DØ Forward Proton Detector Andrew Brandt UTA Q4 D S Q3S A1A2 P 1 UP p p Z(m) D1 Detector Bellows Roman Pot P 2 OUT Q2 P 1 DN P 2 IN D2 Q4Q3Q2 June 23, 2002 Atlas Collab. Meeting Clermont-Ferrand

Diffraction Thesis Topics 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 Diffractive W/Z Diffractive photon Diffractive top Diffractive Higgs Other hard diffractive topics Double Pomeron + jets Other Hard Double Pomeron topics Rapidity Gaps: Central gaps+jets Gap tags vs. proton tags Double pomeron with gaps   E 1000 tagged events in Run II

Data Taking No special conditions required Read out Roman Pot detectors for all events (can’t miss ) A few dedicated global triggers for diffractive jets, double pomeron, and elastic events Use fiber tracker trigger board -- select , |t| ranges at L1, readout DØ standard Reject fakes from multiple interactions (Ex. SD + dijet) using L0 timing, silicon tracker, longitudinal momentum conservation, and scintillation timing Obtain large samples (for 1 fb -1 ): ~ 1K diffractive W bosons ~ 3K hard double pomeron ~500K diffractive dijets with minimal impact on standard DØ physics program

Acceptance Quadrupole ( p or ) Dipole ( only) Dipole acceptance better at low |t|, large  Cross section dominated by low |t|  Quadrupole Dipole M X (GeV) GeV M X (GeV)   Geometric  Acceptance

Constructed from 316L Stainless Steel Parts are degreased and vacuum degassed Plan to achieve Torr Use Fermilab style controls Bakeout castle, then insert fiber detectors Roman Pot Castle Design Detector 50 l/s ion pump Beam Worm gear assembly Step motor

Thin window and flange assembly Bellows Detector is inserted into cylinder until it reaches thin window Motor Flange connecting to vacuum vessel Threaded Cylinder Roman Pot Arm Assembly

Bypass Sep Sep Girder Tunnel Floor Pit Floor Bypass Sep Pot Sep Girder Pit Floor Hole in Floor Run II Girder Configuration Run I Girder Configuration Girder Reconfiguration BEFORE: AFTER: p p

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. Quadrupole castle A2 installed in the beam line. Castle Status

4 fiber bundle fits well the pixel size of H Ch. MAPMT (Multi- Anode Photomultiplier Tube) 7 PMT’s/detector  m fibers each PMT Six planes (u,u’,x,x’,v,v’) of 800  m scintillating fibers (’) planes offset by 2/3 fiber 20 channels/plane(U,V)(’) 16 channels/plane(X,X’) 112 channels/detector 18 detectors 2016 total channels 4 fibers/channel 8064 fibers  m LMB fiber/channel 8 LMB fibers / bundle 252 LMB bundles 80  m theoretical resolution Detector Setup

At the University of Texas, Arlington (UTA), scintillating and optical fibers were spliced and inserted into the detector frames. Detector Assembly

The plastic frames containing the clear fibers are attached to the cartridge bottom. Detectors in Cartridges The cartridge bottom containing the detector is installed in the Roman pot and then the cartridge top with PMT’s is attached.

All 18 cartridges have been assembled, 10 are installed in tunnel (8 with full detectors 2 with trigger scint). The 10 instrumented pots (Phase I) are ups, downs, and dipoles. Cables and tunnel electronics (low voltage, amp/shapers, etc.) installed and operational for full 18 pot (Phase II) setup. 9 more detectors are complete except for final polishing, last 3 (2 spares) will be finished this summer. Tunnel and Detector Status

In the October 2001 shutdown four veto counters (designed at UTA, built at Fermilab) each of which cover 5.2 < |  | < 5.9 were installed between DØ and the first low beta quadrupole (Q4), about 6 m from the interaction point. The counters, two each on the outgoing proton and anti-proton arms, can be used in Diffractive triggering (veto proton remnant). Veto Counters

Pot Motion Pot motion is controlled by an FPD shifter 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.

Stand-alone DAQ Due to delays in DØ trigger electronics, we have maintained our stand-alone DAQ first used in the fall 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 (currently PD spectrometer is read out), although all the trigger scintillators are available for triggering. An elastic trigger is formed from coincidences of the PU+AD spectrometers combined with halo vetoes (early time hits) and vetoes on LM and Veto counters.

FPD Control Room

Elastic  Distribution (raw)  =  p/p should peak at 0 for elastic events!! Require clean events with 0 or 1 hit per plane for initial studies

Data Elastic x,y Correlations PD1x vs. PD2x (mm) PD1y vs. PD2y (mm) Good correlation between x1,x2 and y1,y2 in data but shifted from MC expectation (3 mm in x and 1 mm in y)

Elastic ,t (calibrated) Minimum t about 1.0 Gev 2  peak reasonably Gaussian, still 2x ideal MC resolution Calibrated  now peaks at 0

Proton ID The Proton ID group led by Gilvan Alves and Sergio Novaes has made substantial progress in many software areas: Track reconstruction Monte Carlo Unpacking Single Interaction Tool Alignment Database Regular Proton-ID meetings are held off-week Thursdays 11-12:30 in Black Hole using VRVS

Goals for 2002 Early summer Installation of full readout chain for one spectrometer Late summer/fall Installation of readout chain for Phase I 10 detectors = 5 spectrometers FPD data acquisition integrated into D Ø Elastic + Diffractive dN/dt and  -distribution September FPD triggers in D Ø global list December First Diffractive + jets data analysis shown at QCD meeting

Lessons Learned Bigger project than you (I) might think: more manpower, time, cost, CABLES Using other people ’ s electronics is risky Need a budget and some level of priority (beyond the baseline syndrome) Early integration is essential Good contacts in the Accelerator Division are crucial Halo not well-understood Elastics or alignment, redundancy needed Splicing fibers is painful

FPD Summary FPD will be a completely integrated sub-detector of the DØ detector which will help maximize Run II physics potential Hard diffraction exists, but not well-understood -- large data samples and precise measurements needed Large and L at Tevatron necessary for these measurements Combination of quadrupole and dipole spectrometers gives ability to tag both p’s and p ’s over large kinematic range, allows alignment, understanding of backgrounds Tremendous progress in installation and commissioning, emphasis switches to trigger, software, operations, and data analysis Starting to think about physics a little!

Used finite element analysis to model different window options Built three types of pots and studied deflection with pressurized helium. 150 micron foil with elliptical cutout gives excellent results NIKHEF Window

Measurements Using the FPD Observation of hard diffractive processes. Measure cross sections dominated by angular dispersion 15% error for (resolutions given for dipole spectrometer). Measure kinematical variables with sensitivity to pomeron structure ( , E T, …) Use Monte Carlo to compare to different pomeron structures and derive pomeron structure. Combine different processes to extract quark and gluon content.

(Arbitrary Scale) Dipole Region Quadrupole Region FPD Measurements (1 fb -1 )

E t > 15 GeV 10,000 events Soft (1-x) 5 Hard x(1-x)  E t > 15 GeV 0<|t|<3 GeV 2 Hard gg Hard qq FPD Measurements (1 fb -1 )

Pot Motion Safeguards The software is reliable and has been tested extensively. It has many safeguards to protect against accidental insertion of the pots into the beam. The drivers are disabled with a switch in the Control Room when the pots are not being moved. The pots are hooked to an emergency line which bypasses the software to send the pots back to the home position in case of emergency (tested but not used).

Pot Insertion Monitor Effect of the pot motion on the proton and antiproton losses at DØ and CDF is monitored using ACNET. Current agreement with Beams Division and CDF requires that the effect on halo rates is less than 20%.