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Task B: Lepton-Hadron Collisions

Explore the contributions and achievements of the UW group in lepton-hadron collisions, trigger systems, and physics publications from 1993 to 2006. The group contributed significantly to the Wisconsin ZEUS project, HERA-II upgrades, lumi detector advancements, and more. Discover their pivotal role in advancing research in this field.

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Task B: Lepton-Hadron Collisions

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  1. Task B: Lepton-Hadron Collisions Don Reeder former AmZeus chair, retiring Professors Wesley Smith ZEUS editorial board, Trigger convenor, Former AmZeus chair A. Savin Hadronic Final States Physics coord.Calorimeter Trigger coord. Assistant Scientist (resident at DESY) D. Kçira Left for Louvain - CMS M. Jaworski Electronics Engineer (resident in Madison) Trigger electronics maintenance Eric Brownson Tom Danielson Homer Wolfe Adam Everett Michele Rosin Pat Ryan Graduate students (resident at DESY) Trigger operations Physics Analysis Graduated - Purdue - CMS Graduated - Weizmann - Zeus Graduated - Michigan State - ATLAS

  2. UW DESY Group Organization1993 - 2005 • Beginning Students (2) • Learning • Cal.Trigger shifts • on call 24x7 • Intermediate Students(2) • Resp. for Cal Trig shifts • Begin physics analysis • Senior Students(2) • Released for Thesisanalysis • Consultation,assistance, shifts • Supervision • Local Scientists - A. Savin & D. Kcira • Visits by D. Reeder & W. Smith • Weekly video meetings (DESY- UW) • Now: 3 students & 1 scientist  redirect effort to CMS (lost!) MSU ATLAS Purdue CMS Weizmann ZEUS Louvain CMS “The TEAM!” July ‘05

  3. Since 1993 Wisconsin Contributions • Contributions include supporting M&O • Major task for trigger system • Obligation to exploit investment • Cost effective access to a rich lode of physics Uranium-Scintillator Barrel Calorimeter doneby UW & US group First Level trigger for entire calorimeter built & maintained by UW group Toroidal Iron Magnet designed by UW & coils built by UW

  4. Micro Vertex Detector ZEUS HERA-II Upgrades • Major investment by DESY and ZEUS collaborators Lumi detector upgrades Straw Tube Forward Tracker Argonne built electronics + beam counters,  tagger Beam Pipe Magnets STT MVD

  5. HERA - II • DESY Investment pays off (> 70 new magnets) • Switch to electrons fall 2004 • HERA-I ZEUS total positron/ electron - proton luminosity of 115 pb-1/17pb-1. • Electron-positron collisions ended June 2006 • Electron sample = 214 pb-1. • Switching to positrons for year of final running • Positron sample ~ 400 pb-1. • Increase over HERA-I program of a factor of 4 in statistics (and more than an order of magnitude in electron statistics) • Final run at lower energy • Measure FLgluon for LHC

  6. ZEUS Physics Publications2005-2006 • Since January 2005, submitted 12 papers to refereed journals • 10 have already been published, 2 more accepted for publication • More than 160 articles in refereed journals • 30 physics publications with > 100 citations each. • 4 Journal Articles from UW Group published/accepted: 1. I.P.Ivanov, N.N.Nikolaev, A.A.Savin (UW Scientist), “Diffractive vector meson production at HERA: from soft to hard QCD”, Phys. Element. Part. Atom. Nucl. vol.36 (2006) 1. -- 178 page review of HERA diffraction 2. S. Chekanov et al., “Forward Jet Production in Deep Inelastic ep Scattering and low-x Parton Dynamics at HERA”, Phys. Lett. B632 (2006) 13-26 . -- S. Lammers thesis. 3. S. Chekanov et al., “Multijet Production in Neutral Current Deep Inelastic Scattering at HERA and Determination of s, Euro. Jour. Phys. C44 (2005) 183-193 -- L. Li thesis. 4. S. Chekanov et al., “Event shapes in DIS at HERA”, DESY-06-042, accepted by Nuclear Physics B. -- A. Everett thesis

  7. 1. D. Kcira, Jet production at HERA and the measurement of s, 18th Lake Louise Winter Institute 2005 on Fundamental Interactions, Alberta, Canada, February 2005 2. A. Savin, Jets at HERA and determination of s, 40th Rencontres de Moriond on QCD, La Thuile, Italy, March 2005 3. A. Everett, Event Shapes, 13th International Workshop on Deep Inelastic Scattering (DIS ’05), Madison, USA, April 2005. 4. M. Rosin, Charged multiplicity distributions, 13th International Workshop on Deep Inelastic Scattering (DIS ’05), Madison, USA, April 2005. 5. P. Ryan, Forward jet production at HERA, 2005 Europhysics Conference, Lisbon, Portugal, July 2005. Wisconsin Zeus talksin 2005, 2006 (through June) - 10 Talks • 6. A.Savin. Event shapes in DIS at ZEUS ,DIS06, Tsukuba, Japan, April 2006 • 7. A.Savin K0 and Lambda production at ZEUS , DIS06, Tsukuba, Japan, April 2006 • 8. P.Ryan, Photoproduction of events with rapidity gaps between jets at ZEUS DIS06, Tsukuba, Japan, April 2006 • 9. E.Brownson Prompt-photon plus jet production at ZEUS DIS06, Tsukuba, Japan, April 2006 • 10. P.Ryan Photoproduction of events with rapidity gaps between jets at ZEUS HERA-LHC workshop, CERN, June 2006.

  8. e+e-/ep multiplicity: Breit Frame DIS event • ep: large asymmetry btw. beams • Most of hadronic final state produced near proton and outside acceptance of detector • Method • Use invariant mass for comparing to e+e-, pp • Provide clear separation from leading particle(s) using final state particles from • The current region of Breit frame • The photon region of the Hadronic Center of Mass (HCM) frame Breit Frame definition: 2xp + q = 0 Current region of Breit Frame analogous to one hemisphere of e+e-. Lab Frame Breit Frame PT Breit Frame PL

  9. ep multiplicity vs. other exp’ts • 2<nch> in current and photon regions compared to e+e-, pp & previous ZEUS measurements • ZEUS ep results agree with e+e-, pp at both low and high values of energy • At low energy agreement better than previous ZEUS result vs Q • MC predictions from both frames agree with ZEUS measurements • Thesis research of graduated UW PhD student Michele Rosin, presented at DIS ‘05, ZEUS journal article in Editorial Board.

  10. Axis Dependent: TT, BT, T, B Thrust Broadening Axis Independent: C, M2 C Parameter Jet Mass TT axis T axis TM axis Tm axis Particle and Energy Flow Combination of the hard and soft scales Sums are over all momenta in the current hemisphere of the Breit frame

  11. Event Shape Parameters • Extracted parameters for each shape • Fitted s values consistent to within 5% • Fitted 00.45 to within 10% • (excluding T) • Theory errors dominate, except for  axis shapes • Graduated UW PhD student Adam Everett’s thesis, presented at DIS’05 & accepted for publication by Nuclear Physics B. World Average

  12. Study Differences in summing QCD terms in parton evolution DGLAP: ordering in both kT and x BFKL: not ordered in kT but ordered in x Potential differences DGLAP: Jets strongly correlated in Energy, azimuthal and polar angles BFKL: Jets not necessarily strongly correlated Expect more energetic jets in forward region with BFKL than with DGLAP Parton Energy and kT Ordering

  13. ZEUS Multijet Measurements • ZEUS inclusive dijet and trijet measurements well understood and modeled • Multijet cross sections vs. NLO calculations • Graduated UW PhD student Liang Li’s Thesis, Eur. Jour. Phys. C44 (2005) 183-193 • DGLAP NLO dijet and trijet calculations describe data well in general • Examine if agreement extends to “BFKL” kinematic regions Dijet Trijet

  14. NLO vs. ZEUS Inclusive Jets • Inclusive jet cross sectionvs. DISENT NLO calculation) • Graduated UW PhD student Sabine Lammers’ thesis, Phys. Lett. B632 (2006) 13-26 • Low xBj disagreement btw. data & DISENT • Disagreement evident whenjet required • Structure Function analysesdo not require jets • Further explore this region requiring more than one jet

  15. Probing NLO QCD DGLAP:Dijets at Low-x • Jets not strongly correlated in energy and azimuthal angle indicate BFKL effects • DGLAP: Jets strongly correlated in ET, angles • “Back to back” in f • Find that dijet production with low azimuthal separation are reproduced by pQCD DGLAP • Provided that higher order terms (O(s3)) are included -- important at low-x. • Thesis research of UW PhD student Tom Danielson, presented at ICHEP06

  16. Resolved Resolved proton remnant jet 1 jet 2 gap Color Non-Singlet and Singlet Exchange in Photoproduction Color Non-Singlet Exchange Color Singlet Exchange Jet Jet Jet Jet • Color Non-Singlet Exchange: • Final state partons color connected • Space between final state partonsfilled with final state particles • No Gap between jets • Color Singlet Exchange: • Final state partons not color connected • Space btw final state partons empty • Rapidity Gap between jets--measure ETGap ETGap

  17. Evidence for Color Singlet • Inclusive dijet gap cross section as a function of ETGap vs. Herwig (x 3.3) and Pythia (x 1.8) with and without color-singlet exchange. • MCs without a color-singlet contribution do not describe data in two lowest ETGap bins. • Amount of color-singlet needed to give best fit to data is ~ 3-4% of the total inclusive dijet gap cross section integrated from0 - 12 GeV in ETGap. • Graduated UW PhD student Pat Ryan’s thesis,, presented at DIS ‘06, ZEUS journal article in Editorial Board.

  18. Prompt g + Jet Photoproduction:study hard interactions directly • Use new Barrel Calorimeter Presampler to tag prompt photons & higher statistics sample to improve measurement • Find improved agreement after raising energy cut on prompt photons from 5 to 7 GeV • Find both kT-factorization & NLO QCD models agree well. • Thesis research of UW PhD student Eric Brownson, presented at DIS06, ICHEP06 & submitted to Eur. Phys. J. C (DESY-06-125).

  19. CC inclusive jets in e-p • Measure differential cross sections for jet production in high statistics (125 pb-1) polarized (1st time) & unpolarized electron-proton scattering •  & xBj cross sections agree with leading log parton shower MCs, but Etjet & Q2 are somewhat different. • Thesis research of UW PhD student Homer Wolfe, presented at ICHEP 06

  20. XIIIth Workshop on Deep Inelastic Scattering (DIS05) • in Madison, Wisconsin, April 27 - May 1 • 271 Participants, 240 Talks • Wesley Smith, Chairman • Local Organizing Committee: Sridhara Dasu, Tao Han, Aimee Lefkow, Don Reeder U. Wisconsin Jose Repond, Argonne

  21. ZEUS Trigger • Design & Leadership by Wisconsin • W. Smith trigger co-convenor fromdesign until present (20 years) • Challenge: interaction every 96 ns • Beam-gas background > 100 kHz • Revolutionary3-leveldeadtimelessdesign • A. Wagner: • "The calorimeter ….. readout and trigger have paved the way for the LHC and Tevatron II designs."

  22. Calorimeter First Level Trigger: Challenges • Input requirements • Beam crossing every 96 nsec • Background rate <100 kHz • Max Level 1 Rate < 0.5 kHz • Processing requirements • 5 msec trigger decision time • Data from 13K Phototubes • Dynamic range of 4096:1 • Trigger Functions at Level-1 • Unique to Zeus trigger until LHC • Identify e, . • Sum energy, missing & total Et • Pattern logic to compensatefor non-projective geometry:

  23. Calorimeter First Level Trigger: Front End 270 Trigger Encoder Cards digitize to 12-bits, test for em v. had., quiet(m) & total energies. 720 Trigger Sum Cards collect signals & transmit every 96 ns to TEC's in Electronics House 140 Fanout Cards control TSC's

  24. CAL FLT Logic 2 double-board Adder Cards per crate receive & process data from 14 TEC's at 80 MHz Adder Cards find isolated e's & m's, and sum energies 16 crates report to Global Cal Trigger

  25. Low Lumi High Lumi ZEUS First Level Trigger • Continues superb performance as luminosity increases • Example of Recent HERA Good Run: • High specific lumi. 2.3 x 1031 • Max lumi. to be expected: 5 ~ 6 x1031 • Deadtime less than 1% • Expect always < 5% • Keys to success: • Flexibility & Programmability • Trigger studies by UW group to make changes

  26. Trigger Studies • Adapt trigger to changing beam conditions • Study new configurations • Switch to positrons this summer • Switch to low energy running at end of year to measure FL • Make test runs, study Monte Carlo & data • Understand trigger impact on physics analysis • Demand for increased detail on analysis of trigger performance as preparing for precision measurements during low energy running. • Regional and even tower by tower analyses of efficiencies for various triggers.

  27. Criticality • Unique - Invaluable • Zeus can function without many components but not without the calorimeter and trigger. • Efficiency and performance can be excellent ….. but it requires close monitoring and precise knowledge (it is aging!) • We have maintained and operated it to date and we have the tools, but …. it continues to need vigilant constant attention by an active, experienced staff at DESY.

  28. Expertise at DESY • Assistant Scientist - A. Savin • Calorimeter Trigger Coordinator • Provides technical coordination • Works with other detector leaders • Physics Analysis • Own analyses & supervises students • Leadership @ DESY • Increased burden with departure of D. Kcira

  29. Jade Hall test facility • Calorimeter module electronics test with full module infrastructure • Complete test crate & interface to global cal. trigger for full-scale check of counting house (rucksack) electronics

  30. Technical Support • Technician: Cathy Farrow (formerly UW) • AmZeus/DESY has now hired Cathy and given her predominant responsibility for maintenance of the calorimeter hardware • BUT ….. she can spend some (small) time on CAL FLT • Helps to maintain test facility, makes simple board repairs • Expert Engineer: Matt Jaworski • ~ 5 trips/year for 2-3 weeks to make difficult repairs • Frequency increasing due to aging electronics and to compensate for Cathy Farrow's reduced activity. • Designer (available for consultation) • Joe Lackey (retired) - not supported by grant.

  31. Operations • Detector & Electronics House • Write, test & maintain electronics test programs • Maintain & update bad channel list • < 1% channels w/any trigger problem (none dead) • Diagnose & repair electronics • Experimental downtime due to CAL FLT < 1% • Daily checking programs • Maintain & operate Jade Hall Facility • 24 hour/day support during running • Frequent calibration with charge injectors to set the time & energy. • Special cable-checking charge injection runs after any repairs • Software Operations • Run Control maintenance • Trigger data validation • Online & Offline analysis of rates & efficiencies • Monte Carlo & data trigger simulation maintenance

  32. Online & offline Diagnostics • Trigger bits vs.simulation of trigger using reconstructed data as input. • Each trigger efficiency curve is monitored & checked online. • Each trigger in every data run is analyzed offline to check efficiency and rise of threshold curve.

  33. Conclusions • UW is a leading group ZEUS operation & analysis • Doing great physics • 10 International workshop/conference talks in 2005/6 so far • 4 publications • UW provides continuity & strength vital for ZEUS • ZEUS cannot operate without CAL FLT • Exciting physics amidst shrinking HEP opportunities • ZEUS runs until June 30, 2007 • “Poster child” for an international role for US HEP • Model for future international collaborations (i.e. TESLA) • Producing top-notch physicists • Experience in sophisticated hardware & software • Physics analysis in close collaboration with theorists • 16 Wisconsin ZEUS students received Ph.D.s thus far • 3 More ZEUS students working on Ph.D.s: • Danielson,Brownson, Wolfe:

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