professor peter i. p. kalmus queen mary, university of london

Antimatter Charters School Peter Kalmus March 2005

Professor Peter I. P. KalmusQueen Mary, University of London

RETTAMITNA

ANTIMATTER


Objectives of Particle Physics

atomelectron

nucleus

protonneutron

quarks

Study of the ultimateconstituents of matter

Nature of the interactionsbetween them


Structure of the Atom

Atom

~ 10-10m

Nucleus

Early 20th Century electron, nucleus

electric forceelectromagnetism

1930s

bunch ofgrapes

Proton +

Neutron

strongforcetown

~ 10-15m


Antiparticles equal and oppositeproperties“predicted”, later discovered

> 200 new “elementary” (?) particles

Creation

Annihilation

+ N e- + e+ + N

e- + e+ +

1950s Antiproton, antineutron

Nobel prizes Dirac, Anderson, Blackett, Segre, Chamberlain

Einstein

E = mc2

now used in positron emission tomography

E = mc2

> 1 MeV


Today’s building blocks

Leptons(do not feel strong force)

electron e- -1

e-neutrino e 0

Quarks(feel strong force)

up u +2/3down d -1/3

proton = u u d+2/3 +2/3 -1/3 = +1

neutron = u d d+2/3 -1/3 -1/3 = 0

4 particles very simple

multiply by 3 (generations)multiply by 2 (antiparticles)

First generation




electron e- -1

e-neutrino e 0


up u +2/3

down d -1/3

muon -1

-neutrino 0

tau -1

-neutrino 0

charm c +2/3

strange s -1/3

top t +2/3

bottom b -1/3




electron e- -1

e-neutrino e 0


up u +2/3

down d -1/3

muon -1

-neutrino 0

tau -1

-neutrino 0

charm c +2/3

strange s -1/3

top t +2/3

bottom b -1/3

Also antileptonsantiquarks

6 leptons6 antileptons

6 quarks6 antiquarks

baryons q q q

antibary. q q q

mesons q q


Forces

Gravity

falling objectsplanet orbitsstarsgalaxies

inversesquare law

graviton

inversesquare law

photon

shortrange

W±, Z0

Electro-magnetic

atomsmoleculesopticselectronicstelecom.

Weak

betadecay

solarfusion

Strong

nuclei

particles

shortrange

gluon


Ultra-high energy collision

A B

Equal nos.particles &antiparticles

10 16 1 TeV

10 13 1 GeV

10 10 1 MeV

10 7 1 keV

10 4 1 eV

10 1 meV

T/K Energy

ParticleEra

NuclearEra

AtomicEra

PrimordialSoup

Sun forms

Todayps ns s ms s

1 day

1 year

Time

Era ofAstronomy

TevatronLEP

History of the UniverseLHC


Earth, Moon, X

Solar system X

Antistars in our Galaxy ?

Other (anti-) galaxies ?

Telescopes X

Cosmic rays ?

AMS (Space station)

Antimatter

Anti-hydrogen : made in lab

Bulk antimatter ? Where ?

Difficult to detect

Annihilation ofAntigalaxy ?

Signal ?

e+ + e - +

0.511 MeV -ray “line”

Alfven hypothesis

Radiation pressure


SymmetriesMany in physics Powerful tools. We consider 2

Particle antiparticle

o (1232) p + +

o (1232) p + -should occur atexactly same rate

C chargeconjugation

1


A B

P parity

Mirror symmetry A and B equally probable(parity conservation)

Before 1957 believed valid for all processes

Symmetries

2

Mirrorreflection


Communication with an Alien

radio signals

If parity conservedcannot tell which is his right hand


superimposeobject and mirror image

If parity conserved expect equal probabilities L and R

Parity violated in weakinteractions ! L R

60 Co 60 Ni + e- +

Parity violation

Parity conserved in all strong and e-m interactions

electrons onlyin this direction

direction of electrons in coil

radioactive cobalt source


Alien

Can now ask alien to set upa parity violation experimentand hence deduce right hand

This one

C violation

Also shown by same expts.

P

CC P

e-

e-

positronsin antiwire

Current reversedin antiwire

diagram looks same as original red

e+

wire

CP appearsconserved

emitted positrons go opposite way

e+

e+

e-

Antiblue


C violationP

CC P

e-

diagram looks same as original red

e+

CP appearsconserved

emitted positrons go opposite way

e-

Antiblue

Experiments have been done with spinning muons


Problem

Right-handedgreen man

Left-handedanti green man

R L?


Meet in space

If he holds outhis left hand

Teach him about our customs


Annihilation


CP violation

Discovered in decays of neutral kaons

- + e+ +

+ + e- +

slightly more probable (0.6 %)

K0 ( d s ) ; K0 ( d s )

KL

Now can unambiguouslydefine antimatter

If the less abundant lepton in KL decay has the same sign as the local atomic nuclei, we have antimatter


CP Violation

Believed to be responsible for domination of matter

Reason for CP violation not yet understood

Up till year 2000 only seen in neutral K decays

Where else might we see CP violation ?

Problem : B mesons have only very short lifetime ~ 10-12 s Travel only fraction of millimetre at low energies

Solution : Produce in asymmetric e+ e- collider, and use relativistic boost to increase lifetime.

Neutral B meson system


e+e-

Bo

Bo

Asymmetric : successful

aftercollision

CP violation in B system

BaBar (SLAC, USA)

Belle (KEK, Japan)

includes QMUL physicistsand graduate students

e+ e- (4S) Bo Bo

upsilon

e+e-

Bo

Bo

Symmetric: no good

aftercollision

Measured recently


QMULphysicist

Large CP violation observedAt BaBar and Belle


Unification of the fundamentalforces of nature

Electricity Magnetism Apples Planets

Electro-magnetic

Gravity

Faraday, Maxwell Newton


Unification of the fundamentalforces of nature

Do the W and Z particles really exist ?

Electricity Magnetism Apples Planets

Electro-magnetic

Weak Strong Gravity

Faraday, Maxwell Newton

Electroweakunified force

Salam, Weinberg, Glashow

, W +, W -, Z o 0 80 80 90 GeV


ColliderInject anti-protons

Injectprotons

Collide 2 beamsInside vacuum

RF cavitieselectric kick

~Bendingelectro-magnet

Focusingelectro-magnet

Carlo RubbiaAntiprotons

Simon van der MeerStochastic cooling

ORGANISATION EUROPÉENNE POUR LA RECHERCHE NUCLÉAIRE

CERN EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCH

CERN 71-25Laboratory INuclear Physics Division26 November 1971

CE

RN

71-

25

LOW–MOMENTUM ANTIPROTON PRODUCTION

AT THE CERN PROTON SYNCHROTRON

P. I. P. Kalmus, E. Eisenhandler, W. R. Gibson, C. HojvatL.C.Y. Lee Chi Kwong, T.W. Pritchard, E.C. Usher and D.T.

WilliamsQueen Mary College, London

M. Harrison and W. R. RangeUniversity of Liverpool

M. A. R. Kemp, A. D. Rush and J. N. WouldsDaresbury Nuclear Physics Laboratory

G. T. J. Arnison, A. Astbury, D .P. Jones and A.S.L.ParsonsRutherford High Energy Laboratory


What should we look for ?

W around 1 in 108 collisionsNeedle in a haystack !

p + p W + X

e +

lots of particles

electron

W

neutrino


UA1 ExperimentMuon

Neutrino

Electromagcalorimeter

Hadron calorim.and magnet

Proton Antiproton

Hadron

Electron

Wire

chamber

Vacuumpipe

Muon chambers


Finding the W

p p collisions 109

Record on tape 975,000

Electron trigger 140,000

High ET 28,000

Hi. mom track 2,125

Points to calorim. 1,104

No other calorim. tracks 276

Angles match 167

No hadronic energy 72

Energy matches mom. 39

2 jet

23

electron+ jet11

electronno jet

5

Visualinspection


GeV

40

20

– 40 – 20 20 40

– 20

– 40

electrondirection E parallel

to electron

Eventswith jets

E normalto electron

Missingenergyflow

For each event, plothow much energy is missing, and thedirection relative tothe electron in which this flows


GeV

40

20

– 40 – 20 20 40

– 20

– 40

electrondirection E parallel

to electron

Eventswith jets

E normalto electron

Missingenergyflow

For each event, plothow much energy is missing, and thedirection relative tothe electron in which this flows

Eventswithno jets


W and Z particles discovered

UA1 Collaboration at CERN

Included following members of Queen Mary

Peter KalmusAlan Honma

Eric EisenhandlerRichard Keeler

Reg GibsonGiordi Salvi

Graham ThompsonThemis Bowcock

Results confirmed by another CERN collaboration,and few years later at Fermilab USA

Electroweak unification confirmed

Nature’s fundamental forcesreduced from 4 to 3

Nobel Prizes


[email protected]://www.ph.qmul.ac.uk

professor peter i. p. kalmus queen mary, university of london

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