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Measuring n -mixing parameters at n -telescopes

Measuring n -mixing parameters at n -telescopes. Pasquale Dario Serpico MPI für Physik - Munich. Current Topics in Astroparticle Physics, 25-29 April 2005 – Ringberg Castle. based on hep-ph/0502088 , to appear in PRL, in collaboration with M. Kachelrie ß. Overview of the Talk.

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Measuring n -mixing parameters at n -telescopes

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  1. Measuring n-mixing parametersat n-telescopes Pasquale Dario Serpico MPI für Physik - Munich Current Topics in Astroparticle Physics, 25-29 April 2005 – Ringberg Castle based on hep-ph/0502088, to appear in PRL, in collaboration with M. Kachelrieß

  2. Overview of the Talk • n-telescopes and n-mixing: a (brief) overview • An interesting Galactic Anisotropy in CR: neutron source(s)? • A promising point-like target for n-telescopes • A chance for galactic b-beams • Discussion & Conclusions P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  3. n-telescopes and n-mixing: a (brief) overview

  4. n-telescopes and n-mixing 1. The signature and efficiency of these detectors depend on the flavour! In particular, oscillations may “rescue” signals • In some cases, n-mixing angles might be studied at n-telescopes Only standard physics considered here, otherwise many other interesting possibilities would open! P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  5. Flavour Discrimination nm + N →m + X ne + N → e + X nt + N →t + X <1o O(25o) E > 10-100 GeV E > 1 TeV E > few PeV Simplified picture! Subleading flavour-independent effects (NC showers), “fake signals” (e.g. m events tracks in t→m events) P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  6. A “rescued” signal: the Galactic diffuse nt The pp n-flux from CR hitting Galactic diffuse matter develops a large oscillated t-component. H. Athar et al. APP 18 (2003) 581 Atmospheric n background is softer due to relevant energy losses of mesons. Moreover, it is nt-suppressed: at E≈TeV-PeV the oscillation length is too large (mainly prompt nt!) Event rate of O(1 yr-1 sr-1) for two separable and contained showers with E ≈ PeV in a Km3 n-telescope Independent confirmation of the (large) mixing in the m-t sector. P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  7. n-telescopes, the Glashow resonance and q12 - - ne+ e-→W- → anything Unique to ne, and s enhanced at E ≈ 6.3 PeV “Glashow Resonance” - Standard astrophysical sources produce n and n via pp→pX, pg→pX . Both give flavour ratios at production fe:fm:ft≈⅓:⅔:0, but pg mainly gives ne (via p+), while pp almost equally ne and ne. - - The measurable ratio RGR ≡ neGR/(nm+nm)CCis thus sensitive to mixing angles (mainly to q12) as well as to the nature of the astrophysical source (% of pp “contamination” ≡ k). For q13=0oand q23=45oBhattacharjee & Gupta [astro-ph/0501191] get RGR ≈ 15[Sin2 2q12 +k(1-0.5 Sin2 2q12)] P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  8. n-telescopes, the Glashow resonance and q12 -II • q12=45o q12=32.5o q12=15o q12=0o • ------ q23=40o • q23=45o • q13=0o • q12=45o q12=32.5o q12=15o q12=0o • q23=45o • ------ q13=9o • q23=0o Bhattacharjee & Gupta [astro-ph/0501191] P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  9. An interesting Galactic Anisotropy in CR: neutron source(s)?

  10. A Galactic Plane excess in Cosmic Rays AGASA reported a 4% excess in HECR around 1018 eV (1 EeV) from a couple of hot-spots in the galactic disk Confirmed also by SUGAR and Fly’s Eye: a rare case of concordance in a field where experiments often disagree each other! P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  11. The birth of Galactic neutron Astronomy? Neutrons are natural candidates to explain the signal Signal Energy-range ≈ boosted n-lifetime on galactic scales no GMF bending (huge for p too!) ctn≈ 10 kpc (En / EeV) P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  12. The associated n-flux: a promising point-like target for n-telescopes

  13. From Neutrons to Neutrinos If n explain the excess, a garanteed n flux is the one below PeV from n-decay En/ En ~ Q / mn ~ 0.8 x 10-3 → En ~ PeV, for En ~ EeV The energy-window accessible to “conventional” n-telescopes is from ~100 GeV up to ~1016-17 eV (10-100 PeV). • Conservative! • Lower energy n undetectable • in CR (decay & GMF bending) • Further n‘s from decay of • associated meson decay (to be • discussed at the end) Can we observe them? P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  14. Detectability in IceCube Normalizing to the CR anisotropy, ~ 20 events per year from Cygnus region in IceCube (under construction at the South pole) Standard noscillation phenomenology implies ≈ 4nm/yr tracks in 0.7o circle (Atm. background is~2.3 nm/yr) ≈ 16ne+ntshowers/yr in 25o, cone, due to poor resolution. (Atm. background fluctuation is~12 showers/yr) In a few years, IceCube will attain discovery sensitivity for n→ne→nm!!! L. Anchordoqui, H. Goldberg, F. Halzen & T.J. Weiler PLB 593 (2004) 42 P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  15. A chance for galactic b-beams

  16. n Mixing slk≡ Sin qlk , clk≡ Cos qlk Mixing Matrix U From a pure (anti-)ne flux, the probability Peb to observe the flavour b at a distance much larger than the oscillation lengths (as for galactic scales, E≈ TeV and the actual values of Dm2’s) is Present experiments give at 3 s [Maltoni et al., NJP 6 (2004) 122] Solar/Kamland 28.7o < q12 < 37.5o Atmospheric/K2K 35.7o < q23 < 54.3o CHOOZ+Others q13 < 12.5o dCP??? P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  17. Sensitivity to mixing angles-I • The peculiar state in flavour space at source • (fe:fm:ft= 1:0:0) • allows to perform a combined • disappearence experiment (of ne) • appearence experiment (nm and nt) • that is sensitive to mixing angles via the observable ratio • of tracks to showers • fm • (fe+ft) R= Chance for “Galactic b-beams”! In particular, what is the sensitivity of such a signal to the unknown parametersq13and dCP? P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  18. Sensitivity to mixing angles - II For q12=p/3 and q23=p/2 one has Though in the following we will use the exact formulae, they show some key-features of the signal. P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  19. Sensitivity to q13 (and q23) For best fit q12=32.5o and in the best case dCP=0 one has a variation of order 30-50% in 0o< q13< 10o, depending on q23. In the most likely case q12=45o, the flux ratio differs up to a factor 2 with respect to the expected flavor ratio of generic astrophysical sources, R=0.5 Note the octant dependence! P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  20. Sensitivity to dCP For experimental best fit q12=32.5o andq23=45o, the flux ratio has a maximal variation of about 30% and differs up to a factor 2 with respect to the expected flavor ratio of generic astrophysical sources P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  21. Discussion: models, p-background

  22. Discussion: Nuclei & Pions… The usually discussed astrophysical n sources are based on pp→pX, pg→pX . After oscillations → n flavour ratio 1:1:1 insensitive to q13and dCP !!! Is it possible/realistic to neglect n from these channels? One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A →n→n scenario P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  23. Neutrons (and n) from Nuclei? At E ≈ EeV, few galactic sources match the right acceleration requirments, and the GMF hardly confines cosmic rays. Higher charged particles are easily accelerated and confined. Within a factor of a few, E ≈ O(1 EeV) is the transition region between the Heavy-nuclei end of the Galactic Spectrum and the proton-dominated Extragalactic contribution. Recent CR data support this scenario Conceivable that the n from nuclei dissociations in matter and g-fields in (a few) galactic accelerators may become visible. Favored regions are the Nuclear Bulge and dense clouds of higher B-field intensity… Dova et al. APP 21 (2004) 597 P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  24. Discussion: Nuclei & Pions… The usually discussed astrophysical n sources are based on pp→pX, pg→pX . After oscillations→n flavour ratio 1:1:1 insensitive to q13and dCP !!! Is it possible/realistic to neglect n from these channels? One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A →n→n scenario P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  25. What’s the expected “contamination”? Viable models of the A → n →n scenario exist, e.g.: Cygnus region: L. Anchordoqui et al. PLB 593 (2004) 42 SGR A East SN remnant: Grasso and Maccione [astro-ph/0504323] From astrophysical data e.g. on the Cygnus region (e.g. UV g density) and hadronic physics data (e.g. secondary population yields in hadronic interactions) an effective volume for nuclear dissociation 27 times larger than for hadronic interactions has been estimated. In this case, likely p contaminations to n flux are at the O(10%) level →DR ≈ + 0.02 only! Within the expected statistical accuracy of IceCube & at the same subleading level of other effects neglected in our first estimate (NC role, tracks from t→m events, etc.) P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  26. What’s the expected “contamination”? - II Lower limit to n from nuclei: Only He contribution, metallicity at solar level (SGR A East is known for a high metallicity, ≈ 4 solar) Only single nucleon stripping Only effects of IR background Observable n at Earth, normalized to HESS g data Extreme pp, assumingEpmax = ∞ Again, reasonable to expect a nuclear contribution to n much larger than the one from pp D. Grasso and L. Maccione [astro-ph/0504323] n-decay suppression Behaviour due to s and CR f P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  27. Discussion: Nuclei & Pions… The usually discussed astrophysical n sources are based on pp→pX, pg→pX . After oscillations →n flavour ratio 1:1:1 insensitive to q13and dCP !!! Is it possible/realistic to neglect n from these channels? One has to check that Neutrons from Nuclei at EeV in (some) Galactic sites are expected Viable models can be built compatible with observations and constraints It is experimentally possible to disprove the A →n→n scenario P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  28. Is the Scenario Falsifiable? Provided that the “n-chain” explains the anisotropy, n-fluxes (from n-decay alone!) are easily observable in IceCube, with a detailed measurement in a decade. (normalized to CR data, not a model !!!) If the p-chain dominates, the flux should be much higher (factor>100!) though with a flavour ratio of about 1:1:1 Possible discovery already in AMANDA-II Also g-rays constraints! High n flux and R=0.5 would disprove the dominance of A →n→n! P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  29. Overview If the CR anisotropy around the EeV is confirmed to be of neutronic origin, a likely possibility is that in a next generation n-telescope like IceCube it provides a measurement sensitive to q13and dCP Both improved CR data (AUGER, KASCADE-Grande) and direct measurement of n-flux (AMANDA, IceCube, Mediterranean Telescopes) can falsify the proposed mechanism, thus making feasible in forthcoming years to assess the effective viability of the method P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  30. Conclusions On Earth, the hunting for q13and dCP is open. Terrestrial beta-beam facilities have been proposed, of O(1) G€ cost, with the main issue in the beam preparation n-telescopes are optimized for astrophysical purposes, but they may have a potential for n-mixing physics, too. The scenario discussed here shows that it is conceivable that Nature might provide b-beams “for free”, that could be studied at n-telescopes already in construction. As for the Solar neutrino problem, the Heavens might still be helpful to n-physicists!  P. D. Serpico, MPI für Physik - Munich “ Measuring n-mixing parameters at n-telescopes” CuTAPP ‘05, Ringberg Castle

  31. Happy Birthday!!! I wish you’ll remain forever young…. LEOFEST 2005

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