ISMD04 Detecting Earth-Skimming and Mountain-Penetrating Tau Neutrinos G.-L.Lin National Chiao-Tung University, Taiwan
Outline • Neutrino oscillations and Astrophysical Tau Neutrino Fluxes • The Rationale for Detecting Earth-Skimming/Mountain-Penetrating • The Conversion Efficiency for • The Simultaneous Detections of Earth-Skimming and Mountain-Penetrating • The Event Rate • Conclusions
Neutrino oscillations and astrophysical fluxes • Although flux from the source is generally suppressed compared to that of and e, the oscillation effects make the flux of each flavor comparable at the Earth.
The idea of observing in view of neutrino oscillations, was suggested sometime ago. Learned and Pakvasa1995 For a source in a cosmological distance, with e : : =1:2:0 , the oscillation effects taking place as the neutrinos reach the terrestrial detector make e : : =1:1:1. Athar, Jezabek, Yasuda 2000
Tau neutrino fluxes Athar, Tseng and Lin, ICRC 2003
Detecting Earth-Skimming/Mountain-Penetrating The Rationale
The Earth-skimming detection strategy…. Domokos and Kovesi-Domokos, 1998 Fargion, 1997, 2002 Bertou et al., 2001 Feng et al., 2001 Bottai and Giurgola, 2002 Tseng et al., 2003 Auger, TA,… Mountain-penetrating idea: Ashra-NuTel Hou and Huang, 2002
Cherenkov N only scatters once. produced near the earth surface. effective interaction region– 1 tau range! fluorescence Energy losses and decays N inelasticity Earth-Skimming
The “effective” tau lepton production probability =Tau Range(R) / N interaction length() R increases with energy, while decreases with energy. Hence it is favorable to detect neutrinos of higher energies! Flux?
The calculation of tau lepton range requires the consideration of…
The tau lepton loses its energy in the rock through 4 kinds of interactions: (1). Ionization (): the tau lepton excites the atomic electrons. H. A. Bethe 1934 (2). Bremsstrahlung (): (3). Pair Production (): A. A. Petrukhin &V.V. Shestakov, 1968 A R. P. Kokoulin & A. A. Petrukhin, 1971 A
(4). Photo-nuclear interaction: X N F2(x,Q2) Basic component The nucleus shadowing effect is considered: Brodsky & Lu, 1990; Mueller & Qiu 1986; E665 Collab. Adams et al., 1992; Iyer Dutta, Reno, Sarcevic &Seckel, 2001.
Iyer Dutta, Reno, Sarcevic, & Seckel, 01 Tseng, Yeh, Athar, Huang, Lee, & Lin, 03 Log(E/GeV) Tau lepton range approaches to 20 km in rock. Mountain-penetrating is sufficient!
Mountain-penetrating and Earth-skimming tau neutrinos/tau leptons
Gandhi, Quigg, Reno, Sarcevic, 1998 The N interaction length:
and propagations inside the Earth NC Energy loss CC Decay CC NC
Iong, master thesis, NCTU 04 20 km in rock
100 km in rock minor absorptions
Simultaneous Detection of Mountain-Penetrating and Earth-Skimming ---sensitive to new physics TeV scale gravity, KK excitations…
E: initial energy, E’: final energy, r=Log(E/E’) New physics-- a factor of 10 enhancement on N Mountain-Penetrating Rough estimate Log(E’/eV)
E: initial energy, E’: final energy, r=Log(E/E’) Earth-Skimming Rough estimate Log(E’/eV)
From 30 100 km, a drastic change on the effect of enhanced (NX)! Comparison of event rates in 2 medium lengths probes the new physics.
For the mountain-penetrating case: W=20 km L=20 km H=2 km O H L The solid angle is Not small
AGN flux from Kalashev, Kuzmin, Semikoz, and Sigl, 03 Log(E/GeV) Tseng et al., 03
GRB flux from Waxman and Bahcall 1997 Log(E/GeV) Tseng et al., 03
GZK flux from Engel, Seckel, and Stanev, 01 Log(E/GeV) Tseng et al., 03
Integrated tau lepton flux in units of km-2yr-1sr-1
Effective aperture (A)eff required for 1 event/yr, assuming a 10% duty cycle.
Conclusions • We have presented the essential features of detecting Earth-skimming and mountain-penetrating . • The tau lepton flux already reaches its maximum for a 20 km medium length. This motivates the detections of mountain-penetrating , in addition to the Earth-skimming ones.
Simultaneous detections of mountain-penetrating and Earth-skimming probes the anomalous NX cross section. We give effective aperture required for detecting 1 event/yr assuming a 10% duty cycle.