Processing of 1999 data

1. Processing of 1999 data • 1999Ldt = 2.42 pb-1 • 7.7 × 106f’s collected • 1.1 × 106KSKL tagged by KS p+p- • 6.0 × 105K+K- tagged by vertex • All data reconstructed at acquisition • Analysis executable: • CVS source control • Development history • Version-tagged output

2. Computing resources • All data written to disk in 1 GB files (640 K 1.63 KB evts) • Reconstruction/streaming performed on dedicated farm • Production starts on-line and follows acquisition • Single-CPU job turn-around in 4 hrs FDDI GIGASWITCH FDDI Tape library 6 Magstar drives 15 MB/sec each 40 GB/tape (uncompressed) 5500 slots 220 TB Fast Eth, Gbit Switch ONLINE FARM 7 IBM H50 (4 PPC 604e, 330 MHz) 420 SpecInt95 0.5 TB local disk space (SSA) Fast Eth SCSI Tape server OFFLINE FARM 10 Sun Enterprise 450 (4 UltraSPARCII, 400 MHz) 700 SpecInt95 Fast Eth SCSI Tape server SCSI Gbit Eth Offline farm disk server 2 Sun Enterprise 3500 0.5 TBRAID

3. Overview of offline reconstruction datarec “simplified” flow diagram RAW Translation 5 ms/evt Cluster reconstruction Absolute event t0 Cosmic filter Calibration Bhabhas Background filter DC hit reconstruction DC hit reconstruction 100 ms/evt DC track/vertex recon. DC track/vertex recon. Track-to-cluster assoc. Track-to-cluster assoc. Event classification Dedicated KLKS rp Rad m+m- Bha K+K- UFO

4. Background filters Inefficiency incurred for physics channels • Cosmic ray and machine background filters use complete EmC reconstruction + number of DC hits • Recent changes to filtering algorithms • increase cosmic ray and MB suppression • decrease inefficiency incurred for physics channels • Cosmic filter • suppression raised from 84% to 97% with decreasing physics losses • Machine background filter • suppression highly variable depending on run conditions • 40-90% over all KLOE runs • 50-60% for Dec ’99 data

5. Calorimeter reconstruction ? Improvements to clustering algorithm Improves measurement of p0, h, w masses • Basic clustering algorithm: • cell readout: {EA, EB, TA, TB}i {E, x, y, z, t}i • {x, y, z, t}clust from energy weighted avg. over cells • Missing information  systematically underestimate Eclust • New analysis module: • Uses zclust to get attenuation length correction • Allows EA and/or EB to be summed into Eclust e+e-gg Correction of TDC calibration constants • 1% error on abs. scale for conversion constants (ps/count) • ~60 ps error on prompt TOF • Should improve accuracy of neutral vertex reconstruction

6. Drift chamber reconstruction decay in DC e+e- m+m- decay at IP f  rp KL p+p-p0 KL p+p- KS p+p- KL pln KL pln KL p+p-p0 • Major effort to understand systematics for momentum reconstruction in DC a priori • Ad hoc prescription available for some time Drift chamber geometry Magnetic field map Energy loss corrections Many event samples studied p vs q, Bhabha events dp (MeV/c) p(MeV/c)

7. Drift chamber geometry Vertex fit includes new accounting of materials around interaction point Effect on p vs. q, Bhabha events: OLD: • DC wall: • 650 mm CF + • 50 mm Al • Beam pipe at IP: • Cylindrical p (MeV/c) NEW: • DC wall: • 700 mm CF + • 200 mm Al • Beam pipe at IP: • Spherical q (deg) Stereo angles in reconstruction geometry decreased by ~0.5% Before correction After correction • Effect observed: • 1.5 MeV step in Mmiss(p0) from KL p+p-p0 decaying inside DC (dp 400 KeV)

8. Geometrical adjustments to field map r r z z f f f z z r r r f f g • Various probe alignment errors detected by detailed analysis of trends in field components in raw map: • 10-50 Gauss in Br, Bf • p(q = 20) increased by ~0.7 MeV/c (Bhabha events) Measurement device: Rotating arm with 28 crosses Cross mounting: 6 Hall probes Abs. calib. from NMR probe at r = 0, z = 0 Alignment errors revealed by study of raw field map: Misalignment of probes on cross Gravity-induced torsion on arm Global rotation of arm

9. Saturation of field map Original plan was to run with I = 2660 A Bz = 6 KG Previous reconstruction version: Bz(I = 2660 A) × 2500/2660  Bz(I = 2500 A) ~5.6 6.0 4.5 Comparison of maps at 4.5 and 6 KG shows saturation effects depend on (r,f) and especially z Bz(4.5) – 0.75Bz(6.0) Gauss z mm Bz(I) from NMR probe (r0, z=0) shows non-linearity: ~30 Gauss error in abs. scale of Bz from extrapolation Corrections to Bz using NMR data and maps at 4.5 and 6.0 KG reducep(q) effect to 1 ppt

10. Effect of corrections p (MeV/c) q (deg) Bhabha events KS p+p- ±0.5 MeV/c = dp/p ~ 0.001

11. Energy loss corrections New materials for dE/dx calculation eliminate step in Mmiss(p0) vs. rxy for KL p+p-p0 • Track/vertex fit includes energy-loss corrections in gas/wall using m = mp • 2nd pass to re-track identified K+K- with m = mK in K+K- stream

12. Event classification

13. Event streaming 1.3 KHz cos 40 Hz raw DC recon. Evt. Class bha 10 Hz prescaled cosmic kpm ÷10 ksl 900 Hz 200 Hz EmC recon. MB cosmic Bhahba DC recon. Evt. Class rpi 15 Hz rad clb ÷100 Rates assume typical Dec’99 running conditions flt 190 Hz afl 7 Hz

14. Rates and code optimization • Throughput on 40 CPU offline farm: • Dec ’99 data: 1900 Hz (DBV-2) • L = ~1.7 × 1030 cm-2 s-1 • DC trigger, prescaled cosmics • Aug ’99 data: 2400 Hz (DBV-2) • L = ~1×1030 cm-2 s-1 • no DC trigger, no prescaled cosmics • Work started on CPU optimization • Changes extensive in online reconstruction (monitoring) • Throughput increased by factor of 3! • Some optimizations propagated back to offline reconstruction (work in progress) • DC track fit 46% faster • Reconstruction chain 20% faster

15. Online calibration and monitoring root hist. server • root browser • illumination SWITCH • L3 spies • Bhabha, gg • Cosmic • MIP BUILDER • EMC monitor • t(gg) • E(Bhabha) • MIP • Trigger monitor • trigger performance • background rate • luminosity estimate L3 • DC monitor • cell effic. • residuals • IP, pf monitor raw DAFNE Event display DAFNE Offline monitoring: W, sf, pf OFFLINE Calibration KID

16. Drift chamber online calibration 100% = 400 Hz • DC CHECK • starts automatically every run • integrates 300K cosmics (3 hr) • histograms track-hit residuals • 50 mm residual tolerance EmC recon raw selective filter selcos raw 8% 32 Hz DC tracking • DC CALIB • reconstructs selected evts using residuals (45 evt/sec, ~2hr) • fits s-t relations • stores new calibrations in DB along with DC conditions OK DC CHECK STOP residuals Implemented at script level All reconstruction proceeds with residuals < 50 mm for upcoming data taking GO HepDB DC CALIB

17. Calorimeter online calibration MIP-cosmic run vfib, Dt0, St0, MIP response 24 hrs, every 30-60 days Timing Energy Prescaled cosmics monitor Dt0 online, every run Bhabha events fine equalization by col. update HepDB, online STOP Dt0 shift no gg events Abs energy scale update HepDB, online gg events monitor gbl t0, update DB online, every run gg events fine t0 adj by column 0.5 hr, every 100 nb-1 100 nb-1 yes 100 nb-1 GO

18. Online reconstruction monitor • Bhabha tracks extrapolated to z-axis measure: • position (m) and size (L) of luminous region • machine boost (pf) • Values written to DB, available for analysis Fast versions of reconstruction algorithms run on-line for monitoring L3 Bhabha (+gg) • EMC monitor • Etot, Ecl • Tcl, Tcl-R/c, Tcl-L/v • EgEmC vs. EgDC • for e+e-g EmC + DC reconstruction 65 Hz EmC + DC reconstruction • DC monitor • cell efficiencies • track-hit residuals • IP and boost: m, L, pf L3 cosmic

19. Reconstruction and quality control Many variables continuously monitored during data processing Graphical history interface Web interface

20. Monte Carlo production • Plan to generate and reconstruct ~11M events • Production environment similar to that used for reconstruction: • Same executable used for official reconstruction • Output files are version-tagged, have DB entries • MC production runs on offline farm, or on new Linux farm (to be acquired soon) • Work to be completed: • Not conditioned on data: • precise reconciliation of EmC and DC geometry • introduction of new generators • BABAYAGA (Pavia): Bhabha generator with radiative corrections • EVA (Karlsruhe): e+e-p+p-g generator with ISR+FSR • Conditioned on data: • new field map if next run at IB = 2300 A • finalization of physics program

21. Conclusions • KLOE reconstruction has been thoroughly proven on all fronts: • algorithms, procedures, environment, and monitoring. • Emphasis while waiting for luminosity is on refinements. • New online calibration procedures for upcoming data-taking. • Next step: • Monte Carlo production for studies of efficiencies and systematics • driven by requests from analysis groups.