APS April Meeting 2001 1
DD
Detector Construction of the Forward Proton Detector at D0
Detector Construction of the Forward Proton Detector at D0
Michael Strang
University of Texas at Arlington
• Diffractive Events• FPD Layout• Detector Construction• Status
APS April Meeting 2001 2
DDDiffractive Event TopologiesDiffractive Event Topologies
2
0
)(1
pbedtd
dtd bt
t
Cross section for elastic scattering can be written as:
This has the same form as light diffracting from a small disk
APS April Meeting 2001 3
DDFPD LayoutFPD Layout
Series of 18 Roman Pots forms 9 independentmomentum spectrometers allowing measurementof proton momentum and angle.
1 Dipole Spectrometer ( p ) min
8 Quadrupole Spectrometers (p or p, up or down,
left or right) t > tmin
Q4D SQ2Q2Q3 Q3Q4S
A1QA1S
A2QA2S
P1Q
P2S
P1S
P2Q
p p
Z(m)
AD2 AD1
Detector B
ello
ws
Roman Pot
233359 3323057
pBeam pF
P
2)( FBeam PPt P
Pxp
1
APS April Meeting 2001 4
DDDetector NeedsDetector Needs
• Position resolution of 100µm– Beam dispersion and uncertainty in beam position
make better resolution unnecessary
• Efficiency close to 100%
• Modest Radiation Hardness- Operates at 8 from beam axis, 0.03 MRad yearly
dose expected
• High Rate capability- Active at every beam crossing
• Low background rate- Insensitive to particles showering along beam pipe
• Small dead area close to the beam- Protons are scattered at very low angles, acceptance
is very dependent on position relative to beam
• Scintillating Fiber detector meets these needs
APS April Meeting 2001 5
DDDetector SetupDetector Setup
4 fiber bundlefits well thepixel size ofH6568 16 Ch.MAPMT
7 PMT’s/detector
17.42 mm activearea
UU’
Six planes(u,u’,x,x’,v,v’)of 800 m scintillatingfibers (’) planesoffset by 2/3fiber
20 channels/plane(U,V)(’)16 channels/plane(X,X’)112 channels/detector18 detectors2016 total channels4 fibers/channel8064 fibers1 250 m LMB
fiber/channel8 LMB fibers / bundle252 LMB bundles80 m theoretical
resolution
APS April Meeting 2001 6
DDDetector ComponentsDetector Components
Fibers •Scintillating fiber is spliced to clear fiber
- Increased halo background with scintillating only- Light output improved due to longer attenuation length
of clear fiber- Cross talk is reduced
• Fibers produced by Bicron- 0.80 mm square multiclad fiber emitting in blue
• Square fiber can only be polished using icepolishing method at FermiLab Lab 7
• After polishing fibers are inspected for deformityand cladding damage and repolished if needed
Scint Fibers800m
Clear fiber
Mirrored side4fibers PMT
APS April Meeting 2001 7
DDDetector Components (II)Detector Components (II)
Frames •Cast at FermiLab Lab 5 plastics shop • Original aluminum machined piece is molded and
production pieces are cast in polyurethane
APS April Meeting 2001 8
DDSplicingSplicing
• Splicing being completed at UTA
• Fibers spliced using a version of the MSUsplicing machine modified for square fibers
• With proper setup, light transmission throughsplice point of over 90% possible
•Afterwards, splice point is sensitive to bendingstresses so care must be taken- Shrink tubing cannot be used to strengthen splice due
to space constraints
APS April Meeting 2001 9
DDConstructionConstruction
• Being completed at UTA• Four fibers are aligned together in the frame to
make a channel• X frame also includes trigger scintillating rod
•Bicron optical epoxy is used to secure the fibers
into the frame once completely assembled• After curing, channels are mapped to appropriate
location in cookie, PMT calibration fibers are included, lengths are measured and final gluing with optical epoxy is done
APS April Meeting 2001 10
DDHit ReconstructionHit Reconstruction
• This event (from Engineering Run data) represents a hit in our detector at the location:
xd = 5.6 ± 0.4 mmyd = 3.8 ± 0.4 mm
APS April Meeting 2001 11
DDStatusStatus
• All fibers and frames have been delivered
• Currently have 7 complete detectors– Working on 8th
– Expect to complete 10 by mid-May
• 10 detectors will be installed this Summer
