Status of the Production Ring for Beta Beams Studies ICE Section Meeting, 22/10/10 Status of the Production Ring for Beta Beams Studies E. Benedetto (CERN & NTU Athens) Acknowledgements: G. Arduini, J. Barranco, C. Bracco, M. Chanel, P. Chiggiato, C. Hansen, R. Garoby, B. Holzer, V. Previtali, V. Vlauchoudis, E. Wildner (CERN), D. Neuffer (FNAL), O. Boine-Frankenheim (GSI), Y. Mori (KURRI), M. Schaumann (RWTH Aachen), …

Outline Introduction Status of the studies Next steps Beta-beams and the Production Ring Ionization cooling Status of the studies Preliminary lattice design Tracking simulations Technological challenges Next steps

ISOL target, Collection b beams Aim: production of electron (anti-)neutrino beams from the b decay of radioactive ions circulating in a storage ring ISOL target, Collection Ion production PR Ion Linac 20 MeV 8B/8Li . Radioactive ion production 8Li, 8B 6He, 18Ne

stripper, target & absorber Production Ring 7Li(d,p)8Li 6Li(3He,n)8B 7Li 6Li stripper, target & absorber RF cavity C. Rubbia, A. Ferrari, Y. Kadi, V. Vlachoudis, Beam cooling with ionization losses, NIM A 568 (2006) 475-487 → see also Y.Mori, NIM A 562 (2006) 591, proton FFAG with internal Be target for neutron production (but no need of (dp/p) cooling) Compact ring & thin internal target Enhance production 8Li/8B (~1014/s) by multi passages trough the target Inverse kinematics: Li beam @ ~25MeV and D or 3He supersonic gas-jet target Multi Coulomb Scattering + energy straggling @ target Ionization cooling

Ionization cooling Energy losses (dE/ds) in the target material (Bethe-Bloch) Only longitudinal component recovered in RF cavities → Transverse emittance shrinks Cooling in 6D (dE/ds) ~ b-2 smaller at higher energies → cooling not effective in longitudinal need coupling between transverse and longitudinal: → Dispersion & wedge-shaped target Faster ions will travel on an outer orbit and see a larger target thickness → they will get more (dE/ds) Target: width @ closed orbit = 5 cm t = 0.289 mg/cm2 If angle = 20o → Dx> 24 cm

The proposed lattice 25 MeV 7Li (br ~0.6) C = 12m 5 quadrupole families Normal-conducting magnets 2-fold mirror symmetry Target → Dx~50cm RF cavity → in region Dx=0 m M. Schaumann, CERN-THESIS-2009-128 RF cavity Target NOT OPTIMIZED YET

Tracking simulations SixTrack Adapted to the Production Ring needs Fully 6D, symplectic, reads lattice form MADX output,… Collimation version Tracking large # of particles, Interaction w. collimators Adapted to the Production Ring needs Target implemented as a special collimator element: Random transverse kick Dx’, Dy’ due to Multiple Coulomb scattering (Gaussian distribution, <sc2>) Random energy losses DE : mean value → Bethe-Bloch energy straggling → gaussian distribution assumed Rms emittances & Intensity evolution diagnostics We have Lithium ions, Sixtrack is for protons → need proton equivalent ring (same Br & Dp/p recovered in RF cavity)

Tracking simulations: zero wedge angle From analytical considerations: ex~90 mm ey~11 mm t ~ 170 turns

Tracking simulations: choice of the angle

Tracking simulations: wedge-angle =6o

Technological challenges (1) Production of stable Li in ECR-source if we want 1014 ions/s of 8Li → we need ~1015/s 7Li (since s7Li(d,p)8Li=0.1 stot) “standard” ECR source produces ~30 mA (Li1+) → =1.25 1014 Li1+/s x 50% (transmission through LINAC) =~6.25 1013/s → factor >10 missing

Technological challenges (2) Collection device 2mm Tantalum foils extraction by heating-up Issues: diffusion/effusion efficiency small angle (q~10o) of products → need collection device close to the beam, but it can intercept it!!! Rutherford scattered particles 8B-ions Collection on axis S. Mitrofanov

Technological challenges (3) Supersonic gas jet target Wedge shape (larger thickness for larger Dp/p) Parameters Thickness (mg/ cm2) (atoms/cm2) 0.27 5 1019 Diameter (cm) 5 Density (mg/cm3) ~0.06 Pressure (Torr) 250 Mach n. - 4 Nozzle throat (mm) 3.26 P_plenum (atm) ~3.5 Length ~30 from C.Rubbia’s: existing cluster-jet targets reach up to 1015 atoms/cm2 → factor 104 missing

Cluster supersonic-jet target A. Koukaz Meeting at GSI, 29/10/09

Cluster supersonic-jet target We need ~ 50x50 mm 50 mm 20o Cluster supersonic-jet target A. Koukaz Meeting at GSI, 29/10/09 Target density = 8 1014 /cm2 We need ~ 1019 /cm2

Technological challenges (4) Possible solutions: Increase injected beam intensity → already at limit of stable 7Li ion source (~160mA required from the LINAC) Run with poor vacuum (as long as the residual gas is thin compared to the target) → NO!, causes problems to the RF cavity (capacitive-loaded cavity) Lower target density = less ion productions, but also = better lifetime & higher intensity circulating → more detailed studies are needed, another regime since Multiple Coulomb Scattering not valid any longer… → but gaining a factor 104, hmm… Other possibility: use D or 3He beam & Lithium target (solid, waterfall, droplets,…?) set-up lattice for cooling study feasibility (power dissipation on target, collection,…)

Conclusions Tracking tools for i-cooling studies fully in place and agree with analytical considerations Lattice need to be optimized (reduce bx @ the target, compensate large natural Qp,…) BUT Still a lot of work have a feasible solution to produce enough flux of isotopes for Beta-Beams Neutrino physics. e.g. Existing gas-jet targets cannot reach the densities proposed in [C.Rubbia, et. al] in a vacuum environment

Next steps & ongoing work (1) Conclude work on Li-beam & gas-jet target TO DO: lattice optimization for i-cooling (e.g. reduce b*, eventually compensate large Q’,…) Injection scheme to be studied in more details Collective effects BUT, since gas-jet density maybe a show-stopper... → Started working on an alternative solution: D (or 3He) beam + Li target: technological feasibility !!!, lattice and i-cooling Torsten Weber (RWTH Aachen U.) helping us

Next steps & ongoing work (2) Beam-target interaction: Range of validity of Bethe-Bloch & Multiple Coulomb Scattering formulas for low density target to use correct model inside tracking simulations (since we are at the limits of ionization cooling capabilities) Collaboration with V. Vlachoudis + D. Sinuela Integration of FLUKA in SixTrack Production cross-section (& collection efficiency) Measurements at INFN Legnaro and Napoli ongoing Will have a meeting next week

Next steps & ongoing work (3) Contacts with Y.Mori (KURRI, Osaka) proton FFAG with internal Be target for BNCT They have a running machine! Scaling FFAG (Q’~0) Large acceptance for both horiz.(10-3) and longit.(10%) no need of (dp/p) cooling Similar parameters than ours → Y.Mori, NIM A 562 (2006) 591 → K.Okabe et al, IPAC10, EPAC08,…

Back-up slides

Cooling rates and equilibrium emittance (1) Damping time Equilibrium emittances ex~90 mm ey~11 mm

Cooling rates and equilibrium emittance (2) straggling <0 → blow-up <0 !!!! If now we introduce Dispersion (and a triangular target shape): at a different orbit Dx=D Dp/p

Cooling rates and equilibrium emittance (3) If now we introduce Dispersion (and a triangular target shape):.. Cooling can be transferred from transverse to longitudinal thanks to Dispersion + triangular target can also introduce coupling x-y Since sum of the three partition number is always the same, is computed for Dx=0: 0.4 for 6Li 0.01 for 7Li Due to Bethe-Bloch shape, NO possibility to effectively cool → but only to keep a constant emittance or not to heat it “too much”

FFAG-ERIT Courtesy Y.Mori, K.Okabe

Courtesy Y.Mori, K.Okabe

Courtesy Y.Mori, K.Okabe