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Processing of 1999 data.  1999 L dt = 2.42 pb -1 7.7 × 10 6 f ’s collected 1.1 × 10 6 K S K L tagged by K S  p + p - 6.0 × 10 5 K + K - tagged by vertex All data reconstructed at acquisition. Analysis executable: CVS source control Development history Version-tagged output.

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processing of 1999 data
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
computing resources
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

overview of offline reconstruction
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

background filters
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
calorimeter reconstruction
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
drift chamber reconstruction
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)

drift chamber geometry
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)
geometrical adjustments to field map
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

saturation of field map
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

effect of corrections
Effect of corrections

p (MeV/c)

q (deg)

Bhabha events

KS p+p-

±0.5 MeV/c = dp/p ~ 0.001

energy loss corrections
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
event streaming
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

rates and code optimization
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
online calibration and monitoring
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

drift chamber online calibration
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

calorimeter online calibration
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

online reconstruction monitor
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

reconstruction and quality control
Reconstruction and quality control

Many variables continuously monitored during data processing

Graphical history interface

Web interface

monte carlo production
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
conclusions
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.
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