CMS Detector and its Physics CMS eMasterclass at

CMS Detector and its Physics CMS e-Masterclass at Riyadh

About 10, 000 of its inhabitants came together to build… 12 February 2015 CMS e-Masterclass, André David 2

The Large Hadron Collider
at CERN, Geneva, Switzerland And in July 2012… 12 February 2015 CMS e-Masterclass, André David 3

Two of these 10, 000 people
presented results… Fabiola Gianotti ATLAS Spokesperson 2010 -2012 And in July 2012… 12 February 2015 CMS e-Masterclass, André David Joe Incandela CMS Spokesperson 2012 -2013 4

…that made a lot of 
physicists VERY happy… 12 February 2015 CMS e-Masterclass, André David 5

… including these two guys! Prof. Francois Englert Prof. Peter Higgs 12 February 2015 CMS e-Masterclass, André David 6

SO WHAT IS ALL THE FUSS ABOUT? 12 February 2015 CMS e-Masterclass, André David 7

Our current understanding
of the constituents of matter 12 February 2015 CMS e-Masterclass, André David 8

How do we know this? Smash things together and see what happens! 12 February 2015 CMS e-Masterclass, André David 9

Accelerator Energy 12 February 2015 CMS e-Masterclass, André David 10

12 February 2015 Accelerator Energy CMS e-Masterclass, André David 11

Universal building blocks Quarks Up (u) Lepton electron Chemistry! Down (d) Groups of 3 quarks form Nucleons 12 February 2015 uud = proton udd = neutron CMS e-Masterclass, André David 12

Universal forces 12 February 2015 CMS e-Masterclass, André David 13

Building atoms electrons Helium Atom protons neutrons Multiply by billions and billions… 12 February 2015 CMS e-Masterclass, André David 14

BUT THAT IS NOT THE END OF THE STORY… 12 February 2015 CMS e-Masterclass, André David 15

E=mc 2 The collision energy was used to create something new, that *did* exist but does not any more! 12 February 2015 Accelerator Energy CMS e-Masterclass, André David 16

13, 700, 000 years ago there
were other things in the Universe – that we can “create” in the laboratory So we have built a Time Machine! 12 February 2015 CMS e-Masterclass, André David 17

Fundamental Particles at the time of the Big Bang Leptons Quarks up charm electron muon tau electron neutrino muon neutrino tau neutrino top down strange bottom Le Zoo des particules 12 February 2015 CMS e-Masterclass, André David 18

X It looks like we know everything! In fact we know very little! 12 February 2015 CMS e-Masterclass, André David 19

Answers to simple questions § Since the early 70 s, particle physicists have synthesized all their knowledge in a single model: the «Standard Model» § We know and we understand a lot but we do not know everything … § Mysteries remain unexplained § There are things to discover. . . 12 February 2015 CMS e-Masterclass, André David 20

The massive mystery . . . Why do some fundamental particles have mass while others don’t? 12 February 2015 CMS e-Masterclass, André David 21

Do you remember these guys? Prof. Francois Englert Prof. Peter Higgs 12 February 2015 CMS e-Masterclass, André David 22

Nearly 50 years ago six physicists proposed an explanation of how particles get mass… Higgs Kibble Guralnik 12 February 2015 Englert Brout Hagen CMS e-Masterclass, André David 23

THEORY: The Brout-Englert-Higgs Field The more a particle interacts with this invisible field, the more mass it gets. 12 February 2015 CMS e-Masterclass, André David 24

But if this field is invisible, how
can we PROVE it exists? 12 February 2015 CMS e-Masterclass, André David 25

The theory predicts that the field
has an associated particle: The Higgs Boson! We can try to create the Higgs boson in our experiment! 12 February 2015 CMS e-Masterclass, André David 26

It is predicted to be VERY rare Assume ~7’ 000 grains of rice in a serving of Kabsa… …then the chances of creating and finding a Higgs boson is… Like finding 1 grain if everyone in Riyadh eats Kabsa once a day for a whole month!! 1 in 1, 000, 000 12 February 2015 CMS e-Masterclass, André David 27

And just to make things even more complicated… The Higgs boson would “decay” instantly to lighter particles. We only detect these resulting particles – so we have to be like detectives – look at the evidence to see what happened! 12 February 2015 CMS e-Masterclass, André David 28

But despite all these difficulties Fabiola Gianotti ATLAS Spokesperson 2010 -2012 Joe Incandela CMS Spokesperson 2012 -2013 We found it! 12 February 2015 CMS e-Masterclass, André David 29

We Found Some Higgs Bosons!! These bumps in the data signify a new particle, found in two different ways, at the same mass – about 125 Ge. V/c 2 12 February 2015 CMS e-Masterclass, André David 30

But we have only just started to understand the Higgs boson…and we need to look from every angle 12 February 2015 CMS e-Masterclass, André David 31

SO HOW DO WE “CREATE” PARTICLES IN REALITY? 12 February 2015 CMS e-Masterclass, André David 32

One of the fastest racetracks on earth: The Large Hadron Collider Several thousand billion protons travelling at 99. 9999991% of the speed of light travel round the 27 km ring, 100 m underground, over 11000 times a second! 12 February 2015 CMS e-Masterclass, André David 33

The Lord of the Rings Try it out yourself: http: //natronics. github. io/science-hack-day-2014/lhc-map/ 12 February 2015 CMS e-Masterclass, André David 34

And then what? § After the collisions, we have detectors that “reveal” the presence of different particles. § You will learn today about the CMS detector and how to use it to identify the decays of W and Z bosons. § Enjoy! 12 February 2015 CMS e-Masterclass, André David 35