Journey to the centre
of the atom…
David Jenkins
Department of Physics
University of York
Acknowledgment of support
Intended outcomes
 Increased confidence in tackling nuclear and
particle physics in the classroom
 An understanding of the motivations for
contemporary studies in nuclear and particle physics
 Update to the relevance of nuclear physics in energy,
medicine and other applications
 Ideas for lab experiments and demonstrations
 Opportunity to form collaborations with academics
and other teachers
 Exchange ideas and good practice
STFC opportunities
 IoP/STFC school grant of up to £500
 http://www.iop.org/activity/education/Teacher_
Support/Grants/page_4712.html
 STFC small awards of up to £15k
 http://www.stfc.ac.uk/PandS/Contents.aspx
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From Rutherford to the LHC
David Jenkins
Department of Physics
University of York
Ernest Rutherford
(30 August 1871 - 19 October 1937)
It was as if you fired a 15-inch shell
at a sheet of tissue paper and it
came back to hit you.
In science there is only physics; all the
rest is stamp collecting.
The atomic nucleus
 Ensemble of protons and





neutrons
“Mesoscopic system”
Emergent phenomenon
Nuclear force attractive
at long range, repulsive at
short range
Number of protons defines
element
Isotope has same number
of protons, different
number of neutrons
The particle accelerator
 In 1932, Cockcroft and
Walton split the atom by
accelerating protons
into lithium and splitting
into two alpha particles
 They built the first
particle accelerator to
do this
Contemporary topics
 What are the limits of nuclear
existence?
 Proton- and neutron-dripline
 Superheavy elements
 Nuclear astrophysics
 How are the chemical elements
produced in stars/stellar explosions?
 The origins of mass – the Large Hadron
Collider
Magic numbers
Analogue is closed-shells of electrons in atoms
which define Chemistry e.g. noble gases
What is the next magic
number for protons?
Strong synergies with Chemistry what is the heaviest element?
Currently heaviest
element found in the
laboratory (Dubna,
Russia) is element 118
Nuclear Astrophysics
 Big bang produces only H,He





and Li
All other elements cooked up in
stars through nuclear reactions
Challenge is to explain observed
abundances and energy
generation in stars
Key measurements: nuclear
masses, half-lives, reaction rates
Stars produce only elements up
to iron
To produce heavier elements we
need something dramatic supernova!!
Which nuclear reactions are involved?
Supernova
Challenge is to understand how they explode
and what elements are generated
www.triumf.info
www.gsi.de/fair/
http://www.particledetectives.net/
http://www.lhc.ac.uk/for-teachers.html
The origins of mass
From Rutherford to the LHC
French Alps
Geneva
Lake Geneva
French Jura Mts
Large
Hadron
Collider
Turns on
this year
Designed and built
over last two decades
Will help to answer
some of the
deepest mysteries
in science
Collision points
At four places the
beams intersect
ATLAS
CMS
The new periodic table
Matter Particles
Leptons
Quarks
Commonplace particles
Electron, e
u quark
Photon, γ
d quark
c
t
e
d
s
b
νe νμ
Force carriers
Gluon, g
Not to scale!
μ
u
g
W
Z
γ
τ
ντ
Not seen
h
G
• Components
and theory largely understood
• Underlie all of physics, astronomy, chemistry, life!
• Almost all extremely well tested
Several big unanswered questions at the scientific frontier…
Big questions
Where do the particles get their mass from?
Where has all the anti-matter gone?
What is dark matter made of?
What else is out there?
Mass and the Higgs Boson
The Higgs Field
Endows space with a kind of
all-pervasive sticky-treacle
Interactions with this treacle
gives mass to particles
They then travel slower than the speed of light
In this analogy the Higgs Boson
is a treacle-ball – something which
allows us to see the treacle itself
Where has all the
anti-matter gone?
Matter and antimatter
should have been created
in equal amounts
Subtle differences between
matter and anti-matter
will be investigated at the LHC
What is Dark Matter?
Normal:
Made from atoms
Includes stars,
planets, people…
Dark matter: Unknown substance
(not atoms)
May be a “fat cousin”
of normal light
Hope to make & study
it at the LHC
Dark energy:Even weirder!
What else is out there?
 Various exotics considered…
 New forces of nature
 Extra dimensions of space
 Microscopic black holes
The LHC experiments can look for all of these.
Also sensitive to something “completely different”
How is the science done?
From Rutherford to the LHC
Collaborations
Highly multi-national collaborations - a
good and bad thing!
Average experimental collaboration of
thirty (100s in Particle Physics)
How is scientific quality
established?
 Experiments must be approved by
international programme advisory
committees
 Funding for research is given by funding
council e.g. STFC following consultation and
review by peers
 Publications appear in peer-reviewed
journals
A typical experiment
 Led by a spokesperson
 Experiments run 24 hours a day for typically one week
 Perhaps one week before for setup
 Split into 8 hour shifts
 8am-4am shift not unheard of!
 Data written to tape or hard disk - 100s of GBs of data
not untypical
Data analysis and publication
 Data analysed using high-power PCs
 Most of the software written by us on UNIX computers
 Highly-complex analysis often takes some years to reach
conclusion
 Often we compare to Monte Carlo simulations of the
experimental apparatus
 Papers written up and submitted to journals e.g:
 Nature
 Physics Review Letters
 Physical Review C
 European Journal Physics A
 Nuclear Physics A
 Nuclear Instruments & Methods