Post on 18-Jan-2016
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 )