Detecting Earth-Skimming and Mountain-Penetrating Tau Neutrinos

Detecting Earth-Skimming and Mountain-Penetrating Tau Neut

rinos G.-L.Lin

National Chiao-Tung University, Taiwan

ISMD04

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-Skimmi

ng 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 Pakvasa 1995

For a source in a cosmological distance, with e : : =1:2:0 , the oscillationeffects taking place as the neutrinosreach 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, 1998Fargion, 1997, 2002Bertou et al., 2001Feng et al., 2001Bottai and Giurgola, 2002Tseng et al., 2003

Mountain-penetrating idea:

Hou and Huang, 2002

Auger, TA,…

Ashra-NuTel

N inelasticity

Energy losses and decays

N only scatters once. produced near the earth surface.effective interaction region– 1 tau range!

Earth-Skimming

fluorescence

Cherenkov

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 ():

AA. A. Petrukhin &V.V. Shestakov, 1968

AR. P. Kokoulin & A. A. Petrukhin, 1971

(4). Photo-nuclear interaction:

N

X

Basic component

F2(x,Q2)

The nucleus shadowing effect is considered:

),(

),(),,(

22

222

QxAF

QxFQxAa

N

A

Brodsky & Lu, 1990; Mueller & Qiu 1986;E665 Collab. Adams et al., 1992;

Iyer Dutta, Reno, Sarcevic &Seckel, 2001.

Iyer Dutta, Reno, Sarcevic, & Seckel, 01Tseng, 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

The N interaction length:

rockin g/cm 65.2,eV 10

cm/1km102 3

363.0

15

34

Eg

Gandhi, Quigg, Reno, Sarcevic, 1998

The “effective” tau lepton production probability

The Conversion Efficiency for

and propagations inside the Earth

NC

CC Energy loss

DecayCC

NC

Iong, master thesis, NCTU 04

20 km in rock

100 km in rock

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…

Log(E’/eV)

E: initial energy, E’: final energy, r=Log(E/E’)New physics-- a factor of 10 enhancement on N

Mountain-PenetratingRough estimate

Log(E’/eV)

E: initial energy, E’: final energy, r=Log(E/E’)

Earth-SkimmingRough estimate

From 30 100 km, a drastic change onthe effect of enhanced (NX)!Comparison of event rates in 2 medium lengths probes the new physics.

For the mountain-penetrating case:

The solid angle is

1.0

km 20

km 22022

2

W=20 kmL=20 kmH=2 km

LH

Not small

O

The Event Rate

Log(E/GeV)

AGN flux from Kalashev, Kuzmin, Semikoz, and Sigl, 03

Tseng et al., 03 EddNF 10log/

Log(E/GeV)

GRB flux from Waxman and Bahcall 1997

Tseng et al., 03

Log(E/GeV)

GZK flux from Engel, Seckel, and Stanev, 01

Tseng et al., 03

Energy & flux

AGN GRB GZK

1015-1016 eV

2.2 9.610-3 7.410-5

1016-1017 eV

4.9 7.110-3 1.110-2

1017-1018 eV

0.2 5.410-4 8.210-2

1018-1019 eV

1.110-5 3.310-2

Integrated tau lepton flux in units ofkm-2yr-1sr-1

Energy & Aperture(km2 sr)

AGN GRB GZK

1015-1016 eV

4.5 1000

1016-1017 eV

2.0 1400 910

1017-1018 eV

50 19000 120

1018-1019 eV

290

Effective aperture (A)eff required for1 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-penetratingand Earth-skimming probes the anomalous NX cross section.

We give effective aperture required for detecting 1 event/yr assuming a 10% duty cycle.