# Presentation: 011911

## 
BEAM INSTRUMENTATION
A. Ratti
LBNL

Presented at the DoE Review of the US LARP

FNAL
1-2 Jun 2003

_**BEAM INSTRUMENTATION**_
- A. Ratti
- LBNL
- Presented at the DoE Review of the US LARP
- FNAL
- 1-2 Jun 2003

***brookhaven - fermilab - berkeley***

## Outline

- Introduction - motivation and mission
- Systems description + progress report
- Lumi
- Tune Feedback
- Schottky - new task
- Program management
- Systems definitions, interfaces and responsibilities
- Integration within LARP and the LHC
- Budget
- Conclusions

## LARP Instrumentation Systems

- LARP Instrumentation will deliver unique capabilities that will greatly enhance the LHC and facilitate both commissioning and performance optimization
- Luminosity Monitors
- Bunch-by-bunch measurement of luminosity
- Tune Feedback and Coupling measurements
- Tune measurement and PLL feedback
- Schottky Monitors
- Non invasive bunch-by-bunch tune (+ Chromaticity)

## LARP Instrumentation Goals

- LARP Instrumentation will help:
*Bring LHC to full energy*
- 	Betatron tune, coupling, and chromaticity control during ramp
*Bring LHC to design luminosity*
- 	Real-time luminosity monitor

- These contributions advance the state-of-the-art in beam instrumentation and have direct contributions to present and future US accelerator projects.

## LUMI - Requirements

- Help bring beams into collisions too

## LUMI - Specification

## LUMI - Installation Concept

- DAQ
- TAN

- FE electronics located
- behind TAN
**(shown here for illustration purposes)**

## LUMI  - Detector Assembly

## LUMI - Conceptual DesignArgon Ionization Chamber

- I0

- 

-  = *x*GAP/*v*D

- 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 100 x worse than accelerator instruments have ever seen

- V+

*x*GAP

- NGAP=2

## LUMI - Pulse Shaping + DAQ

- Active termination front end to properly compensate the chamber capacitance
- Initial design in collaboration with Univ. di Pavia, INFN, Italy
- Pulse shaping electronics necessary to limit the noise bandwidth.
- Pulse shaping is also necessary to reduce the width of the pulse to accommodate the 40MHz repetition rate.
- Baseline recovery (Pole-Zero cancellation)
- Shaped pulse is digitized in a mezzanine board designed for the DABIV VME64 card used as standard interface by CERN - BI
- FPGA programming by LBL, controls programming by CERN

## Deconvolution Errors 

- The current method uses the arbitrary waveform generator to the limits of its capabilities.
- The alternative solution is to use a true deconvolution algorithm using Fourier transform.

## LUMI - Status

- Activity started as early as 1997
- initially part of LHC construction project
- Participated in 40 MHz runs at CERN in 2000 and 2001
- Present approach and chamber design developed in 2003
- Beam tested at ALS booster transfer line at 1 Hz
- Validated all system modeling
- Fully tested integration with FE electronics
- Plans for a 40 MHz test with hard X-rays at ALS beamline

## LUMI - LARP Review

- Successful LARP review of LUMI held on April 11, 2005
- Shea (chair), Bravin, Drees, Field, Fisher, Nygren
- Presented technical design, planning, budget & resource loaded schedule
- Program fully endorsed by the committee
- Among recommendations:
- Improve integration with CERN
- Expediting system integration planning and documents
- Import as much knowledge as possible on material properties
- Other findings:
- 1% bunch to bunch resolution and 40  MHz capability is not a baseline requirement for commissioning of LHC and  routine operations. Instead a few percent up to 10% resolution is requested.
- Although prototype construction must remain the highest priority, the committee  endorses continued testing in parallel with this construction.

## LUMI - Integration

- LBNL to deliver
- 4 chambers with electronics
- DAQ with programming
- Installation support
- Hardware commissioning
- CERN to provide
- Local installation
- Control system integration
- VME64 infrastructure
- Agreement being defined in a system integration document part of the LHC document control system

## 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

## 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 (Q’x,y=EdQx,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

## Tune Feedback - Goals and Integration

- 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
- Once the fractional tune is measured with the PLL it is used in a feedback system to regulate the quadrupole current and tune

## The Approach - from RHIC to the LHC

- At RHIC
- resonant pickup, above the coherent spectrum
- defeated by transition - short bunches, fast orbit changes
- defeated 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

## Effects of persistent currents in RHIC

- Qx and Qx’ measured in RHIC

- Energy increasing

## Results - 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

## 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

## TF - LARP Preliminary Design Review

- Review held in Port Jefferson in April 2005
- Pasquinelli (chair), Brennan, Fisher, Lamont, Lebedev, Shea
- Demonstrated potential to satisfy LHC tune feedback requirements
- Established the rapport that enables a successful collaboration
- 3D (Direct Diode Detection) provides a vast improvement over previous attempts
- Proposed coupling compensation is very clever, needs testing
- 60Hz problem needs to be clearly defined by measurements in RHIC
- Modeling of coupled loops (tune, chrom, coupling, orbit feedback, RF,...) is needed
- Fully operational system should be implemented at RHIC

## Scope, Boundaries, 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

## Tune Feedback Milestones

**FY05**
- 	Apr 05 - Preliminary Design Review - completed
- 	Jun 05 - finalize prototype system architecture (need 60Hz balancing at RHIC, clarification of 50Hz magnitude at LHC)
**FY06**
- 	Nov 05 - prototype (4 planes) ready for RHIC beam
- 	Feb 06 - deliver 2 planes to CERN for SPS testing
- 	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

## Schottky Monitor

- Advanced enabling technology
- Extremely versatile instrument will provide unique capabilities
- Only tune measurement during the store
- Bunch-by-bunch measurement of important parameters
- Tune, Chromaticity
- Average measurements as well
- Momentum spread + emittance
- Beam-beam tune shift
- Non invasive Technique
- Very powerful tool for beam physics
- Beam-beam interaction studies
- Bunched beam Schottky signal studies
- Used to measure the stability of beam tunes during each cycle of the LHC

## Schottky - Integration with CERN

## Schottky - Technical approach

*1.7 GHz  109 x 75 mm aperture at Tevatron*
*4.7 GHz 60 x 60 mm proposed for LHC*

## Schottky - Excellent Experience at Tevatron

- Allows measurements of:
-  Tunes from peak positions
-  Momentum spread from average width
-  Chromaticity from differential width
-  Emittance from average band power

## Schottky - LHC Design

## Schottky Planning

- FNAL will deliver:
- 	A complete design and analysis
- 	A drawing package
- 	The analog signal processing electronics
- 	Analysis software
- 	Installation and HW commissioning support at CERN
- CERN will provide:
- 	Manufacturing and local installation
- 	DAQ system
- 	Controls system integration
- BNL is collaborating on DAQ activities thanks to synergy with TF electronics

## Schottky Milestones

**FY06**
- 	S/N study of low intensity bunches in Tevatron
- 	Design pick-up structure
- 	Study PLL DAB board for DAQ (with BNL)
**FY06-07**
- 	Design and build front-end electronics
- 	Adapt Fermilab analysis software
**FY07-08****	**
- 	Hardware commissioning at CERN (w and w/o beam)
- 	Beam studies (e.g. chromaticity, ramp)
- 	Non-destructive average **tune**, emittance, momentum spread and chromaticity measurement capability (LARP)
- 	Non-destructive bunch-by-bunch **tune**, emittance, momentum spread and chromaticity measurement capability (LARP)

## Future Tasks Proposals

- As these tasks are under development, our community is still active
- More activities are ready for consideration
- Will slowly be introduced as the current ones are completed
- Beam/Beam studies
- AC dipole for reactive excitation of beam
- beam-beam compensation with electron lens or wire
- Electron Cloud
- In situ low energy electron spectrometer
- Optical based diagnostics
- Under development at the Tevatron in collaboration with BNL
- These or other ones will be added to the LARP program as need arises and funding permits.

## FY06 Budget

- This remains a best effort program, with short term goals
- A 10% reduction would be have a big impact:
- Milestones will slip
- Deliverables will change (may eliminate task(s))
- Or both
- In the timeframe of these activities the slip could be significant
- Some instruments may miss first collisions in LHC

## Integration and Planning

- As the LHC commissioning approaches, and these programs finalize their efforts towards devices for LHC installation, this collaboration has started to tighten its internal agreements and those with CERN
- So far, things have been handled by CERN specs and LARP task sheets
- Adequate for funding received
- Moving towards a more formal structure
- Developing integration documents
- Define deliverables, interfaces, requirements
- Direct involvement of CERN’s points of contact

## Challenges

- Due to the nature of the devices, instrumentation activities have hard deliverables tied to LHC commissioning, yet are part of an R&D program
- Must manage budgetary uncertainty
- Work closely with LARP management and CERN to define and manage scope on a year to year basis
- Task sheets define FY deliverables
- System integration documents are prepared and authored by all labs involved
- Define deliverables, schedules, responsibilities, interfaces
- Integration with beam commissioning activities is essential to the survival of the instruments provided by the LARP collaboration

## 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 is planning on the same
- Schottky’s 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