SPL, Beta beams and

the Neutrino Factory.

Leslie Camilleri

NuSAG 20th May 2006

What’s needed next?

Determine 13. 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.

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 machinePaul Soler on DetectorsYori Nagashima on Physics

• Roland Garoby and his team

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.

R&D on targets (MERIT) and muon cooling (MICE).

PSB SPL’RCPSB

SPSSPS+

Linac4

SPL

PS

LHCDLHC

Out

put

ener

gy

160 MeV

1.4 GeV~ 5 GeV

26 GeV40 – 60 GeV

450 GeV1 TeV

7 TeV~ 14 TeV

Linac250 MeV

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)

Proton flux / Beam power

Evolution of the CERN accelerator complex:- Proposed combinations

PS2 (PS2+)

Priorities will be driven by LHC upgrade: *1,*2,*3,*4

*1

*2

*3

*4

Superconducting Proton Linac Power : 4 MW Kin. Ener. : Up to 5 GeV. More ’s. Repetition Rate: 50 Hz Accumulator to shorten pulse length.

(Reduce atmospheric ’s 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 m232 = 2.5 x 10-3 eV2

260 MeV 350 MeV more sensitive Detector mass: 440 kton fiducial. Type: Water Cerenkov (Super-K)

MEMPHYS at Fréjus

Up to 5 shafts possibleEach 57m diam., 57m high

For most studies assumed 3 x 145 ktons.Water Cerenkov

Per shaft: 81,000 12” PMT’s 80 M€ including electronics (65M$ KL 62M$ ) +80 M€ for civil engineering. (65M$ KL 29M$ )

Depth: 4800 m.w.e

FOR 100 ktons)

Advantage of mixing neutrino and antineutrino running

• 3.5 and 4.5 GeV proton beam

• 260 and 350 MeV options

• 5 years of running.

• 2 years of running and

8 years of running

The curves flatten.

about 0.001.

Beta beams• Idea introduced by Piero Zucchelli.• Accelerate radioactive ions decaying

via + or -.• Because of Lorentz boost, the decay

electron neutrinos or antineutrinos will be focused forward into a beam.

• Look for: Appearance of or

Advantages: “Clean” beams with no intrinsic

component. No need for magnet. Precisely calculable energy spectra. Energy of beam tunable through

acceleration of ions.

Accelerate protons in SPLImpinge on appropriate sourceBunch resulting ions(atmospheric ’s !) Accelerate ions in PS and SPS.Store in decay ring. 8 bunches. 6He 6Li + e- + e

18Ne 18F + e+ + e

Half lives: 0.8 sec and 0.64 sec.

Stored together if (18Ne) = 1.67

(6He)EeV) x 200 – 500 MeV Detector: Same as for SPL (Frejus)

Very attractive because: Eurisol radioactive beam project for nuclear physics possibly at CERN..

PS and SPS exist.

6He production by 9Be(n,)

need 100μA at 2.0 GeV for needed beta-beam flux

Converter technology: J. Nolen et al., NPA 701 (2002) 312c.

For 18Ne: Proton beam into Magnesium oxide: Produce 18Ne directly by spallationSource must be hot for 18Ne to diffuse out. Cannot cool it. Limits beam and rate.

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 storeGo through jet repeatedly increases probability to form radioactive ionsRegain energy loss with RFHigh energy ions have smaller dE/dx than low energy ones. But will gain same amount from RFeven more energyTo compensate shape jet (fan) such that high energy ions (larger radius) traverse more material. Longitudinal cooling.

High E

Low E

sensitivity for = 60,100

Statistics limited

CP violation Asymmetry decreases with increasing

2% Syst. Unc.

2.9 x 1018 6He ions and 1.2 x 1018 18Ne ions per year decaying in straight sections

M. Mezzetto SPSC Villars

Down to 30o

E= (3 MeV) x = 200 – 500 MeV

Optimization of 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 (18Ne) = 1.67 (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.

Fix baseline at Frejus• 99% CL on improves from

> 30o to > 15o for a

symmetric scheme.

• The 13 sensitivity improves

a little.

60,100 scheme

30o

150

= 100

13 = 8o

= 90o

Fix at maximum SPS value: 150.

• For this the optimum distance is

300 km

• The 99% CL reach can be improved

from 15o to 10o.

• and the 13 sensitivity can also be improved substantially

But no existing laboratory at this distance!

300 km

60,100 130km

150,150 300km

sin2213

L(

L(km)

Optimize for Gran Sasso Optimize for the a detector at the Gran Sasso (730km).

Needs new SPS.

Frejus Standard300 kmGran Sasso

350,350 730km

SPL, Beta-beam (=100), T2HK comparisons

• Mass: Each detector: 440 ktons ,

• Running time: SPL and T2HK: 2 yrs + 8 yrs . Beta-beam: 5 yrs + 5 yrs.

• Systematics: 2% - 5%.

3 discovery potential on sin2 213 3 discovery potential on CP viol.

(Excluding

2%

2%

5%

J-E. Campagne et al hep/ph0603172 v1

Invoking CPT

P(e ) = P( e) Replace beta beam e by SPL

Run simultaneously for A total of 5 yrs only.

Comparable to T2HK 10 yrs.

discovery

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

WithATM

Systematic uncertainties

Must be kept at the

2% level

Most important ones: Target mass difference between near and far detectors.

Uncertainty on and cross sections (will be measured by near detector ?)

Uncertainty on cross-sections.

)(

)()(

)(

e

eDR

Targets: free nucleons and water

???

Below 250 MeV:Very uncertain

At 250 MeV:Double ratio ~ 0.9Nuclear effects ~ 5%How well do we know these?

New idea: Electron capture in 150Dy

• 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?

Atomic electron captured by proton in nucleus

(A,Z) + e- (A,Z-1) + e For instance: Dysprosium.

Advantage: monochromatic ebeam

J. Bernabeu et al hep-ph/0605132

Potential of electron capture beams

CP dependence of e

oscillation probability

Run 5 years each at=90 and =195

440 ktons at Fréjus

5 test points

90

0

90

100 500 MeV

A possible schedule for a European Lab. at Frejus

Year 2005 2010 2015 2020

Safety tunnel Excavation

Lab cavity ExcavationP.S Study

detector PM R&D PMT production

Det.preparation InstallationOutside lab.

Non-acc.physics P-decay, SN

Superbeam Construction Superbeam

betabeam Beta beamConstruction

decision for cavity digging decision for SPL construction decision for EURISOL site

Mandate of the International Scoping Study The InternationalScoping 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.

Neutrino Factory

Being studied in the context of the International Scoping Study

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 theStudy. (The effort was initiated by the UK).

Simplified Neutrino Factory

Protonaccelerator

Muonaccelerator

Muon-to-neutrinodecay ring

Earth’s interiorDetector

Ion source Pion production target

Pion to muon decayand beam cooling

ps 1.2 1014 s =1.2 1021 yr

9 x 1020 yr

e+ e 3 x 1020 eyr

3 x 1020 yr

per straight section

Principle of detection

e+ e

oscillates e

interacts giving

WRONG SIGN MUON

interacts

giving

Need to measure charge Magnetic detector

Look for e oscillations using e from decay

(Golden channel)2 baselines or 2 energies to resolve ambiguities

Other channels: Platinum channel: e T violation Silver channel:e Resolve ambiguities.

Triangle or Race-track?

Or else too many decaysIn 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

Decisions taken at April ISS meeting

Allows simultaneous collection of + and -.

instead of horninstead of solid

1021 (+ + -) decays per year Half per straight section

Knowledge of Matter density along path

2500 km

Lithosphere: solid,heterogeneous

asthenosphere: Viscous, homogeneous

Oceans: simpler, more accurate.Continents: more complicated, less accurate.

“Best” 2errors 1.5-3% Avoid: Alps, Central EuropeFavour:Western Europe to US Atlantic Islands

Usefulness of the silver channel: e

S. Rigolin, hep-ph/0407009 D. Autiero et al. hep-ph/0305185

3000km and 730km eande

Clones at 2 baselines areat different positions

Clones for 2 reactions are also atdifferent positions.

Fine grained detector for secondary vertex or kink: OPERA technology

Alternative to 2 baselines?

eandechannels have “opposite” sign CP violation.

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.

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 APD’s.

• 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

turns

10 solenoids next to each other. Horizontal field perpendicular to beamEach: 750 turns, 4500 amps, 0.2 Tesla. 42 MJoules . 5Meuros.Total: 420 MJoules (CMS: 2700 MJoules)Coil: Aluminium (Alain: LN2 cooled).

Problem: Periodic coil material every 15m: Increase length of solenoid along beam?

How thick?

NOA divided longitudinally into 10 sections Each section surrounded by low field solenoid.

Fully active detector (NOA) with external magnetic field

Giant Liquid Argon Charge Imaging Experiment

A. RubbiaImpression was that magnet limited detector mass to 15 ktons.

US-EuropeSynergy ?

Pb

Emulsion layers

1 mm

Stainless steel or Lead Film

Air Gap

DONUT/OPERA type target + Emulsion spectrometer

B

~ 3Xo ~10Xo

Can measure momentum of muons and of some fraction of electronsdentify usingtopology

Must be placed in a magnet

Comparison of beta-beam and factory

Beta-beam advantages. Synergy with Eurisol (if at CERN) + existing PS,SPS Cost ? Clean e and e 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 disadvantagesLow energy: Cross sections not so well known, muon mass effect Fermi motion Atmospheric neutrinos backgroundSilver channel energetically impossibleNeed of SPL: Improve sensitivity Measure cross-sections

Comparison of beta-beam and factory II

Advantages of Neutrino Factory Ultimate reach Smaller systematic errors Presence of both and e 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

Reach of beta-beams and Factory

About the same for other 4 quadrants of CP phase.

Beta-beams and beta-beams + SPLAre better for sin2 213 > 0.01.(needs confirmation: cuts used in analysis E> 5 GeV)

Below this value factory is more sensitive.

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

MICE: Muon cooling experiment at RAL

Prove the feasibility of ionization cooling. Strong synergy with MUCOOL.

MICE:planning

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 R&D.

Internationally: a) ILC schedule, cost and site.

b) Difficult to conceive the next big project going ahead without having already measured 13. When will this be?

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 13: MINOS, Double CHOOZ

ll-

l+

Muons of both signs circulate in opposite directions in the same ring. The two straight sections point to the same far detector(s). OK

Storing of both charges at once

Discriminate eventsOn the basis of timing ()

Detector

Some decisions taken at April ISS meeting

Sign of m232 resolution with beams

• 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.

m232 > 0 m23

2