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Cosmic Ray Muon Detection

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  1. Cosmic Ray Muon Detection Department of Physics and Space Sciences Florida Institute of Technology Georgia Karagiorgi Julie Slanker Advisor: Dr. M. Hohlmann

  2. p+ -> m+ + nm p- -> m- +`nm Cosmic Ray Muons

  3. Main goals • Equipment setup • Muon flux measurement • Investigation of flux variation with • Altitude • Zenith angle • Cardinal points • Overlap area • Investigation of count rate variation with • Overlap area • Separation distance between the paddles • Investigation of “doubles’ flux” with zenith angle • Muon lifetime experiment • Air shower experiment

  4. 2 scintillation detectors developed at Fermilab 2 PMT tubes 2 PM bases 2 Coincidence logic boards (version 1 and version2) Equipment

  5. A scintillation detector has the property to emit a small flash of light (i.e. a scintillation) when it is struck by ionizing radiation. Scintillation Detectors

  6. The setup is such that the counter on the DAQ board and the computer are recording “coincidences”, i.e. signals sent from both detectors at the same time Setup

  7. DAQ board resolving time for coincidences = 160ns This technique Results in elimination of background noise Offers a great number of possible experiments

  8. I. Setting up equipment • Plateau Measurements for PMTs (Procedure for finding working voltage) Example of a plateau curve: Onset of regeneration effects (afterpulsing, discharges, etc) Plateau

  9. Plateau measurements For coincidences

  10. Plateau measurements For coincidences

  11. II. Flux Muons reach the surface of the Earth with typically constant flux Fμ. (count rate)d2 Fμ =  (area of top panel)(area of bottom panel) Fμ = 0.48 cm-2min-1sterad-1 (PDG theoretical value) Count rate: 0.585cm-2min-1(horizontal detectors) Our experimental value: 36min-1 (8% efficiency)

  12. III. Investigation of flux variation With altitude We collected data on the 7 different floors of Crawford building, on the FIT campus All measurements were taken at a same specific location on each floor, except for the one on floor 7.

  13. III. Investigation of flux variation With altitude Results:

  14. III. Investigation of flux variation With zenith angle θ Expected result: Fμ ~ cos2 θ

  15. III. Investigation of flux variation With zenith angle θ Rotation mount for support of the setup:

  16. III. Investigation of flux variation With zenith angle θ Results: (7th floor Crawford)

  17. III. Investigation of flux variation With zenith angle θ Results: (7th floor Crawford)

  18. III. Investigation of flux variation With zenith angle θ Results: (Observatory)

  19. III. Investigation of flux variation With zenith angle θ Results: (Observatory)

  20. III. Investigation of flux variation With cardinal points Results: (Senior Lab)

  21. III. Investigation of flux variation With cardinal points Results: (Senior Lab)

  22. III. Investigation of flux variation With cardinal points Results: (Senior Lab)

  23. III. Investigation of flux variation With cardinal points Results: (Senior Lab)

  24. III. Investigation of flux variation With cardinal points Results: (Senior Lab)

  25. III. Investigation of flux variation With overlap area

  26. III. Investigation of flux variation With overlap area Results:

  27. IV. Investigation of count rate variation With overlap area Results:

  28. IV. Investigation of count rate variation With separation distance d between the two paddles Expected results: count rate is proportional to stereo angle viewed along a specific direction Rectangular arrangement; top/bottom phase constant (lxl); d varies (multiples of l) Values calculated using Mathematica integral output

  29. IV. Investigation of count rate variation With separation distance d between the two paddles Results:

  30. V. Investigation of “doubles’ flux” variation Using the DAQ v.1 board, we recorded low energy (decaying) muon events on the computer. These events are called “doubles.”

  31. V. Investigation of “doubles’ flux” variation With zenith angle θ Results: (Observatory)

  32. VI. Muon lifetime experiment • We collected data of double events • We plotted tdecay of an initial sample N0 of low energy muons • We fit the data to an exponential curve of the form: N(t) = N0e^(-t/T); where T = muon lifetime

  33. VI. Muon lifetime experiment Results: y = -63.856 + 616.791e-0.4552x Lifetime T: T = 2.1965μs Tth= 2.1970μs

  34. VI. Muon lifetime experiment Results: y = 14.7029 + 1493.09e-0.4601x Lifetime T: T = 2.1733μs Tth= 2.1970μs

  35. VI. Muon lifetime experiment (verification) Results: Lifetime T: T = 2.1422μs Tth= 2.1970μs

  36. VI. Muon lifetime experiment (verification) Results: Lifetime T: T = 2.1678μs Tth= 2.1970μs

  37. IX. Air shower experiment In progress… Make use of: • DAQ v.2 board – GPS option • Another 5 detector setups assembled during QuarkNet

  38. References • http://pdg.lbl.gov/2002/cosmicrayrpp.pdf • http://www2.slac.stanford.edu/vvc/cosmicrays/crdctour.html • http://hermes.physics.adelaide.edu.au/astrophysics/muon/