EJB April 2006

Nuclear Science: The Mission

Understand the origin, evolution, and structure of the baryonic matter of the Universe

Cosmic acceleration

Rotation curves & lensing

Stars, planets, Human life

from M. Ramsey-Musolf, Caltech

EJB April 2006

FUNDAMENTAL PARTICLES+INTERACTIONS redux

EJB April 2006

Some of the Big Questions of Nuclear Physics

Hot Dense Matter and Phase Transitions

(What are the phases, how did the early universe behave?)QCD and the Structure of Matter

(How are nucleons constructed from quarks and gluons, what about nuclei? )

Fundamental Symmetries

(’s, neutron beams, radioactive ion traps)Origins of the Elements

(How are elements formed in stars, how do stars burn, what are the limits of stability?)

EJB April 2006

heavyheavynucleinuclei

fewfewbodybody

quarksquarksgluonsgluons

vacuumvacuum

relativisticrelativisticheavy ionsheavy ions

electronelectronscatteringscattering

stable and stable and radioactiveradioactive

beamsbeams

Modern Tools of Nuclear Physics

From W. Nazarewicz, ORNL

EJB April 2006

neutrons

protons

rp processrp process

r processr process

Mass knownHalf-life knownnothing known

s processs process

stellar burningstellar burning

Big BangBig Bang

p processp process

SupernovaeSupernovae

Cosmic RaysCosmic RaysH(1)

Fe (26)

Sn (50)

Pb (82)

What is the Origin of the Elements?

from MSU Phys 983 web sitewww.nscl.msu.edu/~schatz/PHY983/topics.htm

Supernova

E0102-72.3

Time (s)

X-ray burst

331

330

329

328

327

Fre

quen

cy (

Hz )

10 15 20

4U1728-34

n-Star

KS 1731-260

EJB April 2006

Relativistic Heavy Ion Collider, Brookhaven, NY

Search for evidence of transition from nucleons to “free” quarks + gluons at very high energy density.

EJB April 2006

Hot Dense Matter

PHENIX detector

compare d-Au collisions with Au-Au collisions

EJB April 2006

Fundamental Symmetries of Nature

a trapped 21Na atom at Berkeley

Nuclear Physics is a Tool

test time reversal invarianceunitarity of quark mixingneutron lifetime -> He abundance

atomic trapping of radioactive atoms

neutron decay

solar neutrino mixing showed that neutrinos have mass what are the masses? Are there more than 3 types?

Sudbury NeutrinoObservatory (SNO)

EJB April 2006

Jefferson Laboratory, Newport News, VA

A 6 GeV continuous electron beam acceleratorsuperconducting RF cavities

First beam in 19953 experimental halls 50-100 people per

experiment

Research program hadron structure properties of light nuclei strangeness in nuclei

EJB April 2006

e p(,q)

Atomic Structure and Quantum Electrodynamics

=p

e

137

12

c

e

r

kerV

2

)(

Energy Levels of H:

),,(4

1

2

32

4

1

11

2

1

325

212

24

2222

ljnFn

mc

j

n

nmc

nnmcE

fi

(Lamb shift)

(Fine structure)

(Bohr Model)

e p+ …

EJB April 2006

QCD and the Structure of Matter

Strong interaction QCD

can also have:do not exist in QED!

e.g. Proton: u + u + d Qp = 2(2/3) + (-1/3) = 1 Neutron: u + d + d Qn = (2/3) + 2(-1/3) = 0

BUT: quarks are very light and relativistic gluons carry angular momentuminteraction is STRONG and INCREASING with distance

q q

gluon

u u

dp

s 1

EJB April 2006

Ground State Structure of Matter

Example 1: Hydrogen atom

q q

gluon

MH = 1.00794(7) amu = 938.89(6) MeV

Mp = 938.27231(28) MeV

me = 0.51099906(15) MeV

Ionization energy = 13.6 eV = 10-8 MH

Example 2: pion

M = 139.57072(35) MeVmu 4 MeVmd 7 MeV

(mu+md) 0.1 M

ud

uudd

du

2

10

Example 3: proton

epH

ddun

duup

Mp = 938.27231(28) MeV

(2mu+md) 0.015 Mp

EJB April 2006

Determining the structure of small things

d

d

dd<

d>

visible: ~ 500 nm, E ~ few eV atomic structure

X-rays: ~ 0.01-1 nm, E ~ few keV crystallography

gamma rays: < 0.1 nm E ~ MeV (106 eV) nucleons inside nucleiE ~ GeV (109 eV) quark structure of

nucleons

De Broglie Wavelength: ~ h/p (~ hc/E)

(1 electron-Volt = 1.602 x 10-19 Joules)

EJB April 2006

Theoretical Tools

Effectivefield

theory

latticeQCD

find “effective” degrees of freedom to

relate observation to measurement.

Works well for 2 nucleons, not so

well for > 2.

perturbativeQCD

quarks + gluonsare weakly interacting

at high energy. Can use successive approximations

“brute force”: large scale computingPut quarks on a grid in (x,y,z,t),

compute interactions, build nucleon

measurements are guide

EJB April 2006

G0 Apparatus One octant’s scintillator array

20 cm LH2 Target

determine how strange quarks contribute to proton’s charge

EJB April 2006

Applications of Nuclear Physics (and NP training)

• Nuclear medicine and medical imaging• oil exploration/geophysics• materials development w/ neutron beams• homeland security (detection of radioactive materials)• environmental science (waste transmutation, nonproliferation)

• teaching• advanced computation and simulation• technical consulting and management• the stock market (!)• science policy in government

EJB April 2006

Nuclear Science: Ten Questions1. Why is there more matter than anti-matter ?

2. How do the properties of baryons, leptons and their interactions reflect the symmetries of the early Universe?

3. What is the nature of baryonic matter at the highest temperatures and densities ?

4. How do the properties of the vacuum evolve with temperature?

5. How is the nucleon assembled from the quarks and gluons of the Standard Model?

6. How do the interactions between quarks and gluons give rise to the properties of light nuclei?

7. How do the properties of complex nuclei arise from the elementary NN interaction?

8. What are the limits of nuclei and atoms?

9. How does the physics of nuclei impact the physical Universe (origin of heavy elements)?

10. How does the physics of nuclei impact the physical Universe (neutron stars, supernovae, neutrinos…)?