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Status of the atmospheric muon studies

Status of the atmospheric muon studies. OUTLINE:. Primary muon spectrum at the sea level Atmospheric muons underground@ND280 location Geant4 simulation NTUPLES with atmospheric muon data Some results. Piotr Mijakowski. Motivation.

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Status of the atmospheric muon studies

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  1. Status of the atmospheric muon studies OUTLINE: • Primary muon spectrum at the sea level • Atmospheric muons underground@ND280 location • Geant4 simulation • NTUPLES with atmospheric muon data • Some results Piotr Mijakowski SMRD Meeting @KEK, 17-18 April 2007

  2. Motivation • GOAL: determine the requirements for cosmic ray trigger • SMRD will provide c.r trigger for calibration of inner ND280 detector components • No Ecal at the beginning • Calibration data taken between a beam spills • Detector requirements: • not always clear (more communication needed) • TPC+FGD: various samples – crossing FGD&TPC, crossing cathode; giving the 20cm transverse length • P0D: horizontal muons, 100k per week per channel

  3. Primary muon spectrum at the sea level • So far used the official K2K data file – Oyama spectrum • cosmic ray muon simulation • 10k events • structure: event# cos(q) Momentum

  4. Oyama spectrum • FIT:- cos(q)>=0.175 by power factor 2.04- cos(q)<0.175 linear fit • Oyama - cos2.04q; world publ. data - cos2.16q (*) (different geomagnetic locations) Momentum - zoom cos2.04q zenith (*) http://www.scifun.ed.ac.uk/pages/pp4ss/pp4ss-hodoscope.html 2006

  5. Oyama spectrum – P and cosq correlation • for vertical muons P and cosq uncorrelated • for large angles: correlation (LE m decay before reaching the surface, HE p decays mainly contribute)

  6. Simulation of atm. muons underground • muons sampled from a square surface and propagated through the rock • initial energy, zenith angle - Oyama, azimuthal angle – isotropic • normalization: 70 m/(m2s) > 1 GeV at surface (PDG) • 3 sets of simulations: • 22m x 22m, illumination time = ~36.1 sec. • 200m x 200m, illum. time = ~2.2 sec. • 400m x 400m, illum. time = ~0.27 sec. suitable only for veritical muon study small statistics so far

  7. top view side view d = 17.5m 30cm thick cement floor 2m of air below floor 1m cement wall Geant4 simulation - geometry Geometry visualization x z DETECTOR BOX - shifted 1m along z axis from the pit centerlength (z axis) = 7.723 m, width (x axis) = 5.63 m, height (y axis)= 6.150 m

  8. Zenith angle green – 400m x 400m, 0.27 sred – 200m x 200m, 2.2 s blue – 22m x 22m, 36 s • cosq of muons entering the detector box top surface all det. sides Vertical flux information!

  9. Energy spectra green – 400m x 400m, 0.27 sred – 200m x 200m, 2.2 s blue – 22m x 22m, 36 s • kinetic energy of muons entering the detector box top surface all det. sides

  10. Muons@horizontal walls • y coordinate (height) distribution of muons entering the detector box from the sides (only 2 instrumented sides) green – 400m x 400m, 0.27 sred – 200m x 200m, 2.2 s blue – 22m x 22m, 36 s ONLY 2 sides Horizontal flux information!

  11. NTUPLES NTUPLE (ROOT format): • 1 branch „Event” • 11 leaves: • „no_event” (event number) • „charge” (values = „+1” for m+ or „-1” for m-)* • „cos_theta” • „E_kin” • „x”, „y”, „z” • „px”, „py”, „pz” • „ID” (track ID of muon from G4) • files can be downloaded from: • http://neutrino.fuw.edu.pl/public/samples/t2k/nd280_atm_muons/ • see description of the contents in readme.txt file • you will also find some example macro files to read the ntuples (*) implemented mu+/mu- ratio from „Precise Measurements of Atmospheric Muon Fluxes with the BESS Spectrometer” – meas.@Tsukuba (arXiv:astro-ph/0205344 )

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