Processing of 1999 data
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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

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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 classification

    Event classification


    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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