Antimatter and Some Field Trips

 Good morning, everyone!

This morning started with another lecture, but this time it was about how AI is used at CERN.  The main takeaways here were the massive amounts of data needed to process the amount of data generated by the LHC, roughly 40TB/s.  The data first travels to a hardware trigger that looks quickly for interesting physics.

This image is of the Trigger system of the CMS for example.

This trigger drops the data from 40 TB to 100GB/s, then this data is scoured by a machine that has been trained to look for interesting material developed by the coders.  The next Trigger drops the data transfer to 1 GB/s.  This data is sent into the world wide computer grid to be processed.  

We currently are throwing away tons of data but the questions really is, "are we throwing out anything worth keeping?" Maurizio Pierini took time to explain how machine learning could highlight some more interesting runs that would have been thrown out if the decision were left up to the first trigger.  

Later, we learned about how CERN is protected from radiation from the head of radiation protection for CERN, Claudia Ahdida.  She talked first about radiation and defined the ideas of effective dose that measures the effect of ionizing radiation on the health of someone.  It is measured in Sieverts, J/kg.  It takes into account absorbed dose and dose equivalent which is adjusted by radiation type, alpha, beta or gamma.  Lastly, to get effective dose, you must take into account the organ or tissue that is being affected.  

Protection comes in three possible methods, Justification, Limitation and Optimization.  First, anyone put into a radiation zone, must have a reason to be there; there must be a net positive reason to send someone there.  Then, workers must be limited in the time that the spend near the sources.  Finally, personal and collective doses should be made As Low As Reasonably Achievable (ALARA).  This could include training in mock situations, making fast connections or unfastening, using robots, keeping distance with extendable tools, and even using shielding.

Louis came back to spend some time talking to us about the Taming of Small Things where he talked to us about the historical growth of particle physics starting from the 1800's and the development of the processes to find the electron by JJ Thomson and the prediction of the positron by Paul Dirac.  The growth of the science led to the development of the atomic bomb and the Manhattan Engineering District  which employed nearly 130,000 people and cost $2.2 billion from 1939 to 1945, and although they tried their hardest for secrecy, the Soviet spies had stolen enough to build their own technology in a very short time.  We then discussed how by finding new science we should be focused on peaceful use and avoiding the use of findings for war.  In the case of CERN part of their philosophy  is to avoid developing research that could be used for weapons.

In the afternoon we took a field trip to the Antimatter factory were antiparticles like positrons and antiprotons are decelerated and in some cases held in stasis.  The first thing that happens to make the antimatter is the Proton Synchrotron (PS) sends protons to the factory which collide with a target that emits antiprotons.  The antiprotons enter to the AD or Antimatter Deccelerator.  Then the protons enter ELENA which slows the beam down using the same physics that accelerators use.  Lastly, the antiparticles are sent to AEGIS (Antimatter Experiement: Gravity, Interferometry, Spectroscopy), GBAR (Gravitational Behaviour of Antihydrogen at Rest), ALPHA (Antihydrogen Laser Physics Apparatus), BASE (Baryon Antibaryon Symmetry Experiment), or ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons).  

With RF energy pushing back as the antiparticles pass by the RF cavity, the AD, begins to slow in the loop.  As they slow down, though, they must be cooled using an electron bath.  The electron bath enters the beam and bounces around the antiprotons to have them shake and vibrate less, which makes them have less likelihood to bounce out of the beamline.  The electrons each bounce off some antiprotons taking the energy away from the antiprotons as they speed up.  This same process occurs again in ELENA to make the antiparticles even slower.

GBAR uses first year physics to test for the relationship between antimatter and gravity by testing how antiparticles behave in a horizontal launch. 

The last experiment we visited was AEGIS that attempts to trap and experiment with antihydrogen and then record observations made using gravitational and spectroscopy to see if it behaves as hydrogen does. 

After the trip to the AF, we went to see the LEIR, Low Energy Ion Ring.  Because the LHC is currently using protons, experimenters do not need to accelerate large ions like lead, so we were able to go in and see the accelerator up close. 

We also got to see the remains of LINAC 2, the linear accelerator that pushed the protons that created the data to help find the Higgs boson. 

We also got to listen to the current heartbeat of the LHC, LINAC 4 that accelerates protons to enter the PS then the BOOSTER and  then SPS and finally LHC (for now).  Humming with a period of 1.2s, the accelerator pushes particles into the accelerator chain.

Finished with a game of cribbage with my colleague from Canada! 

I lost, but that was a fun game!