# Presentation: 222531

##   Tevatron Beam Diagnostics:     Boosting Collider Performance

- _Vladimir Shiltsev,_
- Ron Moore, Andreas Jansson
- FNAL/Accelerator Division

## “Generals are always 
   prepared to past wars.”

- “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

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## Overview of “the Battle”

- Tevatron Instrumentation

- 05/01/2006

## “Driver’s Nightmare” 

**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

- Tevatron Instrumentation

- 05/01/2006

## “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)**

- Tevatron Instrumentation

- 05/01/2006

## Situation improved: 2005

- Store #4116
- Apr 27, 2005

**Note :**
**Losses 1/20 of ‘01**
**8x proton intensity**
**40x pbar intensity**

- Tevatron Instrumentation

- 05/01/2006

## 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”

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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**

**Echotek board**

**Echotek board**

**53MHz BPF**

**MVME**
**2400**

***Note that “resolution” **
**includes real beam motion, **
**mainly in the horizontal **
**plane (synchrotron osc.)**

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006

## -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**** **

**B0**

**D0**

- Change of beta @ IP
- β*=36cm29cm
- gave _~10% gain in Luminosity_

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006

## CDF detector sinking ~0.5 mm/year Interaction Point Moves  inefficient b-tagging

**Intentional **
**move upon CDF request**

**Reported by CDF**
**Silicon Vertex Detector**

- Tevatron Instrumentation

- 05/01/2006

## CDF and D0 IP Waist Diagnostics

**J.Estrada/A.Chandra**

**01/04**

**01/05**

**01/06**

- 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

- Tevatron Instrumentation

- 05/01/2006

## Tevatron: Life in the “Tune Box”

- 7th order resonances:
- Q=4/7=0.571 -
- HIGH LOSSES

- 12th order resonances:
- Q=7/12=0.583 -
- Bad lifetime

- 5th order resonances:
- Q=3/5=0.600 –
- EMITTANCE BLOWUP

- proton

- pbar

*every bunch has *
*its own tune!*

- Tevatron Instrumentation

- 05/01/2006

## Tune Diagnostics: 21.4 MHz Schottky

- Workhorse for shot setup. Operators determine tune from spectrum peaks
- Often needs excitation (VTICK)
- _But:_ a) does not see pbars anywhere, b) very complicated by coherent tune lines,
- c) does not see bunch-by-bunch tunes

**B. Fellenz**

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 1.7GHz Schottky Bunch Tunes

-      *Bunch-by-bunch tune variation ~0.005 – an indication of parasitic beam-beam interactions*

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## Sampled Bunch Display  (SBD)

- Measure bunch intensities, lengths
- Few – 350 × 109, 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.

- Tevatron Instrumentation

- 05/01/2006

## 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 109 particles in the abort gaps (total beam ~ 1013) as they lead to quench on beam abort (kicker sprays them)

- Tevatron Instrumentation

- 05/01/2006

## Abort Gap Intensity Monitor

-  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 <= 106
- No sensitivity to pre-gate light

**R.Thurman-Keup**

- Tevatron Instrumentation

- 05/01/2006

## DC Beam in Abort Gap:TEL On/Off/On

** ****AGM is calibrated wrt to DCCT - the most precise Tev instrument.**

- Tevatron Instrumentation

- 05/01/2006

## Intensity Measurements: DCCT and FBI

- DCCT (DC Current Transformer)
- Typical intensities 109 → 1013
- 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.

- Tevatron Instrumentation

- 05/01/2006

## Beam Lifetime Depends on Chromaticity

- Two methods for fast Q’ measurements:
- Head-Tail Monitor
- Fast and Accurate TuneTracker

**(CDF Detector Proton Loss Counters)**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## Quadrupole Oscillations due to Lattice Mismatch: Ionization Profile Monitor

- Single bunch turn-by-turn beam size measurement.
- See separate talk.

**1 cm**

**A.Jansson**

- Tevatron Instrumentation

- 05/01/2006

## OTR Monitor

- 5 μm aluminized mylar foils
- Rad hard camera, 130x170μm size pixels
- See poster session!

**V. Scarpine**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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% (!)

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006

## 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)

- Tevatron Instrumentation

- 05/01/2006

## Teaming Up for Instrument Development

- 	Instruments			Developers	         Commissioners, Users
- Beam Line Tuner 		D.McGinnis/V.Scrapine	J.Annala
- dEmm@ Inj, ”last sec”		V.Scarpine		A.Xiao/J.Annala
- BPM upgrade			S.Wolbers/R.Webber	M.Martens/J.Steimel
- 21.4MHz Shottky		B.Fellentz		P.Lebrun/D.Still
- 1.7GHz Shottky  		R.Pasquinelli		A.Jansson/V.Shiltsev
- Tune Tracker			C.Y.Tan			C.Y.Tan/J.Annala
- SyncLite/Abort Gap Monitor	R.Thurman-Keup		A.Valishev/V.Shiltsev
- Flying Wires			J.Zagel/S.Pordes		A.Jansson/E.McCrory
- IBEAM+SBD+FBI		R.Flora/S.Pordes		A.Tollestrup/J.Annala
- Head-Tail Monitor		V.Ranjbar		V.Ranjbar
- Baseband Schottky		A.Semenov/C.Y.Tan	V.Lebedev/J.P.Carneiro
- Vacuum Diagnostics/RGA		B.Hanna			V.Shiltsev
- HLS/Vibrations		J.Volk/T.Johnson		V.Shiltsev/J.Annala
- Longitudinal Phase Monitor	A.Ibrahim		J.P.Carneiro/V.Shiltsev
- Luminosity+IP diagnostics	CDF/D0			V.Papadimitriou/V.Shiltsev
- IPMs/OTRs			A.Jansson/V.Scarpine	A.Jansson
- Beam Loss Monitor upgrade	J.Lewis/S.Pordes		J.Annala/D.Still
- Software (DLPlotter, OAC, SDA)	T.Bolshakov/Cntrls		R.Moore/J.Slaughter

- Tevatron Instrumentation

- 05/01/2006

## So, Have We Won The Battle?

*Yes, but only one one of many...*
*          ...**the campaign is not over*

- Tevatron Instrumentation

- 05/01/2006

## “Waiting for Mr.Higgs...”

- 4 more years
-    > quadruple luminosity integral
-         may be Mother Nature will smile on us

- Tevatron Instrumentation

- 05/01/2006

## 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!

- Tevatron Instrumentation

- 05/01/2006

## backUp Slides

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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)

- Tevatron Instrumentation

- 05/01/2006

## Digital Receiver BLT

- Of course, it measures only DIPOLE oscillations

- Tevatron Instrumentation

- 05/01/2006

## 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 

- Tevatron Instrumentation

- 05/01/2006

## LIST OF INSTRUMENTS

- BLT+dEmm+”last sec”		RM
- BPM+related			AJ
- Shottky I + II+ III+TuneTrk	AJ
- SL+AGM+FWs			VS
- IBEAM+SBD+FBI		RM
- Head Tail Monitor		VS
- Vacuum+RGA			RM
- HLS				VS
- RWM+LPM			AJ
- Luminosity+IP diagnostics	VS
- Software (C49, D44, SDA, ArrView, DLPlotter, OAC)	RM

- Tevatron Instrumentation

- 05/01/2006

## Longitudinal Phase Monitor

**A.Ibrahim**

**Linearity:**

**Simulated phase:**

**Measured phase*:**

***Discrepancies explained **
**by difference in RF voltage **
**and shape asymmetry during **
**acceleration **

- Tevatron Instrumentation

- 05/01/2006

## 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)

- Tevatron Instrumentation

- 05/01/2006

##  1.7 GHz Schottky measurements

**Schottky Horizontal **
**Sync lite Horizontal**
**Schottky Vertical**
**Sync lite Vertical**

**#4058**

**Note: Arbitrary scaling**

**Damper problems**
**→**** ****longitudinal blow up**

**#3989**

**NO fudge factors!!!**

**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.**

- Tevatron Instrumentation

- 05/01/2006

## 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,**

**A.Semenov**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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**

- Tevatron Instrumentation

- 05/01/2006

## 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 Reference

***~20ns***

***Phase***

***~100ns***

- ADC
- Samples 18.8ns

**A.Semenov**

- Tevatron Instrumentation

- 05/01/2006

## 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

- Tevatron Instrumentation

- 05/01/2006