Goal: tracking Pt30...50MeVc in heavyion collision .

1
(No Transcript)
2
(No Transcript)
3
(No Transcript)
4
Goal tracking (Pt30...50MeV/c) in heavy-ion
collision .
Beams
. charged track reconstruction for
primary particles in . _at_ low momenta
(MS up to (10-20) mrad per Si layer) pt
gt30MeV/c high multiplicity events
(combinatorial background) .
Horizontal granularity (0.44-1.0)mm .
non-uniform magnetic field for 2D
Spectrometer . _at_ analog read-out
5
How particle is going ?
6
How particle is going ?
7
How particle is going ?
?Banana
8
How particle is going ?

9
MS - Banana
10
Templates and their fitting/parametrization("larg
e plane" case)
j
j
11
Momentum Resolution
12
Track reconstruction steps
13
Comparison to Optimal Track Fitting (OTF)which
reproduces the results of the global LSM fit
B1 Tesla
14
Momentum resolution for SBTM and OTF
15
Vertex Resolution for SBTM and OTF
16
Angular Resolution for SBTM and OTF
17
Residuals for detector with ideal space
resolution, (how close is SBTM model to actual
hits)
18
Silicon Pad detectors for measuring charged
particles (Multiplicity and Tracking/PID)
Plastic Scintillator for Triggering and TOF

• 137,000 Silicon Readout Channels
• 1,300 Scintillator Readout Channels

19
PHOBOS Si Spectrometer _at_RHIC _at_BNL
20
Implementation for real spectrometer with
complex geometry.
Beams
. charged track reconstruction for
primary particles in multi-layer
Tracker with externally provided Vertex
(K.Wozniak) . _at_ low momenta (MS up to
(10-20) mrad per Si layer) pt gt30MeV/c
high multiplicity events (combinatorial
background) . Horizontal granularity
(0.44-1.0)mm _at_ . non-uniform
magnetic field (for 2D Spectrometer) . _at_
analog read-out (!!! _at_ limited granularity !)
21
Multiple Scattering in 300 ?m Si wafer
22
How particles are going ?
23
Essential points
24
Banana Center, ?_banana, ??MScone, P, ??P,
Length, angles
25
(No Transcript)
26
Test Sample for playing ...
27
AultgtAu collision at sqrt(s_NN) 200 GeV
28
3D - event
29
(No Transcript)
30
(No Transcript)
31
Momentum Resolution for MC (PHOBOS)with exact
Vertex
32
N_track vs N_hit for AuAu 200G
33
Computing time for reconstruction vs N_hitsNO
SEEDS. (Xeon 3GHz)
34
(No Transcript)
35
(No Transcript)
36
Conclusions

• Global method for primary track reconstruction
  with narrow search window with potentially
  better parameters resolutions. Robust.
• MC/GEANT based accumulation of Templates (could
  be non-uniform B) (Mean, ? instead of
  Covariance Matrix a priory to reconstruction )
• "Low momentum 80/160/230 MeV/c" tracks could
  be reconstructed in high multiplicity
  events with MS (10...20)mrad/layer.
• Tracks in the Magnet could be reconstructed
  without "Straight Region" planes/seeds)
• Occupancies up to (25-30) (narrow roads) .
• Having Analog Read-out, one could survive in
  high occupancy case.
• Ghost cleaning algorithm based on Analog
  read-out allows many hits sharing
  (Nsh ltNpl-2...3 ,which are close to the end of
  the track)
• Combinatorial i,j sort out is shortened after
  (1-2) "lost hits in planes"
• and because of narrow Banana and String
  widths.
• Could be implemented into Firmware (model is
  close to the hits)

37
(No Transcript)
38
(No Transcript)
39
Double Metal, Single sided, AC coupled,
polysilicon biased detectors produced by ERSO,
Taiwan
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
(No Transcript)