Beta-beams

1
Beta-beams

• M. Benedikt, A. Fabich and M. Lindroos,
• CERN
• on behalf of the Beta-beam Study Group
• http//cern.ch/beta-beam
• BENE06/CARE06

2
Outline

• Beta-beam concept
• EURISOL DS scenario
• Layout
• Main issues on acceleration scheme
• Other scenarios
• High-Q vlaue Beta-beams
• Study II
• Summary

3
Beta-beam principle

• 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.
• Beta-decay at rest
• n-spectrum well known from electron spectrum
• Reaction energy Q typically of a few MeV
• Accelerated parent ion to relativistic gmax
• Boosted neutrino energy spectrum En?2gQ
• Forward focusing of neutrinos ???1/g
• Pure electron (anti-)neutrino beam!
• NB Depending on b- or b--decay we get a
  neutrino or anti-neutrino
• Two (or more) different parent ions for neutrino
  and anti-neutrino beams
• Physics applications of a beta-beam
• Primarily neutrino oscillation physics and
  CP-violation

4
Guideline to n-beam scenarios based on
radio-active ions

• Low-energy beta-beam relativistic g lt 20
• Physics case neutrino scattering
• Medium energy beta-beam g 100
• E.g. EURISOL DS
• Today the only detailed study of a beta-beam
  accelerator complex
• High energy beta-beam g gt350
• Take advantage of increased interaction
  cross-section of neutrinos
• Monochromatic neutrino-beam
• Take advantage of electron-capture process
• High-Q value beta-beam g 100
• Accelerator physicists together with neutrino
  physicists defined the accelerator case of
  g100/100 to be studied first (EURISOL DS).

5
The EURISOL scenario

• Based on CERN boundaries
• Ion choice 6He and 18Ne
• Relativistic gamma100/100
• SPS allows maximum of 150 (6He) or 250 (18Ne)
• Gamma choice optimized for physics reach
• Based on existing technology and machines
• Ion production through ISOL technique
• Post acceleration ECR, linac
• Rapid cycling synchrotron
• Use of existing machines PS and SPS
• Achieve an annual neutrino rate of either
• 2.91018 anti-neutrinos from 6He
• Or 1.1 1018 neutrinos from 18Ne
• Once we have thoroughly studied the EURISOL
  scenario, we can easily extrapolate to other
  cases. EURISOL study could serve as a reference.

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Intensity evolution during acceleration
Bunch 20th 15th 10th 5th 1st
total

• Cycle optimized for neutrino rate towards the
  detector
• 30 of first 6He bunch injected are reaching
  decay ring
• Overall only 50 (6He) and 80 (18Ne) reach decay
  ring
• Normalization
• Single bunch intensity to maximum/bunch
• Total intensity to total number accumulated in RCS

7
Dynamic vacuum

• Decay losses cause degradation of the vacuum due
  to desorption from the vacuum chamber
• The current study includes the PS, which does not
  have an optimized lattice for unstable ion
  transport and has no collimation system
• The dynamic vacuum degrades to 310-8 Pa in
  steady state (6He)
• An optimized lattice with collimation system
  would improve the situation by more than an order
  of magnitude.

C. Omet et al., GSI
P. Spiller et al., GSI
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Particle turnover

• 1 MJ beam energy/cycle injected
• ? equivalent ion number to be removed
• 25 W/m average
• Momentum collimation 51012 6He ions to be
  collimated per cycle
• Decay 51012 6Li ions to be removed per cycle
  per meter

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Collimation and absorption

• Merging
• increases longitudinal emittance
• Ions pushed outside longitudinal acceptance
• ? momentum collimation
• in straight section
• Decay product
• Daughter ion occurring continuously along decay
  ring
• To be avoided
• magnet quenching reduce particle deposition
  (average 10 W/m)
• Uncontrolled activation
• Arcs Lattice optimized for absorber system OR
  open mid-plane dipoles

s (m)
Straight section Ion extraction et each end
A. Chance et al., CEA Saclay
10
Decay ring magnet protection

• Absorbers checked (in beam pipe)
• No absorber, Carbon, Iron, Tungsten

Theis C., et al. "Interactive three
dimensional visualization and creation of
geometries for Monte Carlo calculations", Nuclear
Instruments and Methods in Physics Research A
562, pp. 827-829 (2006).
11
Longitudinal penetration in coil
Power deposited in dipole
Coil
Coil
Abs
Coil
Abs
No absorber
Carbon
Stainless Steel
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Impedance, 340 steps!
Below 2.3 GHz, a total of 340 steps (170
absorbers) would add up to 0.5 mH, which seems
really high.
lowest cut-off (2.3 GHz)
ImZ/W
Impedance of one step (diameter 6 to 10 cm or 10
to 6 cm)
L 1.53 nH
f/GHz
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Possible new solution
Cu or SS
Between dipoles
Top view, midplane
60 degrees
In dipoles
Cu or SS sheets with 60 degrees opening on the
sides
beams
y m
14
Intra Beam scattering, growth times

• Results obtained with Mad-8
• 6He
• 18Ne

15
A new approach for the production

• Beam cooling with ionisation losses C. Rubbia,
  A Ferrari, Y. Kadi and V. Vlachoudis in NIM A, In
  press
• Many other applications in a number of different
  fields
• may also take profit of intense beams of
  radioactive ions.

7Li(d,p)8Li 6Li(3He,n)8B
7Li 6Li
See also Development of FFAG accelerators and
their applications for intense secondary particle
production, Y. Mori, NIM A562(2006)591
16
Transverse cooling in paper by Carlo Rubbia et al.

• In these conditions, like in the similar case of
  the synchrotron radiation, the transverse
  emittance will converge to zero. In the case of
  ionisation cooling, a finite equilibrium
  emittance is due to the presence of the multiple
  Coulomb scattering.

17
Longitudinal cooling in paper by Carlo Rubbia et
al.

• In order to introduce a change in the dU/dE term
  making it positive in order to achieve
  longitudinal cooling the gas target may be
  located in a point of the lattice with a
  chromatic dispersion. The thickness of the foil
  must be wedge-shaped in order to introduce an
  appropriate energy loss change, proportionally to
  the displacement from the equilibrium orbit
  position.

Number of turns

1. Without wedge, dU/dElt0
2. Wedge with dU/dE0, no longitudinal cooling
3. Wedge with dU/dE0.0094
4. Electrons, cooling through synchrotron radiation

18
Inverse kinematics production and ionisation
parameters in paper by Carlo Rubbia et al.
7Li(d,p)8Li 6Li(3He,n)8B
19
Collection in paper by Carlo Rubbia et al.

• The technique of using very thin targets in
  order to produce secondary neutral beams has been
  in use for many years. Probably the best known
  and most successful source of radioactive beams
  is ISOLDE.

B form compounds and has never been produced in
from a solid ISOL target. Can we use
Flourination and extract BF?
For me this is the most critical point of this
proposal!
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Reactions to study for EURISOL beta-beams

• 20Ne(p,t)18Ne
• H.Backhausen et al, RCA,29(1981)1
• 16O(3He,n)18Ne
• V.Tatischeff et al, PRC,68(2003)025804
• 6C(CO2,6He)18Ne?
• K.I.Hahn et al, PRC,54(1996)1999
• 7Li(T,A)6He

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Collection in a gas cell

• IGISOL technique (Ion Guide)

• Figure from Juha Aysto, Nucl.Phys. A693(2001)477
• At 200 Torr of 4He, 10 efficiency, space charge
  limit at 108 ions cm-3 (peak 1010 ions cm-3?),
  Private communication Ari Jokinen
• Consierably higher efficiency using cryogenic He
  gas.
• Possible to use superfluid helium with very high
  efficiency but method to release ions have to be
  developed
• Will scattered primary ion beam be a problem?
• Can we separate the secondaries from the
  primaries with a fragment separator insertion to
  avoid hole?

22
What about the intensities?

• Cross section similar or larger compared to those
  studied in detail in C. Rubbia et al.s paper
• Heavier ions in the ring will require further
  beam dynamics study
• Space charge effects will set the limit for the
  IGISOL type device. With a 1000 cm3 gas cell, is
  1011 ions s-1 realistic?
• Collection with foils as proposed by C. Rubia et
  al?

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Objectives

• A High Intensity Neutrino Oscillation Facility in
  Europe
• CDR for the three main options Neutrino Factory,
  Beta-beam and Super-beam
• Focus on potential showstoppers
• Preliminary costing to permit a fair comparison
  before the end of 2011 taking into account the
  latest results from running oscillation
  experiments
• Total target for requested EU contribution 4
  Meuro
• 3.5 MEuro from EU for SB, NF and BB WPs plus lab
  contributions
• 1.5 MEuro to be shared between Mgt, Phys and
  Detectors WPs plus lab contributions
• 4 year project

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Beta-beam WPs

• WP leader Michael Benedikt, CERN
• Deputy Adrian Fabich, CERN
• Objective
• Coordination task CERN leads the task, is
  responsible for the parameter list and for the
  overall coherence of the baseline scenario.
• Review task The work will start with a review of
  the base line design for the new isotopes 8B and
  8Li performed by CERN and CEA.
• Bunching task The work at LPSC with the 60 GHz
  ECR source for bunching studies of 6He and 18Ne
  started within EURISOL DS will continue with the
  objective of reaching the high efficiencies
  needed for the beta-beam.. Furthermore, a study
  and first tests will be done at LPSC of necessary
  modification to bunch 8Li and 8B.
• Cross sections and collection device task The
  cross section for the reaction channels of
  interest will be (re-)measured and a prototype
  for the collection device will be built and
  tested with stable beams at LLN.
• Superconducting magnets, magnet protection and
  collimation task A pre-study of possible lay-out
  for superconducting dipoles for the beta-beam
  will be done at CERN and a baseline design will
  be identified. The work started on beam
  collimation and magnet protection in EURISOL DS
  will be adapated for 8Li and 8B at CERN and CEA
• Participating institutes CERN, UCL, IN2P3
  (LPSC), CEA
• Additional partners INFN (LNL), TRIUMF, RAS/IAP,
  Princeton, ANL

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Annual participants meeting EUROn DS

• Annual meeting
• Monitoring of progress and coherence of the study
  by SC and IAP members
• Annual review of project deliverables and
  milestones
• Bringing the European (and International)
  Neutrino oscillation community together
• Physics community and machine community

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Summary

• Beta-beam accelerator complex is a very high
  technical challenge due to high ion intensities
• Activation
• Space charge
• So far it looks technically feasible.
• The physics reach for the EURISOL DS scenario is
  competitive for q13gt1O.
• Usefulness depends on the short/mid-term findings
  by other neutrino search facilities.
• The physics made possible with the new production
  concept proposed by Rubbia and Mori needs to be
  explored
• We need a study II and we are working on a WP in
  Euron Design study
• Plenty of new ideas!
• Working meeting for beta-beams at ANL 24 May!
• Contact Jerry Nolen at ANL.
• Acknowledgment of the input given by S. Hancock,
  A. Jansson, M. Mezzetto, E. Wildner, EURISOL
  beta-beam task group and related EURISOL tasks