Introduction to the Neutrino Factory · neutrino-beam •If θ 13 is zero ... – Beta-beams...

Simone Gilardoni24 Aprile 2003 DPNC

Introduction to theNeutrino Factory

Simone GilardoniDPNC - Université de Genève

CERN - AB/ABP Division


Neutrino oscillation

Observation: ν into another ν of different flavour

Results: NEUTRINOS HAVE MASSMASS STATES ≠FLAVOUR STATES

Parameters:• 3 masses

– Two ∆m2 differences

• Three mixing angles• One delta phase

−

−

−=

−

−

3

2

1

1212

1212

1313

1313

2323

232310000

0010

0

00

001

ννν

ννν

δ

δ

τ

µ cssc

ces

esc

cssc

i

ie


Neutrino Oscillations

ii

iU νν αα ∑=Mixing described by

For 3-flavour eigenstates U is Maki-Nakagawa-Sakata (MNS):

−−−−−−=

−

231312231312231223131223

231312231312231223131223

1312131213

ccescscseccsssscesssccecssscessccc

Uii

ii

i

δδ

δδ

δ

6 parameters: 3 mixing angles - θ23,θ12 and θ13

CP-violation angle - δ

2 mass differences - ∆m223 and ∆m2

12

Transition probability: ( )

∆=→

νµ θθνν

ELmP e 4

sinsin2sin2232

232

132


Three family oscillation

−

−

−=

−

−

3

2

1

1212

1212

1313

1313

2323

2323

10000

0010

0

00

001

ννν

ννν

δ

δ

τ

µ cssc

ces

esc

cssc

i

ie

Atmospheric Neutrinos

SolarNeutrinos Phase δ CP

• Super-K atm.

• P(νµ→ νµ)

• Maximal mixing

• ∆m2 ≈ 3 10-3 eV2

• L/E = 1 GeV/500 km

• SNO

• P(νe→ νx)

• Large Mixing (LMA)

• Kamland

•L/E ≈ MeV/1.5 1011m

• Limit from CHOOZ

• Goal of next generation of neutrino-beam

•If θ13 is zero, IMPOSSIBLE to observe CP violation


Two friends for Nufact

SNO: D2O detector

Non-νe flux in solar neutrinos

Kamland: νe disappearance from Nuclear Reactor

LMA solution for solar neutrinos


THE last results

G.Fogli et al., PR D66, 010001-406,(2002)

The LMA solution for solar neutrinos is confirmed

The L/E oscillation pattern is confirmed


B.Kaiser


Road Map

• Experiments to look for θ13– Look for νµ→ νe in νµ beam (ICARUS, MINOS)– Off-axis beam (JHF-SK, off axis NUMI)– Low energy SuperBeams

• Experiments to look for CP/T violation or for θ13 (if too small)

– Beta-beams (combined with SuperBeam)

– Neutrino Factory

+++→−++→ eeFNeeeLiHe νν 181866

µννµ +++→+ ee


Sensitivity of Nufact

0.1o 1o 2.5o

5o

13o


JHF ready in 2007

Construction2001～2006 (approved)

JAERI@Tokai-mura(60km N.E. of KEK)

(0.77MW)

Super Conductingmagnet for ν beam line

Near ν detectors@280m and@~2km

1021POT(130day)≡ “1 year”


Far Detectors

48m × 50m ×500m,

Total mass = 1 Mton

1st Phase (2007~, ≥5yrs)Super-Kamiokande(22.5kt)

2nd Phase (201x~?)Hyper-Kamiokande(~1Mt)


Proposal for a CERN - Super Beam


Nufact CERN layout


Nufact FAQ

• Why neutrinos from stored muons:– Pure νµ, νe beam– Switching the helicity by switching the muon sign– Hope for a muon collider (may be… one day…)

• Why high energy ?– High cross section neutrino interaction– Small E/L (50GeV/3500 km)

• Why so many neutrinos?

• Is there someone that can do better before?– See the roadmap


Beam Composition

Nufact Beam WANF Beam

The scales are different !


Energy and flux specs

NuFact near detector

1020 µ decay/year4.0 106 ν CC evt. 1.7 106 ν CC evt.

per kg-year

Minos near detector

3.7 1020 pot/year2.5 106 ν CC evt.0.6 106 ν CC evt.

per ton-year

Physics at far detector


The Holy Grail: any leptonic CP violation?

CP is observable IF:

• sin2θ12 and ∆m212 are large (LMA) and

sin2θ13 small (but not too small…)

• Appearance experiment: P(νe→νµ) – P(νe→νe) is T invariant → CP is conserved

(CP not observable from solar or reactor neutrinos)

termsSolarELmA

PPPP

CPee

ee

+∆

∝=→+→

→−→

13

12212

sinsin)4/sin(sin

)()()()(

θθδ

νννννννν

µµ

µµ


• Measure θ13 via P(νe→νµ) with a precision of 10-3 or setting a limit to 10-6

• Determine via MSW the sign of ∆m2

• Discover and measure the CP violation in the leptonic sector (phase δ)

P(νe→νµ) ≠ P(νe→νµ)

Need of high energy νe:µ+ →e++ νe+ νµ

Physics at a Nufact


µ+ → e++ νµ +νe

νµ → µ−

νµ→ µ+Oscillation

Wrong Sign muons

1016p/s

3 1020 νe/yr3 1020 νµ/yr

0.9 1021 µ/yr


• High Power– LINAC @ 4 MW– Rep. Rate 50 Hz– 2.27 1014 p/pulse spaced by 22.7 nsec (44 MHz)

• Accumulator ring to reduce the pulse length

• CERN interested at least in the low energy part forthe LHC upgrade and the improvement of CNGS

Superconducting Proton Linac

SPL @ 2.2 GeV


Accumulator and Compressor

• Accumulator– Macrobunch with internal 23 ns structure (44 MHz)

MUON BUNCHES KEEP THIS STRUCTURE– Macrobunch Rep. rate: 20 ms (50 Hz)

• Compressor– Microbunch length reduction to from 3.5 ns to 1 ns– Time spread due to Pion decay ≈ 1 ns


PDAC time scheme44 MHz structure

50 Hz


Proposed site

Old ISR tunnel, site of accumulator + bunch compressorRadius = 50 m


Target Nufact• Target:

– Mercury: Z = 80 → short targetLiquid → easy to replace

(v// ≈ 20 m/s)– Dimensions: L ≈ 30 cm, R ≈ 1 cm

40000 ×

4 MW

=

→ 4 MW of proton into a pint of beer


Target experiment

Experiments @BNL and @CERN• Measurements of Hg explosion speed

– Speed of protons >> Speed of sound • Maximum v⊥ ≈ 20 m/s• v// ≈ 3 m/s

Protons

1 cm


Jet test a BNL E-951Event #11 25th April 2001

P-bunch: 2.7×1012 ppb100 nsto = ~ 0.45 ms

Hg- jet : diameter 1.2 cm jet-velocity 2.5 m/sperp. velocity ~ 5 m/s

Picture timing [ms]0.000.754.50

13.00

K. Mc Donald, H. Kirk, A. Fabich

Protons


The Harp experiment Hadron production cross section measurement

Simone Gilardoni24 Aprile 2003 DPNCTop view Side view

Front view

Protons 12 GeV

Be target


Magnetic horn

Protons

Current of 300 kA

To decay channelπ

Hg Target B∝1/RB = 0


First piece of Nufact

Merci à l’ atelier du CERN


Time (arb.)

Decay channel

Ene

rgy

(GeV

)

Solenoid B=1.8 T, L=30 mπ “Life Time” → 18 m @ p=400 MeV/cGeometry

Energy spread reduction needed

π

µ

• Huge Energy spread– Huge velocity spread– LEP σE/E≈ 10-3

– NF σE/E≈ 2• Debunching• Beam type

– β ≈ 0.8– E-t correlation

30 m


Nufact CERN layout


What is a “Phase Rotation”?

• Aim: Reducing the energy spread of a non-relativistic beam

• How: series of RF cavities that

- accelerates low-energy particles

- decelerates high-energy particles


Phase rotation example

100 ≤ E ≤ 300 MeV

30 RF cavities: • 2 MV/m• 44 MHz• L = 1 m • B = 1.8 T

E = 200 ± 50 MeV

time

300

200

100

MeV


88 MHz cavity prototype


Cooling: the problem(transverse phase space)

Accelerato

Accelerator acceptance R ≈ 10 cm, x’ ≈ 0.05 rad

rescaled @ 200 MeV

π and µ after focusing

• Problem: µ → Beam pipe radius of storage ringP⊥ or x’ and x reduction needed: COOLING


Ionization Cooling : the principle

H2 rf

Liquid H2: dE/dx

RF restores only P//: E constant

Beam

sol

sol


2) Focusing :

a) Needed whenx’ reduction comparablewith multiple scatteringb) same rotation center forthe spiral motion. (Rematching)

Cooling : the channel

1) Cooling I : x’ reduction 3) Cooling II : x’ reduction

0i

f

EE'-' ϑ+= if xx

Heating term

‘

0

6.130 X

xpcMeV

βϑ =

H2 has X0= 8.9 m

Cooling works best with high x’


Cooling: the results

Results: phase space density increased by 16(Cooling rate for MICE: 16%)

IN

OUT


Channel engineering design


MICE: Muon Ionisation Cooling Experiment

Proposal to be submitted to RAL before end of the year


Accelerator and Particle physics together

TPG TrackerSciFi Tracker

Example of cooling


Mice roadmap (at RAL?)µ

- STEP I: 2004

STEP II: summer 2005

STEP III: winter 2006

STEP IV: spring 2006

STEP V: fall 2006

STEP VI:2007


Nufact CERN layout


Storage ring

• Two straight sections pointing to two detectors

• Two possible shapes– triangle– bow tie

• Lattice design for beam divergencex’=1/10βγ

→ ν beam divergence dominated byµ decay → θ=1/βγ =mµ/pµ= 2mrad (@ 50 GeV)

• ≥ 25% useful decays per direction


Technical problems

14°

Could you imagine a screw driver falling down from here?


Nufact CERN layout


Around Europe...

• First possible location: Gran Sasso 732 km

• Second location: 3500 km away bestCandidates: Svalbards (Norway)

Gran Canaria (Spain)


Where do you prefer to take shifts?


Why two locations?

From P. Hernandez

•Fit of θ13 and δ a the same time

•No sensitivity at 732 km

•Better to combine with 2810 km


But not too far: no CP sensitivity

L = 7332 km

From P. Hernandez


The world as playground


Far Detector• Iron calorimeter• Magnetized

– Charge discrimination– B = 1 T

• R = 10 m, L = 20 m• Fiducial mass = 40 kT

Baseline

3500 Km

732 Km 3.5 x 107

1.2 x 106

5.9 x 107

2.4 x 106

1.1 x 105

1.0 x 105

νµ CC νe CC νµ signalEvents for 1 year


The neutrino factory golden-measurement is the CP violation. Super-Beam+Beta-Beam are competitive in various ways, including T violation!

General Considerations

δ = 90 deg99%C.L. Curves

(M. Mezzetto, NNN02)


Last question: about financing?

• For the time being our situation is not so good….

BUT….. Some ideas are developing…


Reserve ……………………………………


Total flux of 8B neutrinos


SNO detector

• 1000 ton of D20• 12 m diam. • 9456 PMTs

• Aim: measuring non νe neutrinos in a pure solar νe beam• How? Three possible neutrino reaction in heavy water:


SNO: the Puzzle solution

LMA (Large Mixing Angle) is the preferred solution

SNO Day and Night Energy Spectra Alone

Combining All Experimentaland Solar Model information


Usual attitude for LSND


Summary of experimental results

• Good news:– LMA solar solution

still in good shape– To be confirmed by

KAMLAND • SNO data taking

going on• Super-K rebuilt in

short time


sin22θ13

* Designed for ντ appearance

<0.013JHF-SK

<0.028<0.040? Low energy CNGS

<0.033<0.039<0.056CNGSx1.5*

<0.039<0.047<0.067CNGS*

<0.042<0.049<0.06<0.085MINOS

<0.14<0.14<0.14<0.14<0.14<0.14CHOOZ200920082007200620052004

P. MigliozziIndication of time-line


The BETA-BEAM

1. Produce a Radioactive Ion with a short beta-decay lifetime

2. Accelerate the ion in a conventional way (PS) to “high” energy

3. Store the ion in a decay ring with straight sections.

4. It will decay. νe (νe) will be produced.

- SINGLE flavour - Known spectrum- Known intensity- Focussed- Low energy- “Better” Beam of νe (νe)

The “quality factor” QF=Γ/E0 is bigger than in a conventional neutrino factory. In addition, ion production and collection is easier. Then, 500000X more time to accelerate.

Muons:Γ~500E0~34 MeVQF~15

6He Beta-:Γ~150E0~1.9 MeVQF~7918Ne Beta+:Γ~250E0~1.86 MeVQF~135


The Acceleration principle

ISOL Targetand ECR Linac Cyclotron Storage Ring

PS SPS

2500 m

R=300 m

Decay ring/Buncher

Bunch rotation is the crucial issue for atmospheric background control!

Studies are made on EXISTING CERNmachines. Why? Much more detailedknowledge exists, the best way to identifypossible problems and limitations.


channel at neutrino factory

High energy neutrinos at NuFact allow observation of νe→ντ(wrong sign muons with missing energy and P⊥). UNIQUE

Liquid Argon or OPERA-like detector at 3000 km.

Since the sinδ dependence has opposite sign with the wrong sign muons, this solves ambiguitiesthat will invariably appear if only wrong sign muons are used.

ambiguities with only wrong sign muons (3500 km)

equal event number curvesmuon vs taus

associating taus to muons(no efficencies, but only OPERA mass)

studies on-going

A. Donini et al


Why so far?

0.00E+00

5.00E-03

1.00E-02

1.50E-02

2.00E-02

2.50E-02

0 5000 10000 15000Distance L (km)

Vac.

Osc

ill. P

rob.

E = 1GeVE = 30 GeV

Earth diameter:Vertical storage ring?


Degeneracies

Degeneracy: 2 or more parameter sets fit the same data

Three types, all of which can effect measurement of δ & θ13:

( ) ( )1313 ',', θδθδ ↔

223

223 mm ∆−↔∆

4,

2 232323πθθπθ ≠−↔

θ13=8o, δ=-90o, 0o, 90o, 180o

(1)

(2)

(3)

( ) ( )δθδθµµ νννν ,',' 1313 ee

PP =

( ) ( )δθδθµµ νννν ,',' 1313 ee

PP =

(1) ⇒


Degeneracies

∆

∆+≈

−≈

ELm

ELm

44cot2sincotcos'

,'212

213

12231313 θθδθθ

δπδθ13

large

NB depends on L/E ⇒ possible solutions

• Two baselines and E-dependence at NF

• NF + SB combination

• Two off-axis detectors

• νe→ντ as well as νe→νµ

Mena

Huber/Mena

Whisnant

Meloni


Degeneracies

Mena

NuFact at 2810km

+ SB at

130KM

NuFact at 732km

+ SB at

130KM

large

small


νe appearance in JHF-Kamioka (phase 1)

µ eπ0

1.8 events 9.3 events 11.1 events

123.2 events @ sin22θ13=0.1, ∆m2=3×10-3eV2

Backgrounds

Signal

(5 years running)


Europe: SPL FrejusGen

eve

Italy

130km

40kt400kt

CERN

SPL @ CERN2.2GeV, 50Hz, 2.3x1014p/pulse

4MWNow under R&D phase


SPL neutrino beam


CP δ and θ13

40 kt Detector 400 kt Detector

Running time:

• 10 y antineutrinos

• 2 y neutrinos

Introduction to the Neutrino Factory · neutrino-beam •If θ 13 is zero ... – Beta-beams...

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Transcript of Introduction to the Neutrino Factory · neutrino-beam •If θ 13 is zero ... – Beta-beams...