LHCb Masterclass
Good Times
Time scales
10–20
Jonas Rademacker
10–10
1
Good Times
seconds
1010
1020
LHCb Masterclass 2013 2
Time scales
10–20
10–10
1
seconds
1010
1020
D0
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 2
Time scales
10–20
10–10
1
seconds
1010
1020
D0
birth of the universe
4⋅1017s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 2
Time scales
typical life-span
of a person
2.4⋅109s
10–20
10–10
1
1010
seconds
1020
D0
birth of the universe
4⋅1017s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 2
Time scales
Heart beats
once every 1s
10–20
10–10
1
typical life-span
of a person
2.4⋅109s
1010
seconds
1020
D0
birth of the universe
4⋅1017s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 2
Time scales
Heart beats
once every 1s
10–20
10–10
1
typical life-span
of a person
2.4⋅109s
1010
extinction of
dinosaurs
2⋅1015 s ago
seconds
1020
D0
birth of the universe
4⋅1017s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 2
Time scales
Heart beats
once every 1s
10–20
10–10
1
typical life-span
of a person
2.4⋅109s
extinction of
dinosaurs
2⋅1015 s ago
1010
seconds
1020
D0
First homo
sapiens
6⋅1012 s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Good Times
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 2
Time scales
Heart beats
once every 1s
10–20
10–10
D
1
0
extinction of
dinosaurs
2⋅1015 s ago
1010
seconds
1020
This talk: ca
103 s
First homo
sapiens
6⋅1012 s ago
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
typical life-span
of a person
2.4⋅109s
Good Times
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 2
Time scales
Heart beats
once every 1s
10–20
10–10
D
Jonas Rademacker
1
0
Average lifetime
of a D0 meson
4⋅10–13s
typical life-span
of a person
2.4⋅109s
extinction of
dinosaurs
2⋅1015 s ago
1010
seconds
1020
This talk: ca
103 s
T=1/f of a
piano string
4⋅10–3 s
Good Times
First homo
sapiens
6⋅1012 s ago
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 2
Time scales
T=1/f of an
atomic clock
10–10 s
10–20
10–10
D
typical life-span
of a person
2.4⋅109s
1
0
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Heart beats
once every 1s
extinction of
dinosaurs
2⋅1015 s ago
1010
seconds
1020
This talk: ca
103 s
T=1/f of a
piano string
4⋅10–3 s
Good Times
First homo
sapiens
6⋅1012 s ago
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 2
Time scales
Average lifetime
of a Higgs
boson
1.6⋅10–22s
T=1/f of an
atomic clock
10–10 s
10–20
10–10
D
typical life-span
of a person
2.4⋅109s
1
0
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Heart beats
once every 1s
extinction of
dinosaurs
2⋅1015 s ago
1010
seconds
1020
This talk: ca
103 s
T=1/f of a
piano string
4⋅10–3 s
Good Times
First homo
sapiens
6⋅1012 s ago
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 2
Time scales
You measured an incredibly short amount of time!
D0
Average lifetime
of a D0 meson
4⋅10–13s
Heart beats
once every 1s
Jonas Rademacker
Good Times
LHCb Masterclass 2013 3
Time scales
You measured an incredibly short amount of time!
D0
Average lifetime
of a D0 meson
4⋅10–13s
Heart beats
once every 1s
Jonas Rademacker
≈
Heart beats
once every 1s
First homo
sapiens
6⋅1012 s ago
Good Times
LHCb Masterclass 2013 3
Time scales
You measured an incredibly short amount of time!
D0
Average lifetime
of a D0 meson
4⋅10–13s
Heart beats
once every 1s
Jonas Rademacker
≈
Heart beats
once every 1s
First homo
sapiens
6⋅1012 s ago
Good Times
This talk: ca
103 s
≈
extinction of
dinosaurs
2⋅1015 s ago
LHCb Masterclass 2013 3
Time scales
You measured an incredibly short amount of time!
D0
Average lifetime
of a D0 meson
4⋅10–13s
Heart beats
once every 1s
Jonas Rademacker
≈
Heart beats
once every 1s
First homo
sapiens
6⋅1012 s ago
Good Times
This talk: ca
103 s
≈
≈
extinction of
dinosaurs
2⋅1015 s ago
2h
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 3
How did you do it?
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
How did you do it?
• Trick: very high speeds! D mesons travel nearly at the
speed of light at LHCb. Typically v ≈ 0.99919 × c
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
How did you do it?
• Trick: very high speeds! D mesons travel nearly at the
speed of light at LHCb. Typically v ≈ 0.99919 × c
• v × 0.41 ps = 0.12 mm
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
How did you do it?
• Trick: very high speeds! D mesons travel nearly at the
speed of light at LHCb. Typically v ≈ 0.99919 × c
• v × 0.41 ps = 0.12 mm
• However, they really fly typically ~3 mm, much further.
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
How did you do it?
• Trick: very high speeds! D mesons travel nearly at the
speed of light at LHCb. Typically v ≈ 0.99919 × c
• v × 0.41 ps = 0.12 mm
• However, they really fly typically ~3 mm, much further.
• This is because of time dilation (Special Relativity). Fast
D0 mesons live longer. A lifetime at rest of 0.41 ps means
a lifetime inside our experiment of ca 10ps
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
How did you do it?
• Trick: very high speeds! D mesons travel nearly at the
speed of light at LHCb. Typically v ≈ 0.99919 × c
• v × 0.41 ps = 0.12 mm
• However, they really fly typically ~3 mm, much further.
• This is because of time dilation (Special Relativity). Fast
D0 mesons live longer. A lifetime at rest of 0.41 ps means
a lifetime inside our experiment of ca 10ps
• So with incredibly high speeds, we win twice: The D0
travels further in any given time, plus it lives longer ->
measurable distances (several mm).
Jonas Rademacker
Good Times
LHCb Masterclass 2013 4
What you found
• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
K
D0
a
m
m
few
π
primary
vertex
Jonas Rademacker
Good Times
LHCb Masterclass 2013
5
What you found
• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
K
D
a
0
m
m
few
K
D0
π
m
π
a
m
w
e
f
B
primary
vertex
primary
vertex
Jonas Rademacker
Good Times
LHCb Masterclass 2013
5
What you found
• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
K
π
m
B
a
primary
vertex
or
e
a
m
m
π
m
w
e
f
m
a
m
m
few
D0
fe
w
D
0
K
primary
vertex
Jonas Rademacker
Good Times
LHCb Masterclass 2013
5
What you found
• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
K
primary
vertex
π
m
m
B
or
e
a
m
m
π
m
w
e
f
fe
w
a
m
m
few
D0
a
D
0
K
IP
primary
vertex
Jonas Rademacker
Good Times
LHCb Masterclass 2013
5
What you found
Jonas Rademacker
Good Times
LHCb Masterclass 2013 6
Decay time distribution
You found an exponential decay time distribution.
linear scale
log-scale
Jonas Rademacker
Good Times
LHCb Masterclass 2013 7
Decay time distribution
You found an exponential decay time distribution.
linear scale
log-scale
Is this really expected?
Jonas Rademacker
Good Times
LHCb Masterclass 2013 7
Same distribution for humans
(death probability vs age for female
New Zealanders)
!5,000!
!4,500!
!4,000!
!3,500!
!3,000!
!2,500!
!2,000!
!1,500!
!1,000!
!!!500!
!!!!!0!
!!0!
Jonas Rademacker
!20!
!40!
!60!
Good Times
!80!
100!
120!
LHCb Masterclass 2013 8
Decay/death probability
!6,000!
!5,000!
particles
people
!4,000!
!3,000!
!2,000!
!1,000!
!!!!!0!
!!0!
!10!
Jonas Rademacker
!20!
!30!
!40!
!50!
!60!
!70!
Good Times
!80!
!90!
100!
LHCb Masterclass 2013 9
Probability to die/decay next year
probability that, given person/particle survived until year x, she/it will die/decay
within the following year.
particles
people
0.40000#
0.35000#
0.30000#
Particles can decay,
but they don’t age.
0.25000#
0.20000#
0.15000#
0.10000#
0.05000#
0.00000#
##0#
#20#
Jonas Rademacker
#40#
#60#
#80#
Good Times
100#
120#
The shape of the
decay time
distribution is a
direct consequence
of that.
LHCb Masterclass 2013 10
Summary
• You measured an incredibly short
amount of time!
D0
Average lifetime
of a D0 meson
4⋅10–13s
• You did so exploiting enormous speeds,
and special relativity.
Heart beats
once every 1s
≈
First homo
sapiens
6⋅1012 s ago
Heart beats
once every 1s
• ... and one of the most sophisticated
machines in the world.
• You found an exponential decay rate ->
particles don’t age.
!6,000!
!5,000!
!4,000!
!3,000!
• The exact value of your fit result is an
important parameter in particle physics.
Jonas Rademacker
Good Times
!2,000!
!1,000!
!!!!!0!
!!0!
!10!
!20!
!30!
!40!
!50!
!60!
!70!
!80!
LHCb Masterclass 2013 11
!90!
100!
Backup
Jonas Rademacker
Good Times
LHCb Masterclass 2013 12
•
Higgs: 1.56e-22
•
D0: 4.1e-13
•
Middle C: 261.63 Hz -> 3.8e-3
•
second: 1e0
•
minute: 6.0e1
•
hour: 3.6e3
•
day: 8.6e4
•
year: 3.2e7
•
human lifetime: 2.4e9
•
Fall of Rome 4.7e10 (ca 1,500 years ago)
•
end of last ice age 3.2e11 (10,000 years ago)
•
Last neanderthal: 9.5e11 (30,000years ago)
•
first homo sapiens 6.3e12 (200,000 years ago)
•
end of dinosaurs: 2.1e15 (66 M years ago)
•
The alpes: 1.0e16
•
planet earth: 1.4e17
•
universe: 4.3e17 (13.77 billion years)
•
2 hours/age of univers = tauDo/1 second.
Jonas Rademacker
Good Times
LHCb Masterclass 2013 13
Probability to die/decay next year
90.00!
80.00!
70.00!
particles
people
60.00!
50.00!
40.00!
30.00!
20.00!
10.00!
!0.00!
!!0!
!20!
Jonas Rademacker
!40!
!60!
!80!
Good Times
100!
120!
Particles can decay,
but they don’t age.
The shape of the
decay time
distribution is a
direct consequence
of that.
LHCb Masterclass 2013 14
Time scales
Average lifetime
of a Higgs
boson
1.6⋅10–22s
T=1/f of an
atomic clock
10–10 s
10–20
10–10
D
typical life-span
of a person
2.4⋅109s
1
0
Average lifetime
of a D0 meson
4⋅10–13s
Jonas Rademacker
Heart beats
once every 1s
extinction of
dinosaurs
2⋅1015 s ago
1010
1020
This talk: ca
103s
T=1/f of a
piano string
4⋅10–3 s
Good Times
Last
Neanderthal
ca1012 s ago
birth of the universe
4⋅1017s ago
LHCb Masterclass 2013 15