Transcript The Forward Vertex Upgrade Detector for PHENIX Sergey Butsyk for the PHENIX Collaboration

The Forward Vertex Upgrade
Detector for PHENIX
Sergey Butsyk
for the PHENIX Collaboration
Outline
•
•
•
•
•
Muon Identification in PHENIX
FVTX detector for Muon Arm Upgrade
Displaced vertex muon tagging
Signal to Background improvement
Future Outlooks
PHENIX Detector
• Muon
measurements
– 1.2 < |h| < 2.4
– Two separate arms
in forward and
backward rapidity
• No vertex tracking
– All particles assumed
to come from primary
vertex measured by
Beam-Beam Counter
m+
m-
Space for Vertex upgrade detectors
Muon Sources in PHENIX
Muon ID
Muon Tracker
Absorber
Collision
Muons
Hadrons
• Muon arm consists of several layers of detectors and
hadron absorbers
• Muon candidates consists of
for current analysis
–
–
–
–
Prompt muons
Heavy flavor decay muons
Hadronic (p,K) decay muons
“Punch through” hadrons
Background
Signal
Background
Background
Single Muon Analysis
•
Analysis in p+p and Au+Au suffers
from large hadronic background
•
Strongly relies on hadron
production yields and interaction
cross sections for absorber
material
•
Need to improve background
rejection capabilities
•
No accurate vertex information, all
particles assumes to come from
primary vertex
 Propose to upgrade PHENIX
muon arm with precision tracking
detector
FVTX Muon Arm Upgrade
• 4 discs of Si sensor in acceptance of
each Muon Arm
• 75 mm pitch strips accurately measure
R coordinate of track
• Scheduled to be installed in FY11
FVTX Detector Elements
Backplane
HDI
11.2mm
Detector
FPHX Chips
•
•
•
•
•
•
•
4 disks / side
48 wedges/disk
75 um strips,
2.8-11.2 mm long
1664 strips/column
1.1M channels total
Readout with FPHX chip
2.8mm
Rigid, thermally
conductive epoxy
Rigid epoxy
Design Strategies
prompt
pm
• Fitted track provides a DCA to the primary vertex
(measured by central arm barrel VTX detector)
DCA Performance
300 mm
100 mm
• Tracking uses Kalman fit to all the hits from
FVTX and Muon Arm (also include VTX hits)
DCA for Signal and Background
•
•
•
DCA depends both on decay length
and decay angle
Hadron decays are easy to suppress
due to large decay distance
DCA in f already rejects a significant
portion of hadronic background
fvtx
hadrons
K
D decay
B decay
cm
D
B
Radial DCA and c2 cuts
• Adding FVTX hits into Muon
arm help to remove hadronic
decays between FVTX and
MuTr
• c2/n for those tracks is a clear
cut parameter
hadrons
D decay
D decay
hadrons
B decay
chi2
B decay
Cut
region
cm
• Radial direction is much more precise for
DCA measurement
• B and D meson decay muons produce
asymmetric DCA distributions due to large
decay angle
• Cut on negative DCAr improves S/B
substantially
x 10 improvement
Heavy Quark S/B improvement
•
•
•
Signal to background improves by a factor of
10 over the whole range of measurements
At the same time recover 20-30% after all
the cuts
Both statistical and systematic errors on
Heavy Flavor signal improve due to the
smaller background uncertainties
contribution
Heavy Flavor Signal Expectations
• Error bars show combined systematical and statistical error on
Open Charm single muons
– Red : Year2 p+p results
– Blue : Same data with FVTX detector background rejection
Physics Outlook with FVTX
•
Wide variety of physics probes
can be measured with increased
precision with FVTX detector
– Double spin asymmetry ALL
– Open Charm nuclear modification
factor RAA
– J/y and y’ in p+p and Au+Au
– Muons from W decay
Construction Schedule
2008
2009
2010
2011
2012
VTX
pixels
stripixels
FVTX
R&D Phase
Construction Phase
Ready for Data
• Barrel VTX construction well underway
– pixel layers completion in 2009
– stripixels completion in 2010
• FVTX detector construction started in
FY08, installation to be in 2011
Conclusions
• FVTX detector upgrade significantly improves
hadronic background rejection for all muon arm
physics observables
• Tagging displaced vertexes of Heavy Flavor semileptonic decays with FVTX detector is a feasible task
• S/B for the Open Charm and Open Bottom single
muons improves by a factor of 10 while leaving a large
portion 20-30% of the signal after the cuts
• Detector is approved by DOE for construction (starting
April 08) and planed to be put into operation in FY11