1. Status of the beta-beam study
Mats Lindroos on behalf of the EURISOL beta-beam task
UK HEP FORUM 2008
The beta-beam team

2. Outline of message I would like to give in this talk
Beta-beam concept
A beta-beam facility
Layout (e.g EURISOL DS)
Challenges
How can we improve the beta-beam
Before we build it:
High gamma Beta-beams
After we built it:
Intensity and flux
Electron capture Beta-beams
High-Q vlaue Beta-beams
The beta-beam team

3. Introduction to beta-beams
Beta-beam proposal by Piero Zucchelli
A novel concept for a neutrino factory: the beta-beam, Phys. Let. B, 532 (2002)
AIM: production of a pure beam of electron neutrinos (or antineutrinos) through the beta decay of radioactive ions circulating in a high-energy (~100) storage ring.
First study in 2002
Make maximum use of the existing infrastructure.
Ions move almost at the speed of light
The beta-beam team

4. Beta-beam Basics n Beta-beam 6He boost
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
boost n
6He
Beta-beam
g=100
The beta-beam team

5. The beta-beam options Low energy beta-beams
Nuclear physics, double beta-decay nuclear matrix elements, neutrino magnetic moments
The medium energy beta-beams or the EURISOL beta-beam
Lorenz gamma approx. 100 and average neutrino energy at rest approx. 1.5 MeV (P. Zucchelli, 2002)
The high energy beta-beam
Lorenz gamma and average neutrino energy at rest approx. 1.5 MeV
The very high energy beta-beam
Lorenz gamma >1000
The high Q-value beta-beam
Lorenz gamma and average neutrino energy at rest 6-7 MeV
The Electron capture beta-beam
The beta-beam team

6. 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
Bunching and first acceleration: ECR, linac
Rapid cycling synchrotron
Use of existing machines: PS and SPS
Opportunity to share a Mton Water Cerenkov detector with a CERN superbeam, proton decay studies and a neutrino observatory
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.
The beta-beam team

7. Which ion is best? Factors influencing ion choice
Need to produce reasonable amounts of ions.
Noble gases preferred - simple diffusion out of target, gaseous at room temperature.
Not too short half-life to get reasonable intensities.
Not too long half-life as otherwise no decay at high energy.
Avoid potentially dangerous and long-lived decay products.
EURISOL Choice in 2002
Helium-6 to produce antineutrinos:
Neon-18 to produce neutrinos:
The beta-beam team

8. However, there are other…
The beta-beam team

9. Production of beta-beam isotopes
The Isotope Separation On-Line (ISOL) method at medium energy
EURISOL type production, uses typically GeV protons with up to kW beam power through spallation, fission and fragmentation
Direct production
Uses low energy but high intensity ion beams on solid or gas targets. Production through compound nuclei which forms with high cross section at low energies
Direct production enhanced with a storage ring
Enhancing the efficiency of the direct production through re-circulation and re-acceleration of primary ions which doesn’t react in the first passage through the target.
Possible thanks to ionization cooling!
The beta-beam team

10. Options for production
ISOL method at 1-2 GeV (200 kW)
> He per second
< Ne per second
8Li and 8B not studied
Studied within EURISOL
Direct production
> (?) 6He per second
Ne per second
Studied at LLN, Soreq, WI and GANIL
Production ring
1014 (?) 8Li
>1013 (?) 8B
6He and 18Ne not studied
Will be studied in the future
1 GeV p p n 2 3 8 U 1 F r +
spallation L i X
fragmentation 4 C s Y
fission
The beta-beam team

11. 6He production from 9Be(n,a)
Converter technology: (J. Nolen, NPA 701 (2002) 312c)
Converter technology preferred to direct irradiation (heat transfer and efficient cooling allows higher power compared to insulating BeO).
6He production rate is ~2x1013 ions/s (dc) for ~200 kW on target.
The beta-beam team

12. Direct production: 16O(3He,n)18Ne
Measurements at Louvain-La-Neuve (CRC) of cross section
The gas target was constructed like a cell with thin entrance foils
In experiment the target pressure and the 3He beam energy was changed
Beam energy, MeV
Target pressure,
mbar (torr).
Eloss,MeV 13
900 (675) 2
14.8
1200 (900)
2.4
Courtesy to Semen Mitrofanov and Marc Loislet at CRC, Belgium
The beta-beam team

13. Preliminary results from CRC
Production of Ne in a MgO target:
At 13 MeV, 17 mA of 3He
At 14.8 MeV, 13 mA of 3He
Producing Ne could be possible with a beam power (at low energy) of 1 MW (or some 130 mA 3He beam).
To keep the power density similar to LLN (today) the target has to be 60 cm in diameter.
To be studied:
Extraction efficiency
Optimum energy
Cooling of target unit
High intensity and low energy ion linac
High intensity ion source
Thinn MgO target
Water cooled target holder and beam dump
Ion beam
The beta-beam team

14. Light RIB Production with a 40 MeV Deuteron Beam
T.Y.Hirsh, D.Berkovits, M.Hass (Soreq, Weizmann I.)
Studied 9Be(n,α)6He, 11B(n,a)8Li and 9Be(n,2n)8Be production
For a 2 mA, 40 MeV deuteron beam, the upper limit for the 6He production rate via the two stage targets setup is ~6∙1013 atoms per second.
The 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 568 (2006) 475–487
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
The beta-beam team

16. Critical review of the production ring concept
Low-energy Ionization cooling of ions for Beta Beam sources – D. Neufer (To be submitted)
Mixing of longitudinal and horizontal motion necessary
Less cooling than predcited
Beam larger but that relaxes space charge issues
If collection done with separator after target, a Li curtain target with 3He and Deutron beam would be preferable
Separation larger in rigidity
The beta-beam team

17. Problems with collection device
A large proportion of beam particles (6Li) will be scattered into the collection device.
The scattered primary beam intensity could be up to a factor of 100 larger than the RI intensity for 5-13 degree using a Rutherford scattering approximation for the scattered primary beam particles (M. Loislet, UCL)
The 8B ions are produced in a cone of 13 degree with 20 MeV 6Li ions with an energy of 12 MeV±4 MeV (33% !).
Secondary ions
Rutherford scattered particles
Collection off-axes using Wien filter
Beam
Collection on-axes
The beta-beam team

18. Low duty cycle, from dc to very short bunches…
…or how to make meatballs out of sausages!
Radioactive ions are usually produced as a “dc” beam but synchrotrons can only accelerate bunched beams.
For high energies, linacs are long and expensive, synchrotrons are cheaper and more efficient.
The beta-beam team

19. 60 GHz « ECR Duoplasmatron » for gaseous RIB
2.0 – 3.0 T pulsed coils
or SC coils
Very high density
magnetized plasma
ne ~ 1014 cm-3
Small plasma
chamber F ~ 20 mm / L ~ 5 cm
Target
Arbitrary distance
if gas
Rapid pulsed valve ?
1-3 mm
100 KV
extraction
UHF window
or « glass » chamber (?)
20 – 100 µs
20 – 200 mA
1012 per bunch
with high efficiency
60-90 GHz / KW
10 –200 µs /  = 6-3 mm
optical axial coupling
optical radial (or axial) coupling
(if gas only)
P.Sortais et al.
The beta-beam team

20. Charge state distribution!
Multiple charge state acceleration in linac?
The beta-beam team

21. What is important for the decay ring?
The atmospheric neutrino background is large at 500 MeV, the detector can only be open for a short moment every second
The decay products move with the ion bunch which results in a bunched neutrino beam
Low duty cycle – short and few bunches in decay ring
Accumulation to make use of as many decaying ions as possible from each acceleration cycle
Ions move almost at the speed of light
Only “open” when neutrinos arrive
The beta-beam team

22. Injection
The beta-beam team

23. Rotation
The beta-beam team

24. Merging
The beta-beam team

25. Repeated Merging
The beta-beam team

26. Test experiment in CERN PS
Ingredients
h=8 and h=16 systems of PS.
Phase and voltage variations.
time
energy
S. Hancock, M. Benedikt and J-L.Vallet, A proof of principle of asymmetric bunch pair merging, AB-Note MD
The beta-beam team

27. The Large Aperture Dipole, first feasibility study
Courtesy Christine Vollinger
high tip field, non-critical
6 T
LHC ”costheta” design
Good-field requirements only apply to about half the horizontal aperture.
The beta-beam team

28. 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
The beta-beam team

29. Model for absorbers Horizontal Plane Absorber outside beam-pipe
Dipole 1
Dipole 2
Absorber in beam pipe
1 m
1 m
6 m
2 m
6 m
2 m
The beta-beam team

30. Heat Deposition Model, one cellQ
Absorbers B B
”Overlapping” Quad to check repeatability of pattern
Q (ISR model)
B (new design) B
No Beampipe (angle large)
Concentric cylinders, copper (coil), iron (yoke) Q
The beta-beam team

31. 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
The beta-beam team

32. Intra Beam scattering, growth times
Results obtained with Mad-8
6He
18Ne
The beta-beam team

33. 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
The beta-beam team

34. Decay losses Losses during acceleration Preliminary results:
Full FLUKA simulations in progress for all stages (M. Magistris and M. Silari, Parameters of radiological interest for a beta-beam decay ring, TIS RP-TN).
Preliminary results:
Manageable in low-energy part.
PS heavily activated (1 s flat bottom).
Collimation? New machine?
SPS ok.
Decay ring losses:
Tritium and sodium production in rock is well below national limits.
Reasonable requirements for tunnel wall thickness to enable decommissioning of the tunnel and fixation of tritium and sodium.
Heat load should be ok for superconductor.
FLUKA simulated losses in surrounding rock (no public health implications)
The beta-beam team

35. Activation and coil damage in the PS
The coils could support 60 years operation with a EURISOL type beta-beam
The beta-beam team

36. Radiation protection issues
Radiation safety for staff making interventions and maintenance at the target, bunching stage, accelerators and decay ring
88% of 18Ne and 75% of 6He ions are lost between source and injection into the Decay ring
Safe collimation of “lost” ions during stacking
~1 MJ beam energy/cycle injected, equivalent ion number to be removed, ~25 W/m average
Magnet protection
Dynamic vacuum
First study (Magistris and Silari, 2002) shows that Tritium and Sodium production in the ground water around the decay ring should not be forgotten
The beta-beam team

37. Neutrino flux from a beta-beam
EURISOL beta-beam study
Aiming for 1018 (anti-)neutrinos per year
It is possible that it could be increased to some1019 (anti-) neutrinos per year. However, this only be clarified by detailed and site specific studies of:
Production
Bunching
Multiple charge state acceleration in linac
Loss management
Magnet protection
Cooling down times for interventions
Tritium and Sodium production in ground water
The beta-beam team

38. How effective is the different proposed improvements?
Increase production, improve bunching efficiency, accelerate more than one charge state and shorten acceleration
Improves performance linearly
Can be done as an upgrades!
Accumulation
Improves to saturation
Can be done as an upgrade!
Improve the stacking; sacrifice duty factor, add cooling or increase longitudinal bunch size
The beta-beam team

39. Stacking efficiency and low duty factor
Normalized Annual rate
For 15 effective stacking cycles, 54% of ultimate intensity is reached for 6He and for 20 stacking cycles 26% is reached for 18Ne
The beta-beam team

40. Why do we gain with such an accumulation ring?
Left: Cycle without accumulation
Right: Cycle with accumulation. Note that we always produce ions in this case!
The beta-beam team

41. The beta-beam in EURONU DS
The study will focus on production issues for 8Li and 8B
8B is highly reactive and has never been produced as on ISOL beam
Production ring enhanced direct production
Which is the best ring lattice?
How to collect the produced ions?
What are the “real” cross sections for the reactions?
How can the accelerator chain and decay ring be adapted to 8Li and 8B
Magnet protection system
Intensity limitations
The beta-beam team

42. Gamma and decay-ring size, 6He
Rigidity
[Tm]
Ring length
T=5 T
f=0.36
Dipole Field
rho=300 m
Length=6885m
100
935
4197
3.1
150
1403
6296
4.7
200
1870
8395
6.2
350
3273
14691
10.9
500
4676
20987
15.6
New SPS
Civil engineering
Magnet R&D
New version corrected version posted 3 September 2008 thanks to Sanjib Kumar Agarwalla who spotted a mistake in the previous table.

43. Conclusions
The EURISOL beta-beam conceptual design report will be presented in second half of 2009
First coherent study of a beta-beam facility
A beta-beam facility using 8Li and 8B
First result from Euronu DS WP
A beta-beam facility can be built today…
Known technology with good performance
…and tomorrow
In a phased scenario the intensity and type of ion can be improved/changed
Crucial to chose the right machine-detector combination (distance) from the beginning!
The beta-beam team