EMCal Cosmics Run

EMCal Cosmics Run • Cosmics Run Goals • EMCal Status, Goals, Plans:pre-Cosmics Run • Hardware • Firmware • Software • Cosmics Run

Cosmics Run Goals • Primary goal is as “commissioning run” • Demonstrate we can operate EMCal reliably • DCS control • Online Monitoring • Commission EMCal trigger • L0 cosmics? • L1 gamma • EMCal calibration • Demonstrate calibration procedures • Set T-corrected APD biases to match gains of 4 SMs • LED and/or Temperature measurement gain corrections • Use cosmic mip peak to confirm calibration

Installed EMCal SM Status • SMC0 and SMC1: all services installed and connected • Cooling water, LV, HV, DDL, TTC, ethernet, LED… • DCS control “evolving” • HV and LV under PVSS control from ACR, T readout in ACR • FEE slow control in progress • ssh to DCS boards to run scripts to set Bias and setup for running - the “big job” is to do this under PVSS control • Currently using a “dummy” EMCal top level DCS state machine • EMCal always “ready” to take data • First pedestal runs at final Cosmics calibration APD biases • Pedestal data taken with TTC random triggers

First EMCal pedestals in ALICE SMC0 1 channel High Gain <rms>~0.75 Same as during calibration SMC1

EMCal SM Status - Hardware • Next steps: • LED system • LED system is connected • Tests have been made with an LCU (LED Control Unit) “prototype” to extract LED “prepulse” trigger from TTC fiber and distribute to LVDS. Also to test LED driver programmable delay (trigger setup) • Install LCU, test LED data taking, integrate into DCS • LCU PCB Layout is in progress • LCU installation late July? • BUSYBOX • Used by TPC, PHOS, FMD, and EMCal - but many problems reported • Needed to implement deadtime, Multi-event buffering • @P2 but so far untested • SMA0 and SMA1 • Assemble, then test and calibrate @Grenoble • Install, connect, commission @ CERN late July

EMCal SM Status - Hardware • Next steps: • Trigger • Develop and test TRU FPGA code (ongoing) • JTAG adaptor boards produced and successfully tested: Allows remote TRU programming via the DCS card on the RCUs • Jiri starting to test code in Lab • Complete production of 12 TRUs • PCBs and components at Firstec • Completed in ~1-2 weeks • Test TRU+STU in laboratory • Install TRUs in SMC0 and SMC1 (July?) • Install STU in ALICE (July?) • Integrate TRU+STU control into DCS

EMCal SM Status - Firmware • Next steps: • Upgrade Firmware • FEE board controller firmware (to implement Sparse Data Scan) • RCU firmware version • Requires updated FEE scripts • Completed by David last week • SMA0 and SMA1 calibrations @Grenoble with new firmware and scripts • SMC0 and SMC1 firmware will need to be upgrade in situ (early June) • EMCal DAQ Readiness tests (with DAQ group) • Scheduled for June • Certify that EMCal fulfills all ALICE requirements: CDH, SOD, EOD,… • Rate tests • Optimize number of samples: N=50 -> N=25? • With/without Zero Suppression, Sparse Data • Multi-event buffering

EMCal SM Status - Software • Next steps: • DCS • Complete and test underlying code • Being done remotely (Creighton), until late May when Jiro@CERN for 1 yr. • Complete FEE control with final firmware • Integrate LED control into DCS • Integrate Trigger setup and control into DCS • Complete EMCal Top Level DCS state machine for interaction with ECS • Iterate on GUI panels to arrive at final EMCal DCS Interface • Create a simple EMCal Summary DCS panel that can be viewed and understood by non-EMCal shifters to easily identify problems.

EMCal SM Status - Software • Next steps: • Monitoring • Take periodic pedestal runs pre-Cosmics run to monitor “environment” as rest of ALICE turns on - I.e. be sure noise is not introduced • Develop AMORE online monitoring • Pedestals: to monitor electronics • LEDs: to monitor EMCal “alive” and gain stability • HLT monitoring •  invariant mass plots • Trigger threshold/efficiency plots • Track matching, electron ID • Event display (for PR!)

EMCal monitoring LEDs • Compare LED position for each tower (or reference Photodiode) to those at some reference time t0 (a la PHENIX) • Monitors APD gain • If EMCal okay then narrow peak at R=1, otherwise call EMCal expert

EMCal Status • SM view of towers showing state of each tower • Check if signal present, within range, noisey, etc • Structures useful to deduce source of problems • T-card, FEE-card, HV channel, etc

EMCal expert plots •  invariant mass plots • Not useful for shift crew • Too few statistics from single run • Summing over many runs is not useful for feedback to shift crew • Is useful for experts • See that online calibration is reasonable • Use to obtain improved calibration

Cosmics Run Goals • Primary goal is as “commissioning run” • Demonstrate we can operate EMCal reliably • DCS control • Online Monitoring • Commission EMCal trigger • L0 cosmics? • L1 gamma • More?

Trigger Commissioning • L0 and L1 triggers • Adjust phase of EMCal L0 and L1 from STU w.r.t Beam Clock @ CTP • Check L0 phases w.r.t BC to STU across EMCal • Use time measurements from FALTRO and real data • Adjust LED delays to match real data • Rate vs threshold • Can we set L0 thresholds well below mip to have efficient single particle trigger • Yes? Fanastic! • No? Consider other Cosmics L0 triggers, e.g. require more than one TRU L0 at STU

Trigger Commissioning • L0 and L1 triggers • Measure trigger efficiencies • Map trigger frequency vs tower: SM x-y plots • Look for “hot” or “dead” regions • Define trigger mask to mask out “hot” regions • Efficiency plots: E(4x4 | L0/1)/E(4x4) • For all of EMCal, SMs, 4x4s • Do the same for FALTRO data (trigger input) • L1 jet trigger • Perhaps can be tested with Cosmic showers • If yes, then do the above for L1 jet triggers

Trigger Commissioning • HLT triggers • Reconstruct gamma clusters • Frequency vs tower: SM x-y plots • Look for “hot” or “dead” regions • Efficiency plots: E(L1)/E • For all of EMCal, SMs, 4x4s • Electron trigger • Associate gamma clusters to reconstructed track • Do E/p matching to identify electrons • Use lower L0 gamma threshold • Require electron ID or E > higher pT threshold • L1 jet trigger • Perhaps can be tested with Cosmic showers • Reconstruct EMCal jet patches and compare with STU trigger decision • Trigger efficiency • Run jet finding algorithms

Cosmics Run Goals • EMCal calibration - Main tasks for “Analysis” folks • Demonstrate calibration procedures • Set T-corrected APD biases to match gains of 4 SMs • LED and/or Temperature measurement gain corrections • Use cosmic mip peak to confirm calibration • Establish procedures for improving absolute tower calibration factors

EMCal Calibration • Energy Calibration: For each tower j • Ej(GeV) = a0 x bjN x cj(t) x H/Lj x (ADCj - PEDj) • Cj(t): time-dependent calibration factor • Determined from LED and/or T measurements • c(t) = LED(t)/LED(t0): Choice of t0 is arbitrary, but it must correspond to a given bN. Ideally choose c(t0)=1. Natural to choose t0 with first LEDs after installation. • Prefer to use LED since it will track ALL gain changes, not just T-induced, but we need to be able determine cj(t) from T alone (missing LED data, weak LED towers,… • Need to determine cj(t) in real time, store in DB, use immediately for tower energy calibration - This is one of the most important tasks to demonstrate to be ready with Cosmics Run.

EMCal Calibration • Energy Calibration: For each tower j • Ej(GeV) = a0 x bjN x cj(t) x H/Lj x (ADCj - PEDj) • bjN: Individual tower calibration factor • bj0Determined from initial Cosmics calibrations • We should make a first iteration bj1 immediately to correct bj0 from T at time of Cosmics calibration to nominal T in ALICE. Needs to be done pre-Cosmics run. • Subsequent iterations based on 0 mass peak (most likely) for one of two gammas centered on tower. This code should be running “online” after c(t) corrections. • A goal of the Cosmics Run would be to compare mip peaks in neighboring towers to check initial calibrations. Probably should not make a new overall mip correction based on cosmics run data due to trigger and geometrical biases. • Care needs to be taken to keep consistency of bN and c during recalibration iterations.

EMCal Calibration • Energy Calibration: For each tower j • Ej(GeV) = a0Nx bjN x cj(t) x H/Lj x (ADCj - PEDj) • a0N overall calibration factor • Nominal GeV/channel • Use it for an overall scale correction, which may change - • Initially based on understanding of E mip used for cosmics calibrations • Later it may be realized via simulation that m should be slightly adjusted due to detector effects… • H/Lj High/Low gain factor, nominally 16.

EMCal Calibration • Position Calibration: • Warning!!!  mass sensitive to position calibration - how to check position calibration? • PHENIX EMCals found to be ~2cm different from ideal locations, which lead to E calibration error on 0 mass with corresponding error of 10-15% yield. • Use track matching for electrons and hadrons • Use different shower depths of electrons and hadrons to test understanding of position reconstruction • Study Z dependence of residuals between EMCal position projection and reconstructed track incidence position. • Expect different Z dependence for e, h (and )

Summary and Conclusion • Many tasks still to be completed: • Hardware, DCS, commissioning, trigger, Online monitoring, calibration, HLT, etc • Serious need for additional help now • most effective to contribute at CERN. • Most of the work will be (should be) done prior to the start of the Cosmics Run • I.e. now is the time to contribute

EMCal Cosmics Run