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What is this hack?
One of the experiments from the Large Hadron Collider (LHC), the Compact Muon Solenoid (CMS) experiment), has released a small amount of the data for educational purposes. However, it is hard to access and even more difficult to understand. Can we hack a better interface to these data? Can we create a website to allow others to use these data for education or art? Or can we do real science with these data ? I'll bring the data and explain what is in these datasets and some simple tools to interface with these data. Looking for hackers, coders, educators, artists and definitely designers, to figure out if this can be done.
The Large Hadron Collider (LHC)
![[1]](http://lhc-machine-outreach.web.cern.ch/lhc-machine-outreach/images/cern-photos/CE0085M.jpg){kind=link}
``The Large Hadron Collider sits in a circular tunnel 27 km in circumference. The tunnel is buried around 50 to 175 m. underground. It straddles the Swiss and French borders on the outskirts of Geneva."
``The LHC is designed to collide two counter rotating beams of protons or heavy ions. Proton-proton collisions are foreseen at an energy of 7 TeV per beam."
The Compact Muon Solenoid (CMS) detector
The data for this hack
What is a muon?
A muon is a subatomic particle, related to the electron, but 200 times more heavy!
It possesses either a positive or negative charge.
Muons do not interact very often with atomic nuclei that make up the CMS detector, and so they travel through much of the material and are relatively easy to detect.
Where are these muons coming from?
When the protons collide in the LHC they produce many other particles. Some of these particles decay very, very quickly and produce a spray of other particles that are then detected in CMS.
Sometimes one of these particles decays to two muons.
Sometimes the muons are coming from two different parent particles.
The goal of this exercise is to figure out when the muons are coming from the same parent. To do this, we calculate the invariant mass of the two-muon system. If there is a preference for certain values of this mass, we may be seeing signs of the common parent particles!
To calculate the mass, we have two choices:
- Classical physics, which relates momentum, energy and mass from the equations of Newton.
- Special relativity, which relates momentum, energy and mass from the equations of Einstein.
We use the following variables for these values:
- m: mass
- v: velocity
- KE/E: kinetic energy/total energy
- p: momentum
- c: the speed of light (300,000,000 meters per second)
Calculating the mass from Classical Physics
p = mv
KE = 1/2 m v^2
KE = p^2 / (2 * m)
Calculating the mass from Special Relativity
E^2 = (p*c)^2 + (m*c^2)^2
(m*c^2)^2 = E^2 - (p*c)^2
With the data we are using, the units have taken into account the factors of c, so that we do not need to include it in our calculations (c=1).
The analysis chain
Collisions in the detector
Science Hack Day contribution!
These are various images produced using the browser-based iSpy detector, written by the CMS collaboration.
These are just 4 of the 100,000 events we analyzed this weekend!
Muons! Masses!
Science Hack Day contribution!
Check out this interactive demo that accumulates the di-muon masses.
Mass distributions
Science Hack Day contribution!
Calculation of the masses assuming Classical Physics or Special Relativity
This visualization uses d3 and is rendering on-the-fly, so you may have to be patient as it runs over the dataset.