1 Letter of Rossi to Peggs (agred with Schmickler and Devred) April 2005  We strongly believe that the major steps in the near term are: 1)Construction of a quadrupole model, full cross-section, with parameters that are really significant for the LHC upgrade : G  250 T/m,   90 mm….Otherwise there is the risk we give the impression we keep selling goods that never materialize. 2)Construction of simple systems that may address the long magnets issues. We insist on this, as you know since our last recommendation, because we feel that it is vital … The system should be simple, in order to be low cost with fast turn-around, but should contain elements relevant for the actual costheta design…  In longer (but not too much longer, i.e. FY2009) terms, the main focus should be to pursue a 5 m long quadrupole, with characteristics almost final. The manufacturing of a successful prototype for 2009 is real vital to the whole magnet program, on both side of the Atlantic. Failing to produce such a prototype in the proper time may reinforce the idea that technologies beyond NbTi are too difficult and complicated for real accelerator magnets.

2 Letter LR continue  Examining alternative routes may be interesting, and eventually it may be very useful, but it should be a second priority in LARP, at least in my vision. We always understood that LARP should be complemented by a vigorous basic program, that is the most suitable to assess the feasibility of alternative routes without diluting the scope (and the resources) of LARP.  Without entering into the details of the activities and on the subdivision among different laboratories, which I do not want to comment on, I strongly support in its global figures and scope the program that S. Gourlay is going to present at the BNL meeting. I consider this essential if the US wants to play a crucial role in the LHC after LHC commissioning.

3 US LHC Accelerator Research Program Magnet Systems Provide options for future upgrades of the LHC Interaction Regions Primary Focus: Demonstrate by 2009 that Nb 3 Sn magnets are a viable choice for an LHC IR upgrade –The major issues: Nb3Sn technology, consistency, bore/gradient (field), length –Three phase approach 1. 1.Predictable and reproducible performance  TQ models (1 m, 90 mm aperture, G nom > 200 T/m, B coil > 12 T) 2.Long magnet fabrication  LQ models (4 m, 90 mm aperture, G nom > 200 T/m, B coil > 12 T) 3.High gradient in large aperture  HQ models (1 m, 90+ mm aperture, G nom > 250 T/m, B coil > 15 T)

4 TQS/C - Predictable and Reproducible Nb3Sn Performance Technology Quadrupoles (TQ) – 90 mm aperture – Gradient > 200 T/m – Explore alternate shell and collar structures using “identical” conductor / coils, form basis for more ambitious designs – Major initial emphasis to prove Nb3Sn technology – Coil production process developed across laboratories – Tests of TQS01 and TQC01 completed—Excellent First Results – Coils for TQC/S02 in process

5 TQ Coil Design and Fabrication Design features: Double-layer, shell-type One wedge/octant (inner layer) TQ01: OST-MJR strand, 0.7 mm TQ02: OST-RRP strand, 0.7 mm 27-strand, mm width Insulation: S-2 glass sleeve Winding & curing (FNAL - all coils)Reaction & potting (LBNL - all coils)

6 TQS01 Quench History Started training at 80% of short sample reach 87% plateau on the 12th quench. Quenches typically in single coil, at given location High axial tensile stress measured in the island Potential problem pointing at a high strain area between island sections Rebuild addressing problem area and other production lessons learned underway TQS01 SSL 4.5K SSL 3.2K

7 TQC01 Quench History 4.5K plateau with erratic behavior 1.9K plateau at 85% of the expected critical current limit Highest current is at ~12000A  200T/m Training quenches tend to be in inner coil pole, in area of low prestress. Last quenches moved to outer coil. Disassembly and investigation underway

8 LR/LQ: Long Magnet Fabrication Long Racetrack – Coil fabrication scale-up based on well- understood sub-scale coils – Explore length scale-up of coils in shell- based support structure – BNL practice winding, procurement of necessary oven and tooling underway Mirror dipole scale-up via FNAL core program – 2m practice coils under reaction, winding of 2m coils underway Long quadrupole (LQ) – 3.6 m quadrupole based on TQ cross- section—initial coils and tooling designs in study

9 HQ: High Gradient in a Large Aperture High Gradient Quadrupole (HQ) – Explore field and stress limits to performance Increase peak field on the coil to ~ 15 T Precursor to larger aperture Push Nb3Sn technology based on TQ experience Develop reasonable parameter space for final LHC Upgrade design Example: 4-layer, G= T/m Current subject of design studies --set up basis for iteration between magnet design possibilities and IR operating conditions

10 US LHC Accelerator Research Program Magnet Systems FY07 is an exciting transition year Initial TQC/S results are very promising –Coil production technology converged –In depth understanding of results underway –Development of improved 2 nd iterations in process –Technological basis is being formed Length experiments coming on-line –Practice coils wound –4m oven installation done at FNAL, in process at BNL Studies and Designs for the next steps ramping up –LQ detail designs start –HQ parameters becoming understood 1.

11 Feedback and interations  Through frequent exchange and contacts, either at conferences or ad hoc meeting (Jim Kirby visited CERN as soon as he has taken over the charge of S. Gourlay this spring).  Through common workshops: WAMS, WAMDO, CARE general meeting, LUMI, etc.  No participation of the Magnet R&D linkman (L. Rossi) to the LARP collaboration meeting. Amended starting next meeting in Port Jefferson October  membership of CERN magnet people to many reviews: Fermilab director review (Fen 2006, L. Rossi chair), DOE LARP review June 2006 (E. Todesco, P. Fessia), DOE LARP reviews and LAPAC permanent membership (A. Devred). NED/HHH are fully in the game.  I think we have an excellent relation with LBNL and BNL; a good but not so excellent one with Fermilab (simply they have a strong basic program where they pursue their scopes and this they do not necessarily fully discuss with us: should they?)