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

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

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

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.

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

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

Plateau measurements For coincidences

Plateau measurements For coincidences

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)

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: F μ ~ cos 2 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: (7 th floor Crawford) III. Investigation of flux variation

With zenith angle θ Results: (7 th 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

Results: III. Investigation of flux variation

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

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

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) V. Investigation of “doubles’ flux” variation

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

Results: y = e x Lifetime T: T = μs T th = μs VI. Muon lifetime experiment

Results: y = e x Lifetime T: T = μs T th = μs VI. Muon lifetime experiment

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

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

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

References