The beta-beam project in the EURISOL context

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The beta-beam project in the EURISOL context

• Pierre Delahaye, ISOLDE / CERN
• for the beta-beam working group

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The physics reach
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About neutrino physics

• The neutrino a mass-less particle to explain the
  continuous energy spectrum of the beta decay.
  Wolfgang Pauli 1930.
• Only left-handed neutrinos can interact with
  matter. V-A theory 1958.
• Majorana or Dirac neutrinos?
• 3 flavors ne, nm, nt
• A mass is an interaction between flavors

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The flavor mixing matrix

• The mass eigenstates are not flavor eigenstates

3 angles 1 CP violating phase for Dirac
neutrinos
In analogy with the CKM matrix The
Maki-Nakagawa-Sakata matrix
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Oscillation of neutrinos

• A simplified case (2 families)

negt cos? n1gt sin ? n2gt nmgt sin?
n1gt cos ? n2gt n(t0)gt negt n(t)gt
exp(-iE1t) cos? n1gt exp(-iE2t) sin? n2gt
P(ne gtnm) ltnmn(t)gt2 sin22? sin2 (Dm2/4E
t) Dm 2 m12 m22
L osc (m) 2.5 En (MeV) / Dm2(eV2)
A measurement of q and Dm²
E. Kh. Akhmedov hep-ph/0001264
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Oscillation of neutrinos

• Current status
• SUN Dm122 7 10-5 eV2 , ?12 35o
• ATM Dm232 2.5 10-3 eV2 , ?23 45o
• Missing
• ?13 and the phase d
• both govern the nm ?? ne oscillation at the
  atmospheric frequency. We know that ?13 (Chooz)
  is lt 13o
• The hierarchy of the masses

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Overview

• Neutrino mixing matrix
• The mass hierarchy

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The beta-beam concept
P. Zucchelli, PLB 2002

• A pure beam of ne to study the ne?nm oscillation
• A beam of ne, ne from b-decaying nuclides
• A Lorentz boost for a collimated beam (high g)
• From Wikipedia

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Possible synergy with superbeams
Neutrino experiments
Measurement of the mixing angle Study of CP
violation
?e ? ?m (?) ?m ? ?e (p) ?e ? ?m
(?-) ?m ? ?e (p-)
CP
T
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The CERN baseline scenario
Using the existing infrastructure an upgrade of
the proton driver the SPL a new preparation
stage a decay ring (ggt100)
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A beta-beam andits detector
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In more details
From J. Bouchez
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What b-decaying nuclides?

• 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.
• Best compromise
• Helium-6 to produce antineutrinos
• Neon-18 to produce neutrinos

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The requirements

• The first study Beta-beam was aiming for
• A beta-beam facility that will run for a
  normalized year of 107 seconds
• An annual rate of 2.9 1018 anti-neutrinos (6He)
  and 1.1 1018 neutrinos (18Ne) at g100
• with an Ion production in the target to the ECR
  source
• 6He 2 1013 atoms per second
• 18Ne 8 1011 atoms per second
• The often quoted beta-beam facility flux for ten
  years running is
• Anti-neutrinos 29 1018 decays along one straight
  section
• Neutrinos 11 1018 decays along one straight
  section

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Physics potential

• Measurement of the q13 and dCP angles
• dCP as low as 20, q13 as low as 1

M. Mezzetto, Nucl. Phys. 143, (2005).
M. Mezzetto, Talk at NUFACT05, June 2005, Rome.
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Potential with a low energy beta-beam

• Neutrino-nucleus interaction cross sections
  poorly known
• Of interest for nuclear structure and
  astrophysics (nucleosynthesis)
• Improving the limits on the magnetic moment of
  the neutrino
• Improving the limit by one order of magnitude.
  Current limit from reactor experiments (MUNU,
  Kuo-Sheng, Rovno,)
• Some interest for neutrinoless double b-decay
• Populating the states of many virtual transitions
  involved in the neutrino-less double-beta decay,
  for constraining the predictions on the
  half-lives.

C. Volpe, Nucl. Phys. A 752(2005) 38c-41c
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A dedicated storage ring
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The facility overviewaccelerators and storage
ring
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Beam specifications

• 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
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Facility overview
Low-energy part
High-energy part
Ion production
Acceleration
Neutrino source
Beam to experiment
Proton Driver SPL
Acceleration to final energy PS SPS
Ion production ISOL target Ion source
SPS
Decay ring Br 1500 Tm B 5 T C
7000 m Lss 2500 m 6He g 100 18Ne g
100
Neutrino Source Decay Ring
Beam preparation ECR pulsed
Ion acceleration Linac
PS
Acceleration to medium energy RCS
Existing!
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SPS cycle structure
M. Benedikt, S. Hancock and M. Lindroos,
Proceedings of EPAC 2004
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Stacking in the decay ring

• Ions in short bunches to reduce the background
  from the atmospheric neutrinos
• Stacking in the decay ring necessary because
• Not enough flux from the ion source
• The half-life 120s is much longer than the SPS
  cycle (8s).
• Need to stack for at least 10-15 injector cycles
• The electron cooling for such an energy and long
  cycle time is excluded. The stochastic cooling is
  excluded because of the bunch intensity.

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Asymmetric bunch pair merging

• Moves a fresh dense bunch into the core of the
  much larger stack and pushes less dense phase
  space areas to larger amplitudes until these are
  cut by the momentum collimation system.
• Central density is increased with minimal
  emittance dilution.
• Requirements
• Dual harmonic rf system. The decay ring will be
  equipped with 40 and 80 MHz systems (to give
  required bunch length of 10 ns for physics).
• Incoming bunch needs to be positioned in adjacent
  rf bucket to the stack (i.e., 10 ns
  separation!).

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Simulation (in the SPS)
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Test experiment in CERN PS

• Ingredients
• h8 and h16 systems of PS.
• Phase and voltage variations.

S. Hancock, M. Benedikt and J-L.Vallet, A proof
of principle of asymmetric bunch pair merging,
AB-Note-2003-080 MD
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Decay ring parameters
J. Payet and A. Chancé, CEA Dapnia/Saclay
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Decay ring optics
Beam envelopes
In the straight sections, we use FODO cells. The
quadripoles are not superconducting and are 1 m
long The arc is a 2? insertion composed of
regular cells and an insertion for the injection
There are 489 m of 6 T bends with a 5 cm
half-aperture At the injection, the dispersion is
8.25 m while the horizontal beta function is as
21.2 m The injection magnet septum is 18 m long
with a 1 T field
Arc optics
J. Payet and A. Chancé, CEA Dapnia/Saclay
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Synergies with EURISOL and radioactive ion beam
production
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The chart of the nuclidesAn open landscape for
investigations

• In
• Nuclear physics
• Structure, magic numbers, deformations, haloes,
  Superheavy elements, nuclear equation of states
• Nuclear Astrophysics
• Nucleosynthesis, r and rp processes, supernovae
  explosions, X ray bursts
• Weak Interaction physics and fundamental
  symmetries
• CVC, CKM Unitarity, Exotic interactions
• Solid State physics
• Medical Applications!

From the EURISOL report http//www.ganil.fr/euriso
l/Final_Report.html
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EURISOL

• An ISOL-type facility

A next generation facility for

• High intensities
• More exotic beams
• High beam purity
• High beam quality
• More energies
• More users

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ISOL and In-flight
ISOLDE, GANIL/SPIRAL, TRIUMF,
GSI (FAIR project), MSU, ANL
From the EURISOL report
ISOL Such an instrument is essentially a target,
ion source and an electromagnetic mass analyzer
coupled in series. H. Ravn and B.Allardyce, 1989,
Treatise on heavy ion science
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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.

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The 18Ne case

• Spallation reaction in a MgO target, 1m long with
  2.2 GeV protons from the SPL
• At most 8 1011/s instead of the 1.9 1013/s
  required!!
• 19Ne instead? M. Loiselet, Louvain La Neuve
• An production ring with ionization cooling?

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A production ring with ionization cooling?
C. Rubbia, A.Ferrari, Y.Kadi and V. Vlachoudis
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Some tests at LLN

• Work within EURISOL task 2 to investigate
  production rate with medical cyclotron
• Louvain-La-Neuve, M. Loiselet

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The production of the short bunches

• For the injection into the RCS
• Fully stripped radioactive ions at 100 MeV/u
  (from the superconducting linac)
• Bunches of less than 50ms
• An ECR ion source (60GHz) for pulses of high peak
  current 12mA and short bunches 50ms
• Emittance 50p.mm.mrad

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Tests at LPSC Grenoble
Klystron 2 kW_at_18 GHz (not visible)
Gyrotron 1O kW_at_28 GHz
Available for the PreGlow Study
Diagnostics
PHOENIX ECR Source
60 kV Platform
New LPSC Lab
T. Lamy and T. Thuillier
90 Bending Magnet
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Preglow and afterglow modes

• The preglow and afterglow modes are the pulsed
  modes of the ECR. Only scarce data exists on the
  preglow mode.

Pumping effect during the preglow - of high
interest!
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Phoenix 28GHz preliminary results
u.a.
Low pressure Discharge i.e. low density without
MCI
Pre glow with MCI
Ar4
H2
Ar8
Ar2
H
Ar9
T. Lamy and T. Thuillier
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Scaling with the frequency

• 1ms, 10mA pulses were obtained with the 28GHz
  source
• The pulses have to be shortened to 50ms
• A 70GHz gyrotron might be used for first tests in
  Nizhniy Novgorod (V. Zorin) with a magnetic
  confinement structure still to be defined
• Special ion optics for the extraction and
  injection of the high intensity pulses will need
  to be designed

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Conclusion
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Status

• Rather complete studies for the accelerator and
  storage rings have been started.
• Not mentionned here decay losses and space
  charge studies
• The production and charge breeding of such an
  intense beam of 18Ne might be a limitation.
• Some alternative solutions have been proposed
  (19Ne and Carlo Rubbia scenario)
• Some progresses with ISOL target and ion sources
  can be expected in such a timescale

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A project open for new propositions!

• Numerous physics cases, under investigation
• Numerous technical challenges
• The enlargement of the community is desirable,
  participation is welcome
• Timescale not before 2012
• So it is not too late for any suggestion!
• Thanks a lot for your attention!

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The beta-beam project web-site
Members, presentations, progress reports
http//beta-beam.web.cern.ch/beta-beam/
Special thanks to Mats Lindroos ISOLDE, CERN for
his kind help