A neutrino program based on the machine upgrades of the LHC
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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
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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)?
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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
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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”
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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
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Atmospheric + LBL sectorB
y G
.L.
Fogli,
E.
Lisi
, A
. M
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Pala
zzo (
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& IN
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.Phys.
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Solar + reactorsB
y G
.L.
Fogli,
E.
Lisi
, A
. M
arr
one,
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Pala
zzo (
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.Phys.
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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
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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
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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?
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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!
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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
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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
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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)
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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!
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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
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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
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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)
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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
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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
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Event classification
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Efficiency and background as a function of the neutrino enery
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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!!!
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(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!!!
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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!