BETABEAM RD in EUROPE Michael Benedikt AB Department

BETA-BEAM R&D in EUROPE Michael Benedikt AB Department, CERN on behalf of the Beta-Beam Study Group http: //cern. ch/beta-beam/ Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 1

Outline • Beta-beam baseline design – The baseline scenario, ion choice, main parameters – Ion production – Decay ring design issues • Ongoing work and recent results – Asymmetric bunch merging for stacking in the decay ring – Decay ring optics design & injection • Future R&D within EURISOL – The EURISOL Design Study – The Beta-beam Task • Conclusions Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 2

Introduction to Beta-beams • Beta-beam proposal by Piero Zucchelli: – A novel concept for a neutrino factory: the beta-beam, Phys. Let. B, 532 (2002) 166 -172. • AIM: production of pure beams of electron neutrinos (or antineutrinos) from the beta decay of radioactive ions, circulating in a high energy decay ring (g~100) • The baseline scenario – Avoid anything that requires a “technology jump” which would cost time and money (and be risky) – Make use of a maximum of the existing infrastructure Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 3

Beta-beam baseline design Ion production Acceleration Experiment Proton Driver SPL Acceleration to final energy PS & SPS Ion production ISOL target & Ion source Neutrino Source Beam preparation ECR pulsed SPS Ion acceleration Linac Acceleration to medium energy RCS Osaka, 25/07/04 Neutrino source PS Decay Ring Decay ring Br = 1500 Tm B=5 T C = 7000 m Lss = 2500 m 6 He: 18 Ne: Nu. FACT’ 04 - Beta Beam R&D 4 g = 150 g = 60

Main parameters (1) • Ion choice – Possibility to produce reasonable amounts of ions – Noble gases preferred - simple diffusion out of target, gas phase at room temperature – Not too short half-life to get reasonable intensities – Not too long half-life as otherwise no decay at high energy – Avoid potentially dangerous and long-lived decay products • Best compromise – 6 Helium 2+ to produce antineutrinos: – 18 Neon 10+ to produce neutrinos: Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 5

Main parameters (2) • Target values in the decay ring 6 Helium 2+ – – Intensity (av. ): Energy: Rel. gamma: Rigidity: 18 Neon 10+ 1. 0 x 1014 ions 139 Ge. V/u 1500 Tm – – (single target) Intensity (av. ): Energy: Rel. gamma: Rigidity: 4. 5 x 1012 ions 55 Ge. V/u 60 335 Tm • The neutrino beam at the experiment has the “time stamp” the circulating beam in the decay ring. • The beam has to be concentrated in as few and as short bunches as possible to maximize the peak number of ions/nanosecond (background suppression). • Aim for a duty factor of 10 -4 -> this is a major design challenge! Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D of 6

Ion production - ISOL method • Isotope Separation On. Line method. • Few Ge. V proton beam onto fixed target. + spallation 201 Target 1 Ge. V protons 18 Ne 6 He + U 11 Li fission n p Osaka, 25/07/04 + X + 143 via spallation n Fr fragmentation 238 directly Cs + Y Nu. FACT’ 04 - Beta Beam R&D 7

6 He production from 9 Be(n, a) Converter technology: (J. Nolen, NPA 701 (2002) 312 c) • • Converter technology preferred to direct irradiation (heat transfer and efficient cooling allows higher power compared to insulating Be. O). 6 He production rate is ~2 x 1013 ions/s (dc) for ~200 k. W on target. Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 8

18 Ne production • Spallation of close-by target nuclides: 18 Ne from Mg. O: – 24 Mg 12 (p, p 3 n 4) 18 Ne 10 – Direct target: no converter technology can be used, the beam hits directly the oxide target. – Production rate for 18 Ne is ~ 1 x 1012 ions/s (200 k. W dc proton beam at a few Ge. V beam energy). – 19 Ne can be produced with one order of magnitude higher intensity but the half life is 17 seconds! Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 9

From dc ions to very short bunches 2 x 1. 1 ms to decay ring (4 bunches with few ns) B SPS 2. 2 ms B 1 s PS 2. 2 ms SPS: injection of 8 (16) bunches from PS. Acceleration to decay ring energy and ejection of 4 + 4 bunches. Repetition time 8 s. PS: 1 s flat bottom with 8 (16) injections. Acceleration in ~1 s to top PS energy t B 1 s PS t t RCS: further bunching to ~100 ns Acceleration to ~300 Me. V/u. 8 (16) repetitions over 1 s. Post accelerator linac: acceleration to ~100 Me. V/u. 8 (16) repetitions over 1 s. t 1 s Osaka, 25/07/04 60 GHz ECR: accumulation for 1/8 (1/16) s ejection of fully stripped ~20 ms pulse. 16 batches during 1 s. Target: dc production during 1 s. 7 s Nu. FACT’ 04 - Beta Beam R&D t 1 s 10

Decay ring design aspects • • The ions have to be concentrated in very few very short bunches. – Suppression of atmospheric background via time structure. There is an absolute need for stacking in the decay ring. – Not enough flux from source and injection chain. – Life time is an order of magnitude larger than injector cycling (120 s as compared to 8 s SPS cycling). – We need to stack at least over 10 to 15 injector cycles. • Cooling is not an option for the stacking process: – Electron cooling is excluded because of the high electron beam energy and in any case far too long cooling times. – Stochastic cooling is excluded by the high bunch intensities. • Stacking without cooling creates “conflicts” with Liouville. Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 11

Asymmetric bunch pair merging • Moves the fresh bunch into the centre of the stack and pushes less dense phase space areas to larger amplitudes until these are cut by the momentum collimation system. • The maximum density is always in the centre of the stack as required by the experiment. • Requirements: – Dual harmonic RF systems: – Decay ring will be equipped with 40 and 80 MHz system. – Gives required bunch lengths of < 10 ns for physics. • Stack and fresh bunch need to be positioned in adjacent “buckets” of the dual harmonic system (12. 5 ns distance!) Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 12

Full scale simulation for SPS Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 13

Test experiment in CERN PS Merging of circulating bunch with empty phase space. Longitudinal emittances are conserved Negligible blow-up Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 14

Test experiment in CERN PS • Ingredients: energy – Dual-harmonic RF system – 10 and 20 MHz systems of PS – Phase and voltage variations time • Potential applications: – Production of hollow bunches – Stacking in longitudinal phase space Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 15

Decay ring injection design aspects • Asymmetric merging requires fresh bunch injected in adjacent 2 nd harmonic bucket to existing stack • Background suppression requires short bunches and therefore high frequency RF in decay ring ≥ 40 MHz • Combination of both means 12. 5 ns between bunches – Fast injection (septa & kickers) excluded (too fast, too rigid) • Alternative injection scheme proposal – Inject an off-momentum beam on matched dispersion trajectory – No fast elements required (bumper rise and fall ~10 ms) – Requires large normalized dispersion at injection point (small beam size and large separation by momentum difference) – Has to be paid by larger magnet apertures in decay ring Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 16

Decay ring injection layout • Example machine and beam parameters: – – – Dispersion: Dhor = 10 m Beta-function: bhor = 20 m Moment. spread stack: Dp/p = ± 1. 0 x 10 -3 (full) Moment. spread bunch: dp/p = ± 2. 0 x 10 -4 (full) Emit. (stack, bunch): egeom = 0. 6 pmm Injection First turn after injection Beam: ± 2 mm momentum ± 4 mm emittance Septum & alignment 10 mm Required bump 22 mm Septum & alignment 10 mm Stack: ± 10 mm momentum ± 4 mm emittance 22 mm Separation: ~30 mm, corresponds to 3 x 10 -3 off-momentum Central orbit undisplaced Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 17

Decay ring arc lattice design β-functions (m) Dispersion (m) A. Chance, CEA-Saclay (F) FODO structure Central cells detuned for injection Arc length ~984 m Bending 3. 9 T, ~480 m leff 5 quadrupole families Horizontal bx Vertical by Horizontal Dispersion Dx Begin of the arc Osaka, 25/07/04 End of the arc Injection area Nu. FACT’ 04 - Beta Beam R&D 18

Decay ring injection envelopes A. Chance, CEA-Saclay (F) Envelope (m) septum Horizontal envelopes : Δp/p = 0 kickers off Δp/p = 0 kickers on Δp/p = 0. 8% kickers off Δp/p = 0. 8% kickers on Vertical envelopes : stored beam injected beam Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 19

Radiation protection - decay losses • Losses during acceleration – Full FLUKA simulations in progress for all stages (M. Magistris and M. Silari, Parameters of radiological interest for a beta-beam decay ring, TIS-2003 -017 -RP-TN) • Preliminary results: – Manageable in low energy part – PS heavily activated (1 s flat bottom) • Collimation? New machine? – SPS ok. – Decay ring losses: • Tritium and Sodium production in rock well below national limits • Reasonable requirements for tunnel wall thickness to enable decommissioning of the tunnel and fixation of Tritium and Sodium Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D FLUKA simulated losses in surrounding rock (no public health implications) 20

Future R&D • Future beta-beam R&D together with EURISOL project • Design Study in the 6 th Framework Programme of the EU • The EURISOL Project – – Design of an ISOL type (nuclear physics) facility Performance three orders of magnitude above existing facilities A first feasibility / conceptual design study was done within FP 5 Strong synergies with the beta-beam especially low energy part: • • Ion production (proton driver, high power targets) Beam preparation (cleaning, ionization, bunching) First stage acceleration (post accelerator ~100 Me. V/u) Radiation protection and safety issues Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 21

EURISOL Design Study Production of an Engineering Oriented Design, of the facility, in particular in relation to its most technologically advanced aspect (i. e. excluding the detailed design of standard elements of the infrastructure). • • Technical Design Report for EURISOL. Conceptual Design Report for Beta-Beam (first study). Acronym: EURISOL DS Requested budget: About 9 M€ Deadline for proposal: 4 March 2004 Starting date: January 2005 Duration of the project: 48 months Coordinating Institution: GANIL, Techn. Coordinator: John Cornell Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 22

Eurisol Design Study Tasks 12 TASKS LEADER INSTITUTE * NATURE OF WORK 1) Liquid Metal Target/Ion Source H. Ravn/U. Koester CERN-PH PW - PRO - E 2) Direct Target / Ion-Source J. Lettry CERN-AB PW - PRO - E 3) Solid Converter Target / Ion–Source L. Tecchio INFN PW - PRO – E 4) Safety & Radioprotection D. Ridikas CEA SACLAY PW 5) Heavy-Ion Accelerator Design M-H. Moscatello GANIL PW -PRO 6) Proton Accelerator Design A. Facco INFN PW - PRO 7) SC Cavity Development S. Bousson IPNO PW –PRO 8) Beam Preparation A. Jokinen JYFL PW - PRO - E 9) Physics and Instrumentation R. Page U LIVERPOOL PW - PRO 10) Beam Intensity Calculations K. H. Schmidt GSI PW – E 11) Beta Beams Aspects M. Benedikt CERN-AB PW 12) Global Coherence and Layout TO BE DEFINED *PW=Paperwork Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D PRO=Prototype E =Experiment 23

EURISOL - Participating Institutes PARTICIPANTS PERSON IN CHARGE 1 GANIL (F) D. GOUTTE 13 FZ JULICH (G) D. GRZONKA 2 IN 2 P 3 (F) D. GUERREAU 14 UNIV. MAINZ (G) C. SPATH 3 INFN-LNL (I) G. FORTUNA 15 IOP (LI) 4 INFN-LNS (I) E. MIGNECO 16 UNIV. WARSAW (PL) W. MACIEJEJEWSKI 5 INFN (I) G. RICCO 17 IOP (SK) E. BETAK 6 CERN M. LINDROOS 18 UNIV. SURREY (UK) LILIARD 7 UNIV. UPPSALA (S) C. EKSTROM 19 UNIV. LIVERPOOL (UK) R. D. PAGE 8 CEA (F) N. ALAMANOS 20 GSI (G) W. HENNING 9 UNIV. FRANKFURT (G) 21 USDC (E) G. R. GAYOSO 10 NIPNE (RO) D. BUCURESCU 22 CCLRC RAL (UK) D. WARNER 11 JYVASKYLA (FI) R. JULIN 23 PSI (CH) W. FISCHER 12 UNIV. MUECHEN (G) AUMULLER 24 UNIVERSITY HOSPITAL OF GENEVE Osaka, 25/07/04 ? Nu. FACT’ 04 - Beta Beam R&D ? ? 24

Task: Beta Beam Aspects Starts at exit of heavy ion LINAC (~100 Me. V/u) to Decay Ring (~100 Ge. V/u). Experiment Proton Driver SPL Acceleration to final energy PS & SPS Ion production ISOL target & Ion source Beam preparation ECR pulsed Neutrino Source SPS Ion acceleration Linac Acceleration to medium energy RCS Osaka, 25/07/04 PS Decay Ring Decay ring Br = 1500 Tm B=5 T C = 7000 m Lss = 2500 m 6 He: 18 Ne: Nu. FACT’ 04 - Beta Beam R&D g = 150 g = 60 25

Beta-Beam Sub-Tasks • Beta Beam task starts at exit of the EURISOL post accelerator. • Comprises the design of the complete chain up to the decay ring. • Organisation: „parameter and steering committee“ and 3 sub-tasks: – ST 1: Design of the low energy ring(s) – ST 2: Ion acceleration scenarios in PS/SPS and required upgrades of the existing machines including new designs to eventually replace PS/SPS – ST 3: Design of the high energy Decay Ring – Detailed work and man-power planning is under way – Around 38 (13 from EU) man-years for beta beam R&D over next 4 years (only within beta-beam task, not accounting linked tasks) Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 26

Conclusions • Well established beta-beam base line scenario • R&D work has started on several critical aspects (mainly decay ring) • Beta-Beam Task well integrated in the EURISOL DS • Strong synergies between Beta Beam and EURISOL • Definitive EU decision expected these days • Detailed planning for coming 4 years under way Osaka, 25/07/04 Nu. FACT’ 04 - Beta Beam R&D 27