Identifying p-p collision events
@ 8 TeV with HYPATIA
●
Look at event displays of 50-100 collision
events from LHC
–
Identify electrons, muons and photons
–
Calculate invariant mass of particle pairs
–
Combine results with others
Invariant mass
E1, p1
c
e
d
Z
E1, p1
s
y
a
E2, p2
E2, p2
mZ =
(√
E 1+ E 2
c
2
2
) (
−
⃗
p1 + ⃗
p2
c
https://kjende.web.cern.ch/kjende/en/zpath_equation.htm
2
)
Invariant mass
s
g ys
g
Hi ca
de
(a bot more complicated when 4 leptons in final state; need to calculate each
lepton pair first to find mass of each Z-boson. Then use the formula below to find
mass of Higgs)
mH=
(√
E 1+ E 2
c
2
2
) (
−
⃗
p1 +⃗
p2
c
https://kjende.web.cern.ch/kjende/en/zpath_equation.htm
2
)
Invariant mass – in practice
Invariant mass – for discovery
Invariant mass – for discovery
The exercise
●
●
●
●
Analyse 50-100 real collision events from LHC at 8TeV
Categorize eache event into either:
● Di-lepton event (e+e- or μ+μ-)
● 4-lepton event (e+e-μ+μ- , μ+μ-μ+μ- or e+e-e+e-)
● Di-photon event
Calculate invariant mass (program does it for you)
Upload your results - to be combined with the other students
Go to this page and follow instructions:
https://kjende.web.cern.ch/kjende/en/zpath_data.htm
Student #
Distribution
of datasets
Datasets
1
1A
1B
2
1C
1D
3
1E
1F
4
1G
1H
5
1I
1J
6
1K
1L
7
1M
1N
8
1O
1P
9
1Q
1R
10
1S
1T
11
2A
2B
12
2C
2D
13
2E
2F
14
2G
2H
http://cernmasterclass.uio.no/OPloT/
15
2I
2J
16
2K
2L
uname: ippog
paswd: imc
17
2M
2N
18
2O
2P
19
2Q
2R
20
2S
2T
21
3A
3B
22
3C
3D
23
3E
3F
24
3G
3H
https://kjende.web.cern.ch/kjende/en/zpath_data.htm
25
3I
3J
●
●
●
●
●
●
Two datatsets per student
Each dataset contains 50 events
● A total of 100 events per student
When finished with one dataset (i.e.
50 events) export results to textfile
(see description on next slide) and
upload to:
Choose today's data, «FYS3510 –
Oslo» and your datatset number
Upload file
Start analysing next file!
How to upload events
●
When finished analysing:
– Choose «File» -> «Export Invariant Masses»
● Save the file somewhere you'll remember
– Go to: http://cernmasterclass.uio.no/OPloT/
– Choose «Student»: choose today's date (April 16) ->
«FYS3510 – Oslo» -> your dataset number and letter (see
password, username below)
– Upload file and hit submit
– Your done!
Password: ***, username: ippog