Small_X / 09/17 – 09/20Jorge Barreto – UFRJ The D0 Forward Proton Detector (FPD) Status Jorge Barreto UFRJ/CBPF - Brazil D1 TDC D2 TDC pbar p

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Forward 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 GeV 2 ) where the high t range was never before explored at Tevatron energies  Allows combination of tracks with high-p T scattering in the central detector D S Q2Q2 Q3Q3 Q4Q4 S A1A1 A2A2 P 1U P 2I P 2O P 1D p p Z(m) D2 D Veto Q4Q4 Q3Q3 Q2Q2

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 Status

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ FPD 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 mm U U’ X X’ V V’ Trigger

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Detector Construction At 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 Hits y x 10  u x 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 with up and down detectors installed Detector 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 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 Operations

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Stand-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 A1UA2U P2D P1D P Pbar Halo Early Hits LM VC  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 (mm) X (mm) Reconstructed  beam Initial Reconstruction DØ Preliminary Y (mm) X (mm)

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Spectrometer 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 GeV 2 ; t min 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 Distributions DØ Preliminary

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ TDC 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 t p – t p = 18ns t p – t p = 4ns DØ Preliminary

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ TDC 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 TDC pbar p DØ Preliminary

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ FPD Trigger and Readout – Phase 2

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Standalone 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 x1x1 x2x2 y1y1 y2y2 D0 Preliminary x1x1 x2x2 y1y1 y2y2

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Dipole 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 Preliminary All units in mm  t (GeV 2 ) X1X1 X1X1 X2X2 X2X2 Y1 Y2Y2 Y2Y2 Beam

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ  Shifts ΔY 1 = ΔY 2 =+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 Preliminary Dipole Diffraction Results - II MCData X1X1 X2X2 X1X1 X2X2 Y1Y1 Y2Y2 Y2Y2 Y2Y2  t (GeV 2 ) All units in mm

Small_X / 09/17 – 09/20Jorge Barreto – UFRJ Dipole Diffraction Results - III  Geometrical Acceptance 14σ Data |t| (GeV 2 ) D0 Preliminary Flat-t distribution  |t| (GeV 2 )

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 1000 tagged events expected in Run II DØ Run II Diffractive Topics

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