SPL, Beta beams and

1

• SPL, Beta beams and
• the Neutrino
  Factory.
• Leslie Camilleri
• NuSAG 20th May 2006

2
Whats needed next?

• Determine q13.
• Plans for several experiments using
  reactors, accelerators, etc
• Determine the mass hierarchy.
• Some of these experiments, specially if
  extended through the use of upgraded
  accelerators, would address this.
• Any CP violation in the neutrino sector?
• A new neutrino facility (a neutrino factory
  or a beta-beam complex) would be the only sure
  way to address this problem.

3
Acknowledgments

• Beta Beams Mats Lindroos, Mauro Mezzetto, J-E.
  Campagne.
• Neutrino Factories.
• Alain Blondel,
• Talks based on April 2006 International
  Scoping Study meeting at RAL.
• Presentations by

• Bob Palmer on machine
• Paul Soler on Detectors
• Yori Nagashima on Physics

• Roland Garoby and his team

4
European efforts on Future Neutrino Facilities

• Superconducting Proton Linac (SPL).
• Beta-beams.
• Conceptual design for a Nuclear Physics
  facility (ISOLDE type) Eurisol
• financed by European Union . Includes
  beta-beam studies.
• Synergy with beta-beams (radioactive ions)
• Proton driver, high power targets, beam
  cleaning ionization and bunching
• First stage acceleration , radiation
  issues.
• Will it be at CERN ? Decision in 2010.
• Neutrino Factory
• The ultimate. Study under way through the
  International Scoping Study.
• RD on targets (MERIT) and muon cooling (MICE).

5
Evolution of the CERN accelerator complex-
Proposed combinations
Proton flux / Beam power
Linac4
Linac2
50 MeV
1
160 MeV
3
PSB
SPL RCPSB
SPL
1.4 GeV
5 GeV
PS
2
26 GeV
PS2 (PS2)
40 60 GeV
SPL Superconducting Proton Linac ( 5 GeV) SPL
RCPSB injector (0.16 to 0.4-1 GeV) RCPSB Rapid
Cycling PSB (0.4-1 to 5 GeV) PS2 High Energy
PS ( 5 to 50 GeV 0.3 Hz) PS2
Superconducting PS ( 5 to 50 GeV 0.3
Hz) SPS Superconducting SPS (50 to1000
GeV) DLHC Double energy LHC (1 to 14 TeV)
Output energy
SPS
SPS
4
450 GeV
1 TeV
LHC
DLHC
7 TeV
14 TeV
Priorities will be driven by LHC upgrade
1,2,3,4
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Superconducting Proton Linac

• Power 4 MW
• Kin. Ener. Up to 5 GeV. More ps.
• Repetition Rate 50 Hz
• Accumulator to shorten pulse length. (Reduce
  atmospheric ns contam.)
• Target Liquid Mercury Jet to cope with stress
  due to high flux.
• Focusing Horn and Reflector optimized for 600
  MeV/c particles
• Detector New lab in Frejus tunnel
• (Safety gallery approved April 2006 opportunity)
• Distance 130km
• Neutrino energy to be at oscillation maximum for
  Dm232 2.5 x 10-3 eV2 260 MeV ? 350 MeV more
  sensitive
• Detector mass 440 kton fiducial.
• Type Water Cerenkov (Super-K)

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MEMPHYS at Fréjus
Up to 5 shafts possible Each 57m diam., 57m
high For most studies assumed 3 x 145
ktons. Water Cerenkov
Depth 4800 m.w.e
FOR 100 ktons)
Per shaft 81,000 12 PMTs ? 80 M including
electronics (65M KL 62M )
80 M for civil
engineering. (65M KL 29M )
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Advantage of mixing neutrino and antineutrino
running

• 3.5 and 4.5 GeV proton beam
• 260 and 350 MeV options
• 5 years of n running.
• 2 years of n running and
• 8 years of n running
• The curves flatten.
• ? about 0.001.

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Beta beams

• Accelerate protons in SPL
• Impinge on appropriate source
• Bunch resulting ions(atmospheric ns !)
• Accelerate ions in PS and SPS.
• Store in decay ring. 8 bunches.
• 6He 6Li e- ne
• 18Ne 18F e ne
• Half lives 0.8 sec and 0.64 sec.
• Stored together if g(18Ne) 1.67 g(6He)
• En (3 MeV) x g 200 500 MeV
• Detector Same as for SPL (Frejus)

• Idea introduced by Piero Zucchelli.
• Accelerate radioactive ions decaying via b or
  b-.
• Because of Lorentz boost, the decay electron
  neutrinos or antineutrinos will be focused
  forward into a beam.
• Look for Appearance of nm or nm
• Advantages
• Clean beams with no intrinsic nmcomponent. No
  need for magnet.
• Precisely calculable energy spectra.
• Energy of beam tunable through acceleration of
  ions.

• Very attractive because
• Eurisol radioactive beam project for
• nuclear physics possibly at CERN..
• PS and SPS exist.

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6He production by 9Be(n,a)
Converter technology J. Nolen et al., NPA 701
(2002) 312c.
need 100µA at 2.0 GeV for needed beta-beam flux
For 18Ne Proton beam into Magnesium oxide
Produce 18Ne directly by spallation Source must
be hot for 18Ne to diffuse out. Cannot cool it.
Limits beam and rate.
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Production ring with ionization cooling
Production

• Major challenge for 18Ne But new production
  method C. Rubbia et al.

D2

• D2 gas jet in storage ring.
• Inject ions (19F) and store
• Go through jet repeatedly increases
• probability to form radioactive ions
• Regain energy loss with RF
• High energy ions have smaller dE/dx
• than low energy ones. But will gain
• same amount from RF?even more energy
• To compensate shape jet (fan) such that high
• energy ions (larger radius) traverse
• more material.
• ? Longitudinal cooling.

High E
Low E
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d sensitivity for g 60,100
En (3 MeV) x g 200 500 MeV
M. Mezzetto SPSC Villars
Statistics limited
2 Syst. Unc.
CP violation Asymmetry decreases with
increasing q13
Down to 30o
2.9 x 1018 6He ions and 1.2 x 1018 18Ne ions per
year decaying in straight sections
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Optimization of g

• J. Burguet-Castell, hep/ph/0503021 and M.
  Mezetto.
• Not necessary to store the 2 ion types
  simultaneously 4 bunches each.
• Store 8 bunches of given type at a time and run
  each type half as long as in joint run.
• Frees from g(18Ne) 1.67 g(6He) constraint.
• Different schemes tried, all leading to higher
  energies. This is profitable because
• Higher event rates because of larger cross
  sections.
• Better directionality lower atmospheric
  background.
• Signal events are in a region of lower
  atmospheric rate.
• Fermi motion relatively less of a problem better
  
• correlation between reconstructed and
• actual neutrino energy.
• Can analyze energy dependence of appearance
  events instead of just counting them.

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Fix baseline at Frejus
g 60,100 scheme
30o 150
q13 8o

• 99 CL on d improves from
• gt 30o to gt 15o for a
• symmetric g gt 100 scheme.
• The q13 sensitivity improves
• a little.

g 100
d 90o
d -90o


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Fix g at maximum SPS value 150.

• For this g the optimum distance is
• 300 km
• The 99 CL d reach can be improved
• from 15o to 10o.
• and the q13 sensitivity can also be improved
  substantially
• But no existing laboratory at this
  distance!

d
q13 8o
300 km
10o
L(km)
L(
60,100 130km
sin22q13
150,150 300km
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Optimize for Gran Sasso

• Optimize g for the a detector at the Gran Sasso
  (730km).
• g 350. ? Needs new SPS.

350,350 730km
300 km
Standard
Frejus
Gran Sasso
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SPL, Beta-beam (g100), T2HK comparisons
J-E. Campagne et al hep/ph0603172 v1

• Mass Each detector 440 ktons ,
• Running time SPL and T2HK 2 yrs n 8 yrs n .
  Beta-beam 5 yrs 5 yrs.
• Systematics 2 - 5.
• 3s discovery potential on sin2 2q13
  3s discovery potential on CP viol.
• 
  (Excluding d0,p)

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2
2
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Invoking CPT
Replace beta beam ne by SPL nm Run
simultaneously for A total of 5 yrs only.
P(ne ? nm) P(nm ? ne)
3s discovery
Comparable to T2HK 10 yrs.
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Mass Hierarchy
Use atmospheric neutrinos (ATM) observed in
MEMPHYS, in conjunction with SPL, beta and T2HK
beams. Makes up for small matter effects due to
short baseline
With ATM
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Systematic uncertainties
Must be kept at the 2 level

• Most important ones
• Target mass difference between
• near and far detectors.
• Uncertainty on n and n
• cross sections
• (will be measured by near detector ?)

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Uncertainty on n cross-sections.
Targets free nucleons and water
Below 250 MeV Very uncertain
At 250 MeV Double ratio 0.9 Nuclear effects
5 How well do we know these?
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New idea Electron capture in 150Dy
J. Bernabeu et al hep-ph/0605132
Atomic electron captured by proton in nucleus
(A,Z) e- ? (A,Z-1) ne For instance
Dysprosium. Advantage monochromatic ne beam

• Partly stripped ions The loss due to stripping
  smaller than 5 per minute in the decay ring
• Possible to produce 1 1011 150Dy atoms/second
  (1) with 50 microAmps proton beam with existing
  technology (TRIUMF).
• Problem long lived 7 minutes.
• An annual rate of 1018 decays along one straight
  section seems a challenging target value for a
  design study
• Beyond EURISOL Design Study Who will do the
  design?
• Is 150Dy the best isotope?

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Potential of electron capture beams
Run 5 years each at g90 and g195 440 ktons at
Fréjus
d 90
d 0
d -90
5 test points
100 500 MeV
CP dependence of nm?ne oscillation probability
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A possible schedule for a European Lab. at Frejus
decision for cavity digging decision for SPL
construction decision for EURISOL site
???
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Mandate of the International Scoping Study
Neutrino Factory
Being studied in the context of the
International Scoping Study
The International Scoping Study of a future
accelerator neutrino complex will be carried by
the international community between NuFact05,
Frascati, 21-26 June 2005, and NuFact06, August
2006. The physics case for the facility will be
evaluated and options for the accelerator
complex and neutrino detection systems will be
studied. Its reach and feasibility will be
compared to the Beta-beam and SPL options. The
principal objective of the study will be to lay
the foundations for a full conceptual-design
study of the facility.
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WHO ?

• International effort
• The ECFA/BENE network in Europe.
• The Japanese NuFact-J collaboration.
• The US Muon Collider and Neutrino Factory
  Collaboration.
• The UK Neutrino Factory collaboration.

CCLRC's Rutherford Appleton Laboratory will be
the 'host laboratory' for the Study. (The effort
was initiated by the UK).
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Simplified Neutrino Factory
1.2 1014 m/s 1.2 1021 m/yr
1016p/s
Pion production target
Ion source
Pion to muon decay and beam cooling
Muon accelerator
Proton accelerator
9 x 1020 m/yr
Muon-to-neutrino decay ring
m ? e ne nm
3 x 1020 ne/yr 3 x 1020 nm/yr per straight section
Detector
Earths interior
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Principle of detection
Look for ne ? nm oscillations using ne from m
decay (Golden
channel) 2 baselines or 2 energies to resolve
ambiguities
m ? e nm ne
oscillates ne ? nm interacts giving m- WRONG
SIGN MUON
interacts giving m
Need to measure m charge ?Magnetic detector
Other channels

• Platinum channel nm ? ne T violation.
• Silver channelne ? nt Resolve ambiguities.

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Triangle or Race-track?
Or else too many decays In 3rd useless leg.
Minimum length of 3rd leg for given angle is
when ring is vertical
400m. Limited by geology
If two far sites needed
30
Decisions taken at April ISS meeting
Allows simultaneous collection of m and m-.
instead of solid
instead of horn
1021 (m m-) decays per year Half per
straight section
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Knowledge of Matter density along n path
Lithosphere solid,heterogeneous
2500 km
asthenosphere Viscous, homogeneous
Best 2s errors 1.5-3 Avoid Alps, Central
Europe FavourWestern Europe to US
Atlantic Islands
Oceans simpler, more accurate. Continents more
complicated, less accurate.
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Usefulness of the silver channel ne ? nt
Fine grained detector for t secondary vertex or
kink OPERA technology
S. Rigolin, hep-ph/0407009 D. Autiero
et al. hep-ph/0305185
ne ? nt and ne ? nm channels have opposite
sign CP violation.
n
n
3000km and 730km ne ? nt and ne ?
nm
Clones for 2 reactions are also at different
positions.
Clones at 2 baselines are at different positions
Alternative to 2 baselines?
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Detectors

• Magnetized iron/scintillator.
• Fully active scintillator External magnetic
  field.
• Water Cerenkov
• Liquid argon in solenoidal field.
• Hybrid emulsion detector in a magnetic field
  (Electron charge).
• Near Detectors.

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A Strawman Concept for a Nufact Iron Tracker
Detector

• 1 cm Iron sheets
• Planes of triangular
• 4cm x 6 cm PVC tubes.
• Filled with liquid scintillator
• Read by looped WLS fibres
• Connected to APDs.
• 60kA-turn central coil
• 0.5m x 0.5m
• Average field of 1.5T
• Extrapolation of MINOS

• Structure based on NOvA using MINERvA-like shapes
• Based on 175M for 90kt

35
Fully active detector (NOnA) with external
magnetic field
NOnA divided longitudinally into 10 sections
Each section surrounded by low field solenoid.
10 solenoids next to each other. Horizontal
field perpendicular to beam Each 750 turns, 4500
amps, 0.2 Tesla. 42 MJoules . 5Meuros. Total
420 MJoules (CMS 2700 MJoules) Coil Aluminium
(Alain LN2 cooled).
750 turns
n
B
Problem Periodic coil material every 15m
Increase length of solenoid along beam?
How thick?
36
Giant Liquid Argon Charge Imaging Experiment
US-Europe Synergy ?
Impression was that magnet limited detector mass
to 15 ktons.
A. Rubbia
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DONUT/OPERA type target Emulsion spectrometer
Must be placed in a magnet
B
Air Gap
Film
Stainless steel or Lead
3Xo 10Xo
Can measure momentum of muons and of some
fraction of electrons Identify t using topology
38
Comparison of beta-beam and n factory

• Beta-beam advantages.
• Synergy with Eurisol (if at CERN) existing
  PS,SPS
• Cost ?
• Clean ne and ne beams no need for magnet.
• Negligible matter effects. (But hierarchy?)
• Does not need 4 MW of power.
• (But if SPL is needed for better
  sensitivity?)

• Beta-beam disadvantages
• Low energy
• Cross sections not so well known,
• muon mass effect
• Fermi motion
• Atmospheric neutrinos background
• Silver channel energetically impossible
• Need of SPL
• Improve sensitivity
• Measure n cross-sections

39
Comparison of beta-beam and n factory II

• Advantages of Neutrino Factory
• Ultimate reach
• Smaller systematic errors
• Presence of both nm and ne in beam allows
  measurement of cross-sections in near detector
• Higher energies better measured cross sections.
• Disadvantages of Neutrino Factory.
• Technically more challenging
• Cost
• Deeper tunnel limits sites.
• Matter effects must be well understood.
  Baselines carefully chosen.
• Need for a magnetic detector to separate signal
  from background

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Reach of beta-beams and n Factory
About the same for other 4 quadrants of CP phase.
Beta-beams and beta-beams SPL Are better for
sin2 2q13 gt 0.01. (needs confirmation cuts
used in analysis Em gt 5 GeV) Below this value n
factory is more sensitive.
41
MERIT Hg jet target tests at CERN PS

• Test performed in magnetic field (15T)
• To simulate actual conditions
• collection solenoid
• Proton intensity 2 x 1013 protons/pulse
• at 24 GeV

1cm diameter jet at small angle(40 mrad) to beam
to maximize overlap 2 inter. lengths.
Aims Proof of principle. Jet dispersal. Effect
of field on jet flow and dispersal.
Scheduled to run in Spring 2007
42
MICE Muon cooling experiment at RAL
Prove the feasibility of ionization cooling.
Strong synergy with MUCOOL.
43
MICEplanning
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Problems a personal view.

• CERN
• The priority will be given to
• a) Consolidation of existing machines.
• b) LHC luminosity upgrades, including
  whatever replacement machines it takes,
  including Nb3Sn IR quads.
• c) Possibly an energy upgrade of LHC.
  Nb3Sn dipoles ?
• d) Ongoing CLIC RD.
• Internationally
• a) ILC schedule, cost and site.
• b) Difficult to conceive the next big n
  project going ahead without having already
  measured q13. When will this be?

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Time line

• 2010 A critical year in many ways.
• Possible ILC decision.
• CLIC possibilities.
• LHC results.
• Decision on LHC upgrade.
• Eurisol siting. CERN ?
• Possible first measurement of q13 MINOS, Double
  CHOOZ

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Storing of both charges at once
l
l-
l
m m-
Muons of both signs circulate in opposite
directions in the same ring. The two straight
sections point to the same far detector(s). OK
d
Discriminate events On the basis of timing (d)
Detector
48
Some decisions taken at April ISS meeting
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Sign of Dm232 resolution with b beams
Dm232 gt 0
Dm232 lt 0

• At Frejus baseline there is NO sensitivity to the
  sign of the mass hierarchy.
• At 300 km there is some.
• But, clearly, the longer baseline (Gran Sasso)
  would be needed to make a significant statement.