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Beta-beams. M. Benedikt, A. Fabich and M. Lindroos, CERN on behalf of the Beta-beam Study Group http://cern.ch/beta-beam BENE06/CARE06. Outline. Beta-beam concept EURISOL DS scenario Layout Main issues on acceleration scheme Physics reach Other scenarios High-energy Beta-beams

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  1. Beta-beams M. Benedikt, A. Fabich and M. Lindroos, CERN on behalf of the Beta-beam Study Group http://cern.ch/beta-beam BENE06/CARE06 Beta-beam team

  2. Outline • Beta-beam concept • EURISOL DS scenario • Layout • Main issues on acceleration scheme • Physics reach • Other scenarios • High-energy Beta-beams • Study II • Summary Beta-beam team

  3. g=100 Beta-beam principle Aim: production of (anti-)neutrino beams from the beta decay of radio-active ions circulating in a storage ring • Similar concept to the neutrino factory, but parent particle is a beta-active isotope instead of a muon. Beta-decay at rest • n-spectrum well known from electron spectrum • Reaction energy Q typically of a few MeV • Accelerated parent ion to relativistic gmax • Boosted neutrino energy spectrum: En2gQ • Forward focusing of neutrinos: 1/g • Pure electron (anti-)neutrino beam! • NB: Depending on b+- or b--decay we get a neutrino or anti-neutrino • Two (or more) different parent ions for neutrino and anti-neutrino beams • Physics applications of a beta-beam • Primarily neutrino oscillation physics and CP-violation • Cross-sections of neutrino-nucleus interaction Beta-beam team

  4. Guideline to n-beam scenarios based on radio-active ions • Low-energy beta-beam: relativisticg < 20 • Physics case: neutrino scattering • Medium energy beta-beam: g ~ 100 • E.g. EURISOL DS • Today the only detailed study of a beta-beam accelerator complex • High energy beta-beam: g >350 • Take advantage of increased interaction cross-section of neutrinos • Monochromatic neutrino-beam • Take advantage of electron-capture process • High-Q value beta-beam: g ~ 100 Accelerator physicists together with neutrino physicists defined the accelerator case of g=100/100 to be studied first (EURISOL DS). Beta-beam team

  5. EURISOL scenario The EURISOL scenario • Based on CERN boundaries • Ion choice: 6He and 18Ne • Relativistic gamma=100/100 • SPS allows maximum of 150 (6He) or 250 (18Ne) • Gamma choice optimized for physics reach • Based on existing technology and machines • Ion production through ISOL technique • Post acceleration: ECR, linac • Rapid cycling synchrotron • Use of existing machines: PS and SPS • Achieve an annual neutrino rate of either • 2.9*1018 anti-neutrinos from 6He • Or 1.1 1018 neutrinos from 18Ne • Once we have thoroughly studied the EURISOL scenario, we can “easily” extrapolate to other cases. EURISOL study could serve as a reference. Beta-beam team

  6. Missed opportunities A new approach for the production Beam cooling with ionisation losses – C. Rubbia, A Ferrari, Y. Kadi and V. Vlachoudis in NIM A, In press “Many other applications in a number of different fields may also take profit of intense beams of radioactive ions.” 7Li(d,p)8Li 6Li(3He,n)8B 7Li 6Li See also: Development of FFAG accelerators and their applications for intense secondary particle production, Y. Mori, NIM A562(2006)591 Beta-beam team

  7. Transverse cooling in paper by Carlo Rubbia et al. “In these conditions, like in the similar case of the synchrotron radiation, the transverse emittance will converge to zero. In the case of ionisation cooling, a finite equilibrium emittance is due to the presence of the multiple Coulomb scattering.” Beta-beam team

  8. Longitudinal cooling in paper by Carlo Rubbia et al. “In order to introduce a change in the dU/dE term — making it positive in order to achieve longitudinal cooling — the gas target may be located in a point of the lattice with a chromatic dispersion. The thickness of the foil must be wedge-shaped in order to introduce an appropriate energy loss change, proportionally to the displacement from the equilibrium orbit position.” Number of turns • Without wedge, dU/dE<0 • Wedge with dU/dE=0, no longitudinal cooling • Wedge with dU/dE=0.0094 • Electrons, cooling through synchrotron radiation Beta-beam team

  9. Inverse kinematics production and ionisation parameters in paper by Carlo Rubbia et al. 7Li(d,p)8Li 6Li(3He,n)8B Beta-beam team

  10. Collection in paper by Carlo Rubbia et al. “The technique of using very thin targets in order to produce secondary neutral beams has been in use for many years. Probably the best known and most successful source of radioactive beams is ISOLDE.” Beta-beam team

  11. Reactions to study for our application • 20Ne(p,t)18Ne • H.Backhausen et al, RCA,29(1981)1 • 16O(3He,n)18Ne • V.Tatischeff et al, PRC,68(2003)025804 • 6C(CO2,6He)18Ne? • K.I.Hahn et al, PRC,54(1996)1999 • 7Li(T,A)6He Beta-beam team

  12. Cool gas in Gas cell BEAM Extraction Collection in a gas cell • IGISOL technique (Ion Guide) • Figure from Juha Aysto, Nucl.Phys. A693(2001)477 • At 200 Torr of 4He, 10% efficiency, space charge limit at 108 ions cm-3 (peak 1010 ions cm-3?), Private communication Ari Jokinen Beta-beam team

  13. What about the intensities? • Cross section similar or larger compared to those studied in detail in C. Rubbia et al.’s paper • Heavier ions in the ring will require further beam dynamics study • Space charge effects will set the limit for the IGISOL type device. With a 1000 cm3 gas cell, is 1011 ions s-1 realistic? • Collection with foils as proposed by C. Rubia et al? Beta-beam team

  14. Intensity evolution during acceleration Cycle optimized for neutrino rate towards the detector • 30% of first 6He bunch injected are reaching decay ring • Overall only 50% (6He) and 80% (18Ne) reach decay ring • Normalization • Single bunch intensity to maximum/bunch • Total intensity to total number accumulated in RCS Bunch 20th 15th 10th 5th 1st total Beta-beam team

  15. Dynamic vacuum • Decay losses cause degradation of the vacuum due to desorption from the vacuum chamber • The current study includes the PS, which does not have an optimized lattice for unstable ion transport and has no collimation system • The dynamic vacuum degrades to 3*10-8 Pa in steady state (6He) • An optimized lattice with collimation system would improve the situation by more than an order of magnitude. C. Omet et al., GSI P. Spiller et al., GSI Beta-beam team

  16. primary collimator Optical functions (m) Deposited Power (W/m) s (m) Collimation and absorption • Merging: • increases longitudinal emittance • Ions pushed outside longitudinal acceptance  momentum collimation in straight section • Decay product • Daughter ion occurring continuously along decay ring • To be avoided: • magnet quenching: reduce particle deposition (average 10 W/m) • Uncontrolled activation • Arcs: Lattice optimized for absorber system OR open mid-plane dipoles s (m) Straight section: Ion extraction et each end A. Chance et al., CEA Saclay Beta-beam team

  17. Decay ring magnet protection • Absorbers checked (in beam pipe): • No absorber, Carbon, Iron, Tungsten Theis C., et al.: "Interactive three dimensional visualization and creation of geometries for Monte Carlo calculations", Nuclear Instruments and Methods in Physics Research A 562, pp. 827-829 (2006). Beta-beam team

  18. Longitudinal penetration in coil Power deposited in dipole Coil Abs Coil Abs Coil No absorber Stainless Steel Carbon Beta-beam team

  19. Impedance, 340 steps! Below 2.3 GHz, a total of 340 steps (170 absorbers) would add up to 0.5 mH, which seems really high. lowest cut-off (2.3 GHz) Im{Z}/W Impedance of one step (diameter 6 to 10 cm or 10 to 6 cm): L = 1.53 nH f/GHz Beta-beam team

  20. Possible new solution Cu or SS Between dipoles Top view, midplane 60 degrees In dipoles Cu or SS sheets with 60 degrees opening on the sides beams y [m] Beta-beam team

  21. Intra Beam scattering, growth times Results obtained with Mad-8 • 6He • 18Ne Beta-beam team

  22. Objectives • A High Intensity Neutrino Oscillation Facility in Europe • CDR for the three main options: Neutrino Factory, Beta-beam and Super-beam • Focus on potential showstoppers • Preliminary costing to permit a fair comparison before the end of 2011 taking into account the latest results from running oscillation experiments • Total target for requested EU contribution: 4 Meuro • 1 MEuro each for SB, NF and BB WPs • 1 MEuro to be shared between Mgt, Phys and Detectors WPs • 4 year project Beta-beam team

  23. Beta-beam WPs • WP leader: Michael Benedikt, CERN • Deputy: Adrian Fabich, CERN • Objective: • Coordination task: CERN leads the task, is responsible for the parameter list and for the overall coherence of the baseline scenario. • Review task: The work will start with a review of the base line design for the new isotopes 8B and 8Li performed by CERN and CEA. • Bunching task: The work at LPSC with the 60 GHz ECR source for bunching studies of 6He and 18Ne started within EURISOL DS will continue with the objective of reaching the high efficiencies needed for the beta-beam.. Furthermore, a study and first tests will be done at LPSC of necessary modification to bunch 8Li and 8B. • Cross sections and collection device task: The cross section for the reaction channels of interest will be (re-)measured and a prototype for the collection device will be built and tested with stable beams at LLN. • Superconducting magnets, magnet protection and collimation task: A pre-study of possible lay-out for superconducting dipoles for the beta-beam will be done at CERN and a baseline design will be identified. The work started on beam collimation and magnet protection in EURISOL DS will be adapated for 8Li and 8B at CERN and CEA • Participating institutes: CERN, UCL, IN2P3 (LPSC), CEA • Additional partners: INFN (LNL), TRIUMF, RAS/IAP, Princeton, ANL Beta-beam team

  24. Management structure STEERING COMMITTEE 1 representative of each Participant + Management Board and representatives of ECFA, ESGARD, BENE, IDS, EURISOL (all ex-officio) 1 meeting/year INTERNATIONAL ADVISORY PANEL 3 Members – 1 Meeting/year MANAGEMENT BOARD Project Leader + 2 Members MANAGEMENT SUPPORT COORDINATION BOARD Management Board + Task Leaders + Coordinators of related EU activities (ex-officio) 2-3 Meetings/year ANNUAL PARTICIPANT MEETING 1 Meeting/year WP MGT WP Nufact WP BetaB WP SuperB WP Phys WP Detec Beta-beam team

  25. Annual participants meeting • Annual meeting: • Monitoring of progress and coherence of the study by SC and IAP members • Annual review of project deliverables and milestones • Bringing the European Neutrino oscillation community together • Physics community and machine community Beta-beam team

  26. Summary • Beta-beam accelerator complex is a very high technical challenge due to high ion intensities • Activation • Space charge • So far it looks technically feasible. • The physics reach for the EURISOL DS scenario is competitive for q13>1O. • Usefulness depends on the short/mid-term findings by other neutrino search facilities. • The physics made possible with the new production concept proposed by Rubbia and Mori needs to be explored • We need a study II • Plenty of new ideas! Acknowledgment of the input given by M. Benedikt, A. Jansson, M. Mezzetto, E. Wildner, beta-beam task group and related EURISOL tasks Beta-beam team

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