Download - Tracking and particle-matter interaction studies in the beta-beam decay ring

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


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 tasks (Eurisol Design Study)From ”Overview” by M. Benedikt, Beta Beam Task Meeting in May 2007


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


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


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.


The Decay Products in the arcs

s (m)

Dep

osite

d P

ower

(W/m

)Courtesy: A. Chancé

Arc, repetitive pattern

Dipole


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


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


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.


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


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


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


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


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.


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.

Download - Tracking and particle-matter interaction studies in the beta-beam decay ring

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