what is the nature of our universe? what is it ......scientists from around the world go to cern to...

Brenda Baldacchino, CERN February 2019 1 | P a g e

What is the nature of our universe? What is it

made of? Scientists from around the world go to

CERN to seek answers to such fundamental

questions using particle accelerators and pushing

the limits of technology.

During February 2019, I was

given a once in a lifetime

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.

What does “CERN” stand for? At an

intergovernmental meeting of UNESCO in Paris in

December 1951, the first resolution concerning the

establishment of a European Council for Nuclear Research

(in French Conseil Européen pour la Recherche Nucléaire)

was adopted. Two months later, the acronym CERN was

born. Today, our understanding of matter goes much deeper

than the nucleus, and CERN's main area of research is

particle physics. Because of this, the laboratory operated by

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

record the results of these collisions.

Founded in 1954, the CERN laboratory

sits astride the Franco-Swiss border

joint ventures and now has 22 member

states.

----------------------------------------- DAY 1 --------

The 600 MeV Synchrocyclotron (SC), built in

1957, was CERN’s first accelerator. It provided

beams for CERN’s first experiments in particle and nuclear

physics. In 1964, this machine started to concentrate on

nuclear physics alone, leaving particle physics to the newer

and more powerful Proton Synchrotron.

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

nuclear physics to astrophysics and medical physics. In 1990,

ISOLDE was transferred to the Proton Synchrotron Booster, and

the SC closed down after 33 years of service.

SM18 is CERN’s main facility for testing large and heavy

superconducting magnets at liquid helium temperatures. The

facility provides the required technical infrastructure for

continuous and reliable operation. Test capabilities comprise

electrical, cryogenics, vacuum and mechanical verification,

and validation at ambient and liquid helium temperatures.

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

(-269 degrees Celsius) equivalent.

What is a superconductor? Superconductors are

materials that conduct electricity with no resistance, below a

certain temperature. This means that, unlike the more

familiar conductors such as copper or steel, superconductors

can carry a current indefinitely without losing any energy.


Superconductors already have drastically changed the world

of medicine with the advent of MRI machines, which have

meant a reduction in exploratory surgery. Power utilities,

electronics companies, the military, transportation, and

theoretical physics have all benefited strongly from the

discovery of these materials.

Superconductor cable – very thin, super light flexible wire made of

even finer filaments (to make the material as homogeneous as

possible), used to produce an LHC coil. The superconductor wire

can carry a current as high as 13,000Amps when cooled to -

271degrees Celsius using liquid helium.

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.

What is the LHC? The Large Hadron Collider is the

world’s largest and most powerful particle accelerator. It first

started up on 10 September 2008, and remains the latest

addition to CERN’s accelerator complex. The LHC consists

of a 27-kilometre ring of superconducting magnets with a

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,

The main part of the LHC consists of about 9600 magnets that are

needed to keep the particles in their nearly circular orbits and to

focus them. The biggest magnets are the 1232 ‘dipole’ magnets of

length 15m and mass 35 tons,

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.

.


.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

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.

The Birth of the

WORLD WIDE WEB

- Tim Berners-Lee, a British

scientist, invented the World

Wide Web (WWW) in 1989,

while working at CERN.

The web was originally

conceived and developed to

meet the demand for

automated information-

sharing between scientists in

universities and institutes

around the world.

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.

At CERN, there are more than

50,000 CPUs at work. But that’s not

enough…If the LHC data were

written to standard CDs, a stack

about 20km tall would be produced

each year.

On 30 April 1993, CERN put the

World Wide Web software in the

public domain. Later, CERN made a

release available with an open

licence, a more sure way to maximise

its dissemination. These actions

allowed the web to flourish


(Above) NEXTCUBE –

1991, one of the two

first Web Servers in the

world.

Optical Fibre Bundle –

12x12 fibres – 10Gb/s,

current technology of

CERNs local area

network.

----------------------------------------- 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.

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.

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.


----------------------------------------- DAY 3 --------

The AMS looks for dark matter, antimatter and

missing matter from a module on the

International Space Station. The Alpha Magnetic

Spectrometer (AMS-02) is a particle-physics detector that

also performs precision measurements of cosmic rays:

particles from outer space. The Earth is subject to a constant

bombardment of subatomic particles that can reach energies

far higher than the largest machines

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

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

the extreme thermal conditions encountered in space.

The AMS detector measures 64 cubic metres

and has a mass of 8.5 tonnes.

What is S'Cool LAB? S’Cool LAB is a Physics

Education Research facility at CERN which offers high

school students and their teachers the chance to take part in

hands-on & minds-on particle physics experiment sessions.

These activities enable teachers to give their students a

glimpse of life and work in a world-leading international

research institute. By getting hands-on with physics in S'Cool

LAB, students can make discoveries independently, learn to

work scientifically and apply their knowledge in a new

setting.

Mr Jeff Weiner - our teacher programme manager.

Building our own particle detector - the cloud

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.

It is very easy to build a cloud chamber at home with everyday

material, dry ice, and Isopropyl alcohol.


Our very own cloud chamber…you can see different kinds of tracks,

which differ in length, thickness and shape and are produced by

different types of particles.

In the link below, S’Cool Lab provides a DIY manual

including many information on how to interpret the

observations, and what do with cloud chamber (e.g. using

balloons as radioactive sources).

https://scool.web.cern.ch/classroom-activities/cloud-chamber

Ending the day at the Globe…A unique visual

landmark by day and by night, the Globe of Science and

Innovation is a symbol of Planet Earth. It is CERN's outreach

tool for its work in the fields of science, particle physics,

leading-edge technologies and their applications in everyday

life.

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

----------------------------------------- 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

one for an electron with

negative energy. Dirac

interpreted the equation to

mean that for every particle

there exists a corresponding

antiparticle, exactly matching the particle but with opposite

charge. For example, for the electron there should be an

"antielectron", or "positron", identical in every way but with

a positive electric charge.

The insight opened the possibility of entire galaxies and

universes made of antimatter. But when matter and antimatter

come into contact, they annihilate – disappearing in a flash of

energy. The Big Bang should have created equal amounts of

matter and antimatter. So why is there far more matter than

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.

https://scool.web.cern.ch/classroom-activities/cloud-chamber


What is LEIR for? LEIR is an important step in the

sequence of events that inject lead ions into the LHC. In the

LHC, high collisions between the beams of heavy ions create

a quark-gluon plasma that is analysed by the ALICE detector.

This plasma is identical to the state of the universe just after

the Big Bang.

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

magnets. Antimatter is now studied with the AD (Antiproton

Decelerator).

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!

The Antiproton Decelerator is the antimatter ‘factory’ of CERN.

A proton beam that comes from the PS (Proton Synchrotron)

is fired into a block of metal. These collisions create a

multitude of secondary particles, including lots of

antiprotons. These antiprotons have too much energy to be

useful for making antiatoms. They also have different

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.

The AD is a ring composed of bending and focussing magnets that

keep the antiprotons on the same track, while strong electric fields

slow them down.

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 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.

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

experiment to use antiprotons prepared by ELENA, the new

decelerator.

CERN Safety Rules for risks associated with

ionising radiation. Dosimeters are devices used to

measure an estimate of the effective dose received by the

human body through

exposure to external

ionising radiation.

(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.

Thick shielding construction in high-energy facilities

Acknowledgements - I would like to express my deepest

appreciation to all those who provided me with the possibility to

visit CERN. A special gratitude I give to our programme

coordinator, Mr Elton Micallef, engageSTREAM President, who

made this opportunity possible. Furthermore, many thanks goes to

the Teacher Programme Manager at CERN, Mr Jeff Wiener who

invested his full effort in guiding the Maltese team during our stay,

as well as the Professors and lecturers: Dr Kate Shaw (University of

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/

[email protected]

http://cern.ch/jeff.wiener

https://home.cern/

https://indico.cern.ch/event/756371/timetable/

https://scool.web.cern.ch/

mailto:[email protected]

http://cern.ch/jeff.wiener

what is the nature of our universe? what is it ......scientists from around the world go to cern to...

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