DD THE FORWARDTHE FORWARDPROTON PROTON DETECTORDETECTOR AT DZERO AT DZERO
Gilvan Alves Lafex/CBPF
1) MOTIVATION
2) DETECTOR OPTIONS
3) FPD R&D
4) OUTLOOK Lishep 98
Lafex/CBPFFeb 17, 1998
ion Collaborat OD
DD
pBeam pF
P2)( FBeam PPt
P
Pxp
1
sM x
Diffractive Kinematics
Rapidity Gap Approach Need to Tag and Measure p( p )
p p
Detector
DD
DETECTOR GOALSDETECTOR GOALS
• Position resolution of 100µm
• Efficiency close to 100%
• Radiation Hardness
•High Rate capability
• Low background rate
• Small dead area close to the beam
DDACCEPTANCEQuadrupole ( p or )p
Dipole ( only)p
Dipole acceptance better at low |t|, large Cross section dominated by low |t| ||6/ tedtd
0 0.02 0.04 1.4 1.4 1.3 2 35 95
(%)AQuadrupole Dipole
MX (G
eV)
450
400
350
280
200
GeV2
GeV2
450
400
350
280
200
MX (G
eV)
Geo
met
ric
A
ccep
tan
ce
DD
DETECTOR OPTIONSDETECTOR OPTIONS
Detector Pro Con
Silicon SuperiorResolution
Dead AreaTrigger
MSGC GoodResolution
Dead Area
Fiber AdequateResolution
Light Out.
DD
photonageneratetoenergyeffectivetheisE
efficiencyquantumfiberscitheisQ
efficiencyconversionlightfiberscitheisC
corefibertheofvolumefractionaltheisV
fibertheinparticletheoflengthpatheffectivetheisx
where
E
QCVx
dx
dE
eff
s
s
eff
ssY
nAttenuatioFiberA
EfficiencyTrappingF
YieldInitialY
AFYY
YYieldLight
.
.
)(0
0
0
04.0
1
)(
DD
Photon Detection DeviceQuantum Efficiency Light Charge
• VLPC ( 80%)• APD ( 70%)• Image Intensifier CCD ( 20%)
Low rate • MAPMT ( 20%)
VLPC the best optionBut... cryogenics$$$
DD
DETECTOR OPTIONSDETECTOR OPTIONS
Fiber Options Investigated
Scint. Tile to Clear Fiber
Scint. Tile to WLS Fiber
Scint. Fiber Straight
Scint. Fiber to Clear Fiber
Round vs. Square Fibers
DD
DETECTOR OPTIONSDETECTOR OPTIONS
Scint Tile800m thick
Clear Fiber
Scint Tile800m thick
WLS fiber
4fibers PMT
2 WLS fibers PMT
DD
DETECTOR OPTIONSDETECTOR OPTIONS
Scint Fibers800m
Scint Fibers800m
Clear fiber
Mirrored side
Mirrored side 4fibers PMT
4fibers PMT
DD
DETECTOR OPTIONSDETECTOR OPTIONS
Square Fibers Increase
light Yields by 20%
Scint. Tile to Clear Fiber or
WLS discarded for low yield
Reduce Pot Size Using tilted
planes (U,V)
Fiber bend does not affect
performance(limited to = 5cm)
DD
Similar to Uncut Straight FibersGain Attenuation length Losses due to• Cutting Fiber at 45 (5%)• Fiber Splicing (5-10%)
# Preferred Option • Accelerator Background• Cross Talk
Scint. Fiber+ Clear Fiber
OutputH6568
<NPE>=7.4
DDCross Talk ResultsH6568 1.3mm window thickness
Improved by new 0.8mm window
0.4 0.6 0.3 *
1.2 100 2.2 *
0.4 1.0 0.3 *
* 0.08 * *
Using Scintillating Fibers w/oEMA => 25% increase
DDEfficiency MeasurementUse 106
44Ru 3.5 MeV e- Source
Source
Collimator
D
T1T2
D - Detector Cell T1&T2 - Trigger Scintillators
= 90-95%(not corrected for background)
DD
Six planes(u,u’,v,v’,x,x’)of 800 scintillatorfibers (’) planesoffset by 1/3fiber
THE DETECTOR
20 channels/plane(U,V)’16 channels/plane(X,X’)112 channels/detector2016 total channels80 teor. resolution
DD
4 Fiber bundlefits well thepixel size ofH6568 16 Ch.MAPMT
7 PMT’s/detector(most of the cost)
THE DETECTOR
UU’