What is the nature of our universe? What is it ------DAY 1 ------made of? Scientists from around the world go to The 600 MeV Synchrocyclotron (SC), built in CERN to seek answers to such fundamental 1957, was CERN’s first accelerator. It provided questions using particle accelerators and pushing beams for CERN’s first experiments in particle and nuclear the limits of technology. physics. In 1964, this machine started to concentrate on nuclear physics alone, leaving particle physics to the newer During February 2019, I was given a once in a lifetime and more powerful Proton Synchrotron. opportunity to be part of The Maltese Teacher Programme at CERN, which introduced me, as one of the participants, to cutting-edge particle physics through lectures, on-site visits, exhibitions, and hands-on workshops.
Why do they do all this? The main objective of these type of visits is to bring modern science into the classroom. Through this report, my purpose is to give an insight of what goes on at CERN as well as share my experience with you students, colleagues, as well as the general public. The SC became a remarkably long-lived machine. In 1967, it started supplying beams for a dedicated radioactive-ion-beam facility called ISOLDE, which still carries out research ranging from pure What does “CERN” stand for? At an nuclear physics to astrophysics and medical physics. In 1990, intergovernmental meeting of UNESCO in Paris in ISOLDE was transferred to the Proton Synchrotron Booster, and the SC closed down after 33 years of service. December 1951, the first resolution concerning the establishment of a European Council for Nuclear Research SM18 is CERN’s main facility for testing large and heavy (in French Conseil Européen pour la Recherche Nucléaire) superconducting magnets at liquid helium temperatures. The was adopted. Two months later, the acronym CERN was facility provides the required technical infrastructure for born. Today, our understanding of matter goes much deeper continuous and reliable operation. Test capabilities comprise than the nucleus, and CERN's main area of research is electrical, cryogenics, vacuum and mechanical verification, particle physics. Because of this, the laboratory operated by and validation at ambient and liquid helium temperatures. CERN is often referred to as the European Laboratory for Particle Physics.
Physicists and engineers at CERN use the world's largest and most complex scientific instruments to study the basic ingredients of matter – fundamental particles - the smallest building blocks of our universe. Subatomic particles are made to collide together at close to the speed of light. This process gives us clues about how the particles interact, and provides insights into the fundamental laws of nature.
The instruments used at CERN are purpose-built particle accelerators and detectors. Accelerators boost beams of particles to high energies before the beams are made to collide with each other or with stationary targets. Detectors observe and The facility, erected in a large assembly hall with cranes capable of up to 100 tonnes, provides a cooling capacity of 1.2 kW at 4.5 K record the results of these collisions. (-269 degrees Celsius) equivalent.
What is a superconductor? Superconductors are Founded in 1954, the CERN laboratory materials that conduct electricity with no resistance, below a sits astride the Franco-Swiss border certain temperature. This means that, unlike the more joint ventures and now has 22 member familiar conductors such as copper or steel, superconductors states. can carry a current indefinitely without losing any energy.
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Superconductors already have drastically changed the world What is the LHC? The Large Hadron Collider is the of medicine with the advent of MRI machines, which have world’s largest and most powerful particle accelerator. It first meant a reduction in exploratory surgery. Power utilities, started up on 10 September 2008, and remains the latest electronics companies, the military, transportation, and addition to CERN’s accelerator complex. The LHC consists theoretical physics have all benefited strongly from the of a 27-kilometre ring of superconducting magnets with a discovery of these materials. number of accelerating structures to boost the energy of the particles along the way. The beams inside the LHC are made to collide at four locations around the accelerator ring, corresponding to the positions of four particle detectors – ATLAS, CMS, ALICE and LHCb,
Superconductor cable – very thin, super light flexible wire made of The main part of the LHC consists of about 9600 magnets that are even finer filaments (to make the material as homogeneous as needed to keep the particles in their nearly circular orbits and to possible), used to produce an LHC coil. The superconductor wire focus them. The biggest magnets are the 1232 ‘dipole’ magnets of can carry a current as high as 13,000Amps when cooled to - length 15m and mass 35 tons, 271degrees Celsius using liquid helium.
Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide. The beams travel in opposite directions in separate beam pipes – two tubes kept at ultrahigh vacuum. They are guided around the accelerator ring by a strong magnetic field maintained by superconducting electromagnets. The electromagnets are built from coils of superconducting cable that conducting electricity efficiently without resistance or loss of energy. This requires chilling the magnets to ‑271.3°C – a temperature colder than outer space. For this reason, much of the accelerator is connected to a distribution system of liquid helium, which cools the magnets, as well as to other supply services.
Width of copper cable which would be needed to carry the same current as the thin superconductor – very impractical to be used to wind into a coil due to its inflexibility and large mass. .
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.Inside the LHC
Accelerate! The particles are accelerated by electromagnetic waves that are generated in radio- frequency cavities. There are 8 superconducting cavities per beam operating at -269 degrees Celsius
The Computer Centre at CERN provides the infrastructure for analysing the enormous amount of LHC data; roughly 25 petabytes = 25 million gigabytes of data, per year! The computer centre provides currently 14 PB of disk space (on 42,600 drives) and 34 PB of tape space (45,000 cartridges). The LHC data is distributes via the Worldwide LHC Computing GRID to 11 large computer centres and from there to another 140 computing centres world-wide.
How do you make sure an accelerator is healthy? All the controls for the accelerator, its services and technical infrastructure are housed under one roof at the CERN Control Centre. You can check on it in real time. CERN’s accelerators are outfitted with special technology that monitors things such as beam quality, beam intensity, spacing between the proton bunches, cooling and the power supplies. The computer monitors lining the walls of the CCC give the operators real-time updates about the health of the accelerators so that they can quickly respond if anything goes wrong.
At CERN, there are more than The Birth of the 50,000 CPUs at work. But that’s not enough…If the LHC data were
WORLD WIDE WEB written to standard CDs, a stack - Tim Berners-Lee, a British about 20km tall would be produced scientist, invented the World each year. Wide Web (WWW) in 1989, while working at CERN. The web was originally On 30 April 1993, CERN put the conceived and developed to World Wide Web software in the meet the demand for public domain. Later, CERN made a automated information- release available with an open sharing between scientists in licence, a more sure way to maximise universities and institutes its dissemination. These actions around the world. allowed the web to flourish Brenda Baldacchino, CERN February 2019 3 | P a g e
------DAY 2 ------The CMS detector uses a huge solenoid magnet to bend the paths of particles from collisions in the LHC. The Compact Muon Solenoid has a broad physics programme ranging from studying the Standard Model (including the Higgs boson) to searching for extra dimensions and particles that could make up dark matter.
An unusual feature of the CMS detector is that instead of being built on-site like the other giant detectors of the LHC experiments, it was constructed in 15 sections at ground level before being lowered 100m into an underground cavern near Cessy in France and reassembled.
(Above) NEXTCUBE – 1991, one of the two first Web Servers in the world.
The CMS detector has the shape of a cylinder with a diameter of
15m and a length of 21m, and it has a mass of 12,500 tons.
Optical Fibre Bundle – 12x12 fibres – 10Gb/s, current technology of CERNs local area network.
The CMS detector is built around a huge solenoid magnet. This takes the form of a cylindrical coil of superconducting cable that generates a field of 4 tesla, about 100,000 times the magnetic field of the Earth.
The CMS experiment is one of the largest international scientific collaborations in history, involving 4300 particle physicists, engineers, technicians, students and
support staff from 182 institutes in 42 countries.
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------DAY 3 ------What is S'Cool LAB? S’Cool LAB is a Physics Education Research facility at CERN which offers high The AMS looks for dark matter, antimatter and school students and their teachers the chance to take part in missing matter from a module on the hands-on & minds-on particle physics experiment sessions. International Space Station. The Alpha Magnetic These activities enable teachers to give their students a Spectrometer (AMS-02) is a particle-physics detector that glimpse of life and work in a world-leading international also performs precision measurements of cosmic rays: research institute. By getting hands-on with physics in S'Cool particles from outer space. The Earth is subject to a constant LAB, students can make discoveries independently, learn to bombardment of subatomic particles that can reach energies work scientifically and apply their knowledge in a new far higher than the largest machines setting.
The AMS detector was assembled at CERN. In its seven years on board the Space Station, AMS has collected a huge amount of cosmic-ray data. Data are received by NASA in Houston, and then relayed to the AMS Payload Operations Control Mr Jeff Weiner - our teacher programme manager. Centre (POCC) at CERN for analysis. The AMS detector's first year in space was a learning curve: the data were used to calibrate the detector and fully understand its performance in Building our own particle detector - the cloud the extreme thermal conditions encountered in space. chamber workshop... one of the first particle detectors. Today, cloud chambers are only used in education. Particles coming from the universe are crossing the Earth all the time – they are harmless but invisible to us. Cloud Chambers are detectors which make the tracks of these particles visible. Some decades ago these detectors were used in the first particle physics experiments.
The AMS detector measures 64 cubic metres It is very easy to build a cloud chamber at home with everyday and has a mass of 8.5 tonnes. material, dry ice, and Isopropyl alcohol.
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------DAY4 ------
What is Antimatter? For every particle, there exists an antiparticle, identical except that is has opposite characteristics, such as an opposite charge.
In 1928, British physicist Paul Dirac wrote down an equation – which won Dirac the Nobel Prize in 1933 – which posed a problem: just as the equation x2 = 4 can have two possible solutions (x = 2 or x = −2), so Dirac's equation could have two solutions, one for an electron with positive energy, and Our very own cloud chamber…you can see different kinds of tracks, one for an electron with which differ in length, thickness and shape and are produced by negative energy. Dirac different types of particles. interpreted the equation to In the link below, S’Cool Lab provides a DIY manual mean that for every particle including many information on how to interpret the there exists a corresponding observations, and what do with cloud chamber (e.g. using antiparticle, exactly matching the particle but with opposite balloons as radioactive sources). charge. For example, for the electron there should be an "antielectron", or "positron", identical in every way but with https://scool.web.cern.ch/classroom-activities/cloud-chamber a positive electric charge.
Ending the day at the Globe…A unique visual The insight opened the possibility of entire galaxies and landmark by day and by night, the Globe of Science and universes made of antimatter. But when matter and antimatter Innovation is a symbol of Planet Earth. It is CERN's outreach come into contact, they annihilate – disappearing in a flash of tool for its work in the fields of science, particle physics, energy. The Big Bang should have created equal amounts of leading-edge technologies and their applications in everyday matter and antimatter. So why is there far more matter than life. antimatter in the universe? At CERN, physicists make antimatter to study in experiments. The starting point is the Antiproton Decelerator, which slows down antiprotons so that physicists can investigate their properties.
The Globe (above) - 27 metres high and 40 metres in diameter, it's about the size of the dome of Saint Peter's in Rome!
Wandering the Immeasurable - Sculpture by Gayle Hermick
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What is LEIR for? LEIR is an important step in the A proton beam that comes from the PS (Proton Synchrotron) sequence of events that inject lead ions into the LHC. In the is fired into a block of metal. These collisions create a LHC, high collisions between the beams of heavy ions create multitude of secondary particles, including lots of a quark-gluon plasma that is analysed by the ALICE detector. antiprotons. These antiprotons have too much energy to be This plasma is identical to the state of the universe just after useful for making antiatoms. They also have different the Big Bang. energies and move randomly in all directions. The job of the AD is to tame these unruly particles and turn them into a useful, low-energy beam that can be used to produce antimatter.
This was the site of LEAR, the Low Energy Antiproton Ring. In 1995, just before the ring was decommissioned in 1996, a team of Italian and German physicists observed atoms of antimatter for the first time: antihydrogen.
LEIR has taken the place of LEAR, and uses the same four bending The AD is a ring composed of bending and focussing magnets that magnets. Antimatter is now studied with the AD (Antiproton keep the antiprotons on the same track, while strong electric fields Decelerator). slow them down. The Antiproton Decelerator - Not all accelerators increase a particle's speed! The AD slows down antiprotons so they can be used to study antimatter. Antiprotons are produced and slowed down to 10% the speed of light. Antiprotons can even be stored in a trap!
ELENA (Extra Low ENergy Antiproton) is a new deceleration ring that will soon be commissioned. Coupled with the AD, this synchrotron, with a circumference of 30 metres, will slow the antiprotons even more, reducing their energy by a factor of 50. The Antiproton Decelerator is the antimatter ‘factory’ of CERN. Brenda Baldacchino, CERN February 2019 7 | P a g e
The AD made the headlines in 2002 when large numbers of antihydrogen atoms were produced for the first time. Initial attempts were made to store antiatoms for a long enough time to be able to measure their characteristics. In 2011, an experiment announced that it had produced and trapped antihydrogen atoms for sixteen minutes, which was long enough to be able to study their properties in detail.
(Above RIGHT) You will require a personal dosimeter (DIS) as soon as you need to work in a Radiation Area. This dosimeter is personal and not transferable. In the past, this dosimeter was called a 'film badge'. It includes two dosimeters: one to measure gamma and beta radiation; and one to measure neutron radiation. (Above LEFT) The operational dosimeter is required, in addition to your personal dosimeter, for working in Limited Stay and High Radiation Controlled Radiation Areas. It features a direct dose display, audible indication of the radiation level and alarm functions when thresholds for dose or dose rates are exceeded.
Currently the AD serves several experiments that are studying antimatter and its properties ALPHA, ASACUSA, ATRAP and BASE. Two other experiments, AEGIS and GBAR, are preparing to study the effects of gravity on antimatter. GBAR will be the first Thick shielding construction in high-energy facilities experiment to use antiprotons prepared by ELENA, the new Acknowledgements - I would like to express my deepest decelerator. appreciation to all those who provided me with the possibility to visit CERN. A special gratitude I give to our programme CERN Safety Rules for risks associated with coordinator, Mr Elton Micallef, engageSTREAM President, who ionising radiation. Dosimeters are devices used to made this opportunity possible. Furthermore, many thanks goes to measure an estimate of the effective dose received by the the Teacher Programme Manager at CERN, Mr Jeff Wiener who human body through invested his full effort in guiding the Maltese team during our stay, exposure to external as well as the Professors and lecturers: Dr Kate Shaw (University of ionising radiation. Sussex, GB), Mr Markus Joos, Mr Muhammed Sameed (University of Manchester, GB) and Ms Anja Kranjc Horvat (Univeristy of Potsdam, DE) whose insight further enhanced my knowledge in particle physics. Last but not least, I would also like to acknowledge with much appreciation Mr Joseph Ellul, the Head of School of St. Margaret College Secondary School, who granted the consent and motivated me to engage in this experience.
References: https://home.cern/
https://indico.cern.ch/event/756371/timetable/
https://scool.web.cern.ch/
http://cern.ch/jeff.wiener
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