HERAB

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HERA-B
A. Zoccoli Università and INFN - Bologna
PRC open session 16th May 2002
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Outline

• Status of the 2000 data analysis
• Detector and trigger
• present status
• results of 2001 data analysis
• 2002/3 Physics program
• Summary

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Run 2000 Analysis Topics

• Statistics
• Minimum Bias 2 million events (C, Al, Ti, W
  targets)
• DiLepton trigger 0.45 million events DI-?
• 0.90 million events DI-e

? IR 5 MHz
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Minimum Bias V0 production
V0 Cross section
K0s L mass distr.
K0s L nuclear dependence
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Dilepton trig. Prompt J/? (Muon)
Trigger tracks confirmed by reconstruction
PID? likelihood from MUON detector and RICH

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Dilepton trig. Prompt J/? (Electron)
Trigger tracks confirmed by reconstruction
Particle ID E/P bremsstrahlung
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Fraction of J/y from cc
cc ? J/y g
Preliminary results Rcc 0.351 ? 0.077 ? 0.037
(Carbon) Rcc 0.32 ? 0.15 ? 0.03 (Titanium)
In agreement with previous p-N experiments.
In 2002 - First measurement of cc suppression in
nuclear matter. - Study of production ratios
between J/y , cc and Y. - Disentangle the 2 cc
states (?)

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The HERA-B ?(bb) Measurement
Principle of the measurement
Normalization on the inclusive prompt J/? cross
section. ? Systematic error minimization

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The Muon Channel b-cuts
Cuts applied ?z gt 7.5 ?z ?? Imp. Param. to
wire Iw gt 35 ?m ?? Imp. Param. to primary vtx
Ipgt 160 ?m
UNBINNED LIKELIHOOD FIT (due to low
statistics) - Sig. shape from MC, - BKG shape
from data.
Mass spectrum upstream and downstream
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The Electron Channel b-cuts
Cuts applied ?z gt 0.5 cm e? Imp. Param.
wire Iw gt 200 ?m , or Min. dist. _at_ ZW to any
other track gt 250 ?m
UNBINNED LIKELIHOOD FIT (due to low
statistics) - Sig. shape from MC, - BKG shape
from data.
Mass spectrum upstream and downstream
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?(bb) Determination
QCD calculations and experimental results
Simultaneous fit to ee- ??- (in acceptance)
Extrapolation to the Hera-B acceptance
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Summary of 2000 analysis

• The analyses on Dilepton and Minimum Bias data
  taken during the 2000 run are well advanced.
• Understanding of the detector, of the
  efficiencies, of the performances, etc.
• Preparation of the analysis codes in view of the
  2002/3 run.
• ? Papers on bb cross section (almost final),
  production of J/y from cc , V0 production cross
  section and J/y decay spectra are in preparation.

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2002/3 Detector Configuration
Thinner beam pipe 500?m ? 300?m
No magnet tracker! Motivation to reduce
material - Improve calorimeter performance.
e.g. 1.5x better resolution on (?c - J/?) mass
difference - Influence on tracking shown to be
small at 5 - 10 MHz interaction rate. - (being
kept in a safe place in case of possible future
use)
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Status of detector components

• The HERA-B detector was operational in 2000 run.
• Many improvements during the shutdown.
• ? Partially checked in the short run end of 2001.

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Status of First Level Trigger
The First Level trigger was not fully
commissioned in 2000. Low efficiency due to both
trigger and detector performances.

• Main activities
• Optical Links despite large effort, will remain
  the most critical HW item
• Flt Algorithm fully optimized.
• Processor logic fully verified (vector test).
• Detector mapping ready, verification in progress
• Online software improved system
• New RICH multiplicity veto system available

Waiting for data to check the performance !
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December 2001 data
Minimum Bias (int. Trig.) 500k events only
10 hours RUN !
Charged tracks Checks on reconstruction and
alignment, comparison with 2000 data
Inclusive distributions
K0s L mass distr.
KS width already smaller than in 2000!
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December 2001 data - II
Neutrals Checks on reconstruction and
calibration

• ?0 seen in the Outer. After one calibration
  iteration (out of three). Width very close to
  that of 2000.

More data welcome !
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2002/3 Physics Program
Base line physics program for next run A)
Detailed measurement of atomic number dependence
of charmonium production - Extend existing
measurements of J/? and ? to negative xF. -
First measurement of atomic number dependence of
?c. B) Improved bb cross section
measurement -Systematics limit at ? 15
(normalization).- Cross section from full
reconstructed B mesons
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2002/3 Physics Program II
Additional topics - Charmonium spectroscopy
Drell-Yan - Measurement of ? production - Open
charm production - Strangeness production in
nuclear matter - ? polarization

• Expected event yields 2002/3 2000
  J/y ( m e ) 4 106
  1 104 ?c? J/y g
  3 105 1 102 Y
  1 105
  4 101
• Targets primarily C, W (but also installedTi, Al
  Pd)
• Acceptance in the range -0.4 lt xf lt 0.3

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Summary

• The analysis of 2000 data is approaching
  completion.
• Improved performance of the HERA-B spectrometer
  and understanding of the trigger.
• ? first data look promising
• ? trigger ready to be tested
• Physics program very large statistics of
  charmonium states expected in the next run.

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Summary

• HERA-B is anxiously waiting for new data to come.

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Systematic checks (e-channel)
DECAY LENGTH LIKELIHOOD FIT
Different background optimisation
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Status of detector components

• The HERA-B detector was operational in 2000 run.
• Many improvements during the shutdown.
• ? Partially checked in the short run end of 2001.

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