Michael Benedikt AB/OP Why and how to prepare for 900 ms basic period operation in the near future Michael Benedikt AB/OP 14/01/05 PS & SPS Days 2005

Outline Introduction Expected performance Other aspects Motivation, basic choices, impact Expected performance Overview Other aspects Implementation Summary and conclusions 14/01/05 PS & SPS Days 2005

Motivation Existing commitments (from HIP WG results) Important shortfall of SPS cycles for physics (CNGS and FT). ISOLDE performance 5 to 10% below request in CNGS era. Upgrade plans of CNGS (>factor 1.5) and ISOLDE (up to factor 5). Proposed improvement plan for SPS physics: Significant increase of CNGS intensity per SPS pulse: Fulfil (nominal) CNGS in shorter period and gain time for FT. Upgrade of CNGS without (further) reduction of cycles for FT. Consequences of higher intensity for SPS: Requires “double batch” filling PSB to PS i.e. more PSB cycles: Needs ~ 4 × 105 more PSB cycles, brings ISOLDE ~ 15% below request. Needs ~ 2 × 106 more PSB cycles, brings ISOLDE ~ 35% below request. Potential solution is an increase of PSB repetition rate 14/01/05 PS & SPS Days 2005

Basic choices and consequences Why 900 ms basic period and not…….e.g.1100 ms or 600 ms: Aim was to look for a short-term, low-cost upgrade that nevertheless gives a significant impact. Upgrade has to be largely compatible with existing hardware and control system (no change of philosophy). Fully exploit the potential from the “PS for LHC” upgrade. Basic period must be compatible with PS cycles to distribute the gain. 900 ms instead of 1200 ms means: 33% increase in PSB cycles. All cycles on all machines have to be integer multiples of 900 ms. Impact of 900 ms basic period operation: Enables improvement for SPS without jeopardizing ISOLDE physics. Improvements for LHC and PS East hall. Generally shorter cycles on PS -> more efficient use, more time for MD. Basis for CNGS and ISOLDE upgrades. 14/01/05 PS & SPS Days 2005

Impact on machine operation Linac2: Pulsing at 900 ms (machine was designed for 2 Hz operation). PS Booster: New magnetic cycle for 900 ms operation (identical for all beams). Nominal performance for high intensity operation was obtained in MD. PS: Choice of 900 ms allows to shorten most PS cycles by simply cutting-off unused parts at the end of cycles. Consequently there is no change of beam dynamics for most beams except SFTPRO for FT and CNGS (acceleration on h=8 only -> to be demonstrated). SPS: Time between multi-batch injections reduced – shorter injection flat. Remaining part of cycles unchanged (ramp up – down). LHC: Time between injections reduced – shorter injection flat. AD, Linac3, LEIR: no significant impact. 14/01/05 PS & SPS Days 2005

Expected performance (SPS users) LHC nominal 25 ns and 75 ns beams: shorter LHC filling PS: cycle 2.7 s instead of 3.6 s. SPS: flat bottom 8.1 s instead of 10.8 s, cycle 18.9 instead of 21.6 s. LHC: filling time reduced by 12.5%. LHC “individual bunch” beams (TOTEM, pilot): neutral. PS: cycle 1.8 s instead of 2.4 s. CNGS: 5% flux reduction (single batch) or neutral (double batch) PS: cycle 0.9 s instead of 1.2 s, compatible with Island extraction, acceleration on h=8 only, to be demonstrated for highest intensities in MD studies, i.e. >2.8E13. SPS: flat bottom 0.9 s instead of 1.2 s, overall cycle length 6.3 s instead of 6.0 s for PSB single batch operation, overall cycle length unchanged at 7.2 s for PSB double batch operation. SPS Fixed Target: neutral, unchanged duty cycle (spill/cycle). PS: cycle 0.9 s instead of 1.2 s, acceleration on h=8 only, see CNGS. SPS: flat bottom 0.9 s instead of 1.2 s, remaining cycle unchanged. 14/01/05 PS & SPS Days 2005

Expected performance (PS and PSB users) PS East hall beams: 20% increased duty cycle (spill/cycle) Cycle 2.7 s instead of 2.4 s. Spill length ~550 ms instead of ~400 ms. Net flux gain ~20%. n_TOF: three scenarios with different proton energies Cycle 1.8 s instead of 1.2 s. Beam energy 20 GeV/c (up to 24 GeV/c). Flux reduction 33% (20 GeV/c) 27% (24 GeV/c) – can be compensated. Cycle 0.9 s instead of 1.2 s. Beam energy change to 15.3 GeV/c from 20 GeV/c. Flux increase by 6% (15.3 GeV/c). 15.3 GeV/c solution is preferred to 24 GeV/c by n_TOF. AD – neutral PS cycle 1.8 s instead of 2.4 s. AD cycle remains unchanged. ISOLDE beams – 33% flux increase PSB cycle 0.9 s instead of 1.2 s. Nominal high intensity achieved in MD. 14/01/05 PS & SPS Days 2005

Other aspects Reliability and lifetime: Radiation aspects PSB: Equipment lifetime is usually proportional to the number of pulses and will therefore decrease like the pulse rate increases (≤ 75% of present). This lifetime decrease concerns PSB and PS but not SPS. Exploitation budget (P+M) has to take this into account. Radiation aspects PSB: 33% more cycles does not mean 33% increase in losses. Losses in PSB at increase more than proportional when pushing the intensity. The last 10 % in peak intensity nearly double the losses at high energy (extraction and recombination). Double batch CNGS will use lower PSB bunch intensity (smaller emittances) which will help PSB, PS, SPS. For highest intensity ISOLDE operation: the larger number of available cycles will allow to reduce the peak intensity. 14/01/05 PS & SPS Days 2005

Implementation strategy 2005 – Linac2 and PSB (approved by ABMB on 06/12/04): Start and run with 1200 ms basic period - prepare 900 ms in parallel: Adjust machine timing layout to be compatible to 900 ms. Perform all relevant tests (DSC software, etc) and modifications. Prepare all operational beams on 900 ms compatible cycles. Switch to 900 ms basic period and test-run for few weeks. Duration of 4-5 weeks (10 days dedicated) (proposed mid May – end June). Sufficiently long time to detect long-term problems. Verify all operational beams under full 900 ms conditions. Switch back to 1200 ms operation for normal run and the start-up 2006. Minimum risk strategy. Sufficient time for preparation (no unnecessary “crash programme”). Results from 900 ms run will facilitate preparations for PS/SPS 2006. 14/01/05 PS & SPS Days 2005

Implementation strategy 2006 – PS and SPS (to be reviewed after PSB test in 2005): Start and run with 1200 ms basic period - prepare 900 ms in parallel: Adjust PS and SPS timing layouts to be compatible to 900 ms. Perform all relevant tests (DSC software, etc) and modifications. Perform MDs to address all open issues (high intensity h=8 in PS, n_TOF). Prepare all operational beams on 900 ms compatible cycles. Switch all machines to 900 ms basic period during dedicated MD. 2 weeks of dedicated MD time for commissioning of 900 ms operation. Verify all operational beams under full 900 ms conditions. Minimum risk strategy. Avoids mixing up with eventual problems during PS/SPS restart after long shut-down and renovation of 40 PS magnets with complete realignment. Enables MDs on PS on h=8 high intensity before switching to 900 ms. Sufficient time for preparation while PS/SPS are running. 14/01/05 PS & SPS Days 2005

Summary Operation Machine aspects Performance for user LHC nominal 25/75ns Shorter PS, SPS cycles 15% shorter LHC filling time CNGS Shorter PS cycle, acceleration on h=8 in PS -5% flux (single batch PSB-PS) Neutral (double batch PSB-PS) SPS Fixed Target Shorter PS cycle Neutral (unchanged duty cycle) PS East hall Longer PS cycle, longer spill 20% increase in duty cycle nTOF 5% flux increase (15.3 GeV/c) Longer PS cycle -30% flux (w/o energy change) AD Neutral PSB ISOLDE - 33% flux increase Group Cost [kCHF] Man-years BT 50 0.2 CO 150 2.0 OP - 4.0 PO 900 3.5 Total 1100 9.7 14/01/05 PS & SPS Days 2005

Conclusions 900 ms basic period operation: Next steps: 33% more proton cycles from PSB. Basis for improvement on SPS and upgrades of CNGS and ISOLDE. Overall cost: ~1.1 MCHF, ~10 man-years. Can be fully implemented at end of run 2006. Next steps: Start preparations for Linac2 and PSB run in 2005. Ensure compatibility of new equipment and software with 900 ms. Specifications of power converter consolidation. Machine timings Linac3 and LEIR, SPS control and timing changes. 14/01/05 PS & SPS Days 2005

Acknowledgements Special thanks for the support and help of: S. Baird, JC. Bau, J. Borburgh, JP. Burnet, C. Carli, E. Carlier, P. Cennini, F. Di Maio, K. Elsener, A. Fabich, T. Fowler, R. Garoby, M. Giovannozzi, M. Haase, W. Heinze, M. Hourican, E. Jensen, R. Jones, S. Hancock, C. Hill, J. Lewis, A. Mengoni, G. Metral, M. O’Neil, U. Raich, M. Rettig, JP. Royer, K. Schindl, R. Scrivens, R. Steerenberg, JL. Sanchez-Alvarez, J. Wenninger, R. Wilfinger, T. Zickler. Many thanks to all colleagues in AB that have contributed to the study. 14/01/05 PS & SPS Days 2005