08/27/04 Strategies for the search for prompt muons in the downgoing atmospheric muon flux with the AMANDA Detector Raghunath Ganugapati(Newt) Preliminary Exam 08/27/04

Outline Physics Goals of the analysis AMANDA detector Search strategies

The AMANDA Detector 19 strings 677 Optical Modules Full 19 string version (AMANDA-II) operational starting in 2000 200 meters diameter 500 meters in height

Cherenkov Radiation   The products of a neutrino-ice interaction emit Cherenkov radiation as they travel faster than the speed of light in ice cosn v/c, n= refraction index

Different Potential Event Origins Extra Terrestrial Neutrinos (E-2 spectrum) Backgrounds Atmospheric Muons (E-3.7 spectrum) Atmosphere Neutrinos from conventional mode(Pions,Kaons) Possible Atmospheric neutrinos from charm (E-2.7 spectrum) (semi leptonic decays of hadrons containing heavy quarks)

Origin of Atmospheric Components The number of particles starts to increase rapidly as the shower moves downwards in the atmosphere on their way and in each interaction the particles loose energy. The number of particles reaching the earth depends on the energy and type of the incident cosmic ray and the ground altitude (sea level)

Interaction VS Decay mc2 (MeV) ct Ecritical (GeV) П+, П- 140 7.8m 115 K+,K- 494 3.7m 855 (D+,D-) 1870 317µm 3.8*107 Ecritical=(mc2/ct)*h0 h0=6.4Km Ref:hep-ph/0010306 v3 19 Jan 2001

Prompt Muons Charmed particles decay before interacting .Hence muons from decays of charm (and heavier flavors) are called prompt muon. The flux of prompt muons differs qualitatively from ordinary muons (conventional pions and kaon decay) in two ways The Energy spectrum is flatter (E-2.7) VS E-3.7 for conventional muons due to interaction The angular distribution is isotropic

Detection of muonic neutrinos Occasional Interaction AMANDA does detect electron and tau neutrinos as well but for purposes of the analysis I will be concerned only with muon neutrinos Original neutrino and the resulting muon is significantly less than the detector resolution (2 – 3 degrees)

Neutrino Fluxes Can we do better with downgoing Muons? The ZHV-D model of charm neutrinos could not be constrained by looking at the neutrino data for one single year. We shall see towards the end if we could constrain this model of charm production from the stand point of looking at muon data. AMANDA-II E-2 nm

Neutrino Vs Muon Fluxes The prompt electron and the muon neutrino fluxes and the prompt muon flux are essentially the same at sea level. This result is independent of the charm production model and hence a charm muon limit is a limit on charm neutrinos Ref:GGV,hep-ph/0209111 v1 10 Sep 2002

Uncertainty in Charm Cross Sections The uncertainty spans three orders of magnitude. This is mainly because of the need to extrapolate accelerator data to very high energies and not much is know about p-p interactions. Note that the crossing between conventional to prompt muon fluxes happens between 40TeV and 3 PeV. Ref: GGV,hep-ph/0209111 v1 10 Sep 2002

Charm Mechanism Vs Pion/Kaon Mechanism The interaction of a high energy cosmic ray with air nuclei produces a charm meson which takes up most of the energy and momentum of the primary. Showering effect and the production of accompanying Pions and Kaons is negligible when required to estimate the flux at the surface of the earth. Ref: Doctoral thesis of Prof.Varieschi

Cherenkov Geometry Given a track hypothesis we can calculate the expected photon arrival times from an unscattered Cherenkov cone. The time residual is the difference between the actual arrival time and the expected arrival time using a Cherenkov geometry

Ice Properties The scattering coefficient over a range of wave lengths is shown.This plot shows that there are layers of ice with different properties. The clearest ice has a lower scattering coefficient compared to dusty ice.

Why Charm Physics? The level of contribution to charm to the atmospheric neutrinos is something that would hamper the sensitivity of detectors like AMANDA (IceCube) to neutrinos of extra terrestrial origin. To study heavy hadron Physics which is not well understood at high energies due to the energies we can go in particle accelerators.