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Alternating ions in a Beam to solve degeneracies
E. Fernández-Martínez, IFT-U.A.M. Madrid
Based on A. Donini, E.F.M. hep-ph/0603261
Motivations Evidence of physics beyond the SM Many open questions:
Masses? Absolute mass scale? Normal or inverted hierarchy?
Mixing? Large compared with CKM 23 = 45º? 13 = 0º? CP violation?
Dirac or Majorana particles?
Origin of masses
Leptogenesis
A new generation of neutrino experiments is needed to answer these questions
The oscillation parameters
What we already know
Solar sector
Atm sector
What we still don’t know sin2(213) < 0.12
cp
Mass hierarchy
Octant of 23
223msignsatm
232tan signsoct
06.005.012
2
257.07.0
212
314.0sin
eV109.7
m
18.010.023
2
235.06.0
223
44.0sin
eV104.2
m
23 = 36º–52º
12 = 31º–38º
13 < 10º
G.L. Fogli et al. hep-ph/0506083
Waiting for a global fit including MINOS!
The degeneracy problem
There is a curve of solutions
J. Burguet-Castell et al. hep-ph/0103258
Black square = input “true” value
If we add antineutrinos the two curves intersect in 2 regions: The true solution and an intrinsic degeneracy
The degeneracy problem
Two other unknown parameters:
Eightfold degeneracy:Intrinsic sign octant mixed
octatmss ,
There are 4 different sets of curves for different choices of
2 Intersections each
H. Minakata et al. hep-ph/0108085G.L.Fogli et al. hep-ph/9604415 V. Barger et al. hep-ph/0112119
octatmss ,
Beam
Maximum limited to 250/150 for 18Ne/6He with the SPS
Beam fluxes
6LiE=3.5MeV
18Ne
6He
500kt fiducial mass water Cerenkov detector at L=130km
18FE=1.7MeVE=2.4MeVE=3.4MeV
e GeVE 44.0=1.7s
GeVE 46.0e=0.8s
1180 109.2 yrdecays
1180 101.1 yrdecays
Beam fluxes
6LiE=3.5MeV
19Ne
6He
500kt fiducial mass water Cerenkov detector at L=130km
19FE=2.2MeV
e GeVE 47.0=17.2s
GeVE 46.0e=0.8s
1180 109.2 yrdecays
1180 101.1 yrdecays
Event Rates
E (GeV) 0-0.5 0.5-0.75
0.75-0.9
18Ne 710 403 40
Background 476 138 20
6He 852 595 50
Background 585 32 3
Migration and Background matrices from J. Burguet-Castell et al. hep-ph/0503021
For 10yr exposure of each beam to a 500kt water Cerenkov detector
= 5º= 0ºL = 130km
Beam degeneracies
Intrinsic sign octant mixed90% cl contours
Ne/He at L=130Km
Inputs 13 = 5º, 8º= 0º, -90º, 45º
B And LiBeam fluxes
8BeE=13.0MeV
8B
8Li
8BeE=13.9MeV
e GeVE 44.1=0.77s
GeVE 34.1e=0.8s
1180 109.2 yrdecays
1180 101.1 yrdecays
A new way to produce 8B and 8Li can be found in C.Rubbia et al. hep-ph/0602032
Event Rates
E (GeV) 0-0.5 0.5-0.75
0.75-0.9
18Ne 23 9 1
Background 10 3 0
6He 36 19 1
Background 12 0 0
E (GeV) 0.5-0.75
0.75-1
1-1.25
1.25-1.5
1.5-1.75
1.75-2
2-2.45
8B 4 7 10 11 8 5 3
Background 18 8 4 2 0 1 08Li 6 7 13 16 12 9 5
Background 23 4 1 1 0 0 0Migration and Background matrices from J. Burguet-Castell et al. hep-ph/0503021
For 5yr exposure of each beam to a 500kt water Cerenkov detector
= 5º= 0º
L = 650km
Solving degeneracies
Intrinsic sign octant mixed90% cl contours
Ne/He at L=130Km Ne/He/B/Li at L=650Km
Inputs 13 = 5º, 8º= -90º, 45º
Sensitivities
3 contours
Sensitivity to sin2(213)
Ne/He at L=130Km
Ne/He/B/Li at L=650Km
Sensitivities
3 contours
Sensitivity to sin2(213)
Ne/He at L=130Km
Ne/He/B/Li at L=650Km
Ne/He at L=650Km
Sensitivities
3 contours
Sensitivity to sin2(213) Sensitivity to the hierarchy
Ne/He at L=130Km
Ne/He/B/Li at L=650Km
Ne/He at L=650Km
Conclusions
If 13 is large, i.e. it is measured at T2K-I, alternating B and Li at the first peak with Ne and He at the second at L=650km reduces the eightfold degeneracy to a twofold one
The remaining octant degeneracy could be solved by combining with reactor, see K. Hiraide et al. hep-ph/0601258, or atmospheric data, see P. Huber et al. hep-ph/0501037 and J. E. Campagne et al. hep-ph/0603172
Sensitivity to the hierarchy is achieved for low and even if higher are accessible, the ion mix with lower outperforms it for some values of
B and Li accelerated to higher give very energetic neutrino fluxes that could exploit denser detectors like iron calorimeters or ECC
Beam degeneracies
Intrinsic sign octant mixed90% cl contours
Ne/He at L=650Km B/Li at L=650Km
Inputs 13 = 5º,8º= -90º,45º
The ionization cooling procedure
Li + D →Li + p
Li + He →B + n
C.Rubbia et al. hep-ph/0602032
An excess of 1014 ions/scould be accumulated
Cross sections
Different cross-sections can differ up to a factor of 2 below 0.5GeV (at 0.2GeV)
Comparison of LIPARI (black) and NUANCE (red) cross-section
We used the LIPARI cross-section that takes into account nuclear effects important below 0.2GeV
The cross-sections will be measured by the experiments