within the RICH detectors. Gauss Boole Occupancy Thanks to Young Min for helpful discussions on Simulation work Slide 2

Simulation Data Physics Events Simulated in Gauss and digitized in Boole according to the MUL and the occupancy per HPD is extracted from the expert histograms. The total number of events analysed in my work so far is: ~10k events at Lumi20 ~25k events at Lumi2 Only Lumi20 results will be discussed in the main talk with Lumi2 Occupancies given in backup Slides Slide 3

Cable & Bandwidth Numerical Example: For each module in RICH, the number of GBT cables required is Determined by the number of hits in each module and this is calculated from it's occupancy 1 cable carries 80bits per cable per event[1] 1 hit in RICH module (1024 pixel) binary readout, zero suppressed = 10bits of data/hit Numerical Example: E.g. 4 cables per module: (suitable for outer detector) 4 x 80 / 10 gives a BW limit of 32 hits/ (module * event) = occupancy of ~3% for each module. Slide 4 [1] Johans slides on Torch: http://lhcb-elec.web.cern.ch/lhcb-elec/html/upgrade.htm

Module Occupancies Lumi 20 Typical Low Occupancy: Outer Detector Occupancy PDF typical of most low occupancy modules within both Rich1&Rich2 Typical Low Occupancy: Outer Detector Red: Data Blue: Fit Slide 5

Module Occupancies Lumi 20 Highest Occupancy: Inner Detector Occupancy PDF typical of High Occupancy modules at the centre of the detector planes in Rich1&Rich2 Highest Occupancy: Inner Detector Red: Data Blue: Fit Slide 6

Cables required to read 99% of all events across RICH 1 at Lumi20 Slide 7

Cables required to read 99% of all events across RICH 2 at Lumi20 Slide 8

Example link-map required for 99% data readout for Rich1 Slide 9

Example link-map required for 99% data readout for Rich2 Slide 10

Efficiency Map of Rich1 Slide 11

Efficiency Map of Rich1 Slide 12

Efficiency vs Bandwidth Hits are truncated between events if BW limit is exceeded: for a fixed number of links with the single highest occupancy module at Lumi20 one gets: Same module as on Slide 6 (Rich1 Col7 Row4) Number of Links % of events with truncated data Max Number of transmitted hits Average number of lost hits 2 90.5 16 51.8 4 76.4 32 38.5 8 47.3 64 19.6 12 24.7 96 8.3 10.5 128 3.0 20 3.8 160 0.9 24 1.2 192 0.2 Slide 13

Zero Suppression Threshold Passing just binary readout data from the module equates to 1024 bits of data per event. 1024 / 80 = 12.8 Hence 13 cables required for all data to be transmitted from each module. When zero suppression requires more than 13 cables it is more efficient to change the data transmission strategy to binary only readout. Slide 14

Cable Numbers Only zero-suppressed data transmitted: Rich1 Rich2 Only zero-suppressed data transmitted: Total Number of Cables: 1200 1632 Max per Module: 24 16 With non-zero-suppressed data transmitted in centre modules: Total Number of Cables: 992 1484 Max per Module: 13 13 Slide 15

Number of Cables for Rich1 non-zero suppressed in centre Slide 16

Number of Cables for Rich2 non-zero suppressed in centre Slide 15

Conclusions Developed method to study the number of required links in RICH for expected occupancies in LHCb Minimal Upgrade Layout. Large numbers of cables per module required at the centre of the RICH detectors to read zero suppressed data at high efficiencies. Moderate numbers of links required at outer regions of detector planes. Link numbers suggest to employ zero-suppressed readout for most of the detector planes, but non-zero-suppressed readout for centre areas. Slide 18

Further Work Repeat the Study for MUL with Aerogel for the simulation (occupancy in RICH1 may be higher) Obtain Better Statistics for Lumi20 and directly compare to Lumis 5 & 10 as well (to check for proper evolution of occupancies) Optimise cable number / module Slide 19

BACKUPS

Module Occupancies Lumi 2 Typical Low Occupancy: Outer Detector Occupancy PDF typical of most low occupancy modules within both Rich1&Rich2 Typical Low Occupancy: Outer Detector Red: Data Fit not plotted Slide 5

Module Occupancies Lumi 2 Highest Occupancy: Inner Detector Occupancy PDF typical of High Occupancy modules at the centre of the detector planes in Rich1&Rich2 Highest Occupancy: Inner Detector Red: Data Fit not plotted Slide 6