TRACKING AND PARTICLE-MATTER INTERACTION STUDIES IN THE BETA-BEAM DECAY RING
E.Wildner, A. Fabich (CERN)
Common EURISOL DS - EURONS Town MeetingHelsinki, Finland, 17-19 September 2007
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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: En2Q Forward focusing of neutrinos: 1/
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 3
Possible Beta Beam Complex
.
Neutrino
Source Decay Ring
Ion production ISOL target &
Ion source
Proton Driver SPL
Decay ringB = 1500 Tm B = ~6 T C = ~6900 m Lss= ~2500 m 6He: = 100 18Ne: = 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 sourceLow-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
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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 cycleDecay: ~5*1012 6Li ions to be removed per cycle per meter
p-collimation
merging
decay losses
inje
ctio
n
Straight section
Straight section
Arc
Arc
Momentum collimation
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The Decay Ring OpticsA. Chance et al., CEA Saclay
-5
0
5
10
15
20
0 1000 2000 3000
b1/2 (m) bx1/2
by1/2
Dx
nx = 18.23
ny = 10.16
s (m)
xb
Opt
ical
func
tions
(m) primary
collimatoryb
Decay ring:• C~7km• LSS~2.5 km
One straight section used for momentum collimation.
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
Particle removal & loss1. Arcs
Decay products2. 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)
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Large Aperture Requirements
aperture
child beams
ion beam
absorber
child beams
ion beam
absorber
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
6Li 3+
18F 9+Absorber
Dipole
Beam Pipe
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The Large Aperture Dipole, first feasibility study
high tip field, non-critical6 T
LHC ”costheta” design
Courtesy Christine Vollinger
Good-field requirements only apply to about half the horizontal aperture.
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The Decay Products in the arcs
s (m)
Dep
osite
d P
ower
(W/m
)Courtesy: A. Chancé
Arc, repetitive pattern
Dipole
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Heat Deposition CalculationsNeed 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
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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
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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: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.
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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
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Coordinate transformationACCSIM/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
300 250 200 150 100 50 0
0.5
0
0.5
1
1 0.5 0 0.5 1 1.5
0.5
0
0.5
1
x
x
ACCSIM
FLUKA
y
y
[cm]
[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
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Particle generation and treatment1. ACCSIM tracks 6Li and 18F particle decaying in the ring up to cell entry
Start of cell
End of cell0 10 20 30 40
0.01
0.005
0
0.005
0.01
0.015
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
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Overall Power Deposition
Normalized to a decay rate in cell:
He: 5.37 109 decays/sNe: 1.99 109 decays/s
18F
6Li
Compare to technical limits (10W/m)• not exceeding for either ion
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Local Power Deposition
Limit for quench 4.3mW/cm3 (LHC cable data including
margin)• Situation fine for 6Li• 18F: 12 mW/cm3
Local power deposition concentrated around the mid plane.
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Alternative solutions
Open Mid Plane Magnet a better solution?
Profit of work ongoing at CERNUse this model in simulations
Absorber
Liner
Cooling pipes
Beam Pipe
Absorber
Liner
Cooling pipes
Beam Pipe
Introduce a “Beam Screen”Courtesy Erk Jensen, CERN
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
Conclusion and FutureA 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.