Oxygen pilot run in LHC Summary of where

  • Slides: 12
Download presentation
Oxygen pilot run in LHC: Summary of where we stand today and bunch intensity

Oxygen pilot run in LHC: Summary of where we stand today and bunch intensity estimations at the LHC injection R. Scrivens, D. Kuchler, R. Alemany for the ion team 14/05/2019 LHC Oxygen run preparation meeting

Action list from last meeting Status Who Comment 1 Bunch intensities across the injector

Action list from last meeting Status Who Comment 1 Bunch intensities across the injector chain up to LHC injection D. Kuchler, R. Scrivens, R. Alemany Link to document 2 RP impact M. Widorski Link to document 3 Investigate PS RF constraints F. Tecker Link to document 4 Expected LHC luminosities based on 1 B. Pedersen, F. Moortgat Link to document 5 Define ion species O 4+ All O 4+ or O 8+ 6 Define type of beam EARLY All EARLY or NOMINAL 7 Define running year 2023 2022 or 2023 8 Define schedule All 9 Define resources needed All 10 Present proposal to LPC (20. 05. 2019) LHCC (05. 06. 2019) & LMC B. Pedersen, F. Moortgat 11 Present proposal to IEFC R. Alemany 14/05/2019 All LHC Oxygen run preparation meeting

Bunch intensities across the injector chain up = C 5 to LHC injection C

Bunch intensities across the injector chain up = C 5 to LHC injection C 10 0. 9 C 11 0. 9 1 C 12 8/4 1 RF splitting: EARLY = no splitting NOMINAL = each LHC Oxygen run preparation meeting. LEIR bunch is split into 2 bunches Intensity/bunch injected into LHC (1 e 10 elementary charges) SPS transmission efficiency TT 2 charge stripping ratio Number of capture bunches C 9 1 1 2 2 Transfer line transmission efficiency C 8 0. 8 PS transmission efficiency We select the lowest value of the two C 7 1 1 2 2 #PS splitting C 6 2. 25 0. 6 LEIR transmission efficiency C 5 1. 1 1. 4 7. 7 9. 8 #LEIR bunches 14/05/2019 C 4 0. 5 LEIR Space charge limit (1 e 10 ions) EARLY cycle (1 injection) NOMINAL cycle (7 injections) C 3 2. 19 2. 81 #Ions accumulated at LEIR injection (1 e 10 ions) C 2 1 1 7 7 LEIR injection efficiency C 1 4 8 Ions from L 3 per 200 µs pulse (1 e 10 ions) Ion charge #injections per cycle Q C 13 0. 7 If = 1 there is no stripping, i. e. charge does not change C 14 3. 97 2. 42 2. 04 0. 61

14/05/2019 LHC Oxygen run preparation meeting

14/05/2019 LHC Oxygen run preparation meeting

Atomic number Atomic mass Q/A 8 16 0. 5 17 0. 47 18 0.

Atomic number Atomic mass Q/A 8 16 0. 5 17 0. 47 18 0. 44 Stable Oxygen is a support gas for Pb: Pb 26+/O 2+ Q A 2 14/05/2019 Pb 53+ Q/A 0. 5 8 4 Q/A 16 0. 255 Makes things simpler 0. 125 LHC Oxygen run preparation meeting

Brief history of Oxygen in the injector complex • In 2005, after the installation

Brief history of Oxygen in the injector complex • In 2005, after the installation of the GTSLHC ECR ion source, O 4+ was delivered to LEIR for transfer line and ring commissioning [Ref. 1] • In parallel, Linac 3 beam transport studies were performed [Ref. 2] • O 4+ extrapolations from LEAR observations with O 8+ and O 6+: O 4+ longer life time (4 e- vs 28 e- in Pb 54+) and Q/A ≈ 14/05/2019 Pb 54+ To LEIR ITH ITL ITM ITF ITH 2 O 4+ injections in LEIR + capture + acceleration LHC Oxygen run preparation meeting

Charge state options Option 2 Option 1 O 2+ Stripper Pb 54+/Pb 82+ stripper

Charge state options Option 2 Option 1 O 2+ Stripper Pb 54+/Pb 82+ stripper O 8+ Fully stripped ions IT H 14/05/2019 To LEIR LHC Oxygen run preparation meeting O 8 + O 4 +

Pros & Cons SOURCE Option 1: O 2+ O 8+ before LEIR Already optimized

Pros & Cons SOURCE Option 1: O 2+ O 8+ before LEIR Already optimized for the maximum extracted intensity; ~ 400 eµA after stripping to O 8+ Less setting up time, ~ 1 day L 3 Needs very high fields in the tanks, therefore more X-ray production could potentially restrict the access to some areas of L 3 if NOMINAL beam requested; no issue if EARLY is requested Stripper Optimized stripper, no loss of beam intensity After stripping Everything after the stripper changes out of the linear regime (including ramping and debunching) LEIR Fully strip ions e- stripping from no beam-gas interaction better life time 14/05/2019 Option 2: O 4+ O 8+ in TT 2 Needs full retuning of the source to get ~ 200 – 300 eµA More setting up time, ~ 3 days Lower fields in the tanks, less X-rays no access restriction might be possible O 4+ O 8+ in TT 2 with Pb stripper, might be too thick and worse stripping efficiency Stays in the linear regime (Q/AO 4+ ~ Q/APb 53+) O 4+: 4 e- left e- stripping from beam-gas interaction. 2005 commissioning report (Ref. Lifetime in LEAR for 08+ at K=11. 5 Me. V/u = 600 minutes with 2) says O 4+ lifetime was poor, not clear how stochasting cooling, K=200 -250 minutes witout stochasting LHC Oxygen run preparation meeting much this would be an issue now, cooling [Ref. 4]

Pros & Cons Brho at LEIR injection (Tm) Option 1: O 2+ O 8+

Pros & Cons Brho at LEIR injection (Tm) Option 1: O 2+ O 8+ before LEIR 0. 59 ( = ~ 400 A, the power converter or the main dipole magnets can regulate down to 120 A) 4. 78 Brho at LEIR extraction (Tm) Switch over time 1 hour (without contingency) from Pb O in source and linac 3 14/05/2019 LHC Oxygen run preparation meeting Option 2: O 4+ O 8+ in TT 2 1. 18 (similar to Pb 54+) 4. 78 Few hours (without contingency)

Pros & Cons Option 1: O 2+ O 8+ before LEIR Option 2: O

Pros & Cons Option 1: O 2+ O 8+ before LEIR Option 2: O 4+ O 8+ in TT 2 Common Neutrons are produced because of the lower charge. Simulations from RP needed and later problems on real measurements. Could restrict the access to the high-energy part of L 3 personnel protection system + beam stopper and beam interlock system to avoid sending the beam when switch yard in access Resources Grillages for access restriction in Linac 3 due to neutrons (estimate 50 KChf) estimates Beam interlock system to avoid sending the beam to switch yard when in access: beam stopper installation + beam interlock system to handle it (estimate > 100 k. CHF) 1 Fellow: operational aspects, beam parameters, settings management. Currently the ion team do not have the manpower to take care of this new run Improvement of the low energy beam instrumentation (to be defined) Caveat 14/05/2019 The feasibility of this run can be compromised if slip stacking is not commissioned in 2021 and post-poned to 2022 LHC Oxygen run preparation meeting

Proposed schedule Start the ion run with Pb up to PS (if only EARLY

Proposed schedule Start the ion run with Pb up to PS (if only EARLY Oxygen beam needed or only up to LEIR if NOMINAL Oxygen beam needed) to check everything works. EARLY beam: Week 20 switch to oxygen Week 22 beam to LEIR Week 23 beam to PS Week 24 beam to SPS Week 26 beam to LHC Week 27 Pb back to the complex NOMINAL beam: Week 18 switch to oxygen Week 20 beam to LEIR Week 22 beam to PS Week 23 beam to SPS Week 26 beam to LHC Week 27 Pb back to the complex 14/05/2019 Lead LHC Oxygen run preparation meeting Oxygen

Bibliography 1. LEIR COMMISSIONING http: //cdsweb. cern. ch/record/972341/files/lhc-project-report 923. pdf 2. Preliminary Characterization of

Bibliography 1. LEIR COMMISSIONING http: //cdsweb. cern. ch/record/972341/files/lhc-project-report 923. pdf 2. Preliminary Characterization of the O 4+ Beam in Linac 3 https: //core. ac. uk/download/pdf/44163997. pdf 3. Stochastic cooling and storage tests with oxigen ions in LEAR http: //accelconf. web. cern. ch/accelconf/p 89/PDF/PAC 1989_0645. PDF 4. Oxygen ions in LEAR http: //accelconf. web. cern. ch/accelconf/e 90/PDF/EPAC 1990_0580. PDF 14/05/2019 LHC Oxygen run preparation meeting