Tracking and particle-matter interaction studies in the beta-beam decay ring E.Wildner, A. Fabich (CERN) Common EURISOL DS - EURONS Town Meeting Helsinki, Finland, 17-19 September 2007

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner EURISOL Scenario 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. Accelerate parent ion to relativistic gmax Boosted neutrino energy spectrum: En2gQ Forward focusing of neutrinos: 1/g EURISOL scenario Ion choice: 6He and 18Ne Based on existing technology and machines Study of a beta-beam implementation at CERN Once we have thoroughly studied the EURISOL scenario, we can “easily” extrapolate to other cases. EURISOL study could serve as a reference. Neutrino detector Ions move almost at the speed of light EURISOL scenario Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Possible Beta Beam Complex High-energy part Low-energy part Ion production Acceleration Neutrino source Beam to experiment Proton Driver SPL Acceleration to final energy PS & SPS Ion production ISOL target & Ion source Decay ring Br = 1500 Tm B = ~6 T C = ~6900 m Lss= ~2500 m 6He: g = 100 18Ne: g = 100 SPS Neutrino Source Decay Ring Existing!!! Beam preparation ECR pulsed Ion acceleration Linac, 0.4 GeV 93 GeV PS Acceleration to medium energy RCS, 1.5 GeV . 8.7 GeV Detector in the Frejus tunnel Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 3 3

Beta-beam tasks (Eurisol Design Study) From ”Overview” by M. Benedikt, Beta Beam Task Meeting in May 2007 Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 4 4

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner Particle Turnover ~1 MJ beam energy/cycle injected  equivalent ion number to be removed ~25 W/m average Momentum collimation: ~5*1012 6He ions to be collimated per cycle Decay: ~5*1012 6Li ions to be removed per cycle per meter p-collimation merging decay losses injection Straight section Arc Momentum collimation Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner The Decay Ring Optics A. Chance et al., CEA Saclay Decay ring: C~7km LSS~2.5 km s (m) Optical functions (m) primary collimator One straight section used for momentum collimation. Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Particle removal & loss Arcs Decay products Straight section Merging increases longitudinal beam size Momentum collimation Primarily accumulated and extracted at end with first dipole to external dump. Not treated yet: Betatron-Collimation Emergency cases (failure modes) Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Large Aperture Requirements Dipole 6Li 3+ Absorber 18F 9+ Beam Pipe 8 cm radius needed for the horizontal plane where the decay products cause daughter beams + 1 cm for the sagitta (no curved magnet) 4 cm for the vertical plane Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

The Large Aperture Dipole, first feasibility study Courtesy Christine Vollinger high tip field, non-critical 6 T LHC ”costheta” design Good-field requirements only apply to about half the horizontal aperture. Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

The Decay Products in the arcs Courtesy: A. Chancé Dipole Deposited Power (W/m) s (m) Arc, repetitive pattern Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Heat Deposition Calculations Need to interface beam code and code for tracking particles in matter Choice: Beam Code: ACCIM (Developed at TRIUMF, many options developed specifically for the decay simulations, responsible Frederick Jones, TRIUMF) Particle Tracking in Matter: FLUKA "FLUKA: a multi-particle transport code", A. Fasso`, A. Ferrari, J. Ranft, and P.R. Sala, CERN-2005-10 (2005), INFN/TC_05/11, SLAC-R-773 "The physics models of FLUKA: status and recent developments", A. Fasso`, A. Ferrari, S. Roesler, P.R. Sala, G. Battistoni, F. Cerutti, E. Gadioli, M.V. Garzelli, F. Ballarini, A. Ottolenghi, A. Empl and J. Ranft, Computing in High Energy and Nuclear Physics 2003 Conference (CHEP2003), La Jolla, CA, USA, March 24-28, 2003 Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 11 11

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner The beam code ACCSIM Accsim, developed at TRIUMF, is a multiparticle tracking and simulation code for synchrotrons and storage rings. Some applications: CERN (S)PS(B), KEK PS, J-PARC, SNS, ... Incorporates simulation tools for injection, orbit manipulations, rf programs, foil, target & collimator interactions, longitudinal and transverse space charge, loss detection and accounting. Interest for Betabeam: to provide a comprehensive model of decay ring operation including injection (orbit bumps, septum, rf bunch merging), space charge effects, and losses (100% !) Needed developments for Betabeam: Arbitrary ion species, decay, secondary ions. More powerful and flexible aperture definitions (for absorbers) Tracking of secondary ions off-momentum by >30% (unheard of in conventional fast-tracking codes) Detection of ion losses: exactly where did the ion hit the wall? -- a challenge for tracking with the usual ”element transfer maps” Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner Accsim and Fluka Accsim as event generator for FLUKA Identify “region of interest”: sequence of Accsim elements corresponding to the representative arc cell modeled in FLUKA. Tracking 100000 macro-particles representing fully populated ring (9.66×1013 He or 7.42×1013 Ne), with decay. Detect and record two types of events: Ions that decayed upstream of the cell and have survived to enter the cell. Ions that decay in the cell. For each event the ion coordinates and reference data are recorded for use as source particles in FLUKA. Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Heat Deposition Model, one cell Q Absorbers B B ”Overlapping” Quad to check repeatability of pattern Q (ISR model) B (new design) B No Beampipe (angle large) Concentric cylinders, copper (coil), iron (yoke) Q Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Coordinate transformation ACCSIM/FLUKA and inverse We used Mathematica based on the survey options of ”BeamOptics” * to generate FLUKA Particle file Useful if ACCSIM could integrate the transformation code y ACCSIM x y FLUKA [cm] x [cm] * ”Beam Optics : a program for analytical beam optics” Autin, Bruno; Carli, Christian; D'Amico, Tommaso Eric; Gröbner, Oswald; Martini, Michel; Wildner, Elena; CERN-98-06 Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Particle generation and treatment 1. ACCSIM tracks 6Li and 18F particle decaying in the ring up to cell entry 2. ACCSIM gives coordinates and momentum vectors of particles just decayed in cell 3. Particles escaping the vacuum pipe are treated by Fluka End of cell Decayed in cell Escaping Decayed in machine with absorbers inserted in ACCSIM Start of cell Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Overall Power Deposition Normalized to a decay rate in cell: He: 5.37 109 decays/s Ne: 1.99 109 decays/s 6Li 18F Compare to technical limits (10W/m) not exceeding for either ion Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Local Power Deposition Local power deposition concentrated around the mid plane. Limit for quench 4.3mW/cm3 (LHC cable data including margin) Situation fine for 6Li 18F: 12 mW/cm3 Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Alternative solutions Open Mid Plane Magnet a better solution? Profit of work ongoing at CERN Use this model in simulations Introduce a “Beam Screen” Courtesy Erk Jensen, CERN Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner Conclusion and Future A protocol between the beam code Accsim and the material tracking code (FLUKA) has ben developed for the beta beam studies. ACCSIM to be used for the whole accelerator chain, for decay data production. Accsim now to be complemented with the packages made for model creation and for coordinate transformation (Accsim->FLUKA->Accsim) First results indicate that the deposited power is exceeding the limits locally, but not globally. Optimisation or another magnet design needed. The structure with absorbers would need special arrangements for the impedance induced. A thick liner inside the dipole could be an alternative Alternative dipole design with VERY large aperture or open mid-plane (new development, ongoing). Apply simulation tools for momentum collimation. Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner