Minerva is a Masterclass tool allowing students to learn more about the physics that goes on in the ATLAS detector at the LHC. Currently, Minerva has two scenarios. One a tried and tested, well established exercise, where students must analyse events, using information from all parts of the detector to identify W and Z bosons. Another is an exercise where students must find the decay products of neutral strange particles, which will eventually culminate in the calculation of the mass and lifetime of the strange particle.
The aim of the exercise was to identify particles in the ATLAS detector at the LHC.
Identify electrons (e), muons (m), neutrinos(n) in the ATLAS detector
Types of Events (“particles produced in one collision”)
Do W and Z decay equally often in electrons and muons?
Students scanned a mix of various physics events and classified them in the following categories
Background from jet production (which might look like W or Z event)
All the above events are ‘well-known’ processes
Data came from 2010 LHC collisions!
In addition one event was added which was a candidate Higgs event, it may appear as:
After the students finished the results from each group were collected and the ratio of
was calculated and the ratio of Z/W production was compared with the predictions.
To do the exercise the Atlantis visualisation program was used
Principle of collider experiment
The LHC collide protons against protons
The collision energy is used to create particles
The particles created in the detector are identified. This done through their interaction with matter
Only the end products of the reaction can be ‘seen’ not the reaction itself. A deduction needs to be made about what happened from this.
A detector is built symmetrically around the collision point. It is composed of several layers of detectors; each detector probes a different aspect of the event
The first event to be analysed was already displayed
The students had to study each event and classify it into 5 different categories
Many more W’s are produced compared to Z events
Note: in reality there many more background events than here
The students were given some additional sheets to help them
They had to decide what type it was and tick the corresponding box
Only one tick per event!
When everything was done the totals were added up.
If the students had finished their 20 events they could hunt for the Higgs by looking at other set(s) of events
There is only one Higgs event
in the whole sample
At the end a final summary was done and the group looked at the ratio
and the ratio W/Z production together
The photographs show the year 13 students doing the analysis. Unfortunately they were not able to find the Higgs Boson this year. Just as well CERN found it in 2012.