cosmic ray mu on

7/27/2019 Cosmic Ray Mu On

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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


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Cosmic Ray Muons

p+ -> m+ + nm

p- -> m- +`nm


3/38

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


4/38

Equipment

2 scintillation detectorsdeveloped at Fermilab

2 PMT tubes

2 PM bases

2 Coincidence logicboards (version 1 andversion2)


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Scintillation Detectors

A scintillation detector has the property to emit a small flashof light (i.e. a scintillation) when it is struck by ionizingradiation.


6/38

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


7/38

DAQ board resolving time

for coincidences = 160ns

This technique

Results in elimination

of background noise

Offers a great number

of possible

experiments


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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)


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Plateau measurements

For coincidences

Coincidence Plateau (superimposed)

0

50

100

150

200

250

300

350

6.80 7.80 8.80 9.80

HV#13 (dial units)

Counts/2mins

HV#14 = 7.00

HV#14 = 7.20

HV#14 = 7.40

HV#14 = 7.60

HV#14 = 7.80

HV#14 = 8.00

HV#14 = 8.20

HV#14 = 8.40


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Plateau measurements

For coincidences

Coincidence Plateau (superimposed)

050

100

150

200

250300

350

6.80 7.30 7.80 8.30 8.80

HV#14 (dial units)

Counts/2mins

HV#13 = 7.00

HV#13 = 7.20

HV#13 = 7.40

HV#13 = 7.60

HV#13 = 7.80

HV#13 = 8.00

HV#13 = 8.20

HV#13 = 8.40

HV#13 = 8.60

HV#13 = 8.80

HV#13 = 9.00

HV#13 = 9.20

HV#13 = 9.40

HV#13 = 9.60

HV#13 = 9.80

HV#13 = 10.00


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II. Flux

Muons reach the surface of the Earth with typically constant flux F.

(count rate)d2

F = (area of top panel)(area of bottom panel)

F = 0.48 cm-2min-1sterad-1 (PDG theoretical value)

Count rate: 0.585cm-2min-1(horizontal detectors)

Our experimental value: 36min-1 (8% efficiency)


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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


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With altitude

Results:


Flux vs. floor level

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 1 2 3 4 5 6 7 8

floor

flux(count/min.cm^2.s

terad)


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With zenith angle

Expected result:

F ~ cos2



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With zenith angle

Rotation mount for support of the setup:



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With zenith angle Results:

(7th floor Crawford)


Flux vs. zenith angle

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

-150 -100 -50 0 50 100 150

zenith angle (degrees)

Flux(count/min.cm^2.s

terad)


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(7th floor Crawford)


Flux vs. cosine squared of zenith angle (expect lin. dependence)

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 0.2 0.4 0.6 0.8 1 1.2

cosine squared of zenith angle (degrees)

Flux(count/min.cm^2.s

terad)


18/38


(Observatory)


flux vs.

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

-100 -50 0 50 100

(degrees)

flux(count/

min.cm^2.s

terad


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(Observatory)


flux vs. (cos)^2

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

0 0.2 0.4 0.6 0.8 1 1.2

(cos)^2

flux(count/min.cm^2.s

terad


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With cardinal points

Results:

(Senior Lab)


(total) count rate with azimuthal angle

EW rotation

0.00

0.501.00

1.50

2.00

2.50

3.00

3.50

-100 -50 0 50 100

angle (degrees)

coun

trate(min^-1)


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Results:

(Senior Lab)


(total) count rate with cosine squared of azimuthal

angle

EW rotation

0.00

1.00

2.00

3.00

4.00

0.000 0.200 0.400 0.600 0.800 1.000 1.200

cos^2()

countrate(min^-1)


22/38


Results:

(Senior Lab)


(total) count rate with azimuthal angle

NS rotation

0.00

1.00

2.00

3.00

4.00

-100 -50 0 50 100

angle (degrees)

coun

trate(min^-1)


23/38


Results:

(Senior Lab)


(total) count rate with cosine squared of azimuthal

angle

NS rotation

0.00

1.00

2.00

3.00

4.00

0.000 0.200 0.400 0.600 0.800 1.000 1.200

cos^2()

countrate(min^-1)


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Results:

(Senior Lab)


Superimposed count rate for NS and EW rotation

0.00

0.50

1.00

1.50

2.00

2.50

3.00

3.50

4.00

-100 -50 0 50 100

zenith angle (degrees)

countra

te(counts/min)

EW rotation

NS rotation


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With overlap area


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With overlap areaResults:


flux vs. overlap area

0

0.0015

0.003

0.0045

0.006

0.0075

0.009

0.0105

0 20 40 60 80 100 120

% overlap

flux(co

unt/min.cm^2.s

terad)

Series1

Series2


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IV. Investigation of count rate variation

With overlap areaResults:

count rate vs. overlap area (min separation distance)

y = 0.2971x + 1.4425R

2= 0.9938

y = 0.2575x + 1.5875

R2 = 0.99980

5

10

15

20

25

3035

0 20 40 60 80 100 120

% overlap

coun

trate(min^-1)

Series1

Series2

Linear (Series1)

Linear (Series2)


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With separation distance d between the two paddlesExpected results: count rate is proportional to stereo angle viewed

along a specific direction

stereo angle vs. d

0

0.5

1

1.5

2

0 2 4 6 8

d (in multiples of l)

stereoangle

(*s

terad)

Values calculatedusing Mathematicaintegral output

Rectangular

arrangement;top/bottom phase

constant (lxl); d

varies (multiples of l)


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With separation distance d between the two paddlesResults:

count rate (about vertical direction) vs. separation dis tance d

0.00

2.00

4.00

6.00

8.00

10.00

12.00

0 20 40 60 80 100 120

distance d (cm)

counts/min


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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


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(Observatory)

V.Investigation of doubles flux variation

data plot for double hits at different angles

0

20

40

60

80

100

120

140

160

180

200

-100 -50 0 50 100

angle (degrees)

# of doubles

% of doubles

total # of hits


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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


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Results:

y = -63.856 + 616.791e-0.4552x

Lifetime T:

T = 2.1965s

Tth= 2.1970s



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Results:

y = 14.7029 + 1493.09e-0.4601x

Lifetime T:

T = 2.1733s

Tth

= 2.1970s



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Results:

Lifetime T:

T = 2.1422s

Tth

= 2.1970s

VI. Muon lifetime experiment (verification)

N(t) = No e^(-t/T)y = 696.16e-0.4668x

R2 = 0.996

0

100

200

300

400

500

600

700

800

0 5 10 15 20

time t (microseconds)

N(t)(sample) noise level

N(t) before noise

subtraction

Expon. (N(t) before

noise subtraction)


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Results:

Lifetime T:

T = 2.1678s

Tth

= 2.1970s

VI. Muon lifetime experiment (verification)

N(t) = No e^(-t/T) [after noise subtraction]

y = 465.2e-0.4613x

R2 = 0.9795

0

100

200

300

400

500

600

0 5 10 15 20

time t (microseconds)

N(t)(remainingsam

ple)

after noise subtraction

Expon. (af ter noise

subtraction)


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In progress

Make use of:

DAQ v.2 boardGPS option

Another 5 detector setups assembled

during QuarkNet

IX. Air shower experiment


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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/
http://pdg.lbl.gov/2002/cosmicrayrpp.pdfhttp://www2.slac.stanford.edu/vvc/cosmicrays/crdctour.htmlhttp://hermes.physics.adelaide.edu.au/astrophysics/muon/http://hermes.physics.adelaide.edu.au/astrophysics/muon/http://www2.slac.stanford.edu/vvc/cosmicrays/crdctour.htmlhttp://pdg.lbl.gov/2002/cosmicrayrpp.pdf

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