1. Beta-beams M. Benedikt, A. Fabich and M. Lindroos, CERN
on behalf of the Beta-beam Study Group
BENE06/CARE06
IDS, March, CERN 2007
Beta-beam team

2. Beta-beam concept EURISOL DS scenario Other scenarios Study II Summary
Outline
Beta-beam concept
EURISOL DS scenario
Layout
Main issues on acceleration scheme
Other scenarios
High-Q vlaue Beta-beams
Study II
Summary
IDS, March, CERN 2007
Beta-beam team

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
Cross-sections of neutrino-nucleus interaction
g=100
IDS, March, CERN 2007
Beta-beam team

4. Guideline to n-beam scenarios based on radio-active ions
Low-energy beta-beam: relativistic g < 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 >350
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 g=100/100 to be studied first (EURISOL DS).
IDS, March, CERN 2007
Beta-beam team

5. The EURISOL scenario Based on CERN boundaries Ion choice: 6He and 18Ne
Relativistic gamma=100/100
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
2.9*1018 anti-neutrinos from 6He
Or 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.
IDS, March, CERN 2007
Beta-beam team

6. 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
IDS, March, CERN 2007
Beta-beam team

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 3*10-8 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
IDS, March, CERN 2007
Beta-beam team

8. 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 cycle
Decay: ~5*1012 6Li ions to be removed per cycle per meter
LHC project report 773 bb
p-collimation
merging
decay losses
injection
Straight section
Arc
Momentum
collimation
IDS, March, CERN 2007
Beta-beam team

9. 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
Optical functions (m)
primary collimator
s (m)
Straight section:
Ion extraction et each end
s (m)
Deposited Power (W/m)
A. Chance et al., CEA Saclay
IDS, March, CERN 2007
Beta-beam team

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 (2006).
IDS, March, CERN 2007
Beta-beam team

11. Longitudinal penetration in coil
Power deposited in dipole
Coil
Abs
Coil
Abs
Coil
No absorber
Carbon
Stainless Steel
IDS, March, CERN 2007
Beta-beam team

12. 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)
Im{Z}/W
Impedance of one step (diameter 6 to 10 cm or 10 to 6 cm):
L = 1.53 nH
f/GHz
IDS, March, CERN 2007
Beta-beam team

13. 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]
IDS, March, CERN 2007
Beta-beam team

14. Intra Beam scattering, growth times
Results obtained with Mad-8
6He
18Ne
IDS, March, CERN 2007
Beta-beam team

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
Missed opportunities
See also: Development of FFAG accelerators and their applications for intense secondary particle production, Y. Mori, NIM A562(2006)591
IDS, March, CERN 2007
Beta-beam team

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.”
IDS, March, CERN 2007
Beta-beam team

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
Without wedge, dU/dE<0
Wedge with dU/dE=0, no longitudinal cooling
Wedge with dU/dE=0.0094
Electrons, cooling through synchrotron radiation
IDS, March, CERN 2007
Beta-beam team

18. Inverse kinematics production and ionisation parameters in paper by Carlo Rubbia et al.
7Li(d,p)8Li
6Li(3He,n)8B
IDS, March, CERN 2007
Beta-beam team

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!
IDS, March, CERN 2007
Beta-beam team

20. 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
IDS, March, CERN 2007
Beta-beam team

21. Collection in a gas cell
IGISOL technique (Ion Guide)
BEAM
Gas cell
Extraction
Cool gas in
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?
IDS, March, CERN 2007
Beta-beam team

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?
IDS, March, CERN 2007
Beta-beam team

23. A High Intensity Neutrino Oscillation Facility in Europe
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
IDS, March, CERN 2007
Beta-beam team

24. 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
IDS, March, CERN 2007
Beta-beam team

25. 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
IDS, March, CERN 2007
Beta-beam team

26. 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 q13>1O.
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
IDS, March, CERN 2007
Beta-beam team