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, September

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 2 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  max Boosted neutrino energy spectrum: E n  2  Q Forward focusing of neutrinos:  1/  EURISOL scenario Ion choice: 6 He and 18 Ne 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 3 Possible Beta Beam Complex. Neutrino Source Decay Ring Ion production ISOL target & Ion source Proton Driver SPL Decay ring B  = 1500 Tm B = ~6 T C = ~6900 m L ss = ~2500 m 6 He:  = Ne:  = 100 SPS Acceleration to medium energy RCS, 1.5 GeV PS Acceleration to final energy PS & SPS Beam to experiment Ion acceleration Linac, 0.4 GeV Beam preparation ECR pulsed Ion production Acceleration Neutrino source Low-energy part High-energy part Detector in the Frejus tunnel Existing!!! 8.7 GeV 93 GeV

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 4 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 5 Particle Turnover ~1 MJ beam energy/cycle injected  equivalent ion number to be removed ~25 W/m average Momentum collimation: ~5* He ions to be collimated per cycle Decay: ~5* Li 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 6 The Decay Ring Optics A. Chance et al., CEA Saclay s (m) Optical functions (m) primary collimator Decay ring: C~7km L SS ~2.5 km One straight section used for momentum collimation.

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner Particle removal & loss 1. Arcs Decay products 2. Straight section Merging increases longitudinal beam size Momentum collimation Decay products Primarily accumulated and extracted at end with first dipole to external dump. Not treated yet: Betatron-Collimation Emergency cases (failure modes) 7

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 8 Large Aperture Requirements 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 6 Li F 9+ Absorber Dipole Beam Pipe

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 9 The Large Aperture Dipole, first feasibility study high tip field, non-critical 6 T LHC ”costheta” design Courtesy Christine Vollinger Good-field requirements only apply to about half the horizontal aperture.

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 10 The Decay Products in the arcs s (m) Deposited Power (W/m) Courtesy: A. Chancé Arc, repetitive pattern Dipole

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 11 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), 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 12 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” The beam code ACCSIM

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 13 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 macro-particles representing fully populated ring ( 9.66×10 13 He or 7.42×10 13 Ne), with decay. Detect and record two types of events: 1.Ions that decayed upstream of the cell and have survived to enter the cell. 2.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 14 Heat Deposition Model, one cell Absorbers B B (new design) B B Q Q (ISR model) Q No Beampipe (angle large) Concentric cylinders, copper (coil), iron (yoke) ”Overlapping” Quad to check repeatability of pattern

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 15 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 x x ACCSIM FLUKA y y [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 16 Particle generation and treatment 1. ACCSIM tracks 6Li and 18F particle decaying in the ring up to cell entry Start of cell End of cell Decayed in machine with absorbers inserted in ACCSIM Decayed in cell 2. ACCSIM gives coordinates and momentum vectors of particles just decayed in cell 3. Particles escaping the vacuum pipe are treated by Fluka Escaping

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 17 Overall Power Deposition Normalized to a decay rate in cell: He: decays/s Ne: decays/s 18F 6Li Compare to technical limits (10W/m) not exceeding for either ion

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 18 Local Power Deposition Limit for quench 4.3mW/cm3 (LHC cable data including margin) Situation fine for 6 Li 18 F: 12 mW/cm 3 Local power deposition concentrated around the mid plane.

Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner 19 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 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.