A neutrino program based on the machine upgrades of the

LHC

Pasquale MigliozziINFN – Napoli

A. Donini, E. Fernandez Martinez, P.M., S. Rigolin, L. Scotto Lavina, T.Tabarelli de Fatis, F. Terranova

Motivations

Is there a window of opportunity for neutrino oscillation physics compatible with the machine upgrades of the LHC (>2015)?

Can we immagine an affordable facility that could fully exploit european infrastructures during the LHC era?

Is the sensitivity adequate for an experiment aiming at closure of the PMNS (precision measurement of the 1-3 sector)?

Neutrino oscillations(a glimpse beyond the Standard Model)

The most promising way to verify if m > 0(Pontecorvo 1958; Maki, Nakagawa, Sakata 1962)

Basic assumption: neutrino mixinge, , are not mass eigenstates but linear superpositionsof mass eigenstates 1, 2, 3 with masses m1, m2, m3, respectively:

i

iiU

ii V

= e, , (“flavour” index)i = 1, 2, 3 (mass index)

Ui: unitary mixing matrix (PMNS)*)( ii UV

NotationMixing parameters: U = U (12, 13, 23, ) as for CKM matrix

Mass-gap parameters:

M2 = m212 , ± m2

23

The absolute neutrino mass scale should be set by direct mass measurements:

-decay02-decay“W-MAP”

So what do we have to measure?

Three angles (12, 13, 23)

Two mass differences (m212 (or m2), m2

23 (or m2)) The sign of the mass difference m2 (±m2

23) One CP phase () The source of atmospheric oscillations (detect

appearance) The absolute masse scale Are neutrino Dirac or Majorana particles (or both)? Are there more - sterile - neutrinos?

All the underlined items can be studied with LBL experiments

Atmospheric + LBL sectorB

y G

.L.

Fogli,

E.

Lisi

, A

. M

arr

one,

A.

Pala

zzo (

Bari

U.

& IN

FN

, B

ari

) Subm

itte

d t

o P

rog.P

art

.Nucl

.Phys.

e-P

rint

Arc

hiv

e:

hep-p

h/0

50

60

83

Solar + reactorsB

y G

.L.

Fogli,

E.

Lisi

, A

. M

arr

one,

A.

Pala

zzo (

Bari

U.

& IN

FN

, B

ari

) Subm

itte

d t

o P

rog.P

art

.Nucl

.Phys.

e-P

rint

Arc

hiv

e:

hep-p

h/0

50

60

83

Overall picture

By G

.L.

Fogli,

E.

Lisi

, A

. M

arr

one,

A.

Pala

zzo (

Bari

U.

& IN

FN

, B

ari

) Subm

itte

d t

o P

rog.P

art

.Nucl

.Phys.

e-P

rint

Arc

hiv

e:

hep-p

h/0

50

60

83

Why13 is important?

If 13 is vanishing or too small the possibility to observe CP violation in the leptonic sector vanishes!!!

4321

2

122

2322

13

13

2

2

232

132

ˆ

ˆsin2sincos

ˆ1

ˆ1sinˆ

ˆsincoscossin

ˆ1

ˆ1sinˆ

ˆsinsinsinsin

ˆ1

ˆ1sinsin2sin

OOOO

P

CP

CP

e

2A

A

A

A

A

A

A

A

A

A

A

A

12

231

221

m

meffects Matter A

for

for

small (~1/30) butnon negligible

2009 2012

T2KNoa

discovery ?

2007 2012

LHC and Double CHOOZ startup End of CNGS

Phase I

Sensitivity plot vs time for Phase I experiments

Phase II

2014 2022

Beam upgrade and HK construction

Data taking...

2015 2022

“Phase 2” lumi upgrade of the LHC

LHC Energy upgrade?

How to approach Phase II in Europe?

Many ideas have been put on the market Different accelerator technologies Different baselines Different detector technologies

We think that Phase II in Europe should be part of a common effort of the Elementary Particle community

Exploit as much as possible technologies common to other fields (e.g. LHC upgrades, EURISOL)

Exploit already existing infrastucture (e.g. LNGS halls)

Costs reduction!

Multi-MW SuperBeam

Technology similar to conventional beams Neutrino beam has contamination from other

flavours Main source of systematics

Proton driver to be built from scratch Useful for Neutrino Factory

Low energy neutrino beams Huge low density detectors mandatory (i.e. water Č)

Underground laboratory to be built from scratch (e.g. SPL-Frejus) Gran Sasso halls are too small to host Mton

detectors

Neutrino Factory

Excellent neutrino beam Flux composition very well known

Very challenging technology Start operations > 2020

No relevant overlap with CERN accelerators Possible the study of the “silver channel”

(νe→ν) If built at CERN, Gran Sasso Lab maybe too

close

Beta Beam

Excellent neutrino beam Flux composition very well known

Possibility to work in νμ appearance mode νμ CC are an easier channel than e CC and allows

for dense detector No need to distinguish νμ from anti-νμ

No need for magnetic detectors! Many energy configurations are envisaged: ~150 (current design), ~350 (S-SPS based design), >1000 (LHC based design)

Comparison of the different designs

Current design (EURISOL DS) Strong synergy with present CERN accelerator complex Low energy beam: needs huge and low density detectors Underground lab to be built from scratch (e.g. Frejus) Counting experiment Excellent θ13 and δ sensitivity No sensitivity to neutrino hierarchy

S-SPS Strong synergy with a LHC energy/luminosity upgrade Medium energy beam: small and high density detectors start to be

effective Underground lab already exists (e.g. Gran Sasso) Spectrum analysis possible Very good θ13 and δ sensitivity (slightly smaller than current desing)

Sensitivity to neutrino hierarchy NB both designs need an ion decay ring!

The Beta Beam complex

+ a decay ringPresent design

lenght: 6880museful decays: 36%5 T magnets

S-SPS based designlenght: 6880museful decays: 23%8.3 T magnets (LHC)N

ot

needed f

or

a B

eta

B

eam

Why S-SPS is so interesting? It is able to bring 6He up to ≤350 (18Ne up to ≤580)

Neutrino energy above 1 GeV (spectrum analysis) It is not in contrast with the LHC running

ν

anti-ν

• Iron detectors are already effective• Fermi motion is no more dominant (energy reconstruction)• Baseline fits the CERN-LNGS distance (730 km) and is large enough to study neutrino hierarchy

S-SPS technology (accidentally) ideal for high-energy BB

It provides a fast ramp (dB/dt=1.21.5 T/s) allowing for a reduction of the ion decays during the acceleration phase

Super-SPS more performant than SPS (x2 intensity, faster cycle)

Fluxes could be smaller than Frejus (higher means higher lifetime) High field magnets (11-15 T) in the decay ring would increase

the number of useful decays (higher flux) OPTIONAL! We can allocate more ion bunches in the decay ring

because we do not need a <10ns bunch length to get rid of the atmospheric background We can recover the losses due to the higher (see next slide)

The duty cycle issue

In order to reduce the atmospheric backouground the timing of the parent ion is needed

Strong constraint on the number of circulating bunches and on the bunch length

In the present design1. bunch length 10 ns (very challenging) (10-3

suppression factor)2. 8 circulating bunches

With the S-SPS based scenario the atmospheric background is reduced by about a factor 10 and the bunch length can be correspondently increased

Frejus

S-SPS

ν

anti-ν

The detector at the Gran Sasso

40 kton iron (4 cm thickness) and glass RPC Digital readout (2x2 cm2 pads)

Full simulation but event selection based on inclusive variables only (n. hits, layers etc.) can be improved with pattern recognition

See

e .g.

T.T

abar

elli

@ L

CW

S05

Event classification

Efficiency and background as a function of the neutrino enery

Discovery potential

(18Ne)=350 , (6He)=350, 10y with “nominal” flux (F0)

=-90o

=0o

=90o

Assuming =90°

T2

K

Assuming =3°

Both plots have been obtained by assuming 5% systematic error and are computed at 99%C.L.

Energy reconstruction not exploited yet!!!

(18Ne)=350 , (6He)=350, 10y with “nominal” flux

Both plots have been obtained by assuming 5% systematic error and are computed at 99% C.L.

F0x½F0

F0x2

Exclusion plots @99%C.L.

Discovery plots @99%C.L.

Sensitivity to sign of m223

In progress. We expect sensitivity for 13>5°

Energy reconstruction not exploited yet!!!

Conclusion

The Super-SPS option for the luminosity/energy upgrade of the LHC strenghten enormously the physics case of a Beta Beam in Europe No need of ultra-massive (1Mton) detectors Possibility to leverage existing underground facilities (Gran

Sasso laboratories) Full reconstruction of the event in appearance mode Baseline appropriate for exploitation of matter effects

We strongly support a more detailed machine study. If technically affordable, this option is

an opportunity we cannot miss!