Processing of 1999 data
1999 L dt = 2.42 pb-1
7.7 × 106 f’s collected
1.1 × 106 KSKL tagged by KS  p+p6.0 × 105 K+K- tagged by vertex
All data reconstructed at acquisition
Analysis executable:
• CVS source control
• Development history
• Version-tagged output
0
Short data-taking periods in Aug, Oct, Nov ’99 at
acquistion (total ~1 pb-1)
1
Main data-taking Dec’99 at acquisition (1.4 pb-1)
Aug, Oct, Nov ’99 data off-line (Feb ’00)
2
Changes to algorithms in this report (DC reconst.)
Currently underway for all data
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
SCSI
Fast Eth
Tape
server
Fast Eth,
Gbit
Switch
220 TB
SCSI
ONLINE FARM
7 IBM H50 (4 PPC 604e, 330 MHz)
420 SpecInt95
0.5 TB local disk space (SSA)
Fast Eth
Tape
server
OFFLINE FARM
10 Sun Enterprise 450
(4 UltraSPARCII, 400 MHz)
700 SpecInt95
Gbit Eth
Offline farm disk server
2 Sun Enterprise 3500
SCSI
0.5 TB RAID
Overview of offline reconstruction
datarec “simplified” flow diagram
RAW
Typical data stream composition, Dec ’99
L = ~1.7  1030 cm-2 s-1  Tot. rate
~1.3 KHz
Translation
Cluster reconstruction
5 ms/evt
Absolute event t0
Cosmic filter
Calibration Bhabhas
Background filter
DC hit reconstruction
DC track/vertex recon.
Unvetoed cosmics
~700 Hz
Prescaled cosmics
~400 Hz
Mach. Bkg + Bhabha < 20°
~200 Hz
Physics (f + Bhabha >
20°)
~15 Hz
DC hit reconstruction
100 ms/evt
DC track/vertex recon.
Track-to-cluster assoc.
Track-to-cluster assoc.
Event classification
Dedicated
K+K-
KLKS
rp
Rad
m+m-
UFO
Bha
Background filters
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
Inefficiency incurred for physics channels
Cosmic filter
1-e
MB filter
1-e
KSKL
0.02%
0.2%
K+K-
2.4%
1.1%
p+pg
0.07%
0.07%
Neutral
Radiative
0.3%
<0.01%
rp
0.2%
<0.04%
Final state
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
Correction of TDC calibration constants
e+e- gg
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
•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
p vs q, Bhabha events
dp (MeV/c)
Many event samples studied
decay in DC
decay at IP
e+em+m-
f  rp
KL  p+p-p0
KL  p+p-p0
KL  p+pKS  p+pKL  pln
KL  pln
p(MeV/c)
Drift chamber geometry
Vertex fit includes new accounting of
materials around interaction point
OLD:
Stereo angles in reconstruction
geometry decreased by ~0.5%
Effect on p vs. q, Bhabha events:
DC wall:
650 mm CF +
50 mm Al
Beam pipe at IP:
Cylindrical
Before correction
After correction
NEW:
DC wall:
700 mm CF +
200 mm Al
Beam pipe at IP:
Spherical
Effect observed:
~ 1.5 MeV step in Mmiss(p0) from KL  p+p-p0
decaying inside DC (dp  400 KeV)
q (deg)
Geometrical adjustments to field map
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:
r
Cross
mounting:
6 Hall
probes
Alignment errors revealed by
study of raw field map:
Misalignment of
probes on cross
Global
rotation
of arm
f
f
r
f
Rotating
arm with
28 crosses
r
Abs. calib.
from NMR
probe at
r = 0, z = 0
r
f
Gravity-induced
torsion on arm
g
Saturation of field map
Original plan was to run with
I = 2660 A 
Bz = 6 KG
~5.6
Previous reconstruction version:
Bz(I = 2660 A) × 2500/2660  Bz(I = 2500 A)
6.0
Bz(4.5) – 0.75Bz(6.0) Gauss
4.5
Bz(I) from NMR probe (r0, z=0)
shows non-linearity:
~30 Gauss error in abs. scale of Bz
from extrapolation
Comparison of maps at 4.5
and 6 KG shows saturation
effects depend on (r,f)
and especially z
z mm
Corrections to Bz using NMR data and maps
at 4.5 and 6.0 KG reduce p(q) effect to 1 ppt
Effect of corrections
KS  p+p-
Bhabha events
±0.5 MeV/c = dp/p ~ 0.001
q (deg)
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+Kstream
Event classification
Retained
Events/nb-1
MB/nb-1
raw
762000
1260
K+K- w/w/o vtx, single K±
recon
1000
33
ksl
KS: chg vtx in DC, KL  EmC, KL p+p-p0, KL 
3p0
KL: KS  p+p-, KS  p0p0
KS pln
recon
6700
190
rpi
rp, p+p-p0 (prompt chg vtx w/ KS veto)
recon
270
6
rad
neutral radiative f decays (prompt neutral energy in EmC)
charged/neutral radiative f decays
recon
720
13
clb
p+p-,
m+ m -
recon
60
1
bha
Golden Bhabhas (5.7 mb)
Large-angle Bhabhas (0.75 mb)
recon
5700
91
Stream
Tagging algorithms/channels
raw
kpm
flt
All events passing FILFO
raw
112000
180
afl
1/100 of events rejected by FILFO
raw
4200
6
cos
1/10 of prescaled trigger cosmics
raw
23000
33
Event streaming
1.3 KHz
cos
raw
DC recon.
prescaled
cosmic
900 Hz
EmC
recon.
Evt. Class
bha
÷10
10 Hz
kpm
ksl
200 Hz
MB
cosmic
40 Hz
Bhahba
DC recon.
rpi
Evt. Class
15 Hz
rad
clb
÷100
Rates assume
typical Dec’99
running
conditions
flt
190 Hz
afl
7 Hz
Rates and code optimization
DBV-1
Algorithm
CPU/call
(ms)
DBV-2
CPU %
of job
CPU/call
(ms)
Throughput on 40 CPU offline farm:
CPU %
of job
Dec ’99 data: 1900 Hz
(DBV-2)
L = ~1.7 × 1030 cm-2
s-1
DC trigger, prescaled cosmics
Overhead
Translation
3.1
12.4
2.9
14.2
EmC recon.
Global t0
1.3
4.9
2.2
10.3
FILFO
Prescale filter
0.4
3.3
0.3
3.8
L =
cm-2 s-1
no DC trigger, no prescaled cosmics
DC track fit
110
67
75
55
Work started on CPU optimization
Other DC recon.
8.0
4.8
10.4
7.4
Track-to-cluster
8.4
4.9
9.9
7.0
Event classific.
1.5
0.9
2.1
1.6
Changes extensive in online reconstruction
(monitoring)
• Throughput increased by factor of 3!
Diagnostics
3.9
1.6
1.0
0.5
Total Rate
Aug ’99 data: 2400 Hz
(DBV-2)
~1×1030
40 Hz
48 Hz
Some optimizations propagated back to offline
reconstruction (work in progress)
• DC track fit 46% faster
 Reconstruction chain 20% faster
Online calibration and monitoring
SWITCH
root hist. server
L3 spies
Bhabha, gg
Cosmic
MIP
BUILDER
raw
Trigger monitor
trigger performance
background rate
luminosity estimate
root browser
illumination
EMC monitor
t(gg)
E(Bhabha)
MIP
L3
DC monitor
cell effic.
residuals
IP, pf monitor
DAFNE
Event display
DAFNE
OFFLINE
Offline monitoring: W, sf, pf
Calibration
KID
Drift chamber online calibration
100% = 400 Hz
selcos raw
EmC recon
selective filter
raw
8%
32 Hz
DC tracking
OK
STOP
DC CHECK
residuals
DC CHECK
• starts automatically every run
• integrates 300K cosmics (3 hr)
• histograms track-hit residuals
• 50 mm residual tolerance
DC CALIB
• reconstructs selected evts using
residuals (45 evt/sec, ~2hr)
• fits s-t relations
• stores new calibrations in DB
along with DC conditions
Implemented at script level
GO
DC CALIB
HepDB
All reconstruction proceeds with
residuals < 50 mm for
upcoming data taking
Calorimeter online calibration
MIP-cosmic run
vfib, Dt0, St0, MIP response
24 hrs, every 30-60 days
Timing
Prescaled cosmics
monitor Dt0
online, every run
STOP
Dt0 shift
no
gg events
monitor gbl t0, update DB
online, every run
100 nb-1
gg events
fine t0 adj by column
0.5 hr, every 100 nb-1
yes
Energy
Bhabha events
fine equalization by col.
update HepDB, online
gg events
Abs energy scale
update HepDB, online
100 nb-1
GO
Online reconstruction monitor
Fast versions of reconstruction
algorithms run on-line for monitoring
L3 Bhabha
(+gg)
EmC + DC
reconstruction
EMC monitor
Etot, Ecl
Tcl, Tcl-R/c, TclL/v
EgEmC vs. EgDC
for e+e-g
65 Hz
EmC + DC
reconstruction
L3 cosmic
DC monitor
cell efficiencies
track-hit residuals
IP and boost: m, L, pf
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
Reconstruction and quality control
Rejected rates:
MB, cosmics,
Bhabhas
Bhabha rate:
L dt, L
Event rates, sf:
Bhabha:
W, pf, Etot, E/p,
T-L/c
KSp+p-:
Minv, pK,
c2(dN/dcosq)
K+K-:
KS  p+p-,
p 0 p 0 , KL 
Minv,
EmC, f  rp,
pm(Kmn),
+
f K K
pp(Kpp0)
Web interface
Many variables continuously monitored
during data processing
Graphical history interface
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
Event type
f
Request
 all
5.0M
f  KS KL
KS  pp; KL  pp
KS  pp; KL  charged
KS  pmn, pen
f  K +K K±  pmn,
1.9M
0.5M
pen
radiative channels
f  p0g, hg,
hg, f0g, a0g
e+e-  m+m-g,
p+p-g, wp0
3.1M
calibration channels
e+e-  e+ee+e-  m+mcosmic rays
0.3M
Total
~11 M
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.