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A recoil detector to measurehard exclusive reaction at HERMES experiment
A recoil detector to measurehard exclusive reaction at HERMES experiment
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Lecture Week on The Physics of Hadrons
and Ultrarelativistic Heavy Ion Collisions
Lecture Week on The Physics of Hadrons
and Ultrarelativistic Heavy Ion Collisions
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OutlineOutline
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
• Motivation– DESY & HERA– Spin of the Nucleon
• DVCS & BH• HERMES
– End of polarized gaz Target– Hermes Recoil Detector
• Design Requirement• Recoil Detector
– Silicon Strip Detector (SSD)– Scintillating Fiber Tracker (SFT) – Photon Detector (PD)
• SFT Performance
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DESY @ Hamburg - GermanyDESY @ Hamburg - Germany
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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HERA @ DESYHERA @ DESY
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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Spin of the NucleonSpin of the Nucleon
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Naïve parton modelNaïve parton model
43 vu 1
3 vdBUTBUT
1989 EMC measured1989 EMC measured = 0.120 0.094 0.138= 0.120 0.094 0.138± ±
Spin PuzzleSpin Puzzle
Unpolarised structure fct.Unpolarised structure fct.
Gluons are important !Gluons are important !
Sea quarks Sea quarks qqss
GG
Full description of JFull description of Jqq and J and Jgg
needsneedsorbital angular momentumorbital angular momentum
1 1( )
2 2 v vu d 1 1
( )2 2 v gsv qLd LGqu
1 1( )
2 2 v svu q Gd
( ) s su d u d s s
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The hunt for LThe hunt for L
Study of hard Study of hard exclusive processesexclusive processes leads to leads toa new class of PDFsa new class of PDFs
GGeneralized eneralized PParton arton DDistributionsistributions , , ,
qqq q HH EE
exclusive:exclusive: all products of the reaction are detected all products of the reaction are detected missing energy (missing energy (E) and missing Mass (ME) and missing Mass (Mxx) = 0) = 0
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
possible access topossible access toorbital angular momentumorbital angular momentum
1
1 0
1
2q
t
HJ Exdx
1
2q qLJ
from DIS:from DIS:HERMES ~0.3HERMES ~0.3
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isolate isolate BH-DVCS interferenceBH-DVCS interference term non-zero azimuthal asymmetries term non-zero azimuthal asymmetries
DVCSDVCS Bethe-Heitler (BH)Bethe-Heitler (BH)
HERMES kinematics:HERMES kinematics:BH c.s. >> DVCS c.s.BH c.s. >> DVCS c.s.
DVCS & BHDVCS & BH
p + p +
two experimentally undistinguishable processes:two experimentally undistinguishable processes:
* 2 2*~ | | | |BH DVCS DVC BS HB DVCSHd
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
HERMES HERMES
•The Missing mass resolution of the Hermes is not sufficient to identify exclusive events individually and separate to them
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End of Polarized targets at HERMESEnd of Polarized targets at HERMESDVCS exclusivity by missing mass MDVCS exclusivity by missing mass Mxx
Improve ExclusivityImprove Exclusivity
Detect recoiling protonDetect recoiling protonmodify target regionmodify target region
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Detector to measure recoiling protonDetector to measure recoiling proton
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detection of the recoiling protondetection of the recoiling proton
P: 135 – 1500 MeV/cP: 135 – 1500 MeV/c
76% 76% acceptance acceptance
/p PID via dE/dx/p PID via dE/dx
background suppressionbackground suppression
semi-incl.: 5 %semi-incl.: 5 %associated: 11% associated: 11%
improved t-resolutionimproved t-resolution
study kinematical study kinematical dependencesdependences
data taking 2006/2007data taking 2006/2007
HERMES Recoil DetectorHERMES Recoil Detector
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Build by DESY, Erlangen, Ferrara, Frascati,Build by DESY, Erlangen, Ferrara, Frascati,Gent, Gent, GießenGießen and Glasgow and Glasgow
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Silicon Strip Detector (SSD) Silicon Strip Detector (SSD)
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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Scintillating Fiber Tracker (SFT)Scintillating Fiber Tracker (SFT)
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
p-measurement 300-1500 MeV/c π/p PID from dE/dx for p<700 MeV/c 2 cylinders of 2x2 layers, 10° stereo angle 1mm Kuraray fibers, mirrored ends and double cladding PMT Hamamatsu H7546B
5120 channels total full Ф coverage
Remove edge fibers
42 (36) inner (outer) modules
1318 (1320) fibers in inner parallel (stereo) sub-barrel
2198 (2180) fibers in outer parallel (stereo) sub-barrel
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Scintillating Fiber Tracker (SFT)Scintillating Fiber Tracker (SFT) Space point reconstruction
Parallel & stereo configuration High detection efficiency
Double fiber layer per sub-barrel MIP signal separated from noise
Spacial resolution σ V Multiple scattering limits resolution
1mm fiber sufficient Minimise suport structure
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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Photon DetectorPhoton Detector
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Detect f ´s from ∆ resonnance
Reconstruction if both decay f ´s detected
Contribute to the pion/proton PID separation (together with SFT) for p> 600 MeV/c
MIP signal are far away from pedestal
multilayer construction with parallel and stereo strips
Cosmic trigger generator
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Photon DetectorPhoton Detector
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
6 layer (inside out) 6mm Tungsten A layer: 60 strips along z axis 3mm Tungsten B layer: 44 strips -45° stereo angle 3mm Tungsten C layer: 44 strips +45° stereo angle
2 WLS on both side of each strips
radius 20cm dimensions of strips 2cm x 1.1cm x 28cm
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Recoil Detector - installationRecoil Detector - installation
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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SFT Current StatusSFT Current Status
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Clear hit in SFT with low background
of course subject to optimization but nevertheless the SFT detector worked from the beginning as expected
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
SFT CallibrationSFT Callibration
Callibration data (blue LED pulser) from Gießen test was re-fitted with Poisson & Gauß fit
Gain (extracted from fit) vs. high voltage
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
SFT Origins of CrosstalkSFT Origins of Crosstalk
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
SFT Crosstalk CorrectionSFT Crosstalk Correction Tracklet Algorithm: combine
signal in adjacent fibers into one cluster.
Cluster Algorithm: search for the hightest signal, then add the signal of the PMT channels left, right, up and down.
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SFT Crosstalk & Clustering SFT Crosstalk & Clustering
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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SFT perfect agreement between MC and data SFT perfect agreement between MC and data
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Digitization carfully improved
reasonable energy reponse of the SFT
MC and cosmics data agree perfectly
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
SFT Gain Correction & TDC cut SFT Gain Correction & TDC cut
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Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
More positive More positive
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Summary and Outlook Summary and Outlook
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
• Silicon – Hardware not yet in perfect shape– Some more time needed– Need to understand data
• Scintillating Fiber Tracker– Fine calibration – Crosstalk correction and Clustring– π/p PID from dE/dx
• Photon Detector – Comparision with MC for energy
deposition need more investigation– Crosstalk in PMT
ENDEND
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Extra Extra
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Extra Extra
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Extra Extra
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Extra Extra
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Extra Extra
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Extra Extra
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SFT CrosstalkSFT Crosstalk
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
h1,2,3,4
h
=
=+h2 h3 h4h1 ++h +
+h2 h3 h4h1 ++h +
h1,2,3,4
+h2 h3 h4h1 ++
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Extra Extra
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Extra Extra
Extra
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Extra Extra
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Extra Extra
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Extra Extra
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Extra Extra
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Extra Extra
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Design RequirementDesign Requirement
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
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SSD Current Status SSD Current Status
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
• SFT only track Prediction for Hits in SSD SFT integrates over several bunches TDC cut
•Each hit used in track needs to have one correct timestamp
•Good tool for alignment
• P and N side different gain.
Signal on N side cut off
Hardward not yet in perfect shape.
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Photon DetectorPhoton Detector
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
Roberto Francisco
Perez Benito
Hyytiälä, 25 -30 September 2006
• Require exactly 1 lepton in Spectrometer with cut on momentum (and coplanarity)
• Require lepton momentum in [25.5-27.6552](GeV/c)
• In addition proton momentum > 1.2 GeV/c
• Fine calibration