1. Tevatron Beam Diagnostics: Boosting Collider Performance Vladimir Shiltsev, Ron Moore, Andreas Jansson FNAL/Accelerator Division

2. 05/01/2006Tevatron Instrumentation2 Winston Churchill “Generals are always prepared to past wars.” “Soldiers usually win the battles and generals get the credit for them.” Napoleon Bonaparte Tevatron Collider Run II Was/Is a Battle

3. 05/01/2006Tevatron Instrumentation3 So, Purposes of This Talk Are: Give credit to soldiers Show some remarkable luminosity-related examples of diagnostics progress: –Lattice /helix issues  BPM Upgrade –Reliability/uptime  orbit stabilization + HLS + vibrations –CDF/D0 discrepancy  IP vertex diagnostics –Beam-Beam  1.7GHz Schottky + Tune Stabilization –Losses on ramp  IBEAM + FBI + Tune Tracker –Losses at 150  Head-Tail Monitor –DC beam  AbortGapMonitor + LPM +SBD –Injection mismatch  FWs + IPM + OTR Outline lessons learned during the Run II

4. 05/01/2006Tevatron Instrumentation4 Tevatron Collider 1.96 TeV Proton-Antiproton Colider - worlds’ most powerful accelerator Run I (1992-96) t-quark Run II (2001-09) Higgs, SS, >SM

5. 05/01/2006Tevatron Instrumentation5 Overview of “the Battle”

6. 05/01/2006Tevatron Instrumentation6 0.5-1% of loss  Poor lifetime  0.5-1 mm orbit error  Collimator malfunct  Sequencer error  QUENCH ! 2-4 hrs to recover 4-8 hrs for new pbars or Blow Up  tune few 0.001  coupling ‘s wrong  instability  kicker malfunct  1000’s of PSs “Driver’s Nightmare” Store #535 Jun 15, 2001

7. 05/01/2006Tevatron Instrumentation7 “Things going wrong”: 2001 Store #535 Jun 15, 2001  So called “comfort plot” (at that time – more of discomfort) as seen by operators in Main Control Room and automatically saved in E-log Shows intensity over the most critical times of injection, ramp and squeeze: Blue – protons Red – antiprotons Green – total (DCCT)

8. 05/01/2006Tevatron Instrumentation8 Situation improved: 2005 Store #4116 Apr 27, 2005 Note : Losses 1/20 of ‘01 8x proton intensity 40x pbar intensity

9. 05/01/2006Tevatron Instrumentation9 Importance of Helical Orbits Beams share beam pipe  be separated –Helical separation ~(10-22)mm at 150 GeV –S ~(3-6) mm at 980 GeV Lifetime is strong function of S –30 sec at 2σ, 50 hrs at 7σ –Aperture limited at 150 GeV  “smooth”

10. 05/01/2006Tevatron Instrumentation10 Orbit Smoothing and Understanding Optics ~0.5 mm rms orbit drift in 1-2 weeks proton and pbar Qx,y, Q’, lifetimes vary significantly due to such COD  needed regular orbit smoothing at 150, ramp, flat-top, squeeze, low-beta. … PLUS lattice had to be known to <5% (was ~25%) TBT not reliable dependent on bunch structure/length did not see pbars  Decided to upgrade BPMs (2003-05) “orbit – silver orbit” +-2 mm at collisions after about 2 weeks in September’02

11. 05/01/2006Tevatron Instrumentation11 Beam Position Monitors Existing BPMs fitted with new electronics based on Digital Down- Conversion Resolution ~5µm (previously LSB was 0.15mm) Eliminated difference between coalesced and uncoalesced beams. Measures pbar orbit,too S.Wolbers et al A/D DDC FPGA A/D DDC FPGA Echotek board 53MHz BPF MVME 2400 *Note that “resolution” includes real beam motion, mainly in the horizontal plane (synchrotron osc.)

12. 05/01/2006Tevatron Instrumentation12 New BPMs  De-coupling and Lattice measurement Calculating all optics functions and coupling correction using TBT data from many BPMs E.Gianfelice-Wendt # corrections min tune split Beta-functions measured to better than 5% accuracy on both helices, errors cor- rected, lattice modified so that β*=36cm  29cm, giving ~10% gain in Luminosity

13. 05/01/2006Tevatron Instrumentation13  -functions : before & after Upgraded Tevatron BPMs ! Oct’05 Mar’05 Vertical beta-function A/Valishev, Y.Alexahin J.Annala, V.Lebedev 150 m Horizontal beta-function B0D0 Change of beta @ IP β*=36cm  29cm gave ~10% gain in Luminosity

14. 05/01/2006Tevatron Instrumentation14 Orbit stabilization Slow (~1/min) automatic continuous correction of orbit variations using several dipole correctors close to the IPs Standard at most Light Sources – only recently commissioned in Tevatron with new BPMs (old were too sensitive to bunch structure  quench fear) Now need fast FB orbit stabilization ON vertical horizontal 0.4mm 1 day V.Ranjbar

15. 05/01/2006Tevatron Instrumentation15 Sensitivity to quakes  “Fire-truck-quake” ~200 um orbit jitter New diagnostics: tiltmeters, Water Levels on every LB quad M8.7 Sumatra earthquake 03/28/05

16. 05/01/2006Tevatron Instrumentation16 CDF detector sinking ~0.5 mm/year  Interaction Point Moves  inefficient b-tagging Intentional move upon CDF request Reported by CDF Silicon Vertex Detector

17. 05/01/2006Tevatron Instrumentation17 CDF and D0 IP Waist Diagnostics J.Estrada/A.Chandra 01/04 01/0501/06 Vertical beta-function measured at D0 Jan’2004 to Mar’2006 (“beam diagnostics for free”) Vertices of p-pbar collisions analyzed and processed (on- line @ CDF, off-line with ~day delay @D0)  IP position, luminous region waist size vs z

18. 05/01/2006Tevatron Instrumentation18 Tevatron: Life in the “Tune Box” 7 th order resonances: Q=4/7=0.571 - HIGH LOSSES 12 th order resonances: Q=7/12=0.583 - Bad lifetime 5 th order resonances: Q=3/5=0.600 – EMITTANCE BLOWUP proton pbar every bunch has its own tune!

19. 05/01/2006Tevatron Instrumentation19 Tune Diagnostics: 21.4 MHz Schottky Workhorse for shot setup. Operators determine tune from spectrum peaks Often needs excitation (VTICK) But:But: a) does not see pbars anywhere, b) very complicated by coherent tune lines, c) does not see bunch- by-bunch tunes B. Fellenz

20. 05/01/2006Tevatron Instrumentation20 1.7 GHz Schottky Detector 1.7 GHz 109 x 75 mm aperture R.Pasquinelli Vertical and horizontal units Proton and pbar ports 100 MHz bandwidth

21. 05/01/2006Tevatron Instrumentation21 1.7GHz Schottky Spectra #3226 02/11/04 Q and 1-Q lines are seen Fit gives: –Betatron frequency (accuracy ~0.001) –dP/P  sum of two widths –C_vh  difference of two widths –Emittance  area under the peaks For each bunch! … non-invasive! A.Jansson/P.Lebrun

22. 05/01/2006Tevatron Instrumentation22 Tune stabilization Starting tune correction Pbar horizontal tune Pbar vertical tune Operators use 1.7 GHz Schottky data to keep pbar tunes within a predefined range as the beam-beam tune shift changes 4 weeks R.Moore

23. 05/01/2006Tevatron Instrumentation23 1.7GHz Schottky Bunch Tunes Bunch-by-bunch tune variation ~0.005 – an indication of parasitic beam-beam interactions

24. 05/01/2006Tevatron Instrumentation24 Plotting Bunch-by-Bunch Data for each of 36 p + 36 pbar bunches Live data Instability @ 150 GeV resulted in interesting intensity and emittance patterns Logged data Proton bunch centroid motion during longitudinal instabilitity Observing differences in bunch-by-bunch behavior is very useful for understanding beam dynamics in the Tevatron ±4deg

25. 05/01/2006Tevatron Instrumentation25 Longitudinal Instability  Sampled Bunch Display and Phase Monitors bunchlength RF phase of bunch bunch # Bunch tomography  Weird bunch shapes during instability burst (snapshop taken by SBD) No instability, continuously “dancing” bunches (RWM)  Fast (200Hz) longitudinal phase monitor is under development +-4 deg

26. 05/01/2006Tevatron Instrumentation26 Sampled Bunch Display (SBD) Measure bunch intensities, lengths –Few – 350 × 10 9, 1-4 ns –Updates ≈ 1 Hz LeCroy WaveRunner 6200 captures waveforms over many turns in memory –2 GHz bandwidth, 10 G-samples/sec Macintosh G5 does signal processing –200 tap (0.5 ns/tap) FIR filter removes effect of dispersion in the long cable Resolution of intensity ~0.05% (5e9) Resolution of centroid position and RMS length ≈ 0.02 ns (RMS is ~2ns) Figure 2: a proton bunch signal (raw) and after application of the FIR filter. The feature at the far right is a 3/4 % reflection. from one channel through the splitter to the other. Full height of the main bunch is ~5 amps.

27. 05/01/2006Tevatron Instrumentation27 Longitudinal Oscillations Lead to Generation of DC beam in Abort Gaps The Tevatron operates with 36 bunches in 3 groups called trains Between each train there is an abort gap that is 139 RF buckets long –RF bucket is 18.8 ns  Abort gap is 2.6  s Protons leak out of main bunches to the gaps. Tevatron is sensitive to few x 10 9 particles in the abort gaps (total beam ~ 10 13 ) as they lead to quench on beam abort (kicker sprays them) 139 buckets 21 buckets 1113 RF buckets total Train Bunch Abort Gap

28. 05/01/2006Tevatron Instrumentation28 Abort Gap Intensity Monitor Photocathode Dynode 1 Photocathode HV below photocathode Nominal PMT Behavior (Gated On) Gated Off PMT Behavior   Dynode 2 Dynode 3 Dynode 4 Dynode 1 Dynode 2 Dynode 3 Dynode 4 HV below dynode 3 Hamamatsu gated MCP style PMT on loan from LBNL 5ns minimum gating time w/no noticeable settling time Very large extinction ratio Somewhat expensive (~$20K /tube) 2-stage Micro Channel Plate PMT – Gain of <= 10 6 No sensitivity to pre- gate light R.Thurman-Keup

29. 05/01/2006Tevatron Instrumentation29 DC Beam in Abort Gap:TEL On/Off/On AGM is calibrated wrt to DCCT - the most precise Tev instrument.

30. 05/01/2006Tevatron Instrumentation30 Intensity Measurements: DCCT and FBI DCCT (DC Current Transformer) –Typical intensities 10 9 → 10 13 –Noise ~0.5 e9 or ~0.005% max –24-bit ADC samples @ 6.9 MHz –Output 128-sample average @ 54 kHz –Calibrate via external pulser –N_p+N_pbar together FBI (Fast Bunch Integrator) –Bunch-by-bunch intensities via RWM –Narrow (1) & wide gates (5 buckets) Main and satellite bunches –Updates @ up to few hundred Hz –Sensitivity to temperature improved –Calibrate via DCCT Few % correction for satellites B. Fellenz T.Meyers Resistive Wall Monitor: Ceramic break with 80 120Ω resistors. Signals sampled at four locations are summed.

31. 05/01/2006Tevatron Instrumentation31 Beam Lifetime Depends on Chromaticity Two methods for fast Q’ measurements: –Head-Tail Monitor –Fast and Accurate TuneTracker (CDF Detector Proton Loss Counters)

32. 05/01/2006Tevatron Instrumentation32 Fast Q’ Head-Tail Monitor Particles with different dP/P have different tunes  head- tail phase difference ~Q’ Just few pi d  kick Accuracy ~0.5 unit Very fast method –Ops like it! Currently used for monitoring –No difficulty to measure Q’ with octupoles V.Ranjbar

33. 05/01/2006Tevatron Instrumentation33 Fast and Accurate Tune Tracker Beam is lightly excited over a frequency range around f_betatron Zero phase response frequency declared =Q Accuracy in Q ~0.0001 Very fast method (3Hz) –Works on every Tev ramp and in LB squeeze Change dP/P and determine Q’ –Stat accuracy ~0.2 –Syst error ~0.5 unit Determine and track Phase=0 frequency C.Y.Tan

34. 05/01/2006Tevatron Instrumentation34 Quadrupole Oscillations due to Lattice Mismatch: Ionization Profile Monitor Single bunch turn-by-turn beam size measurement. See separate talk. 1 cm A.Jansson

35. 05/01/2006Tevatron Instrumentation35 OTR Monitor 5 µm aluminized mylar foils Rad hard camera, 130x170µm size pixels See poster session! V. Scarpine

36. 05/01/2006Tevatron Instrumentation36 Both Instruments under development, but the first results are interesting: IPM shows significant (~30%) quadrupole oscillations OTR shows no size change over 1 turn (#2 vs #1, note ampl.) OTR, vert Turn #1 Turn #2 … just one example of importance of having several instruments for cross-checks  IPM, vert mm

37. 05/01/2006Tevatron Instrumentation37 Cross- Checks and -Calibration Intensity: DCCT and FBI and SBD –DCCT is most precise, but limited function –FBI and SBD within 1%, multi-functional Phase oscillations: SBD and LPM (slow and fast) Tunes: Schottky 21MHz, 1.7GHz, TuneTracker –All three in operations for different tasks –Absolute differences dQ~0.005, relative changes <0.001 –TT fastest and precise, 1.7GHz most versatile Emittances: Flying Wires, SyncLite, Schottky –Tons of efforts to bring the three to within ~10% –FWs are ~main tool, used for 1.7 GHz Schottky calibr-n Luminosity: CDF and D0 different by ~20% (!)

38. 05/01/2006Tevatron Instrumentation38 Lessons Learned - I  Due to peculiarities of SC synchrotron operation, non-invasive beam diagnostic instruments should be preferred, effects of intrinsically invasive ones minimized (FW 33  7um)  Having two or more instruments for same beam parameter measurements (makes life more complicated to bring them together but) makes the data more trustworthy  Fast data collection rate (at least 1 sec for all channels) is a must – at all stages, for all bunches, all the time – and saved for years (for postmortem)  Detectors have tons of beam diagnostics, so good communication channels with them are important

39. 05/01/2006Tevatron Instrumentation39 Lessons Learned - II  Accept help/ideas from other groups/labs – many of them have invaluable expertise: - CD: BPM upgr; PPD: BLM upgr/SL/beta* monitors; LBL: Abort Gap Monitor MCP-PMT; ANL: e-cloud detectors, etc.  An instrument development is fast, compared to time needed to make it “fully operational” and satisfactory for operators and physicists – a lot of efforts went into that   Team up diagnostics developers and users from the very beginning till commissioning of the instruments (and even beyond that – in operation)

40. 05/01/2006Tevatron Instrumentation40 Teaming Up for Instrument Development InstrumentsDevelopers Commissioners, Users  Beam Line Tuner D.McGinnis/V.ScrapineJ.Annala  dEmm@ Inj, ”last sec”V.ScarpineA.Xiao/J.Annala  BPM upgradeS.Wolbers/R.WebberM.Martens/J.Steimel  21.4MHz ShottkyB.FellentzP.Lebrun/D.Still  1.7GHz Shottky R.PasquinelliA.Jansson/V.Shiltsev  Tune TrackerC.Y.TanC.Y.Tan/J.Annala  SyncLite/Abort Gap MonitorR.Thurman-KeupA.Valishev/V.Shiltsev  Flying WiresJ.Zagel/S.PordesA.Jansson/E.McCrory  IBEAM+SBD+FBIR.Flora/S.PordesA.Tollestrup/J.Annala  Head-Tail MonitorV.RanjbarV.Ranjbar  Baseband SchottkyA.Semenov/C.Y.TanV.Lebedev/J.P.Carneiro  Vacuum Diagnostics/RGAB.HannaV.Shiltsev  HLS/VibrationsJ.Volk/T.JohnsonV.Shiltsev/J.Annala  Longitudinal Phase MonitorA.IbrahimJ.P.Carneiro/V.Shiltsev  Luminosity+IP diagnosticsCDF/D0V.Papadimitriou/V.Shiltsev  IPMs/OTRsA.Jansson/V.ScarpineA.Jansson  Beam Loss Monitor upgradeJ.Lewis/S.PordesJ.Annala/D.Still  Software (DLPlotter, OAC, SDA)T.Bolshakov/CntrlsR.Moore/J.Slaughter

41. 05/01/2006Tevatron Instrumentation41 So, Have We Won The Battle? Yes, but only one one of many… …the campaign is not over …the campaign is not over

42. 05/01/2006Tevatron Instrumentation42 “Waiting for Mr.Higgs…” 4 more years > quadruple luminosity integral may be Mother Nature will smile on us

43. 05/01/2006Tevatron Instrumentation43 And at the end… On behalf of the Run II team, we’d like to thank all who took part in beam diagnostics development and Thank you for your attention!

44. 05/01/2006Tevatron Instrumentation44 backUp Slides 

45. 05/01/2006Tevatron Instrumentation45 Fast Q’ Head-Tail Monitor Particles with different dP/P have different tunes  head- tail phase difference ~Q’ Just few pi d  kick Accuracy ~0.5 unit Very fast method –Ops like it! Currently used for monitoring –No difficulty to measure Q’ with octupoles V.Ranjbar

46. 05/01/2006Tevatron Instrumentation46 Special BPMs: Beam Line Tuner Measure turn-by-turn position at injection Extract betatron oscillations, do closure for next injection –Reduce emittance dilution from mis- steering –Calculate expected emittance dilution Also determine tune, coupling, energy & phase mismatches at injection Also for post-mortem of lost stores –Stop continuous data acquisition on abort –Look for signs of instabilities in “last second” buffer Tevatron Stripline parameters –1 meter long (< 1/4 ) –~30 dB directionality –Pickup gap = 83 mm –0.65 dB/mm Sensitivity –Located near F0 for maximum proton and pbar separation (in time)

47. 05/01/2006Tevatron Instrumentation47 Digital Receiver BLT Of course, it measures only DIPOLE oscillations 

48. 05/01/2006Tevatron Instrumentation48 Instruments under developments, but first results are interesting: IPM shows significant (>30%) quadrupole oscillations while OTR claims no size change over 1 turn whatsoever OTR, vert Turn #1 IPM, vert Turn #2 … just one example of importance of having several instruments for cross-checks 

49. 05/01/2006Tevatron Instrumentation49 LIST OF INSTRUMENTS  BLT+dEmm+”last sec”RM  BPM+relatedAJ  Shottky I + II+ III+TuneTrkAJ  SL+AGM+FWsVS  IBEAM+SBD+FBIRM  Head Tail MonitorVS  Vacuum+RGARM  HLSVS  RWM+LPMAJ  Luminosity+IP diagnosticsVS  Software (C49, D44, SDA, ArrView, DLPlotter, OAC)RM

50. 05/01/2006Tevatron Instrumentation50 Longitudinal Phase Monitor sin cos FPGA ADC Q-10bits I-10bits x x ADC Clock Gate Timing Beam Pick-up (Stripline) (SIMPLIFIED) A.Ibrahim Linearity: Simulated phase: Measured phase*: *Discrepancies explained by difference in RF voltage and shape asymmetry during acceleration

51. 05/01/2006Tevatron Instrumentation51 BPM Turn-by-Turn 1113 / 5 Artifacts* Betatron Lines R.Kutchke et al *Sampling frequency is 7/5 RF, so clock phase varies slightly with a period of 5 turns. Resolution: 0.3 mm/sqrt(Hz)

52. 05/01/2006Tevatron Instrumentation52 1.7 GHz Schottky measurements Schottky Horizontal Sync lite Horizontal Schottky Vertical Sync lite Vertical #4058Note: Arbitrary scaling Damper problems → longitudinal blow up #3989 NO fudge factors!!! #4000 RMS fluctuation around trend line: 5 10 -4 0.002 Pbar bunch #29 Intensity: 19 10 9 Emittance: ~17  mm mrad Momentum spread Emittance Single bunch tune SBD Schottky Horizontal Schottky Vertical *Note that the 1.7GHz Schottky can not resolve the two normal modes of oscillation by frequency, hence it is insensitive to tune changes due to coupling.

53. 05/01/2006Tevatron Instrumentation53 Schottky development II In-house development Similar to 3D-BBQ Looks at both positive and negative peaks Feed-back to eliminate LF and increase dynamic range Digital Beam Tune Monitor based on 16 bit 100MHz Digitizer RF CLOCK, RevMarker, TCLK, FPGA 100MHz 14 bit DAC Cable from Tunnel Ethernet, OAC INPUTs: BPM Plates TRACK/ HOLD 10Mbit ETHERNET (A-B)- LPF(A-B) TRACK/ HOLD A+B 100MHz 16 bit ADC 64MS RAM DSP SHARC Input from Plate ~40 ns Hold A, B A–B 100MHz 16 bit ADC LPF(A-B) + - Gain 100÷150 Reset A.Semenov

54. 05/01/2006Tevatron Instrumentation54 Schottky Development CERN has provided Direct Diode Detection Base Band Tune (3D- BBQ) module By gating with RF switches, were able to separate proton and pbar signals Issue with 60Hz lines Expert/Study tool for the moment. C-Y. Tan

55. 05/01/2006Tevatron Instrumentation55 Resistive wall monitor Ceramic break with 80 120Ω resistors. Signals sampled at four locations are summed. Calibration signal can be injected. Two monitors: one for FBI/SBD, and one for general use During early 36x36 operation, ferrite inside vacuum heated up and started outgassing. Fixed with a new type of ferrite Recently intermittent problems with some resistors. All swapped out. old ferrite new ferrite B. Fellenz

56. 05/01/2006Tevatron Instrumentation56 Longitudinal Phase Monitor II New development base on the same board as baseband Schottky. Yet to be tested. 2 Channels Longitudinal Phase Meter Based on 16bit 100MHz Digitizer FPGA CYCLONE Cable from Tunnel Ethernet, OAC INPUTs: BPM Plates 5MHz Gauss Filter 10Mbit ETHERNET 5MHz Gauss Filter 100MHz 16 bit ADC 64MS RAM DSP SHARC RF CLOCK, RevMarker, TCLK, 100MHz 16 bit ADC RF Refere nce ~20ns Phase ~10 0ns ADC Sampl es 18.8ns A.Semenov

57. 05/01/2006Tevatron Instrumentation57 Special Equipment on Low-Beta Quads Each low beta quadrupole is now equipped with : Tiltmeters with ~1 urad resolution (above) Water level sensors with ~0.2 micron resolution (right  ) J.Volk T.Johnson Hydrostatic Level Sensors on Low-Beta quads and Alignment data report that CDF detector is continuously sinking by ~0.5-1 mm/yr, distorting vertical position of ~dozen low-beta quadrupoles