Nufact RAL and CERN pdrivers S Gilardoni CERN

Nufact RAL and CERN p-drivers S. Gilardoni – CERN Based on contributions from: J. Thomason, ISIS Accelerator Division M. Aiba, E. Benedetto, R. Garoby and M. Meddahi, CERN

Multi-MW p-driver Basic requirements: - 4 MW power on target Energy between 5 – 15 Ge. V RMS bunch length 1 – 3 ns 50 Hz rep. rate. 3 bunches, spaced by more than 80 μs

UK Green Field Solution

Chris Prior, Grahame Rees, Shinji Machida ( ) • Lower injection energies provide smaller bucket area in the ring and the small longitudinal emittance needed for final ns bunch compression. Studies show that 180 Me. V is a realistic energy for NF Proton Driver for a Neutrino Factory • Separate main ring with optics chosen for ns bunch compression. Could be FFAG (cheaper but insufficiently developed) or a synchrotron (reliable, tried and tested) • Special achromat for collimation (longitudinal and transverse) and momentum ramping for injection 10 Ge. V RCS • Separate booster ring designed for low loss phase space painting for beam injection and accumulation. Synchrotron moving buckets give flexibility to capture all of the injected beam • Compressed bunches need to be held and sent to target at intervals of ~100 μs. Possible in FFAG and also synchrotron with flat top

ISIS Upgrade + NF Solution

ISIS Upgrades • Present operations for two target stations Operational Intensities: 220 – 230 μA (185 k. W) Experimental Intensities of 3 1013 ppp (equiv. 240 μA) DHRF operating well: High Intensity & Low Loss Now looking at overall high intensity optimisation • Study ISIS upgrade scenarios 0) Linac and TS 1 refurbishment 1) Linac upgrade leading to ~0. 5 MW operations on TS 1 Overlap with NF 2) ~3. 3 Ge. V booster synchrotron: MW Target proton driver 3) 800 Me. V direct injections to booster synchrotron: 2 – 5 MW Target 4) Upgrade 3) + long pulse mode option

ISIS MW Upgrade Scenarios 1) Replace ISIS linac with a new ≈ 180 Me. V linac (≈ 0. 5 MW) 2) Based on a ≈ 3. 3 Ge. V RCS fed by bucket-to-bucket transfer from ISIS 800 Me. V synchrotron (1 MW, perhaps more) 3) RCS design also accommodates multi-turn charge exchange injection to facilitate a further upgrade path where the RCS is fed directly from an 800 Me. V linac (2 – 5 MW)

ISIS MW Upgrade Scenarios 1) Replace ISIS linac with a new ≈ 180 Me. V linac (≈ 0. 5 MW) 2) Based on a ≈ 3. 3 Ge. V RCS fed by bucket-to-bucket transfer from ISIS 800 Me. V synchrotron (1 MW, perhaps more) 3) RCS design also accommodates multi-turn charge exchange injection to facilitate a further upgrade path where the RCS is fed directly from an 800 Me. V linac (2 – 5 MW)

Possible ≈ 3. 3 Ge. V RCS Rings

5 SP RCS Ring Energy 0. 8 – 3. 2 Ge. V Rep Rate 50 Hz C , R/R 0 367. 6 m, 9/4 Gamma-T 7. 2 h 9 frf sweep 6. 1 -7. 1 MHz Peak Ksc ≈ 0. 1 B [ t] sinusoidal Peak Vrf ≈ 750 k. V εl per bunch ≈ 1. 5 e. V s

ISIS MW Upgrade Scenarios 1) Replace ISIS linac with a new ≈ 180 Me. V linac (≈ 0. 5 MW) 2) Based on a ≈ 3. 3 Ge. V RCS fed by bucket-to-bucket transfer from ISIS 800 Me. V synchrotron (1 MW, perhaps more) 3) RCS design also accommodates multi-turn charge exchange injection to facilitate a further upgrade path where the RCS is fed directly from an 800 Me. V linac (2 – 5 MW)

Grahame Rees, Ciprian Plostinar ( ) Ion Species Output Energy Accelerating Structures Frequency Beam Current Repetition Rate Pulse Length Duty Cycle Average Beam Power Total Linac Length 800 Me. V, Hˉ Linac Design Parameters H 800 Me. V DTL/SC Elliptical Cavities 324/648 MHz 43 m. A 30 Hz (Upgradeable to 50 ) 0. 75 ms 2. 25 % 0. 5 MW 243 m

Design Options

Common Proton Driver for the Neutron Source and the Neutrino Factory • Based on MW ISIS upgrade with 800 Me. V Linac and 3. 2 (≈ 3. 3) Ge. V RCS • Assumes a sharing of the beam power at 3. 2 Ge. V between the two facilities • Both facilities can have the same ion source, RFQ, chopper, linac, H− injection, accumulation and acceleration to 3. 2 Ge. V • Requires additional RCS machine in order to meet the power and energy needs of the Neutrino Factory • Options for the bunch compression to 1 – 3 ns RMS bunch length: - adiabatic compression in the RCS - ‘fast phase rotation’ in a dedicated compressor ring

Jaroslaw Pasternak, Leo Jenner ( , ) Preliminary design of the second RCS Parameters of 3. 2 – 9. 6 Ge. V RCS Number of superperiods Circumference Harmonic number RF frequency Gamma transition Beam power at 9. 6 Ge. V Injection energy Extraction energy Peak RF voltage per turn Repetition rate Max B field in dipoles Length of long drift • Present-day, cost-effective RCS technology • Only three quadrupole families • Allows a flexible choice of gamma transition • Up to 3. 7 MV/turn? 6 694. 352 m 17 7. 149 – 7. 311 MHz 13. 37 4 MW for 3 bunches 3. 2 Ge. V 9. 6 Ge. V ≈ 3. 7 MW 50 Hz 1. 2 T 14 m

SPL-Based NF Proton Driver Nearly Green Field Solution

Present LIU (2019) Back-up Proton flux / Beam power 50 Me. V Linac 2 Output energy 160 Me. V 1. 4 Ge. V 2. 0 Ge. V 4 Ge. V PSB 26 Ge. V 50 Ge. V PS 450 Ge. V 7 Te. V HP-SPL: Upgrade of infrastructure (cooling water, electricity, cryogenics etc. ) Linac 4 PSB LP-SPL PS LP-SPL: Low Power-Superconducting Proton Linac (4 Ge. V) PS 2 Replacement of klystron power supplies Addition of 5 high b cryomodules to accelerate up to 5 Ge. V Main requirements of PS 2 on its injector: SPS LHC / s. LHC Requirement Parameter Value 2. 2 x ultimate brightness with nominal emittances Injection energy 4 Ge. V Nb. of protons / cycle for LHC (180 bunches) 6. 7 × 1013 Nb. of protons / cycle for SPS fixed target 1. 1 × 1014 Single pulse filling of SPS for fixed target physics

SPL-Based Proton Driver: Principle • • Accumulation of beam from the High Power SPL in a fixed energy Accumulator (5 Ge. V, 4 MW beam power). Bunch compression ( «rotation» ) in a separate Compressor ring

SPL front end (Linac 4): block diagram Linac 4: 80 m, 18 klystrons 45 ke. V 3 Me. V H- RFQ CHOPPER RF volume source (DESY) 45 k. V Extrac. Radio Frequency Quadrupole 3 m 1 Klystron 550 k. W Chopper & Bunchers 3. 6 m 11 EMquad 3 cavities Ion current: 40 m. A (avg. ), 65 m. A (peak) DTL Drift Tube Linac 18. 7 m 3 tanks 3 klystrons 4. 7 MW 111 PMQs 50 Me. V CCDTL Cell-Coupled Drift Tube Linac 25 m 21 tanks 7 klystrons 7 MW 21 EMQuads 94 Me. V 160 Me. V PIMS Pi-Mode Structure 22 m 12 tanks 8 klystrons ~12 MW 12 EMQuads RF accelerating structures: 4 types (RFQ, DTL, CCDTL, PIMS) Frequency: 352. 2 MHz Duty cycle: 0. 1% phase 1 (Linac 4), 3 -4% phase 2 (SPL), (design: 10%)

Linac 4 building Oct 2010 Linac 4 Mar 2011 First user

HP-SPL: Main Characteristics Ion species Output Energy Bunch Frequency Repetition Rate High speed chopper (rise & fall times) H− 5 352. 2 50 <2 Required for low loss in accumulator Ge. V MHz Hz ns Required for muon production Required for flexibility and low loss in accumulator Option 1 Option 2 2. 5 or 5 2. 5 and 5 2. 25 MW (2. 5 Ge. V) or 4. 5 MW (5 Ge. V) 5 MW (2. 5 Ge. V) and 4 MW (5 Ge. V) Protons/pulse (x 1014) 1. 1 2 (2. 5 Ge. V) + 1 (5 Ge. V) Av. Pulse current (m. A) 20 40 Pulse duration (ms) 0. 9 1 (2. 5 Ge. V) + 0. 4 (5 Ge. V) Energy (Ge. V) Beam power (MW) 2 ´ beam current Þ 2 ´ nb. of klystrons etc.

110 m 0. 73 Ge. V 500 m 5 Ge. V Medium b cryomodule High b cryomodules Ejection 291 m 2. 5 Ge. V High b cryomodules 9 x 6 b=0. 65 cavities 11 x 8 b=1 cavities to EURISOL From Linac 4 0 m 0. 16 Ge. V 13 x 8 b=1 cavities Debunchers Segmented cryogenics / separate cryo-line / room temperature quadrupoles: -Medium b (0. 65) – 3 cavities / cryomodule -High b (1) – 8 cavities / cryomodule Low energy Intermediate energy High energy To HP-PS and/or Accumulator HP-SPL: Block Diagram

HP-SPL: R&D Objective Design, construction and test of a string of 4 b=1 cavities equipped with main couplers & tuners inside a “short” prototype cryo-module before the end of 2014 tested in 2014. Cryomodule (CERN – CNRS)

HP-SPL: Cavity & Cryomodule Design SPL b = 1 cavity + helium tank + tuner + main coupler Bulk niobium cavities (CERN) HOM coupler (CERN – Uni Rostock) Helium tank (CERN – CEA) Tuner (CEA) Main coupler (CERN)

Accumulator/compressor lattices from M. Aiba

HP-SPL: Cost Estimate (1/3/12) HP-SPL cost estimate - s. LHC-Project-Note-0037 (F. Gerigk, CERN-BE-RF, public) - Cost estimate : 806. 9 MCHF - Very detailed - Include services, tunnels, L 4 upgrade, even T-line to PS 2 - Does not include contingency - Does not include Linac 4 (~100 MCHF)