1. Experiments to detect q13
M.Apollonio
Universita’ di Trieste e INFN
15/04/2004
IFAE 2004, Torino

2. Layout of the talk q13 and motivations to its measurement Chooz limit
Appearance and disappearance experiments
Accelerators (A)
Nuclear Reactors (R)
(A)
Approved projects (Phase I)
Phase II
Phase III
(R)
Double-Chooz and similar
15/04/2004
IFAE 2004, Torino

3. q13 Scenario: MiniBoone disfavouring LSND “standard picture”
2 Dm2ij (Dm212, Dm223) indipendent
3 mixing angles (q12, q23, q13)
1 CP phase
Mixing Matrix PMNS
1-2 solar mixing
2-3 atmospheric mixing
1-3 o e3 mixing: q13 describes oscillations ne at the atmospheric frequency
dCP  introduces CP violation effects
Current experimental results:
Dm223 ~ 2x10-3 eV2
Dm212 ~ 7x10-5 eV2
Dm223 >> Dm212
q12~35o
q23~45o
15/04/2004
IFAE 2004, Torino

4. Why measuring q13? The least known among the parameters in PMNS
Coupled to eid (Ue3)
q13>0 would allow to access d
CP violation in the lepton sector
15/04/2004
IFAE 2004, Torino

5. What do we know about q13 today?
q13 must be small (maybe null)
The best limit up to date comes from the reactor experiment CHOOZ:
q13 < 10o-17o
(1.3x10-3<Dm232<3x10-3) [J.Bouchez, NO-VE 2003]
[CHOOZ coll., Eur.Phys.J.C27(2003), ]
15/04/2004
IFAE 2004, Torino

6. 3 families scenario: appearance experiments
Accelerators
NB: P sensitive to d (correlated with q13)
a should be considered
sign(Dm213) is present in A
[P.Migliozzi, F.Terranova arXiv:hep-ph/ ]
15/04/2004
IFAE 2004, Torino

7. Accelerators general concept: conventional beam Super Beam (SB)
Broad band (BBB)
Narrow band (NBB)
Super Beam (SB)
Off-Axis Beam (OA)
b-Beam (bB)
Neutrino Factory (NF)
15/04/2004
IFAE 2004, Torino

8. (A) General concept Production & focusing oscillation decay
Main backgrounds:
Initial ne contamination in the beam
p0 production (NC)
Near/Far detection
Production &
focusing
oscillation
decay
(had+m stop)
target
detection (m,e,t) p
p,K nm nm ne
nm(>99%) m- e- CC ne nm e- m-
ne(<1%)
15/04/2004
IFAE 2004, Torino

9. (A)-SB
It is a conventional proton beam whose power is of the order of MW
Produces nm (nm)
Proton-driver: technically feasible
PB: target
Sol.: R&D
Proposed rotating tantalum target ring
15/04/2004
IFAE 2004, Torino

10. (A)-OA Detector laying out of the main beam axis q
Kinematics  n beam energy almost independent from Ep
Monochromatic  suppresses the high energy tails
You pay it in terms of flux
Examples: En at 2 different energy scales for Ep at several OA angles q
Target
Horns
Decay Pipe
15/04/2004
IFAE 2004, Torino

11. (A)b-Beams [P.Zucchelli, Phys.Lett. B532:166,2002]
Original solution: radioactive ions with short lifetime
acceleration
storage
decay
Es.: b- (6He) ne, b+ (18Ne)  ne
15/04/2004
IFAE 2004, Torino

12. (A)-NF
15/04/2004
IFAE 2004, Torino

13. (A) Experiments [J.Bouchez, NO-VE 2003]
Phase I: use an existing facility and approved projects
(q13>5o)
Phase II: go for 1st generation of Super-Beams
(q13>2.5o)
Phase III: 2nd generation of Super-Beams (q13>1o)
[Phase IV: Neutrino Factories see relevant talk]
2006 5o
L-Ar
732 20
0.17
ICARUS 7o
Emulsion
OPERA
2005
Calorimeter
730 3
0.4
MINOS
Starting date
Sens to q13
detector
L (km)
E (GeV)
Power
(MW)
Experiment
2018 ?
0.5o
WC/L-Ar [500kT]
130
0.2
b-Beam
~2015 1o
WC/L-Ar [500kT]
0.27
4.0
SPL-SB
2020 ?
WC (HyperK) [500kT]
295
0.7
T2K-II (OA)
2009
2.3o
WC (SuperK) [20kT]
0.8
T2K (OA)
2008 ?
2.5o
Fine grained calorimeter[20kT]
700/900 2
NuMI-OA
Phase II
Phase III
Phase I
15/04/2004
IFAE 2004, Torino

14. (A) Experiments (cont’d)
Requirements for Super-Beams (nmne appearance case)
Beam side:
Low ne contamination
Good knowledge of ne/nm
Good understanding of the beam (near to far)
Detector side:
Good e- efficiency
Good p0 rejection
Good understanding of bkg
15/04/2004
IFAE 2004, Torino

15. Which energy? Low or high?
Focalisation of neutrinos ~g2~E2
Solid angle L ~1/g2~1/E2
s(n) ~g~E
p flux ~1/g~1/E
The 0th order approximation cannot help that much in the choice
Other considerations mandatory ~1
15/04/2004
IFAE 2004, Torino

16. Low (E<1GeV) or High (E>1GeV) ? [choice related to bkg considered]
intrinsic ne contamination and p0 mimicking e-
WC technique gives a good p0 (NC) vs e- separation (2-ring vs 1-ring)
Less ne (below K threshold)
Fermi momentum  poor E resolution
No matter effects
Better use fine grained detectors or L-Ar TPC
Need good p0 rejection
More ne bkg
Better resolution in E
Matter effects can arise  sign(Dm213)
caveat: stay below
t threshold
15/04/2004
IFAE 2004, Torino

17. Underground or not?
In principle not: just a matter of choosing the right (low) duty cycle [phase II, 20 kton]
BUT it is a must if your detector is “multi-purpose” (e.g. searching for other effects like proton decay) [phase III, 500 kton]
15/04/2004
IFAE 2004, Torino

18. Near/Far
Best way to determine ne bkg: measure it at a near location (before oscillation)
Try to ensure equality of conditions between near and far detectors: i.e. same beam, same target nuclei (cross sections and p0 production do depend on nuclei)
Near detector sufficiently far from the source  point-like assumption (~ 2 km)
If you go closer then the source is not point-like anymore
Near detector able to understand the different n interactions (QE/non-QE)
Ideally TWO near detectors (~300 m, ~2 km):
One giving a clear clue about n interactions
The other as much as identical to the FAR detector
15/04/2004
IFAE 2004, Torino

19. Near/Far (cont’d): strategies for beam understanding
Cheap solution:
N sees a point-like source
F and N use the same detection technique (1/L2 law)
Good for discovery though it does not allow a precise measurement of q13
Beam Near(~2km) Far(700km) N F
“Pricey” solution:
VN  N1: similar detection techniques allowing beam understanding
N1  N2: different in s(n) and detector performances  can be compared
F and N2 using the same detection technique
Should be optimal for high statistics phase III where you want to reduce systematics (less dramatic for phase II) N1
Beam V-Near(300m) Near(~2km) Far(700km) F VN N2
15/04/2004
IFAE 2004, Torino

20. T2K [I/II] OA: q~2o, JHF-PS(50 GeV p) SK[I]  HK[II]
50 kton
Water Cherenkov
T2K [I/II]
Eπ vs. Eν
0.0゜
1.0゜
1.5゜
2.0゜
3.0゜
5.0゜
OA: q~2o, JHF-PS(50 GeV p) SK[I]  HK[II]
Maximize the potential discovery (on-peak)  d,q13,sign(Dm132)
L~295 km, <E>~0.76GeV  on peak
|A|~5x10-2  matter effects negligible
Phase I: use SK detector (20 kton)
Phase II: go for a more ambitious device  HK (500 kton)
Max. osc. energy for 3×10-3eV2
OA3°
OA2°
OA1°
2200 CC νμ　/ year
800 CC νμ　/ year
15/04/2004
IFAE 2004, Torino

21. μ ν Muon detector Water Cherenkov detector
Total mass : 1000ton
Fid. Mass : 100ton
ν beam
Fine grained scintillater detector 5m 8m
Water Cherenkov detector
Muon detector p n
140m 0m
280m
2 km
295 km μ ν
15/04/2004
IFAE 2004, Torino

22. SuperKamiokande Water Cerenkov detector
Sub-GeV  good p0/el. separation
q13: 2.5o sensitivity after 5 yrs of data taking
SK-90%CL allowed
OAB (2degree)
K-decay
m-decay nm ne
0.2%
Signal for non-zero θ13 in JHF-SK (νμ→νe)
BG (NC π0 ….)
T. Kajita, Fermilab – May 2003
15/04/2004
IFAE 2004, Torino