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

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

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

6. Setup 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

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: Plateau Onset of regeneration effects (afterpulsing, discharges, etc)

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)d 2 Fμ =  (area of top panel)(area of bottom panel) Fμ = 0.48 cm -2 min -1 sterad -1 (PDG theoretical value) Count rate: 0.585cm -2 min -1 (horizontal detectors) Our experimental value: 36min -1 (8% efficiency)

12. 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. III. Investigation of flux variation

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

14. With zenith angle θ Expected result: F μ ~ cos 2 θ III. Investigation of flux variation

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

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

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

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

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

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

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

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

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

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

25. With overlap area

26. Results: III. Investigation of flux variation

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 Values calculated using Mathematica integral output Rectangular arrangement; top/bottom phase constant (lxl); d varies (multiples of l)

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

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

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

32. We collected data of double events We plotted t decay of an initial sample N 0 of low energy muons We fit the data to an exponential curve of the form: N(t) = N 0 e^(-t/T); where T = muon lifetime VI. Muon lifetime experiment

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

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

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

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

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

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/