small_x / 09/17 – 09/20jorge barreto – ufrj the d0 forward proton detector (fpd) status jorge...
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Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
The D0 Forward Proton Detector (FPD) Status
The D0 Forward Proton Detector (FPD) Status
Jorge Barreto
IF – UFRJ/CBPF
D1 TDC
D2
TD
C
pbar
p
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Forward Proton Detector LayoutForward Proton Detector Layout
9 momentum spectrometers comprised of 18 Roman Pots
Scintillating fiber detectors can be brought close (~10 mm) to the beam to track scattered protons and anti-protons
Reconstructed track is used to calculate momentum fraction and scattering angle
– Much better resolution than available with gaps alone Cover a t region (0 < t < 4.5 GeV2) where the high t range
was never before explored at Tevatron energies Allows combination of tracks with high-pT scattering in the
central detector
D SQ2Q3Q4S A1A2
P1U
P2I
P2O
P1D
p p
Z(m)
D2 D1
233359 3323057
VetoQ4Q3
Q2
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
FPD Detector SetupFPD Detector Setup
6 planes per detector in 3 frames and a trigger scintillator
U and V at 45 degrees to X, 90 degrees to each other
U and V planes have 20 fibers, X planes have 16 fibers
Planes in a frame offset by ~2/3 fiber
Each channel filled with four fibers
2 detectors in a spectrometer
0.8 mm
3.2 mm
1 mm
17
.39 m
m
17.39 mm
UU’
XX’
VV’
Trigger
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Detector ConstructionDetector ConstructionAt the University of Texas, Arlington (UTA), scintillating and optical fibers were spliced and inserted into the detector frames.
The cartridge bottom containing the detector is installed in the Roman pot and then the cartridge top with PMT’s is attached.
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Segments to HitsSegments to Hits
yx
10
ux
v
Segments
(270 m)
Combination of fibers in a frame determine a segment
Need two out of three possible segments to get a hit– U/V, U/X, V/X
• Can reconstruct an x and y
Can also get an x directly from the x segment
Require a hit in both detectors of spectrometer
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
All 6 castles with 18 Roman pots comprising the FPD were constructed in Brazil, installed in the Tevatron in fall of 2000, and have been functioning as designed.
A1 Quadrupole castle installed in the beam line.
Castle StatusCastle Status
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
• 10 of the 18 Roman pots have been fully instrumented with detectors
• Funds to add detectors to the remainder of the pots have recently been obtained from NSF.
• During the shutdown (Sep-Nov. 2003), the final eight detectors and associated readout electronics are being installed.
P2 Quadrupole castle withup and down detectors installed
Detector StatusDetector Status
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Castle DesignCastle Design
50 l/s ion pump
Beam
Worm gear assembly
Step motor
Detector
• Constructed from 316L Stainless Steel• Parts are degreased and vacuum degassed• Vacuum bettter than 10-10 Torr• 150 micron vacuum window• Bakeout castle, THEN insert fiber detectors
Thin vaccum window
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Pot motion is controlled in the DØ Control Room via a Python program that uses the DØ online system to send commands to the step motors in the tunnel.
The software is reliable and has been tested extensively. It has many safeguards to protect against accidental insertion of the pots into the beam.
Pot Motion SoftwarePot Motion Software
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
• Currently FPD pots are inserted in every store• Commissioning integrated FPD • Have some dedicated FPD triggers, more when TM operational• Working towards automated pot insertion
OperationsOperations
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Stand-alone DAQStand-alone DAQ
•In phase I we used a stand-alone DAQ (2000 engineering run).
•We build the trigger with NIM logic using signals given by our trigger PMT’s, veto counters, DØ clock, and the luminosity monitor.
•If the event satisfies the trigger requirements, the CAMAC module will process the signal given by the MAPMT’s.
•With this configuration we can read the fiber information of only two detectors, although all the trigger scintillators are available for triggering.
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
In-time hits in AU-PD detectors, no early time hits, or LM or veto counter hits
A1U A2U
P2DP1D
P
Pbar Halo Early Hits
LMVC
bp
bfpxp
bpp
Over 1 million elastic trigger events taken with stand-alone DAQ
About 1% pass multiplicity cuts
–Multiplicity cuts used for ease of reconstruction and to remove halo spray background
Quadrupole Elastic Data
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
=p/p should peak at 0 for elastic
events!!Dead Fibers due to cables that have since been fixed
P1D
P2D
beam
Y
X
Y
Reconstructed
beam
Initial ReconstructionInitial Reconstruction
DØ Preliminary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Spectrometer AlignmentSpectrometer Alignment
Good correlation in hits between detectors of the same spectrometer but shifted from kinematic expectations– 3mm in x and 1 mm in y
P1D x vs. P2D x (mm) P1D y vs. P2D y (mm)
DØ Preliminary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
t distribution
Before alignment
After alignment
Gaussian fit
After alignment correction, peaks at 0 (as expected for elastics); MC resolution is 15% lower (including z smearing and dead channels) than data
The t distribution has a minimum of 0.8 GeV2; tmin is determined by how close the pots are from the beam, shape is in rough agreement with expected angular acceptance from MC.
FPD is also a tool helping BD
Elastic Data DistributionsElastic Data Distributions
DØ Preliminary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
TDC Timing from Trigger PMTsTDC Timing from Trigger PMTs
From TDCs :
18ns = (396ns – L1/c) – L1/c
4ns = (396ns – L2/c) – L2/c
L1 = 56.7 m; L2 = 58.8 m
Tevatron Lattice:
L1 = 56.5m; L2 = 58.7m
TOF: 197ns 190ns
tp – tp = 18ns
tp – tp = 4ns
DØ Preliminary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
TDC ResolutionTDC Resolution
Can reject proton halo at dipoles using TDC timing
Can see bunch structure of both proton and antiproton beam
1ns ~ 4 TDC channels
D1 TDC
D2
TD
C
pbar
p
DØ Preliminary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
FPD Trigger and ReadoutFPD Trigger and Readout
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Standalone Readout vs. AFE ReadoutStandalone Readout vs. AFE Readout Standalone Readout No TDC cut
– such cut removes lower correlation in y plot
Diffracted pbars fall in upper correlation of y plot
Uses a trigger based on particles passing through trigger scintillators at detector locations
AFE readout Similar correlations Uses trigger:
– one jet with 25GeV and North luminosity counters not firing
This trigger suppresses the halo band
D0 Prelim
inary
D0 Prelim
inary
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Resolution of Noise problem with AFEResolution of Noise problem with AFE
Moving to AFE readout required use of a Transition Patch Panel
Noticed large rms values with this setup
Traced to a capacitive coupling between grounds
Isolating one of the grounding planes fixes the problem
14A6
0
10
20
30
40
50
60
70
80
90
100
1 39 77 115 153 191 229 267 305 343 381 419 457 495
channel
AF
E c
ou
nts
rms
mean
14A6
0
10
20
30
40
50
60
70
80
90
100
1 39 77 115 153 191 229 267 305 343 381 419 457 495
channel
AF
E c
ou
nts
rms
mean
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Dipole Diffraction Results - AlignmentDipole Diffraction Results - Alignment
Raw data sample has 4640 events
Reconstruction of ~50% of events
Hit patterns: Misalignment?
Hit correlations: pbar halo?
Poor and t distributions
D0 Prelim
inary
All units in mm
t (GeV2)
X1
X1 X2
X2
Y1
Y1 Y2
Y2
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Shifts ΔY1= ΔY2=+2mm
Cut the pbar blob (X2 > -14mm)
Fair agreement between MC and Data
More realistic and t distributions
Allow to study vs t correlation
D0 Prelim
inary
Dipole Diffraction Results - II
MC DataX1
X2X1
X2
Y1 Y2
Y2
Y2
t (GeV2)
All units in mm
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Dipole Diffraction Results - IIIDipole Diffraction Results - III
Geometrical Acceptance 14σ Data
|t| (GeV2 )
D0 Prelim
inary
D0 Prelim
inary
Flat-t distribution
0.
0.02
0.06
0.04
0.08
|t| (GeV2 )
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Run II Diffractive Z → µµ candidate
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
E
Soft Diffraction and Elastic Scattering: Inclusive Single Diffraction
Elastic scattering (t dependence)
Total Cross Section
Centauro Search
Inclusive double pomeron
Search for glueballs/exotics
Hard Diffraction: Diffractive jet
Diffractive b,c ,t , Higgs
Diffractive W/Z
Diffractive photon
Other hard diffractive topics
Double Pomeron + jets
Other Hard Double Pomeron topics
Rapidity Gaps: Central gaps+jets
Double pomeron with gaps
Gap tags vs. proton tags
Topics in RED were studied
with gaps only in Run I
<100 W boson events in Run I, >1000tagged events expected in Run II
DØ Run II Diffractive TopicsDØ Run II Diffractive Topics
Small_X / 09/17 – 09/20Jorge Barreto – UFRJ
Summary and Future PlansSummary and Future Plans Run II analysis still in early stages
Early FPD stand-alone analysis shows that detectors work
FPD now integrated into DØ readout
Commissioning of FPD and trigger in progress
Gap results in Run II not yet approved
Full 18 pot FPD will start taking data after shutdown (12/03)
Tune in next year for first FPD physics results