Accelerator Systems

1. Accelerator Systems Eric Prebys Ezio Todesco Mike Zisman

2. Findings • “accelerator systems” currently includes • Instrumentation • Luminosity monitoring • Tune Feedback • Schottky Detector • (proposed) AC Dipole • (proposed) Synchrotron light based diagnostics • Accelerator Physics • IR and beam-beam issues • Beam-beam compensation • Electron Cloud • Other • Collimation • Simulation • RHIC studies • Phase II collimator design • Commissioning • Hardware & IR • Beam

3. Findings (continued) • From among these activities, four things have been identified as “hard deliverables”, indicating that they are considered crucial to the success of the LHC and that no credible alternative has been identified: • Luminosity monitors • Tune monitoring • Rotating Copper collimators • “Commissioning” • HW and IR: fairly well defined • Beam: “deliverable” = “bodies”

4. Observations • General • Much progress since the last review • The overall structure of the Accelerator Systems group appear well suited to the tasks at hand. • Transition to bigger budget and scale going well • In general, people are availing themselves well of R&D opportunities at existing accelerators • The introduction of “hard deliverables” is a bit of a change for LARP: • It has the benefit of increasing LARP’s importance and visibility. • Doesn’t fit well into the historic budget and resource-driven scheduling (more an issue for management).

5. Observations • Instrumentation • The luminosity, Schottky, and tune monitoring tasks are well thought out, managed, and appear to be well on track. • The success of tune monitoring is seen as reflecting very well on LARP • Both the AC Dipole and synch. light projects appear promising but are in their early stages at this point • Whereas the Schottky, luminosity, and (proposed) synch light monitors are passive measurements, the tune monitoring and (proposed AC dipole) involve perturbing the beam and so may have beam loss consequences.

6. Observations (continued) • Accelerator physics • Electron cloud studies appear well organized and there is good coordination between modeling and beam measurement • In the “quad first” IR upgrade solution appears to be winning by default, but this may change if parasitic beam-beam effects become important. The process for evaluating the importance of this was not apparent to the committee. • Beam-beam compensation studies are proceeding well. • There were some comments about the potential effect of magnet flux jumps, but not yet much progress or integration with magnet group

7. Observations (cont’d) • Collimation • The LHC has made the decision to go with a Carbon-Carbon collimator for initial collimation which will not be sufficient for full luminosity • The lack of resources at the LHC has elevated the proposed “rotating cylinder” collimator to critical path (ie, a “hard deliverable”). • This is a great chance for LARP to make a mark (one way or the other!) • The engineering for this project is well along for this point in the project. • It appears more work is needed in considering accident scenarios • Radiation issues have not yet been specifically considered in any depth. • There is a worrisome disagreement between data and simulation for the proton data taken at RHIC

8. Observations • Commissioning • Hardware and IR commissioning are already underway and appear to going well • Providing generic bodies for beam commissioning is a novel exercise and its success depends critically on how well it is managed • End effects could eat up much if not all of a three month stay. • So far, recruitment for “commissioners” has been bottoms up (ie, those that want to go) rather than targeted toward necessary skills. • LHC@FNAL is has great potential as an orientation tool that should be utilized

9. Recommendations • Instrumentation • Consider potential beam degradation caused by invasive beam measurements • Accelerator physics • Articulate the decision process for deciding among the various IR options • In particular, parameterize the effect of parasitic beam-beam interaction and specify how it will be quantified in terms of modeling and/or beams studies once the LHC is running. • Work with magnet group to formalize magnet specifications for IR upgrades, both in terms of field quality and flux jumps.

10. Recommendations (continued) • Collimation • Investigate the discrepancy between simulation and measurement in the RHIC studies and evaluate its potential implications for LHC operation • Consider accident scenarios and their consequences, particularly if a given accident will result in a component change. • Explicitly consider “operational” radiation issues • Hardware components • Environmental issues (is CERN’s shielding etc adequate) • Hot handling procedure • Coordinate with CERN.

11. Recommendations (cont’d) • Commissioning • Investigate previous experience with “outsiders” helping to commission accelerators. • Take advantage of LHC@FNAL and similar things to familiarize commissioners with CERN control system prior to visit. • May well involve a formal “correspondence course” • Identify a coordinator at the CERN end to help with the mechanics of getting established at CERN. • Manage overlap to maximize collective memory and experience • Possibly identify an official “mentor” • Work from the top down to identify and recruit people with desirable skills as well as potential long term (> 6 month) commissioners. • Actively solicit feedback on the hardware commissioning activities and early beam commissioning to optimize the program in the long (10 year) run.