Small_X / 09/17 – 09/20Jorge Barreto – UFRJ

The D0 Forward Proton Detector (FPD) Status

The D0 Forward Proton Detector (FPD) Status

Jorge Barreto

UFRJ/CBPF - Brazil

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

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

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

• 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

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 DAQ – Phase 1Stand-alone DAQ – Phase 1

•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

beamY

(mm)

X (mm)

Reconstructed

beam

Initial ReconstructionInitial Reconstruction

DØ Preliminary

Y(mm)

X (mm)

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)

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 Readout – Phase 2FPD Trigger and Readout – Phase 2

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 Uses trigger:

– one jet with 25GeV and North luminosity counters not firing

This trigger suppresses the halo band

Similar correlations

x 1

x2

y 1

y2

D0 Prelim

inary

x 1

x2y 1

y2

D0 Prelim

inary

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

Beam

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