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DØ Diffraction/Forward Proton Detector Update

E. f. h. DØ Diffraction/Forward Proton Detector Update. Run I. Andrew Brandt University of Texas at Arlington. Goals of talk: Present FPD status Reality check for 420m project Results relevant for 420m project. Run II. Manchester Workshop December 14, 2004 Manchester, UK.

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DØ Diffraction/Forward Proton Detector Update

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  1. E f h DØDiffraction/Forward Proton Detector Update Run I Andrew Brandt University of Texas at Arlington Goals of talk: Present FPD status Reality check for 420m project Results relevant for 420m project Run II Manchester Workshop December 14, 2004 Manchester, UK

  2. DØ Run I Gaps f Dh h h • Pioneered central gaps between jets: Color-Singlet fractions at s = 630 & 1800 GeV; Color-Singlet Dependence on Dh, ET, s (parton-x). PRL 72, 2332(1994); PRL 76, 734 (1996); • PLB 440, 189 (1998) • Observed forward gaps in jet events at s = 630 & 1800 GeV. Rates much smaller than expected from naïve Ingelman-Schlein model. Require a different normalization and significant soft component to describe data. Large fraction of proton momentum frequently involved in collision. • PLB 531, 52 (2002) • Observed W and Z boson events with gaps: measured fractions, properties first observation of diffractive Z. • PLB 574, 169 (2003) • Observed jet events with forward/backward gaps at s = 630 and 1800 GeV

  3. Run II Improvements • Larger luminosity allows search for rare processes • Integrated Forward Proton Detector (FPD) allows accumulation of large hard diffractive data samples • Measure , t over large kinematic range • Higher ET jets allow smaller systematic errors • Comparing measurements with track tag vs. • gap tag yields new insight into processes

  4. Diffractive Topics and Students!

  5. Forward Proton Detector (FPD) p p • 9 momentum spectrometers comprised of 18 Roman Pots • Scintillating fiber detectors can be brought close (~6 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 < 3.0 GeV2) never before explored at Tevatron energies • Allows combination of tracks with high-pT scattering in the central detector P1U P2O Q4 Q3 Q2 Q2 S D Q3 Q4 S A1 D1 A2 D2 P1D P2I Veto 57 59 23 0 33 23 33 Z(m)

  6. Tevatron Modifications p AFTER: Bypass Pot Sep Sep Sep Pot Sep Girder Pit Floor Hole in Floor Run II Girder Configuration Bypass BEFORE: Sep Sep Sep Modify low beta quad girders, make new extended bypasses (2+1 spare) p Sep Girder Tunnel Floor Pit Floor Run I Girder Configuration Modifying accelerator takes time and money in this case: 2 years and $300k (cryo engineering not included)

  7. Detector/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. • 20 detectors built over a 2+ year period at UTA • In 2001-2002, 10 of the 18 Roman pots were instrumented with detectors. • During the fall 2003 shutdown the final eight detectors and associated readout • electronics were installed. A2 Quadrupole castle with all four detectors installed

  8. Pot Motion Software 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. The software is reliable and has been tested extensively. It has many safeguards to protect against accidental insertion of the pots into the beam. CDF pots (controlled by Beams Div.) accident in 12/03 grounded TeV for 2 weeks, DØ pots for 1 month, CDF pots for seveeral months (who moves pots and how are key issues)

  9. Operations • Operations in 2004 have been routine, only occasional minor problems, much less than average sub-detector • Currently FPD expert shifters inserts pots and Captains remove pots and set system to standby • 18 pots inserted every store when lum<45E30, read out for • all events • Combine shifts with CFT, since similar readout system, • standard FPD fiber plots incorporated into CFT online • examine program • Working towards automated pot insertion by shift captain

  10. Detector Hit Resolutions • Starting in January 2004, all 18 detectors regularly inserted (dipoles since February 2003) • Resolutions calculated by the difference of the x value of a hit calculated from u/v segments compared to the x value of the x segment show that most of the detectors are working as expected • With detectors integrated in readout, focus turns to trigger

  11. 2004 Fall Shutdown Work • Minor repairs • Replace veto counters (minor rad damage) and veto PMT's+survey • Test spares in situ • Camera repairs • Survey before and after separator alignment changes • Grounding studies • Trigger commissioning • FPD_LM commissioning • Automatic pot insertion tests Shutdown list is much shorter than last year’s! Since access is restricted, a reliable robust detector,electronics and pot motion system are essential

  12. Current Diffractive Triggers Jet +Gap(s): 15 GeV jet + 1 or 2 gaps; 2 gap trigger has low prescale up to intermediate lums 45 GeV jet + 1 or 2 gaps; prescale of 2 for single gap up to 60E30, double gap unprescaled at all lum J/ +Gap(s): 2 low pT muons+1 or 2 gaps; unprescaled at all luminosity These triggers are being used to search for exclusive dijets and exclusive c (among other things), a key step towards validating diffractive Higgs models. No results for public display yet.

  13. FPD Trigger and Readout

  14. Trigger Team • Andrew Brandt (UTA prof; Trigger Logic/List/Oversight) • Duncan Brown (UTA post-doc; Trigger Implementation) • Mario Vaz (UFRJ eng/phys; FPD DFE equations/TM firmware) • Wagner Carvalho (UERJ prof; DFE equations/test vectors) • Ricardo Ramirez (UTA EE M.S.; FPD/DFE Interface) • Tom Fitzpatrick (FNAL EE: FPD/DFE Interface/DFE Timing) • Brian Cox, Scott Kolya, Marc Kelly (Manchester; FPD_LM) • Carlos Avila, Luis Mendoza (Los Andes; Stand-alone trigger)

  15. Trigger Manager Inputs 1x96 FPD_LM T M 1x96 LM 3x96 FPD_DFE • FPD_LM • Information on which detectors are hit and halo • 2) LM pass through 16 LM and/or terms • includes GapN GapS GAPSN SI etc. • (much of this info is available through a different path) • DFE information from scintillating fiber detectors, • forseen to give , t; now using segment information, multiplicity

  16. FPD-LM ‘1’ ‘2’ D +V T D C T D C V T X T D C 6 8 8 • TDC Details: • Step I TDC in readout • 3 TDC boards for FPD compared to 6 LM boards • ‘1’ board consists of Px1, and Ax1 where x=Up,Down, In, • Out pots (first quadrupole castle on either side of IP) • ‘2’ board consists of Px2, and Ax2 • (second quadrupole castle) • 2 dipoles + 4 veto counter signals • Step II Add halo bit information to TDC’s (almost finished by • Man. guys during shutdown) • Step III Pass bit info to vertex board (and then to TM) • and add scalar info for pot insertion (January?)

  17. 2004 Trigger Strategy • Input information: • Currently no global run trigger capability • LM Vertex board is delayed (just received) • DFE boards and TM work and ready to be commissioned • Main background not from pileup (multiple interactions) but from • halo spray • Strategy: • Instead of calculating bins of  and t, use fiber hit patterns to • demand 2 or 3 out of 3 planes of each detector have valid hits. • Replaces trigger scintillator, simpler algo • Use multiplicity cut to reject halo spray, code several multiplicity • levels • NOTE fiber ADC threshold must be high enough to avoid noise, low • enough to retain efficiency and allow vetoing of halo • One advantage is pot positions not needed at trigger level

  18. Interim Trigger Plan • Proceed with DFE/TM debugging during shutdown; hardware • and firmware successfully tested, aiming for next major global • trigger list in spring • Since current FPD commissioning is special run intensive and • new elastic triggers with adjacent spectrometer veto have rates • around 1 Hz, we proposed adding an elastic trigger to first • post-shutdown global trigger list • This will only take one exposure group and allow • us to obtain good elastic sample at lums <45E30; • accepted by trigger board, will be operational in December

  19. FPD Trigger List Tentative L1 FPD V14 trigger list (early 2005) 1) elastic (diag opposite spectrometers) +GAPSN 2) soft diffraction (single spectrometers)+GAPS or GAPN 3) overconstrained track (pbar in quadrupole +dipole spectrometers)+GAPN 4) double pom (up-up, dn-dn etc.)+GAPSN if needed 5) Jet + FPD Track (DIFFQ or DIFFD) +GAPS or GAPN if needed 6) EM +FPD track +GAP (if needed) 7) CFT Track(1.5) +FPD track +GAP 8) Muon +FPD track +GAP

  20. Special Run Trigger LM VC Halo Early Hits A1U A2U Pbar P P2D P1D In-time hits in AU-PD detectors, no early time hits, or LM or veto counter hits Current NIM logic allows us to form several elastic and diffractive triggers for special runs using trigger scintillators (in parallel information from scintillators is sent to TDC’s for commissioning FPD_LM system, and CAMAC scalars), veto counters, and LM. Can trivially switch from elastic to double pomeron (Aup-Pup for example)

  21. Elastic Scattering p P A2U A1U p p P1D P2D • Elastic scattering: ξ = 0 (no momentum lost by beam particle) • Quadrupole acceptance: • t > 0.8 GeV2 (requires sufficient scattering angle to leave beam envelope) • all ξ (no longitudinal momentum loss necessary) • Measure dN/dt for elastic scattering using early stand-alone FPD data: • antiproton side: • quadrupole ‘up’ spectrometer • trigger only • proton side: • quadrupole ‘down’ spectrometer • full detector read-out veto on LM and VETO counters, early time hits (halo tracks)

  22. dN/dT Result of the week http://www.fnal.gov/pub/today/archive_2004/today04-03-18.html Tremendous work especially by the Jorge’s to obtain the preliminary dN/dT measurement. Congrats again to Dr. Molina for first FPD PhD!

  23. Separator plates Fall 2003 shutdown survey data (points A+B) made available by accelerator in April show offsets of up to 0.7 cm! Required rewriting of MC to separate separators, reanalysis of acceptance.

  24. Acceptance The acceptance for the PD spectrometer: Before sep correction: After sep correction: Much better high-t acceptance (previously high-t data thought to be halo)

  25. Elastic Status • Re-evaluating acceptance and backgrounds based on new alignment, also studying AU-PD correlations • Will decide soon if data is sufficiently well understood to publish • Silver lining: nearly 100% of effort directly transferable to new analyses

  26. FPD Dipole Jet Data WORK IN PROGRESS pbar beam x p halo y (0,0) D0 pbar halo D2 D1 • Trigger one jet with pT > 25 GeV and Gap on North (pbar side) • Read out using AFE (Analog Front End) board; FPD info extracted from raw data inclusive jet pT tagged jet Δφ

  27. Dipole TDC Resolution • Can see bunch structure of both proton and antiproton beam • Can reject proton halo at dipoles using TDC timing p D2 TDC p halo from previous bunch Timing is important D1 TDC

  28. Software Status • L1 Firmware in good shape • L3 FPD tracking tools and single interaction tools included in latest L3 release • Offline reconstruction modified to run with standard DØ reconstruction program or in standalone mode • Online examine programs incorporated in standard shifts • Alignment and calibration routines being refined • MC and Analysis software well-developed

  29. Lessons Learned • Bigger project than you (I) might think: more manpower, time, cost, CABLES • Need a sufficient budget and some level of priority (Beyond the Baseline Syndrome) • Using other people’s electronics is risky (minor adaptations often aren’t, make sure • their schedule is much earlier than yours) • Early integration (software+hardware) is essential • Good contacts in the Accelerator Division are crucial • Halo not well-understood (mokhov did simulations, but…), collimators not optimized, • using bpm’s as found not so good—do you know how to get bpm’s into data stream, etc. • Commissioning phase long and personnel intensive, must have sufficient physicists and engineers on-site (lack of brazil travel funds really hurt us) • Grounding issues (long cables in tunnel plugged into detector might cause problems—actual or perceived) • Elastics for alignment critical, every store if possible • Splicing fibers is painful • Late trigger -> late calibration sample • Need more access than you might think Not to mention software effort: track reconstruction, Monte Carlo database, online, etc.

  30. Diffractive Z Event Selection:Z→μ+μ- Events from 2003 data sample Two good (PT > 15GeV) oppositely charged muons (at least one isolated), cosmic ray rejection Demand Activity North and South Forward Gap (North or South) Tamsin Edwards (Manchester) thesis work, expected to be completed in next couple months

  31. Outlook and Plans • Finish Level 1 Trigger Commissioning • Continue routine data collection, add new triggers=new data samples • Emphasis on physics/publishing mature results and obtaining new preliminary results • Plan a special low-t (0.1-1) run soon, get your predictions of if/where the dip(s) will be for SD,DPE+Elastic • Accelerator start-up going well (too well!) indications that halo background reduced

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