LUMI and TUNE FEEDBACK

1
BNL - FNAL - LBNL - SLAC

• LUMI and TUNE FEEDBACK
• A. Ratti
• LBNL
• Presented at the DoE Review of the US LARP
• Santa Rosa
• 2-4 Nov. 2005

2
Outline

• Systems description and progress report - Lumi
  and Tune Feedback
• Technical approach
• Progress since June
• Planning and Outstanding issues
• Program management
• Current issues and remedies
• Systems definitions, interfaces and
  responsibilities
• Integration of LARP and the LHC
• Conclusions

3
LUMI - Requirements

• Help bring beams into collisions too

4
LUMI - Specification
5
LUMI - Conceptual DesignArgon Ionization Chamber
V
NGAP2
xGAP
? xGAP/vD
I0
?

• Signal is proportional to the number of parallel
  gaps
• Capacitance add up with n. of gaps slows down
  the signal
• Optimized for 6 gaps
• Must live in a radiation environment 100x worse
  than accelerator instruments have ever seen
• 10Gy/yr, 1018 N/cm2 over lifetime (20 yrs),
  1016 p/cm2 over lifetime

6
Ion Chamber Main Parameters
Example shown (6 atm) is that of the upcoming
RHIC experiment W. Turner - LBL-CBP TN 352, Oct.
2005
7
Bunch-by-bunch Luminosity
m0.33 ?INEL80 mb SNR5 2808 bunches
8
Signal Processing

• Very low noise pre-amp in the tunnel
• Shaper section completes the analog signal
  processing
• ADCs integrated in a VME64 mezzanine card
• Interface defined by CERN BDI group

9
LUMI Front-End Amplifiers Cold Termination
Pavia Amplifier

• Original Design developed by P.F. Manfredi, L.
  Ratti and G.Traversi of the University of Pavia
  using a cold termination technique
• E. Gatti, P.F. Manfredi, IEEE Trans. Nucl. Sci,
  vol. NS 25, 1978, pages 66-74

10
40 MHz Demonstration

• Tested the lumi detector at one of the hard x-ray
  beamlines at the ALS
• X-ray to ion pair production very hard to
  calculate
• White light configuration 70-80 keV x-rays
• Chamber modification needed
• Tested proof of principle in August
• Complete set of data taken in September
• Required dedicated machine time to fill the ring
  with a 40 MHz bunch pattern
• Pattern used allowed for a gap to measure single
  bunch response
• Also tested without gap to see continuous beam
• Enrico Bravin (CERN) at Berkeley during the
  experiments
• Allowed for much more integration efforts

11
LUMI Experimental Setup at ALS

• Built a dedicated part of the case in Aluminum
• Very thin (10 mils) wall exposed to the beam
• Had to add Cu foil to prevent saturation of the
  electronics

New Al housing w. thin wall
12
LUMI Experimental Setup at ALS

• Beam hit the chamber from the side to allow for
  minimal attenuation

LHC Beam Direction
ALS Beam Direction
13
Raw Chamber Signal
20 ns/div
14
After Pre-amp and Shaper
15
40 MHz Demonstration - Results

• Data recorded for multiple cases
• V scans
• Intensity scans (50 mA -gt few mA)
• Multiple turns will give statistics
• Data analysis starting
• Already shown
• No space charge saturation effects
• Minimal pileup
• Greatly simplifies deconvolution
• Analysis underway
• Linearity, precision, dynamic range

16
Last Major RD Issue - Radiation hardness

• Planning a meaningful test of the materials is
  really hard in most cases, test conditions are
  drastically different from LHC conditions
• Shower vs. neutrons
• Dose rate very different
• Parallel paths to minimize risk
• Careful research of materials properties
• Beam test at FNAL - if possible
• Fermilab is preparing a rad test facility at the
  p-bar target at the Tevatron is becoming
  available
• 120 GeV protons
• In collaboration with collimator group
• N. Mokhov is the FNAL contact
• LBL will prepare a plan by December 2005 for a
  test as soon as the facility is available in 2006

17
Plans for a test in RHIC

• Install in IR 10
• Former experiment, now empty
• Goals
• Become familiar with operation in a hadron
  collider environment
• Benchmark device against the proven RHIC ZDC
  luminosity monitors
• Investigate some sources of background
• Develop signal processing implementation
• Integrate electronics in accelerator environment
• RHIC run 6 will have p-p and Au-Au
• Run planned for Jan. to Jun. 2006
• Multiple reasons to prefer Au-Au collisions
• More neutron yield
• Better neutron energy
• Dedicated collisions have less effect on lifetime
  than in p-p mode
• Beam-beam stronger in p-p

18
RHIC Experiment Setup
19
RHIC Experiment Planning

• Formal proposal ready for submission at the APEX
  meeting
• Nov 9-10, 2005
• Will ask for dedicated collisions
• May be able to run briefly in parasitic mode
  during the Au run
• Use the existing ZDCs in the interaction region
• Calibrate the luminometer with known device
• Learn about backgrounds
• Shipment of the equipment next week
• Waiting for release from ALS EHS group
• Will install during the present shutdown
• Complete by December

20
Scope, Boundaries and Responsibilities

• LBNL will deliver
• 4 chambers with electronics for IP1 and 5
• Gas control system
• DAQ with programming
• Installation support
• Hardware commissioning
• CERN will provide
• Local installation
• Gas supply and distribution
• HV and DC power supplies
• Control system integration
• VME64 infrastructure and DABIV boards

21
Integration planning at CERN

• Complete system description
• Technical, installation, safety, electronics,
  responsibilities, deliverables
• Met with all relevant parties at CERN
• Final draft at CERN
• EDMS process underway

22
The case for IP2 and IP8

• LARP is providing four monitors which will be
  installed in IP1 and IP5
• LHC users have expressed written interest in
  having luminosity measurement capabilities at IP2
  and IP8. These devices are viewed as machine
  items. LARP has already clearly stated to CERN it
  cannot provide for local installation and
  customization at IP2 and IP8
• LARP can provide more ionization chambers to
  CERN, which would be identical to those provided
  for IP1 and IP5 if CERN provides funds for the
  additional devices
• this would be cost effective if funded (by CERN)
  during the production of the 4 items funded by
  LARP, scheduled to begin in the summer of 2006
• LARP will not provide local installation in IP 2
  and 8
• Installation and planning for using the devices
  at 2 and 8 is very different
• these IPs dont have TANs and will require a
  dedicated housing
• the supporting electronics is housed in areas not
  accessible during beam runs
• IP2 requires to have an unobstructed path of
  neutrons during the ion runs, adding complexity
  to the integration of the system
• CERN BDI group is working on finding an internal
  solution to the problem with no cost to LARP

23
Current Plans for FY06

• Build one complete unit. This includes
• Final design review (by April 06)
• a chamber, mating TAN bar, gas handling system,
  tunnel electronics package (pre-amps)
• Complete DAQ chain w. shapers, mezzanine boards
  and acquisition firmware integrated in CERN VME
  system
• no luminosity specific firmware/software
• Complete documentation of chamber production and
  electronic processing system
• Test existing prototype in RHIC
• Rad hard study and tests at FNAL (if possible)

24
LUMI Milestones

• FY05
• Complete high speed tests
• Complete conceptual design of FE electronics
• Complete and formalize system integration
  document
• FY06
• Design and build first unit of DAQ system
• Final design of complete first unit
• Test prototype at RHIC
• FY07
• Build all units
• Install and HW commission all units

25
Lumi Budget Summary

• Cost guidelines from task sheets (in k)
• FY 04 05 06 07
• Requested (LBL/BNL) 203 450 1187/25
  811/25-gt1063/25
• Received 395 935
• Note FY07 budget to be finalized by April

26
Tune Feedback

• Challenge persistent current effects in SC
  magnets can strongly perturb machine lattice,
  especially during energy ramp (aka snapback).
  Effects for LHC predicted to be large.
• Betatron tunes (Qx,y) and chromaticities
  (Qx,yEdQx,y/dE) can vary significantly due to
  snapback resulting in beam loss, emittance
  growth.
• Solution make fast, precision Q, Q
  measurements and use these signals to feedback to
  tuning quadrupoles and sextupoles.
• This effort is ideally suited for a collaboration
  with RHIC, which can be the benchmark and testing
  ground for this effort.
• The Two Issues at RHIC
• Dynamic Range
• Coupling

27
Tune Feedback - Specification

• The goal is to control the tune during the
  acceleration ramp to avoid resonance crossing and
  beam loss
• The PLL method is to shake the beam and observe
  the resonant beam transfer function when the
  shaking frequency is at the fractional betatron
  tune
• Bunched beam Schottky signal studies
• Used to measure the stability of beam tunes
  during each cycle of the LHC

28
Effects of persistent currents in RHIC
Qx and Qx measured in RHIC
Energy increasing
29
The Approach - from RHIC to the LHC

• At RHIC
• resonant pickup, above the coherent spectrum
• defeated by transition - short bunches, fast
  orbit changes
• challenged by coupling - strong sextupoles,
  vertical orbit changes affect coupling, coupling
  drives tune feedback unstable
• AT LHC (and next generation RHIC)
• direct diode detection - mix all betatron lines
  to baseband, solves dynamic range problem
• measure all four eigenmode projections - results
  in PLL that is robust in the presence of coupling
• CERN and BNL personnel are actively collaborating
  on tune feedback and using RHIC as a platform for
  developing the system

30
Overcoming Coupling

• Major issue (for both RHIC and LHC) is coupling,
  which drives the Tune Feedback loop unstable.
• Tune control (quadrupoles) is in horizontal and
  vertical planes
• Tune measurement is done with 'horizontal' and
  'vertical' pickups
• Coupling can rotate the normal mode (or
  eigenmode) usually associated with horizontal
  plane into the vertical plane
• Typically, tune measurement consists of measuring
  just one of the two projections of a given
  eigenmode into horizontal and vertical
• However, planes of the normal modes of the tunes
  are determined by coupling
• At this point the Tune Feedback loop becomes
  unstable
• The measurement of amplitudes and phases of both
  projections gives sufficient information to
  correct for the effects of coupling, and have
  stable tune feedback

31
Effects of Coupling
C-A/AP/174 - Possible phase loop for the global
betatron decoupling, Y. Luo et al C-A/AP/204
- Towards a Robust Phase Locked Loop Tune
Feedback System, R. Jones et al both at
http//www.rhichome.bnl.gov/AP/ap_notes/cad_ap_ind
ex.html
32
Configuration - Tune and Coupling

• Tune
• PLL tune measurement operational at RHIC for
  several years, automated, controlled by
  sequencer. Specialist checks status every few
  days.
• Used for ramp tune and chrom measurements, IR
  corrections, machine studies,...
• Coupling
• PLL re-configured to measure all
• four eigenmode projections
• results in PLL that can be made
• robust in the presence of coupling

33
Results - 3D and PLL

• 3D (Direct Diode Detection) - installed at PS,
  SPS, Tevatron, RHIC
• solves dynamic range problem
• significant improvement in sensitivity
• greater sensitivity reveals 60Hz problem
• beam is excited horizontally at betatron line by
  line frequency harmonics
• excitation appears in vertical due to coupling
• It is at baseband, will show up everywhere in the
  spectrum - we can't escape it
• Required modulation of dipole current at harmonic
  300 is actually pretty small - one part in 1011
• Baseband PLL - loop closed, performance superior
  to present RHIC system, but locks on 60Hz lines

34
Results from RHIC Run 5

• Chromaticity measurement
• runs reliably under automatic sequencer control
• data quality appears sufficient for LHC needs
• Coupling correction
• measurement of all eigenmode projections in hand
• formalism and implementation ready for Run 6
• Mains harmonics
• shown that they arise from main dipoles
• recent CERN study indicates not a problem for LHC
• Baseband Tune Measurement (BBQ)
• Direct Diode Detection (3D) AFE solves dynamic
  range problem
• successful tune tracking up the ramp with
  VME-based BBQ, 'out of the box'

35
Good results under sequencer control
gt
5
Q'
ramp 6380
-5
vert
5
ramp 6381
Q'
horiz
-5
gt
in RHIC modulation is at 1Hz
5
Q'
ramp 6382
-5
dp/p of /-10-4 gives /-100m radial modulation
(RHICLHC)
36

Measured eigentunes and 'set' tunes (calculated
from complete measurement of eigentune
projections) during a tune scan in RHIC
Yun's and Rhodri's parameters during tune
crossing
r2
Physical observables are the eigenmodes, which
are what are measured by the tune measurement
system. Eigenmode frequencies are determined by
strength of both normal and skew quadrupole
magnetic fields
Previously, tune feedback adjusted strength of
just normal quadrupoles (did not include skews)
based upon incomplete measurement of eigentunes.
Attempted to control Qx and Qy by measuring Q1
and Q2
r1
df2
df1
Q1
Qx
Qy
Q2
Tune Feedback would break here
PLL jumps eigenmodes here
37
TF - Integration Planning at CERN

• CERN EDMS document generated
• General statement
• The US-LARP tune feedback task is to
  provide
• the necessary instruments for the continuous
  measurement of tune, chromaticity and coupling in
  a robust way, with minimal emittance blow-up in
  the LHC.
• These instruments shall be foreseen to allow for
  the rapid implementation of tune feedback in the
  LHC, and the possibility of subsequent
  chromaticity and coupling feedback.

38
Scope and Responsibilities

• CERN provides essentially all hardware
• kicker amplifiers, kickers, and pickups for LHC
• Direct Diode Detection AFEs
• Digitizer boards
• DAB64 Boards - FPGA for processing plus VME
  interface
• LHC (BPM, BLM, BCM,...) and LARP (PLL, Lumi,
  Schottky) standard
• VME crates and crate computers for CERN
  installation
• LARP provides all software up to LHC Control
  System
• VME crates and crate computers for LHC test
  installation at BNL
• gate array programming
• FEC programming
• LabVIEW control program, collaboration on LHC
  equivalent (FESA)
• specification and testing of LHC TF Applications
  software
• testing at RHIC, with and without beam
• pre-beam and beam commissioning support at LHC

39
Milestones - Pt. Jeff Apr 05

• FY05
• Apr 05 - Preliminary Design Review - favorable
• Jun 05 - finalize prototype system architecture
• move from DAB (late Triumf delivery) to VME for
  prototype
• FY06
• Nov 05 - prototype (4 planes) ready for RHIC
  beam in VME
• Feb 06 - deliver 2 planes to CERN for SPS
  testing in DAB?
• Apr 06 - Final Design Review
• May 06 - SPS testing, initial Controls
  integration (FESA)
• Jun 06 - finalize architecture
• FY07
• Nov 06 - final system (4 planes) ready for RHIC
  beam
• Feb 07 - deliver final system to CERN, system
  integration and testing
• Summer 07 - system commissioning with beam

40
Tune Feedback Budget Summary

• Cost guidelines from task sheets (in k)
• FY 04 05 06 07
• Requested (BNL/FNAL) 138 240/15 300/35
  325
• Received 100 122/15 300/25
• Note FY07 budget to be finalized by April

41
Issues - Funding

• Main problem is budget shortfall in FY06
• Caused in part by additional expenses due to a
  delay in the availability of the DAQ system from
  TRIUMF to CERN
• From the June DoE review
• While the instrumentation items are a small part
  of the overall program, they are well-chosen and
  seem to be adequately supported at present. There
  was a sense, however, that the instrumentation
  activities might be squeezed out by excessive
  demands from other parts of the LARP program
  (magnets and/or commissioning). LARP management
  must guard against this happening, as these
  devices form an entry for the U.S. team into the
  arena of beam commissioning.
• A formal request (261k/2yrs) has been made in
  October to address the problem

42
Summary of Tune Feedback Status

• In good shape technically
• coupling problem solved by complete measurement
  of eigenmode projections
• dynamic range problem solved by direct diode
  detection (3D) analog front end
• ready with complete system (both rings) RHIC Run
  6, intent is to implement tune feedback 'day one'
• Concern with late TRIUMF delivery of DAB board
• See below
• Concern with budget
• LARP management is addressing this
• Budget retune v.2c

43
Common issue - Data Acquisition

• CERN requested that everyone uses the DAB-IV
  board as the interface point and responsible to
  provide these boards to the LARP instruments
• This impacts all LARP instrumentation
• Such boards are under development at TRIUMF and
  the firmware that runs them is late
• LARPs development can be negatively impacted by
  delays in DAB-IV boards
• LARP needs a minimum of 12-15 months with working
  DAB-IV boards to complete the necessary DAQ
  systems
• This has been communicated to CERN
• CERN recognizes the problem (impacts many CERN
  projects as well)
• LARP is working to set up video conferences and
  in person meetings to address the issue
• This caused cost increases in tune feedback
• Need a working solution by January to prevent a
  schedule delay

44
Conclusions - Integration and Planning

• We have created the EDMS documents for both Lumi
  and Tune Feedback defining scope,
  responsibilities, interfaces and overall schedule
• Once entered, goes under configuration control at
  CERN
• Signoff of all stakeholders
• CERN involvement is increasing
• Actively participating to testing of both systems
  
• Plan to continue during the RHIC run
• US colliders continue to be a tremendous setting
  to develop and demonstrate these instruments
• RHIC in particular

45
Conclusions - Challenges

• Funding
• We are working with LARP management to continue
  securing adequate funding
• LARP management is committed to fix the Tune
  Feedback problem
• CERN is also well engaged
• Luminometry at IP2 and 8 is NOT scope creep
• LARP task sheets continue to define scope and
  budget year by year
• Funding requests are also managed through task
  sheets
• Detail project reviews validate overall cost
  and schedule
• Integration with beam commissioning activities is
  essential to the survival of the instruments
  provided by the LARP collaboration and LARP is
  planning accordingly

46
Summary

• LARP Instrumentation will build, commission, and
  integrate into LHC operations advanced
  instrumentation and diagnostics for helping LHC
• reach design energy
• reach design luminosity
• Strong collaborative efforts are in place and
  evolving
• Tune feedback is fully leveraging RHIC experience
  and includes CERN staff
• Lumi plans to do the same with RHIC run 6
• Schottkys experience at FNAL is a great asset
• synergies with BNL are fully leveraged
• This program will advance the US HEP program by
• Enhancing US accelerator skills
• Developing advanced diagnostic techniques that
  will apply to present and future US programs
• Help maximize LHC performance