Rencontres du Viet-Nam 2004 Alain Blondel Challenges of future accelerator-based Neutrino Facilities...
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Rencontres du Viet-Nam 2004 Alain Blondel
Challenges of future accelerator-based Neutrino Facilities
Introduction
Proton drivers Target and Collection Neutrino Factory challenges muon cooling acceleration (FFAGs) Beta-Beam challenges
See NUFACT04 site: http://www-kuno.phys.sci.osaka-u.ac.jp/~enufact04/http://muonstoragerings.cern.ch
Rencontres du Viet-Nam 2004 Alain Blondel
1. We know that there are three families of active, light neutrinos (LEP)2. Solar neutrino oscillations are established (Homestake+Gallium+Kam+SK+SNO+KamLAND)3. Atmospheric () oscillations are established (IMB+Kam+SK+Macro+Sudan+K2K)
4. At that frequency, electron neutrino oscillations are small (CHOOZ) This allows a consistent picture with 3-family oscillations ~300 m12
2~8.5 10-5eV2 ~450 m23 2~ 2.5 10-3eV2 ~ 100 with several unknown parameters mass hierarchy
Where are we?
*)to set the scale: CP violation in quarks was discovered in 1964 and there is still an important program (K0pi0, B-factories, Neutron EDM, LHCb, BTeV….) to go on for >>10 years…i.e. a total of >50 yrs.
and we have not discovered leptonic CP yet!
5. LSND ? ( miniBooNe) This result is not consistent with three families of neutrinos oscillating, and is not supported (nor is it completely contradicted) by other experiments.
If confirmed, this would be even more exciting See Barger et al PRD 63 033002
Where do we go? leptonic CP & T violations=> an exciting experimental program for at least 25 years *)
Rencontres du Viet-Nam 2004 Alain Blondel
Atmospheric “wavelenght”
Rencontres du Viet-Nam 2004 Alain Blondel
Road Map
A Experiments to find : search for e
--in conventional beam (MINOS, ICARUS/OPERA) limitations: NC background, intrinsic e component in beam -- in reactor experiments --Off-axis beam (JHF-SK, off axis NUMI, off axis CNGS) or --Low Energy Superbeam (BNL Homestake, SPL Fréjus)
B Precision experiments to find CP violation -- or to search further if is too small
-- beta-beam and
-- Neutrino factory with muon decay storage ring
and
fraction thereof will exist .
eνLiHe e66 eνFNe e
9181018
μe ννeμ μe ννeμ
Rencontres du Viet-Nam 2004 Alain Blondel
Example: a series of facilities envisaged for CERN
As always in neutrino physics the event rate is a major concernMost future facilities are based on a High Intensity Proton source.
Rencontres du Viet-Nam 2004 Alain Blondel
300 MeV Neutrinos
small contamination from e (no K at 2 GeV!)
A large underground water Cerenkov (400 kton) UNO/HyperKor/and a large L.Arg detector. also : proton decay search, supernovae events solar and atmospheric neutrinos. Performance similar to J-PARC IIThere is a window of opportunity for digging the cavern stating in 2008 (safety tunnel in Frejus)
CERN-SPL-based Neutrino SUPERBEAM
Fréjus underground lab.
target!
Rencontres du Viet-Nam 2004 Alain Blondel
-- Neutrino Factory -- CERN layout --
e+ e
_
interacts
giving
oscillates e
interacts giving
WRONG SIGN MUON
1016p/s
1.2 1014 s =1.2 1021 yr
3 1020 eyr
3 1020 yr
0.9 1021 yr
target!cooling!
acceleration!
Rencontres du Viet-Nam 2004 Alain Blondel
CERN: -beam baseline scenario
PS
Decay
RingISOL target & Ion source
SPL
Cyclotrons, linac or FFAG
Decay ring
B = 5 T
Lss = 2500 m
SPSECR
Rapid cycling synchrotron
Nuclear Physics
,
Same detectors as Superbeam !
EU pride..
target!
Stacking!
Rencontres du Viet-Nam 2004 Alain Blondel
Nuclear and ParticleExperimental Facility
Materials and Life ScienceExperimental Facility
Neutrino to Kamiokande
Linac(350m)
3 GeV Synchrotron(25 Hz, 1MW)
Nuclear Transmutation
The reference facility: J-PARC 0.75 MW at start, evolving
50 GeV Synchrotron(0.75 MW)
J-PARC = Japan Proton Accelerator Research Complex
Rencontres du Viet-Nam 2004 Alain Blondel
Fermilab Proton Driver8 GeV Superconducting Linac
Basic concept inspired by the observation (by Bill Foster) that $/GeV for SCRF has fallen dramatically Consider a solution in which H- beam is accelerated to 8 GeV
in a superconducting linac and injected directly into the Main Injector
Attractions of a superconducting linac: Many components exist (few parts to design vs. new
synchrotron)Copy SNS, RIA, & AccSys Linac up to 1.2 GeV“TESLA” Cryo modules from 1.2 8 GeV
Smaller emittance than a synchrotronHigh beam power simultaneously at 8 & 120 GeV
Plus, high beam power (2 MW) over entire 40-120 GeV rangeFlexibility for the future
IssuesUncontrolled H- stripping Halo formation and controlCost
Rencontres du Viet-Nam 2004 Alain Blondel
Fermilab Proton Driver8 GeV SC Linac: Other possible missions (from the mind of Bill Foster)
~ 700m Active Length8 GeV Linac
X-RAY FEL LAB
Long-Pulse Spallation Source
8 GeVneutrino
MainInjector@2 MW
Anti-Proton
SY-120Fixed-Target
Neutrino“Super- Beams”
NUMI
Off- Axis
& Neutrino Target
Neutrinosto “Homestake”
Short Baseline Detector Array
Target and Muon Cooling Channel
Bunching Ring
RecirculatingLinac for Neutrino Factory
VLHC at Fermilab
Damping Ringsfor TESLA @ FNALWith 8 GeV e+ Preacc.
1% LC Systems Test
Rencontres du Viet-Nam 2004 Alain Blondel
High intensity proton accelerators pose many challenges but certainly one of the most critical one is the
Target !
Typical Dimensions: L 30 cm, R 1 cm
4 MW of protons (i.e. 40 000 light bulbs!)
into a big cigar….
it would immediately go to smoke.
Rencontres du Viet-Nam 2004 Alain Blondel
Liquid Mercury Target R&D
Experiment @BNL and @CERN
Speed of Hg disruptionMax v 20 m/s measured
v// 3 m/s
(design calls for 20m/s)
Protons1 cm
liquid jet of mercury
jet remains intact for more than 20 microseconds.
Rencontres du Viet-Nam 2004 Alain Blondel
A. Fabich et al– CERN-BNL-Grenoble
US scheme: jet is inside a
very high field tapered solenoid
(20 T max)
this was tested at the Laboratoire de Champs Intenses (Grenoble)
Liquid Mercury Target R&D
Rencontres du Viet-Nam 2004 Alain Blondel
Proposed rotating tantalum target ring
Targetry: other ideasMany difficulties: enormous power density
lifetime problems
Replace target between bunches:
rotating solid target
Stationary granular target:
Densham Sievers
Rencontres du Viet-Nam 2004 Alain Blondel
Target & collection
2.2 GeV4 MW
Protons
Current of 300 kA
B1/R
B = 0
The CERN magnetic horn for pion collection
Prototype built at CERN
Major issue is resistance of horn material to combination of shock, Joule heating & irradiation
Rencontres du Viet-Nam 2004 Alain Blondel
Participating Institutions1) RAL2) CERN3) KEK4) BNL5) ORNL6) Princeton University
Proposal to test a 10m/s Hg Jet in a 15T Solenoid with an Intense Proton Beam
Target & collection
aim:Installation and commissioning
at CERN by April 2006
Rencontres du Viet-Nam 2004 Alain Blondel
Hg-jet system
Power absorbed in Hg-jet 1 MW
Operating pressure 100 Bar
Flow rate 2 t/mJet speed 30 m/sJet diameter 10
mmTemperature
- Inlet to target 30° C- Exit from target100° C
Total Hg inventory 10 tPump power 50
kW
Rencontres du Viet-Nam 2004 Alain Blondel
Muon ionization cooling
principle reality (simplified)
Never realized in practice !A realistic prototype should be built and proven to be adequate to the Neutrino Factory requirements.
reduce pt and pl
with as little heating as possible: Hydrogen!
increase pincrease pll
fast fast accelerationacceleration
Frictional cooling is only for +
A novel method for + and - is needed: ionization cooling
Rencontres du Viet-Nam 2004 Alain Blondel
MICE setup: cooling + diagnostics
Rencontres du Viet-Nam 2004 Alain Blondel
Operation of RF cavities at high gradient in magnetic
field
Dark current backgrounds measured on a 805 MHz cavity in magnetic field!with a 1mm scintillating fiber at d=O(1m)
This will be also a source of backgrounds for MICE:
Rencontres du Viet-Nam 2004 Alain Blondel
RF cavity (800 MHz) at Fermilab being pushed to its limits (35 MV/m)to study dark current emission in magnetic field. Sees clear enhancement due to B field. Various diagnostics methods photographic paper, scintillating fibers Microscope ------ BCT and solid state counters have demonstrated this and allowed precise measurementsReal cavities will be equipped with Be windowswhich do not show sign of being pitted contrary to Cu
Rencontres du Viet-Nam 2004 Alain Blondel
MICE cooling channel R&D
LH2 window(IIT, NIU, ICAR)
RF module(Berkeley, Los
Alamos, CERN, RAL)
First cavityFirst cavity
Be window to minimize thickness
The challenge:Thin windows + safety regulations
Rencontres du Viet-Nam 2004 Alain Blondel
- STEP I
STEP II
STEP III
STEP IV
STEP V
STEP VI
MICE installation phases
2006
2007
2008
Rencontres du Viet-Nam 2004 Alain Blondel
Muon acceleration
Previous accelerator scheme: LINAC + Recirculating Linear Accelerator (RLA)Very costly and rigid use.
Proposed solution:Fixed Field Alternating
Gradient (FFAG). a new a new type of accelerator with type of accelerator with B-field shaped as rB-field shaped as rk k
-->particles can be kept -->particles can be kept and accelerated over a and accelerated over a range of energies of range of energies of ~factor 3. ~factor 3.
New US Scheme
Japan Scheme
Rencontres du Viet-Nam 2004 Alain Blondel
Muon acceleration: FFAG
Latest ideas in US have lead to the invention of a new type of FFAG (“non-scaling FFAG”) interesting for more than just Neutrino Factories (e.g. from SPL
to 20 GeV?) require a demonstration experiment (PRISM, electron prototype)
Perhaps US & Japanese concepts are merging to produce something better ??
Much progress in Japan with the development and demonstration of large acceptance FFAG accelerators
Rencontres du Viet-Nam 2004 Alain Blondel
$$$$$ … COST … $$$$$$$$$$ … COST … $$$$$
USA, Europe, Japan have each their scheme for Nu-Fact. Only one has been costed, US 'study II' and estimated (2001) ~2B$.
The aim of the R&D is also to understand if solutions could reduce cost in half.
Neutrino Factory CAN be done…..but it is too expensive as is. Aim of R&D: ascertain challenges can be met + cut cost in half.
+ detector: MINOS * 10 = about 300 M€ or M$
28
Why we are optimistic:
We are working towards a “World Design Study” with an emphasis on cost reduction.
In the previous design ~ ¾ of the cost came from these 3 equally expensive sub-systems.
New design has similar performance to Study 2 performance and keeps both + and - ! (RF phase rotation)
S. Geer:
NUFACT 2004: cost can be reduced by at least 1/3 = proton driver + 1 B €
MAYBE the Neutrino Factory is not so far in the future after all….
$$$$$ … COST … $$$$$$$$$$ … COST … $$$$$
Rencontres du Viet-Nam 2004 Alain Blondel
Beta beam Challenges
1. Intense production of ions, in particular + emitters (18Ne)
2. Clean acceleration: life time is much longer than muons but the decays produce activation in the rings)
3. Stacking in the storage ring
Rencontres du Viet-Nam 2004 Alain Blondel
Layout very similar to planned EURISOL converter target aiming for 1015 fissions per s.
66He production by He production by 99Be(n,a)Be(n,a)
Converter technology: (J. Nolen, NPA 701 (2002) 312c)
Rencontres du Viet-Nam 2004 Alain Blondel
Spallation of close-by target nuclides:18,19Ne from MgO and 34,35Ar in CaO
Production rate for 18Ne is 1x1012 s-1 (with 2.2 GeV 100 A proton beam, cross-
sections of some mb and a 1 m long oxide target of 10% theoretical density)
19Ne can be produced with one order of magnitude higher intensity but the half life
is 17 seconds!
A PULSED souce could be realized by ECR (P.Sortais Moriond 2003)
Production of Production of ++ emitters emitters
Rencontres du Viet-Nam 2004 Alain Blondel
From dc ions to very short bunches
1 s
2.2 s
tB 1 s
t
B
PS
SPS
2.2 s
tB 1 s
PS
t
2 x 1.1 s to decay ring (4 bunches with few ns)
PS: 1s flat bottom with 8 (16) injections. Acceleration in ~1s to top PS energy
Target: dc production during 1 s.
60 GHz ECR: accumulation for 1/8 (1/16) s ejection of fully stripped ~20s pulse. 16 batches during 1s.
RCS: further bunching to ~100 ns Acceleration to ~300 MeV/u. 8 (16) repetitions over 1s.
SPS: injection of 8 (16) bunches from PS. Acceleration to decay ring energy and ejection of 4 + 4 bunches. Repetition time 8 s.
1 s 7 s
Post accelerator linac: acceleration to ~100 MeV/u. 8 (16) repetitions over 1s.
t
Rencontres du Viet-Nam 2004 Alain Blondel
STACKING is necessary to ensure duty cycle less than 10-3
inject off energy(using e.g. dispersive section)
Rencontres du Viet-Nam 2004 Alain Blondel
Summary
The construction of future neutrino facilities poses many stimulating challenges
Enthusiastic R&D is ongoing, and a lot has already been accomplished (despite all the difficulties related to lack of funding) -- much more is needed!
Many of these facilities offer other a large range of physics interests ranging from nuclear physics to rare muon decay and neutrinos -- AND… LHC upgrade…
The long term goal, LEPTONIC CP VIOLATION, makes the effort highly worthwhile