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

Cosmic Ray Muon DetectionCosmic Ray Muon Detection

Department of Physics and Space Sciences

Florida Institute of Technology

Georgia Karagiorgi

Julie Slanker

Advisor: Dr. M. Hohlmann

Cosmic Ray MuonsCosmic Ray Muons

Main goalsMain 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

EquipmentEquipment

2 scintillation detectors developed at Fermilab

2 PMT tubes

2 PM bases

2 Coincidence logic boards (version 1 and version2)

Scintillation DetectorsScintillation 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.

SetupSetup

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.I. Setting up equipment 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 measurementsPlateau 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)

Co

un

ts/2

min

s

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

Plateau measurementsPlateau measurements

For coincidences

Coincidence Plateau (superimposed)

0

50

100

150

200

250

300

350

6.80 7.30 7.80 8.30 8.80

HV#14 (dial units)

Co

un

ts/2

min

s

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

II.II. Flux 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)

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.III. Investigation of flux variation Investigation of flux variation

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

(cou

nt/m

in.c

m^2

.ste

rad)

With zenith angle θ

Expected result:

Fμ ~ cos2 θ



Rotation mount for support of the setup:



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 θ (degrees)

Flu

x (c

ount

/min

.cm

^2.s

tera

d)


Results:

(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 θ (degrees)

Flu

x (

count/

min

.cm

^2.s

tera

d)


Results:

(Observatory)


flux vs. θ

0

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

-100 -50 0 50 100

θ (degrees)

flux

(cou

nt/m

in.c

m^2

.ste

rad)


Results:

(Observatory)


flux vs. (cosθ)^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

(cosθ)^2

flux

(cou

nt/m

in.c

m^2

.ste

rad)

With cardinal points

Results:

(Senior Lab)


(total) count rate with azimuthal angle θEW rotation

0.000.501.001.502.002.503.003.50

-100 -50 0 50 100

angle θ (degrees)

cou

nt

rate

(m

in^

-1)


Results:

(Senior Lab)


(total) count rate with cosine squared of azimuthal angle θ

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(θ)

cou

nt

rate

(m

in^

-1)


Results:

(Senior Lab)


(total) count rate with azimuthal angle θNS rotation

0.00

1.00

2.00

3.00

4.00

-100 -50 0 50 100

angle θ (degrees)

cou

nt

rate

(m

in^

-1)


Results:

(Senior Lab)


(total) count rate with cosine squared of azimuthal angle θ

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(θ)

cou

nt

rate

(m

in^

-1)


Results:

(Senior Lab)


Superimposed count rate for NS and EW rotation

0.000.501.001.502.002.503.003.504.00

-100 -50 0 50 100

zenith angle θ (degrees)

coun

t rat

e (c

ount

s/m

in)

EW rotation

NS rotation


With overlap area

With overlap area

Results:


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

(cou

nt/m

in.c

m^2

.ste

rad)

Series1

Series2

IV.IV. Investigation of count rate variation Investigation of count rate variation

With overlap area

Results:

count rate vs. overlap area (min separation distance)

y = 0.2971x + 1.4425

R2 = 0.9938

y = 0.2575x + 1.5875

R2 = 0.99980

5

10

15

20

25

30

35

0 20 40 60 80 100 120

% overlap

coun

t rat

e (m

in^-

1)

Series1

Series2

Linear (Series1)

Linear (Series2)


With separation distance d between the two paddles

Expected 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)

ster

eo a

ngle

(*π

ste

rad)

Values calculated using Mathematica integral output

Rectangular arrangement; top/bottom phase constant (lxl); d varies (multiples of l)


With separation distance d between the two paddles

Results:

count rate (about vertical direction) vs. separation distance 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)

coun

ts/m

in

Using the DAQ v.1 board, we recorded low energy (decaying) muon events on the computer.

These events are called “doubles.”

V.V. Investigation of “doubles’ flux” variation Investigation of “doubles’ flux” variation


Results:

(Observatory)

V.V. Investigation of “doubles’ flux” variation 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 θ (degrees)

# of doubles

% of doubles

total # of hits

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.VI. Muon lifetime experiment Muon lifetime experiment

Results:

y = -63.856 + 616.791e-0.4552x

Lifetime T:T = 2.1965μs

Tth = 2.1970μs


Results:

y = 14.7029 + 1493.09e-0.4601x

Lifetime T:

T = 2.1733μs

Tth = 2.1970μs


Results:

Lifetime T:

T = 2.1422μs

Tth = 2.1970μs

VI.VI. Muon lifetime experiment (verification) 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

) (s

ampl

e)

noise level

N(t) before noisesubtraction

Expon. (N(t) beforenoise subtraction)

Results:

Lifetime T:

T = 2.1678μs

Tth = 2.1970μs

VI.VI. Muon lifetime experiment (verification) 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

) (r

emai

ning

sam

ple)

after noise subtraction

Expon. (after noisesubtraction)

In progress…

Make use of: DAQ v.2 board – GPS option Another 5 detector setups assembled

during QuarkNet

IX.IX. Air shower experiment Air shower experiment

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

Documents

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