John Marshall, 1 John Marshall, University of Cambridge LCD WG6 Meeting, February

John Marshall, 2 Overview For latter half of 2010, CLIC studies used CLIC_ILD_01 model and stable reconstruction code from Ilcsoft v01-09/v With this stability, we were able to perform a number of important validation studies and become quite comfortable with the software (PandoraPFA very well validated during this time). However, in the past month, a large number of changes have been made to the software to address issues of overlaid background and features of the new CLIC_ILD_CDR model. Now aim to perform a high-level validation of these changes to check that software is of the required standard for the CLIC CDR studies. Results in this talk correspond to 64-bit gcc builds of Ilcsoft v01-10 and v01-11-pre02. CLIC_ILD_CDR sample consisted of the following Z  uds events: 91GeV: 9,000 events, process id: GeV: 10,000 events, process id: GeV: 10,000 events, process id: 124 1TeV: 5,000 events, process id: 123 Plus, samples of similar size and specification for CLIC_ILD_01.

John Marshall, 3 Baseline, CLIC ILD 01 Consider results for CLIC_ILD_01 model with Ilcsoft v01-10 as baseline for these validation studies. This represents most recent point at which, I believe, we understood our reconstruction software. PandoraPFA is a special case; in every single validation job, I used the latest Pandora packages and settings. EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_01, v01-10: rms 90 (E j ) / E j 3.42 ± ± ± ± 0.06

John Marshall, 4 CLIC ILD 01, “old config” To add complexity to the validation, recent changes to reconstruction software actually involve adoption of new Marlin processors: Overlay, CLICCDRMaterialDB, NewFTDDigiProcessor, ILDCaloDigi, SiliconTrackingCLIC To try to isolate changes to upgraded packages from use of brand new software, I ran some jobs termed as “old config”, in which the Ilcsoft v01-10 scripts and choice of Marlin processors were used with the Ilcsoft v01-11 tagged packages. Noticed that (for 64-bit build) must use gfortran FORTRAN compiler for MarlinReco in preference to g77 (passing of variables between C++/FORTRAN fails and tracks are lost). EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_01, v01-10, old config3.42 ± ± ± ± 0.06 CLIC_ILD_01, v01-11, old config3.40 ± ± ± ± 0.06

John Marshall, 5 CLIC ILD 01, “new config” Quickly notice degradation in performance of jet energy reconstruction: investigation shows that the degradation can be traced to the calo hit digitization processor and the move from NewLDCCaloDigi to ILDCaloDigi. Impact of changing digitization, and the timing cuts applied in the new processor, are magnified by the subsequently incorrect calibration constants passed to Pandora. Understand that calibration has an impact and that the timing cuts are important, but possible more is going on. Noticed that, if steering parameters UseECalTiming/UseHCalTiming are disabled, further degradation occurs (large effect at high energies). EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_01, v01-10, old config3.42 ± ± ± ± 0.06 CLIC_ILD_01, v01-11, old config3.40 ± ± ± ± 0.06 CLIC_ILD_01, v01-11, new config3.71 ± ± ± ± 0.06 Next step: process the CLIC_ILD_01 samples using v01-11 and the latest v01-11 steering files, from:

John Marshall, 6 CLIC ILD CDR The motivation for these tests was to isolate the impact of changes to the detector. Tried to remove impact of calibration, by applying “official” calibration constants for relevant detector. When moving from CLIC_ILD_01 to CLIC_ILD_CDR, see an overall small degradation in the jet energy reconstruction performance. Not unexpected. EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_01, v01-10, old config3.42 ± ± ± ± 0.06 CLIC_ILD_01, v01-11, old config3.40 ± ± ± ± 0.06 CLIC_ILD_01, v01-11, new config3.71 ± ± ± ± 0.06 CLIC_ILD_CDR, v01-11, old config3.56 ± ± ± ± 0.05 CLIC_ILD_CDR, v01-11, new config3.74 ± ± ± ± 0.06 Next, move to examination of CLIC_ILD_CDR samples, with Ilcsoft v01-11, using both new and old steering file configurations:

John Marshall, 7 CLIC ILD CDR  (truncated width) for reconstructed energy distributions as a function of |cos  | CLIC_ILD_CDR, v01-11, new configCLIC_ILD_01, v01-10, old config

John Marshall, 8 Overlay Aim to add Overlay processor to standard steering files, so that only difference between overlay and non-overlay reconstruction is specified number of background events. EjEj 45GeV100GeV250GeV500GeV No Overlay3.74 ± ± ± ± 0.06 Overlay, NBackgroundEvents=  3.72 ± For 45GeV jets, find that the Overlay processor actually produces a small improvement in reconstructed jet energies. It seems that the Ilcsoft v01-11 version of the processor leaks memory; unable to reconstruct higher energy samples. Running Overlay alone on.slcio files, see that memory usage quickly swells to multiple GB. If this has yet to be resolved, will need to investigate with Valgrind memcheck tool, etc.

John Marshall, 9 CLICTrackSelector Included in new reconstruction software is a new Marlin processor, the CLICTrackSelector. This processor aims to filter out tracks that shouldn’t be considered by the subsequent reconstruction, including PandoraPFA. Reconstructed tracks are selected based on the number of Si hits and the time taken for the track to reach the ECAL. EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_CDR, v01-11, new config3.74 ± ± ± ± 0.06 CLICTrackSelector, 100ns cut3.79 ± ± ± ± 0.06 CLICTrackSelector, 50ns cut3.90 ± ± ± ± 0.06 CLICTrackSelector, 20ns cut4.24 ± ± ± ± 0.06 Results reveal that initial decision of a 20ns cut on arrival time at the ECAL is perhaps too tight. Scanning a few other possibilities, select 50ns as preferred value for further tests.

John Marshall, 10 CLICTrackSelector Sum of selected pfo energies for 200GeV Z  uds events in barrel region, |cos  | < 0.7  (truncated width) for reconstructed energy distributions as a function of |cos  | 100GeV jets

John Marshall, 11 CLICPfoSelection The CLICPfoSelection processor is not included in the Ilcsoft pre-release, but should be available soon. A Pandora algorithm that produces the same functionality is available. The processor filters the output from the Pandora reconstruction, applying a number of timing and p T cuts to photons, neutral hadrons, charged hadrons and tracks without associated clusters. EjEj 45GeV100GeV250GeV500GeV CLIC_ILD_CDR, v01-11, new config3.74 ± ± ± ± 0.06 CLICTrackSelector, 50ns cut3.90 ± ± ± ± 0.06 CLICPfoSelection, loose4.40 ± ± ± ± 0.06 CLICPfoSelection, default5.18 ± ± ± ± 0.06 CLICPfoSelection, tight6.00 ± ± ± ± 0.06 Some further tuning may help reduce degradation of jet energy reconstruction. The addition of this new processor does complete the reconstruction chain for CLIC_CDR.

John Marshall, 12 CLICPfoSelection Sum of selected pfo energies for 200GeV Z  uds events in barrel region, |cos  | < 0.7  (truncated width) for reconstructed energy distributions as a function of |cos  | 100GeV jets