LHCb Masterclasslhcb-public.web.cern.ch/.../LHCbMasterclassWrapUp.pdf · piano string 4⋅10–3 s...
Transcript of LHCb Masterclasslhcb-public.web.cern.ch/.../LHCbMasterclassWrapUp.pdf · piano string 4⋅10–3 s...
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10 1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10 1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10 1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10 1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10 1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10
First homo sapiens
6⋅1012 s ago
1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 sD0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10
First homo sapiens
6⋅1012 s ago
1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 s
T=1/f of a piano string
4⋅10–3 s
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10
First homo sapiens
6⋅1012 s ago
1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 s
T=1/f of a piano string
4⋅10–3 s
T=1/f of an atomic clock
10–10 s
D0
Average lifetime of a D0 meson
4⋅10–13s
10–20 10–10
First homo sapiens
6⋅1012 s ago
1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
2
1 1020
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 s
T=1/f of a piano string
4⋅10–3 s
T=1/f of an atomic clock
10–10 s
D0
Average lifetime of a D0 meson
4⋅10–13s
Average lifetime of a Higgs
boson 1.6⋅10–22s
10–20 10–10
First homo sapiens
6⋅1012 s ago
1010seconds
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
3
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
You measured an incredibly short amount of time!
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
3
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
You measured an incredibly short amount of time!
≈Heart beats
once every 1s
First homo sapiens
6⋅1012 s ago
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
3
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
You measured an incredibly short amount of time!
≈Heart beats
once every 1s
First homo sapiens
6⋅1012 s ago
≈extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 s
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
3
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
You measured an incredibly short amount of time!
≈Heart beats
once every 1s
First homo sapiens
6⋅1012 s ago
≈extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103 s
2h≈birth of the universe
4⋅1017s ago
Jonas Rademacker Good Times LHCb Masterclass 2013
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
4
Jonas Rademacker Good Times LHCb Masterclass 2013
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
4
Jonas Rademacker Good Times LHCb Masterclass 2013
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.
4
Jonas Rademacker Good Times LHCb Masterclass 2013
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
4
Jonas Rademacker Good Times LHCb Masterclass 2013
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).
4
Jonas Rademacker Good Times LHCb Masterclass 2013
What you found• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
5
primary vertex
D0
K
πa few mm
Jonas Rademacker Good Times LHCb Masterclass 2013
What you found• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
5
primary vertex
D0
K
πa few mm
B
primary vertex
D0
K
πa few mm
Jonas Rademacker Good Times LHCb Masterclass 2013
What you found• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
5
primary vertex
D0
K
πa few mm
a few
mor
e mm
B
primary vertex
D0
K
πa few mm
Jonas Rademacker Good Times LHCb Masterclass 2013
What you found• It’s tricky. There is background, and there are D
mesons that don’t come from the primary vertex
5
primary vertex
D0
K
πa few mm
a few
mor
e mm
B
primary vertex
D0
K
πa few mm
IP
Jonas Rademacker Good Times LHCb Masterclass 2013
Decay time distribution
7
You found an exponential decay time distribution.
log-scale linear scale
Jonas Rademacker Good Times LHCb Masterclass 2013
Decay time distribution
7
You found an exponential decay time distribution.
log-scale linear scale
Is this really expected?
Jonas Rademacker Good Times LHCb Masterclass 2013
Same distribution for humans
8
!!!!!0!
!!!500!
!1,000!
!1,500!
!2,000!
!2,500!
!3,000!
!3,500!
!4,000!
!4,500!
!5,000!
!!0! !20! !40! !60! !80! 100! 120!
(death probability vs age for female New Zealanders)
Jonas Rademacker Good Times LHCb Masterclass 2013
!!!!!0!
!1,000!
!2,000!
!3,000!
!4,000!
!5,000!
!6,000!
!!0! !10! !20! !30! !40! !50! !60! !70! !80! !90! 100!
Decay/death probability
9
particlespeople
Jonas Rademacker Good Times LHCb Masterclass 2013
0.00000#
0.05000#
0.10000#
0.15000#
0.20000#
0.25000#
0.30000#
0.35000#
0.40000#
##0# #20# #40# #60# #80# 100# 120#
Probability to die/decay next year
10
particlespeople
Particles can decay, but they don’t age.
The shape of the decay time
distribution is a direct consequence
of that.
probability that, given person/particle survived until year x, she/it will die/decay within the following year.
Jonas Rademacker Good Times LHCb Masterclass 2013
Summary• You measured an incredibly short
amount of time!
• You did so exploiting enormous speeds, and special relativity.
• ... and one of the most sophisticated machines in the world.
• You found an exponential decay rate -> particles don’t age.
• The exact value of your fit result is an important parameter in particle physics.
11
Heart beatsonce every 1s
D0
Average lifetime of a D0 meson
4⋅10–13s
≈Heart beats
once every 1s
First homo sapiens
6⋅1012 s ago
!!!!!0!
!1,000!
!2,000!
!3,000!
!4,000!
!5,000!
!6,000!
!!0! !10! !20! !30! !40! !50! !60! !70! !80! !90! 100!
Jonas Rademacker Good Times LHCb Masterclass 2013
• 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.
13
Jonas Rademacker Good Times LHCb Masterclass 2013
Probability to die/decay next year
14
!0.00!
10.00!
20.00!
30.00!
40.00!
50.00!
60.00!
70.00!
80.00!
90.00!
!!0! !20! !40! !60! !80! 100! 120!
particlespeople
Particles can decay, but they don’t age.
The shape of the decay time
distribution is a direct consequence
of that.
Jonas Rademacker Good Times LHCb Masterclass 2013
Time scales
15
1 10201010
birth of the universe 4⋅1017s ago
typical life-span of a person 2.4⋅109s
Last Neanderthalca1012 s ago
Heart beatsonce every 1s
extinction of dinosaurs
2⋅1015 s ago
This talk: ca 103s
T=1/f of a piano string
4⋅10–3 s
T=1/f of an atomic clock
10–10 s
D0
Average lifetime of a D0 meson
4⋅10–13s
Average lifetime of a Higgs
boson 1.6⋅10–22s
10–20 10–10