MUONS!

What are we going to talk about?

• How muons are created• Detecting methods• Muon half life and decay rate• Muon decay data• Problems with the data and muons

How muons are created.

• Protons from the cosmic rays interact with the atoms in the upper atmosphere and create a shower of particles which decay further to produce muons.

Feynman diagrams

Detecting methods

Muon Enters

A flash is emitted

Decays into an electron

The scintillator detects the electron and emits

a flash

Muon Half Life and Decay Rate.

dN-Change in muons N(t)-Number of muons at given time.

λ-Decay rate dt-change in time

= = hence t= t=0 => No= Our = 0.388 N(t)=No Meaning that half life= 2.6

Muon decay data

1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000 140000

50

100

150

200

250

300

f(x) = 296.890266235369 exp( − 0.388234452776655 x )

Events

Exponential (Events)

Time/ Nanoseconds

Eve

nts

per

ms

Rate of Muon Decay (T)

01/07/2014 – 02/07/2014

1000 2000 3000 4000 5000 6000 7000 8000 90000

50

100

150

200

250

f(x) = 341.212283954139 exp( − 0.408590390039453 x )

Events

Exponential (Events)

Time/ Nanoseconds

Eve

nts

per

ms

02/07/2014 – 03/07/2014

03/07/2014 – 04/07/2014

Problems with the data

• Systematic errors:• The PMT cable was faulty which fluctuated the results

giving inaccurate results as it affected the rate of decay.• Affecting flux rate.

“11’o’clock drop”

How many muons pass through you everyday?

When the person is standing up:• 0.155*(6719073/24)*16=515129 (±0.5)

• When the person is lying down:

0.885*(6719073/24)*8=1982127 (±0.5)

Shoulder: 0.115m2

0.5m

0.23m

Standing: 0.885m2

0.5m

0.177m

How many interact with you

Muons decayed in detector

Total muons through detectorMuons passed

through your body

= 3946

Problems with muons

• They have a half life of 2.2µ yet they can still travel 660m.

• This is due to time dilation, as muons travel 98% the speed of light.

• Therefore, time slows down.

𝛾=1

√¿¿¿5.03 (±0.05 )