QuarkNet and Cosmic Ray Muon Flux Experiments

Florida Academy of Sciences Spring Conference 2009

Alfred Menendez and Michael Abercrombiewith

Dr. Marcus Hohlmannfrom

Florida Institute of Technology

Outline

• What is QuarkNet?• How are cosmic rays and muons related?• How do we detect muons?• What kind of analysis can be done through

QuarkNet?• What do we plan to do in the future?

What is QuarkNet?

• Educational outreach program run by Fermilab, sponsored by the National Science Foundation and the Department of Energy.

• Provides the basis for understanding frontline physics research currently being conducted.

• Involves high school students and teachers in an effort to inform and excite them about this research.

What Are Cosmic Rays?

• 90% are protons (other 10% are nuclei) from outside of our solar system

• Travel at nearly the speed of light• Observed to have reached energies up to 1021 eV• Ideas about possible sources of these high-energies include:

– Active galactic nuclei– Quasars– Gamma Ray Bursts– Dark Matter

How Do Cosmic Rays Form Muons?• Cosmic rays strike the

Earth’s atmosphere, undergo nuclear reactions produce pions (π)

• Pions then decay into a muon (μ) and a muon neutrino (v).

• Some muons decay into two neutrinos and an electron (e), while others last long enough to reach the Earth’s surface.

How Do We Detect Muons?

The setup we use todetect muons includes:

– Two scintillation paddles– Photomultiplier tube– Data Acquisition Board

(supplied by QuarkNet)– Computer

• Muon passes through paddles• Muon generates light burst in

scintillator paddles

• The Photo Multiplier Tube (PMT) converts light burst into electric pulse which is read by the QuarkNet Data AcQuisition card (DAQ)

• The DAQ card connects to a computer which records the data (via HyperTerminal)

How Do We Detect Muons?

• Our DAQ card is set to record only coincidences

• A coincidence occurs when both paddles register a muon “hit” within a preset amount of time (25 ns)

• This arrangement helps to reduce noise and false “hits”

• This allows for some interesting experiments and analysies

What Does the DAQ Card Do?

• Used to determine quality of data

• Can see how much “noise” is in the data

• Many short pulses with few longer pulses indicates a noisy counter

• Time over threshold is a measure of energy deposited in scintillator for any given muon

Data Performance StudyN

umbe

r of

PM

T P

ulse

s

Time over Threshold (nanoseconds)

• Flux is a detector-independent quantity

• Gives number of particles per amount of time to pass through an area.

• Varies with different thresholds.

Flux Introduction

(Flux = particles/area/time)

Flu

x (e

vent

s/m

2 /60

sec

onds

)

Time UTC (hours)

Flux Orientation Study•Detector is horizontal (i.e. in the x-y plane)

•Using data from channel 1

•Flux average is about 750 events/m2/60 sec

(Flux = particles/area/time)

Flu

x (e

vent

s/m

2 /60

sec

onds

)

Time UTC (hours)

Flux Orientation Study

•Using data from channel 1

•Flux average is about 450 events/m2/60 sec

Flux = particles/area/time

•Detector is vertical (i.e. in the x-z plane)

Flux Dependence on Threshold

•Detector is horizontal

•Flux is dependent on threshold of detector

•Threshold is level at which DAQ card starts recording data

•Flux increases with decreasing threshold

Flux = particles/area/time

Current Work• We are currently using a

pulse-height spectrometer to measure the energy deposited in the paddles by the muons

• Plan to involve this equipment in future experiments

• Working to improve quality of our data

Energy lost by muon (KeV)

Num

ber

of m

uons

Num

ber

of m

uons

Energy lost by muon (KeV)

http://imagine.gsfc.nasa.gov/docs/science/know_l1/cosmic_rays.html

http://www.cosmicrays.org/

Acknowledgements:

Questions?

http://cosmic.lbl.gov/more/SeanFottrell.pdf