Transcript Slide 1

TRACKING AND PARTICLEMATTER 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
1
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.
Ions
move almost
at the speed of light

Accelerate parent ion to relativistic gmax


Neutrino detector
EURISOL scenario
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.
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
2
Possible Beta Beam Complex
High-energy part
Low-energy part
Acceleration
Ion production
Proton Driver
SPL
Ion production
ISOL target &
Ion source
Beam preparation
ECR pulsed
Beam to experiment
Acceleration to final energy
PS & SPS
Decay ring
Existing!!!
SPS
Ion acceleration
Linac, 0.4 GeV
Acceleration to
medium energy
RCS, 1.5 GeV
Neutrino source
93 GeV
PS
Br = 1500 Tm
Neutrino B = ~6 T
Source C = ~6900 m
Decay Lss= ~2500 m
Ring
6He: g = 100
18Ne:
g = 100
.
8.7 GeV
Detector in the Frejus tunnel
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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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
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Particle Turnover
~1 MJ beam energy/cycle injected
 equivalent ion number to be removed
~25 W/m average
injection
merging
Momentum
collimation
p-collimation
Arc
Arc
Straight section
Momentum collimation: ~5*1012 6He ions to be collimated per cycle
Decay: ~5*1012 6Li ions to be removed per cycle per meter
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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The Decay Ring Optics
20
A. Chance et al., CEA Saclay
b
1/2
(m)
bx1/2
Decay ring:
• C~7km
• LSS~2.5 km
15
10
by1/2
nx = 18.23
ny = 10.16
5
0
Dx
-5
1000
2000
3000
One straight section used
for momentum collimation.
Optical functions (m)
0
by
primary
bcollimator
x
s (m)
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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Particle removal & loss
1.
Arcs

2.
Decay products
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)
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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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)
ion beam
aperture
4 cm for the vertical plane
child beams
absorber
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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The Large Aperture Dipole, first feasibility study
Courtesy Christine Vollinger
6 T
high tip field,
non-critical
LHC ”costheta” design
Good-field requirements only apply to about
half the horizontal aperture.
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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The Decay Products in the arcs
Deposited Power (W/m)
Courtesy: A. Chancé
Dipole
s (m)
Arc, repetitive pattern
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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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
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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
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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.
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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Heat Deposition Model, one cell
Q
Absorbers
B
B
Q (ISR model)
B (new design)
”Overlapping” Quad
to check
repeatability of
pattern
B
No Beampipe (angle large)
Q
Concentric cylinders, copper (coil), iron (yoke)
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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Coordinate transformation
ACCSIM/FLUKA and inverse
y
ACCSIM
We used Mathematica based on the
survey options of ”BeamOptics” * to
generate FLUKA Particle file
x
Useful if ACCSIM could integrate the
transformation code
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
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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
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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
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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
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Alternative solutions
Open Mid Plane Magnet a better
solution?
Profit of work ongoing at CERN
Use this model in simulations
Liner
Beam Pipe
Cooling pipes
Introduce a “Beam Screen”
Courtesy Erk Jensen, CERN
Absorber
Beta Beam - Loss Deposition, EURONS/EURISOL, E.Wildner
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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