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## Cosmic Ray Muon Detection

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**Cosmic Ray Muon Detection**Department of Physics and Space Sciences Florida Institute of Technology Georgia Karagiorgi Julie Slanker Advisor: Dr. M. Hohlmann**p+ -> m+ + nm**p- -> m- +`nm Cosmic Ray Muons**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**2 scintillation detectors developed at Fermilab**2 PMT tubes 2 PM bases 2 Coincidence logic boards (version 1 and version2) Equipment**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**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**DAQ board resolving time**for coincidences = 160ns This technique Results in elimination of background noise Offers a great number of possible experiments**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**Plateau measurements**For coincidences**Plateau measurements**For coincidences**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)**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.**III. Investigation of flux variation**With altitude Results:**III. Investigation of flux variation**With zenith angle θ Expected result: Fμ ~ cos2 θ**III. Investigation of flux variation**With zenith angle θ Rotation mount for support of the setup:**III. Investigation of flux variation**With zenith angle θ Results: (7th floor Crawford)**III. Investigation of flux variation**With zenith angle θ Results: (7th floor Crawford)**III. Investigation of flux variation**With zenith angle θ Results: (Observatory)**III. Investigation of flux variation**With zenith angle θ Results: (Observatory)**III. Investigation of flux variation**With cardinal points Results: (Senior Lab)**III. Investigation of flux variation**With cardinal points Results: (Senior Lab)**III. Investigation of flux variation**With cardinal points Results: (Senior Lab)**III. Investigation of flux variation**With cardinal points Results: (Senior Lab)**III. Investigation of flux variation**With cardinal points Results: (Senior Lab)**III. Investigation of flux variation**With overlap area**III. Investigation of flux variation**With overlap area Results:**IV. Investigation of count rate variation**With overlap area Results:**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**IV. Investigation of count rate variation**With separation distance d between the two paddles Results:**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.”**V. Investigation of “doubles’ flux” variation**With zenith angle θ Results: (Observatory)**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**VI. Muon lifetime experiment**Results: y = -63.856 + 616.791e-0.4552x Lifetime T: T = 2.1965μs Tth= 2.1970μs**VI. Muon lifetime experiment**Results: y = 14.7029 + 1493.09e-0.4601x Lifetime T: T = 2.1733μs Tth= 2.1970μs**VI. Muon lifetime experiment (verification)**Results: Lifetime T: T = 2.1422μs Tth= 2.1970μs**VI. Muon lifetime experiment (verification)**Results: Lifetime T: T = 2.1678μs Tth= 2.1970μs**IX. Air shower experiment**In progress… Make use of: • DAQ v.2 board – GPS option • Another 5 detector setups assembled during QuarkNet**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/