The%20Beta-beam%20http://cern.ch/beta-beam

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The Beta-beamhttp//cern.ch/beta-beam

• Mats Lindroos
• on behalf of
• The beta-beam study group

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Collaborators

• The beta-beam study group
• CEA, France Jacques Bouchez, Saclay, Paris
  Olivier Napoly, Saclay, Paris Jacques Payet,
  Saclay, Paris
• CERN, Switzerland Michael Benedikt, AB Peter
  Butler, EP Roland Garoby, AB Steven Hancock, AB
  Ulli Koester, EP Mats Lindroos, AB Matteo
  Magistris, TIS Thomas Nilsson, EP Fredrik
  Wenander, AB
• Geneva University, Switzerland Alain Blondel
  Simone Gilardoni
• GSI, Germany Oliver Boine-Frankenheim B. Franzke
  R. Hollinger Markus Steck Peter Spiller Helmuth
  Weick
• IFIC, Valencia Jordi Burguet, Juan-Jose
  Gomez-Cadenas, Pilar Hernandez, Jose Bernabeu
• IN2P3, France Bernard Laune, Orsay, Paris Alex
  Mueller, Orsay, Paris Pascal Sortais, Grenoble
  Antonio Villari, GANIL, CAEN Cristina Volpe,
  Orsay, Paris
• INFN, Italy Alberto Facco, Legnaro Mauro
  Mezzetto, Padua Vittorio Palladino, Napoli Andrea
  Pisent, Legnaro Piero Zucchelli, Sezione di
  Ferrara
• Louvain-la-neuve, Belgium Thierry Delbar Guido
  Ryckewaert
• UK Marielle Chartier, Liverpool university Chris
  Prior, RAL and Oxford university
• Uppsala university, The Svedberg laboratory,
  Sweden Dag Reistad
• Associate Rick Baartman, TRIUMF, Vancouver,
  Canada Andreas Jansson, Fermi lab, USA, Mike
  Zisman, LBL, USA

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The beta-beam

• Idea by Piero Zucchelli
• A novel concept for a neutrino factory the
  beta-beam, Phys. Let. B, 532 (2002) 166-172
• The CERN base line scenario
• Avoid anything that requires a technology jump
  which would cost time and money (and be risky)
• Make use of a maximum of the existing
  infrastructure
• If possible find an existing detector site

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CERN b-beam baseline scenario
SPL
Decay ring Brho 1500 Tm B 5 T Lss 2500 m
SPS
Decay Ring
ISOL target Ion source
ECR
Cyclotrons, linac or FFAG
Rapid cycling synchrotron
PS
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Target values for the decay ring

• 18Neon10 (single target)
• In decay ring 4.5x1012 ions
• Energy 55 GeV/u
• Rel. gamma 60
• Rigidity 335 Tm

• 6Helium2
• In Decay ring 1.0x1014 ions
• Energy 139 GeV/u
• Rel. gamma 150
• Rigidity 1500 Tm

• The neutrino beam at the experiment will have the
  time stamp of the circulating beam in the
  decay ring.
• The beam has to be concentrated to as few and as
  short bunches as possible to aim for a duty
  factor of 10-4

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SPL, ISOL and ECR
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Rapid cycling synchrotron
PS
SPS
Decay ring

• Objective
• Production, ionization and pre-bunching of ions
• Challenges
• Production of ions with realistic driver beam
  current
• Target deterioration
• Accumulation, ionization and bunching of high
  currents at very low energies

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ISOL production
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6He production by 9Be(n,a)
Converter technology (J. Nolen, NPA 701 (2002)
312c)
Courtesy of Will Talbert, Mahlon Wilson (Los
Alamaos) and Dave Ross (TRIUMF)
Layout very similar to planned EURISOL converter
target aiming for 1015 fissions per s.
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Mercury jet converter
H.Ravn, U.Koester, J.Lettry, S.Gardoni, A.Fabich
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Production of b emitters

• Spallation of close-by target nuclides 18,19Ne
  from MgO and 34,35Ar in CaO
• Production rate for 18Ne is 1x1012 s-1 (with 2.2
  GeV 100 mA proton beam, cross-sections of some mb
  and a 1 m long oxide target of 10 theoretical
  density)
• 19Ne can be produced with one order of magnitude
  higher intensity but the half life is 17 seconds!

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60-90 GHz  ECR Duoplasmatron  for pre-bunching
of gaseous RIB
2.0 3.0 T pulsed coils or SC coils
Very high density magnetized plasma ne 1014 cm-3
Very small plasma chamber F 20 mm / L 5 cm
Target
Arbitrary distance if gas
Rapid pulsed valve

• 1-3 mm
• 100 KV
• extraction

60-90 GHz / 10-100 KW 10 200 µs / ? 6-3
mm optical axial coupling
UHF window or  glass  chamber (?)
20 100 µs 20 200 mA 1012 to 1013 ions per
bunch with high efficiency
Moriond meeting Pascal Sortais et
al. LPSC-Grenoble
optical radial coupling (if gas only)
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Low-energy stage
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Rapid cycling synchrotron
PS
SPS
Decay ring

• Objective
• Fast acceleration of ions and injection
• Acceleration of 16 batches to 100 MeV/u

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Rapid Cycling Synchrotron
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Rapid cycling synchrotron
PS
SPS
Decay ring

• Objective
• Accumulation, bunching (h1), acceleration and
  injection into PS
• Challenges
• High radioactive activation of ring
• Efficiency and maximum acceptable time for
  injection process
• Charge exchange injection
• Multiturn injection
• Electron cooling or transverse feedback system to
  counteract beam blow-up?

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PS
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Fast cycling synchrotron
PS
SPS
Decay ring

• Accumulation of 16 bunches at 300 MeV/u
• Acceleration to g9.2, merging to 8 bunches and
  injection into the SPS
• Question marks
• High radioactive activation of ring
• Space charge bottleneck at SPS injection will
  require a transverse emittance blow-up

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Overview Accumulation

• Sequential filling of 16 buckets in the PS from
  the storage ring

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SPS
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Fast cycling synchrotron
PS
SPS
Decay ring

• Objective
• Acceleration of 8 bunches of 6He(2) to g150
• Acceleration to near transition with a new 40 MHz
  RF system
• Transfer of particles to the existing 200 MHz RF
  system
• Acceleration to top energy with the 200 MHz RF
  system
• Ejection in batches of four to the decay ring
• Challenges
• Transverse acceptance

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Decay ring
SPL
ISOL Target ECR
Linac, cyclotron or FFAG
Fast cycling synchrotron
PS
SPS
Decay ring

• Objective
• Injection of 4 off-momentum bunches on a matched
  dispersion trajectory
• Rotation with a quarter turn in longitudinal
  phase space
• Asymmetric bunch merging of fresh bunches with
  particles already in the ring

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Injection into the decay ring

• Bunch merging requires fresh bunch to be injected
  at 10 ns from stack!
• Conventional injection with fast elements is
  excluded.
• Off-momentum injection on a matched dispersion
  trajectory.
• Rotate the fresh bunch in longitudinal phase
  space by ¼ turn into starting configuration for
  bunch merging.
• Relaxed time requirements on injection elements
  fast bump brings the orbit close to injection
  septum, after injection the bump has to collapse
  within 1 turn in the decay ring (20 ms).
• Maximum flexibility for adjusting the relative
  distance bunch to stack on ns time scale.

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Horizontal aperture layout

• Assumed machine and beam parameters
• Dispersion Dhor 10 m
• Beta-function bhor 20 vm
• Moment. spread stack Dp/p 1.0x10-3 (full)
• Moment. spread bunch dp/p 2.0x10-4 (full)
• Emit. (stack, bunch) egeom 0.6 pmm

Beam 2 mm momentum 4 mm
emittance
Required bump 22 mm
Required separation 30 mm, corresponds to
3x10-3 off-momentum.
Septum alignment 10 mm

Stack 10mm momentum 4 mm
emittance
22 mm
Central orbit undisplaced
M. Benedikt
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Full scale simulation with SPS as model

• Simulation conditions
• Single bunch after injection and ¼ turn rotation.
• Stacking again and again until steady state is
  reached.
• Each repetition, a part of the stack
  (corresponding to b-decay) is removed.
• Results
• Steady state intensity was 85 of theoretical
  value (for 100 effective merging).
• Final stack intensity is 10 times the bunch
  intensity (15 effective mergings).
• Moderate voltage of 10 MV is sufficient for 40
  and 80 MHz systems for an incoming bunch of lt 1
  eVs.

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Stacking in the Decay ring

• Ejection to matched dispersion trajectory
• Asymmetric bunch merging

SPS
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Asymmetric bunch merging
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Asymmetric bunch merging
(S. Hancock, M. Benedikt and J,-L.Vallet, A proof
of principle of asymmteric bunch pair merging,
AB-note-2003-080 MD)
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Decay losses

• Losses during acceleration are being studied
• Full FLUKA simulations in progress for all stages
  (M. Magistris and M. Silari, Parameters of
  radiological interest for a beta-beam decay ring,
  TIS-2003-017-RP-TN)
• Preliminary results
• Can be managed in low energy part
• PS will be heavily activated
• New fast cycling PS?
• SPS OK!
• Full FLUKA simulations of decay ring losses
• Tritium and Sodium production surrounding rock
  well below national limits
• Reasonable requirements of concreting of tunnel
  walls to enable decommissioning of the tunnel and
  fixation of Tritium and Sodium

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Decay losses

• Acceleration losses

6He (T1/20.8 s) 18Ne (T1/21.67 s)
Accumulation lt47 mW/m lt2.9 mW/m
PS 1.2 W/m 90 mW/m
SPS 0.41 W/m 32 mW/m
Decay ring 8.9 W/m 0.6 W/m
A. Jansson
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How bad is 9 W/m?

• For comparison, a 50 GeV muon storage ring
  proposed for FNAL would dissipate 48 W/m in the
  6T superconducting magnets. Using a tungsten
  liner to
• reduce peak heat load for magnet to 9 W/m.
• reduce peak power density in superconductor
  (to below 1mW/g)
• Reduce activation to acceptable levels
• Heat load may be OK for superconductor.

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SC magnets

• Dipoles can be built with no coils in the path of
  the decaying particles to minimize peak power
  density in superconductor
• The losses have been simulated and one possible
  dipole design has been proposed

S. Russenschuck, CERN
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Tunnels and Magnets

• Civil engineering costs Estimate of 400 MCHF for
  1.3 incline (13.9 mrad)
• Ringlenth 6850 m, Radius300 m, Straight
  sections2500 m
• Magnet cost First estimate at 100 MCHF

FLUKA simulated losses in surrounding rock (no
public health implications)
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Intensities
Stage 6He 18Ne (single target)
From ECR source 2.0x1013 ions per second 0.8x1011 ions per second
Storage ring 1.0x1012 ions per bunch 4.1x1010 ions per bunch
Fast cycling synch 1.0x1012 ion per bunch 4.1x1010 ion per bunch
PS after acceleration 1.0x1013 ions per batch 5.2x1011 ions per batch
SPS after acceleration 0.9x1013 ions per batch 4.9x1011 ions per batch
Decay ring 2.0x1014 ions in four 10 ns long bunch 9.1x1012 ions in four 10 ns long bunch
Only b-decay losses accounted for, add efficiency
losses (50)
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CERN to FREJUS
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The Super Beam
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LOW-ENERGY BETA-BEAMS
Beta-beam
n
n
6He
C. Volpe, hep-ph/0303222 To appear in Journ.
Phys. G. 30(2004)L1
boost
THE PROPOSAL
To exploit the beta-beam concept to produce
intense and pure low-energy neutrino beams.
PHYSICS POTENTIAL
e
ne
C
N
Neutrino-nucleus interaction studies for
particle, nuclear physics, astrophysics
(nucleosynthesis).
Neutrino properties, like n magnetic moment.
A BETA-BEAM FACILITY FOR LOW-ENERGY NEUTRINOS.
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Prospects for the neutrino magnetic moment
PRESENT LIMIT mn lt 1.0 x 10-10 mB.
6He
6Liene Qb4. MeV
n
5 X 10-11 mB
6He
e
ne
e
ne
10-11 mB
ne-e events with beta-beams (10 15 n/s) with a
4p low threshold detector.
mn0
THE LIMIT CAN BE IMPROVED BY ONE ORDER of
MAGNITUDE (a few x 10-11 mB) .
G.C. McLaughlin and C. Volpe, hep-ph/0303222, to
appear in Phys. Lett. B.
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Neutrino-nucleus Interaction Rates At a
Low-energy Beta-beam Facility
Neutrino Fluxes
Events/year for g14
Small Ring
Large Ring
ne Nucleus
Small Ring Lss 150 m, Ltot 450 m. Large
Ring Lss 2.5 km, Ltot 7.5 km
25779
1956
ne D
82645
9453
ne 16O
103707
7922
ne 208Pb
INTERESTING INTERACTION RATES CAN BE OBTAINED.
J. Serreau and C. Volpe, hep-ph/0403293,
submitted to Phys. Rev. D.
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Possible sites
g
Detectors
Intensities
GANIL
1012 n/s
1
4p
A. Villari (GANIL)
109 n/s
1-10
4p and Close detector
GSI
H. Weick (GSI)
4p and Close detector
CERN
1-100
1013 n/s
(EURISOL)
Autin et al, J.Phys. (2003).
CERN IS A UNIQUE SITE BOTH FOR THE n-INTENSITIES
AND THE n-ENERGIES.
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RD (improvements)

• Production of RIB (intensity)
• Simulations (GEANT, FLUKA)
• Target design, only 200 kW primary proton beam in
  present design
• Acceleration (cost)
• FFAG versa linac/storage ring/RCS
• High gamma option
• Tracking studies (intensity)
• Loss management
• Superconducting dipoles (g of neutrinos)
• Pulsed for new PS/SPS (GSI FAIR)
• High field dipoles for decay ring to reduce arc
  length
• Radiation hardness (Super FRS)

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Comments speculationsNe and He in decay ring
simultaneously

• Possible gain in counting time and reduction of
  systematic errors
• Cycle time for each ion type doubles!
• Requiring g(60)150 for He will at equal rigidity
  result in a g(100)250 for Ne
• Physics?
• Detector simulation should give best compromise
• Requiring equal revolution time will result in a
  DR of 97(16) mm (r300 m)
• Insertion in one straight section to compensate

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Comments sepculationsAccumulation Ne He in
DECAY RING
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Comments sepculationsAccumulation Ne He
before acceleration

• Base line scenario assumes accumulation of 16
  bunches for one second at 300 MeV/u (PS) for both
  He and Ne
• Optimization assuming fixed ECR intensity (out)
• Longer accumulation
• SPS accumulation

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Comments speculationsAccumulation before
acceleration
SPS Ne, one fill of 1 unit of ions every 1.2 s
SPS He, one fill of 1 unit of ions every 1.2 s
Increase of intensity
PS Ne, one fill of 1 unit of ions every 1/16 s
PS He one fill of 1 unit of ions every 1/16 s
Number of fills
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Comments speculationsWasted time?
Decay ring
SPS
PS
Production
8
Time (s)
0
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Comments speculationsHigher Gamma?

• Requires either a larger bending radius or a
  higher magnetic field for the decay ring, the
  baseline circumference is 6885 m and has a
  bending radius (r) of 300 m
• At g500 (6He) , r935 m at B5 T
• To keep the percentage of straight section the
  same as the baseline the ring would become 21.4
  km long
• Alternatively new dipoles r300 m at B15.6 T
• Or LHC type dipoles at B10 T and r468 m with a
  circumference of 7794 m
• Requires an upgrade of SPS or ramping of the
  decay ring
• SPS upgrade expensive and time consuming
• Ramping of decay ring requires less frequent
  fills and higher total intensity

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Comments speculationsDuty factor (or empty
buckets)

• The baseline delivers a neutrino beam with an
  energy badly troubled by atmospheric background
• Duty factor4 10-4, 4 buckets out of 919 possible
  filled 10 ns total bunch length
• At g500 the duty factor can be increased to 10-2
  (P. Hernandez), 92 buckets filled or 23 times the
  intensity theoretically, can that be realised?

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Comments speculationsElectron Capture,
Monochromatic beams

• Nuclei that only decay by electron capture
  generally have a long half-life (low Q value,
  lt1022 keV)
• Some possible candidates 110Sn (4.1 h half life)
  and 164Yb (75.8 min half life)
• Maybe possible if very high intensities can be
  collected in the decay ring and a high duty
  factor can be accepted (0.1)
• High gamma with ramping of the decay ring?
• For the baseline With g259, assuming 2.3 1016
  ions in the decay ring and a duty factor of 0.1
  there would be 4 109 neutrinos per second at
  259x0.326 MeV84.434 MeV, is that useful?

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Design Study
EURISOL Beta-beam Coordination Beta-beam
parameter group Above 100 MeV/u Targets 60 GHz
ECR Low energy beta-beam And many more
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Superbeam Beta Beam cost estimates (NUFACT02)
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A EURISOL/beta-beam facility at CERN!

• A boost for radioactive nuclear beams

• A boost for neutrino physics

The chances of a neutrino actually hitting
something as it travels through all this
emptiness are roughly comparable to that of
dropping a ball bearing from a cruising 747 and
hitting, say an egg sandwich, Douglas Adams,
Mostly Harmless, Chapter 3
) European A380, Prototype will fly in 2005
EURISOL Design Study, when will the beta-beam
fly?