The D 0 Forward Proton Detector FPD Status

The D 0 Forward Proton Detector (FPD) Status D 2 TDC Jorge Barreto UFRJ/CBPF - Brazil pbar p D 1 TDC Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

Forward Proton Detector Layout p p D 2 D 1 59 57 D A 2 33 S A 1 23 Q 4 Q 3 Q 2 Q 3 Q 4 Veto 0 P 1 U S P 2 O P 1 D P 2 I 23 33 Z(m) Ø 9 momentum spectrometers comprised of 18 Roman Pots Ø Scintillating fiber detectors can be brought close (~10 mm) to the beam to track scattered protons and antiprotons Ø Reconstructed track is used to calculate momentum fraction and scattering angle – Much better resolution than available with gaps alone Ø Cover a t region (0 < t < 4. 5 Ge. V 2) where the high t range was never before explored at Tevatron energies Ø Allows combination of tracks with high-p. T scattering in the central detector Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

Castle Status 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. A 1 Quadrupole castle installed in the beam line. Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

FPD Detector Setup Ø 6 planes per detector in 3 frames and a trigger scintillator Ø U and V at 45 degrees to X, 90 degrees to each other 17. 39 mm Ø U and V planes have 20 fibers, X planes have 16 fibers V’ V Trigger X X’ 17. 39 mm U’ U Ø Planes in a frame offset by ~2/3 fiber Ø Each channel filled with four fibers 8 0. m 1 m m m 3. 2 Jorge Barreto – UFRJ mm Ø 2 detectors in a spectrometer Small_X / 09/17 – 09/20

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

Segments to Hits Segments x Ø Combination of fibers in a frame determine a segment (270 m) y Ø Need two out of three possible segments to get a hit – U/V, U/X, V/X 10 • Can reconstruct an x and y Ø Can also get an x directly from the x segment v x Jorge Barreto – UFRJ u Ø Require a hit in both detectors of spectrometer Small_X / 09/17 – 09/20

Detector Status • 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. P 2 Quadrupole castle with up and down detectors installed Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

Pot Motion Software 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. Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

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

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

Quadrupole Elastic Data A 1 U A 2 U LM VC Pbar Halo Early Hits P In-time hits in AU-PD detectors, no early time hits, or LM or veto counter hits P 1 D P 2 D ØOver 1 million elastic trigger events taken with stand-alone DAQ ØAbout 1% pass multiplicity cuts –Multiplicity cuts used for ease of reconstruction and to remove halo spray background Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

Initial Reconstruction Y (mm) Reconstructed beam P 1 D ry na i X (mm) Y (mm) P 2 D beam lim e Ø D Pr = p/p should peak at 0 for elastic events!! Dead Fibers due to cables that have since been fixed Jorge Barreto – UFRJ X (mm) Small_X / 09/17 – 09/20

Spectrometer Alignment P 1 D x vs. P 2 D x (mm) P 1 D y vs. P 2 D y (mm) ry na i lim e Ø D Pr Ø Good correlation in hits between detectors of the same spectrometer but shifted from kinematic expectations – 3 mm in x and 1 mm in y Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

Elastic Data Distributions Before alignment After alignment Gaussian fit t distribution After alignment correction, peaks at 0 (as expected for elastics) The t distribution has a minimum of 0. 8 Ge. V 2; 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 Jorge Barreto – UFRJ DØ Preliminary Small_X / 09/17 – 09/20

TDC Timing from Trigger PMTs tp – tp = 18 ns ry na i Ø D Pr lim e tp – tp = 4 ns TOF: 197 ns 190 ns From TDCs : 18 ns = (396 ns – L 1/c) – L 1/c 4 ns = (396 ns – L 2/c) – L 2/c L 1 = 56. 7 m; L 2 = 58. 8 m Tevatron Lattice: L 1 = 56. 5 m; L 2 = 58. 7 m Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

TDC Resolution Ø Can reject proton halo at dipoles using TDC timing D 2 TDC Ø Can see bunch structure of both proton and antiproton beam pbar p y ar in m Ø 1 ns ~ 4 TDC channels DØ eli r P D 1 TDC Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

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

y 1 x 1 Standalone Readout vs. AFE Readout Ø Standalone Readout Ø No TDC cut ry a in lim e – such cut removes lower correlation in y plot Ø Diffracted pbars fall in upper correlation of y plot Ø Uses a trigger based on particles passing through trigger scintillators at detector locations Pr 0 D – one jet with 25 Ge. V and North luminosity counters not firing Ø This trigger suppresses the halo band Ø Similar correlations y 1 Ø AFE readout Ø Uses trigger: y 2 x 1 x 2 D 0 x 2 Jorge Barreto – UFRJ re P ry a in lim y 2 Small_X / 09/17 – 09/20

Dipole Diffraction Results - Alignment All units in mm Y 2 Y 1 Ø Raw data sample has 4640 events Ø Reconstruction of ~50% of X 1 events X 1 Ø Hit patterns: Misalignment? Ø Hit correlations: pbar halo? 0 D Beam Y 1 ary re P X 2 in lim Y 2 Ø Poor and t distributions Jorge Barreto – UFRJ t (Ge. V 2) Small_X / 09/17 – 09/20

Dipole Diffraction Results - II All units in mm Ø Shifts ΔY 1= ΔY 2=+2 mm Y 1 Y 2 Ø Cut the pbar blob (X 2 > 14 mm) Ø Fair agreement between X 1 MC and Data X 1 MC 0 D Ø More realistic and t distributions X 2 Y 2 ry 2 na X i. Data lim re P Y 2 Ø Allow to study vs t correlation Jorge Barreto – UFRJ t (Ge. V 2) Small_X / 09/17 – 09/20

Dipole Diffraction Results - III Geometrical Acceptance 14σ Flat-t distribution in ry a 0 D lim e Pr Data ry na i lim 0. 08 0. 06 0. 04 D re P 0 0. 02 0. |t| (Ge. V 2 ) Jorge Barreto – UFRJ |t| (Ge. V 2 ) Small_X / 09/17 – 09/20

Run II Diffractive Z → µµ candidate Jorge Barreto – UFRJ Small_X / 09/17 – 09/20

DØ Run II Diffractive Topics Soft Diffraction and Elastic Scattering: Rapidity Gaps: Inclusive Single Diffraction Elastic scattering (t dependence) Total Cross Section Centauro Search Inclusive double pomeron Search for glueballs/exotics Central gaps+jets Double pomeron with gaps Gap tags vs. proton tags Topics in RED were studied with gaps only in Run I 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 Jorge Barreto – UFRJ E <100 W boson events in Run I, >1000 tagged events expected in Run II Small_X / 09/17 – 09/20

Summary and Future Plans Ø Run II analysis still in early stages Ø Early FPD stand-alone analysis shows that detectors work Ø FPD now integrated into DØ readout Ø Commissioning of FPD and trigger in progress Ø Gap results in Run II not yet approved Ø Full 18 pot FPD will start taking data after shutdown (12/03) Ø Tune in next year for first FPD physics results Jorge Barreto – UFRJ Small_X / 09/17 – 09/20