Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs...

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H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester
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Page 1: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 1

Evolution of the Universe

Frank L. H. WolfsDepartment of Physics and Astronomy

University of Rochester

Page 2: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 2

Outline

Why do I talk about this topic?

Tools used to probe the evolution of the Universe:Astronomy

Nuclear PhysicsHigh-Energy Physics

Going back in time in New York State:The Relativistic Heavy-Ion Collider (RHIC)

Conclusions

Page 3: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 3

Why do I talk about this topic?I am just a nuclear physicist!

Because I was asked to give a talk about PHOBOS.

Because my primary interest in relativistic heavy-ion physics is motivated by the astrophysical implications of our studies of properties of nuclear matter under extreme conditions.

Because our study of the evolution of the universe is a great example of how distinct areas of basic science can contribute different components / solutions to the same puzzle.

Page 4: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 4

What happened during the last 15 x 109 years?

Page 5: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 5

Going back in time: Astronomy

Page 6: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 6

Nuclear physics allows us to describe stellar nucleosynthesis

Page 7: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 7

The binding energy per nucleonSource of nuclear energy

Page 8: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 8

Nucleosynthesis in stars forms all elements heavier than Lithium

Death of an “Ordinary” Star Death of a Massive Star

Page 9: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 9

Nucleosynthesis

Hydrogen burning (He production)

Helium burning (C and O production)

Carbon, Oxygen, and Neon burning (16 ≤ A ≤ 28 production)

Silicon burning (28 ≤ A ≤ 60 production)

The s-, r-, and p-processes (A ≥ 60 production)

The l-process (D, Li, Be, and B production)

Page 10: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 10

Experimental nuclear physics:Measuring stellar reaction rates

Converting protons to helium

Page 11: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 11

The evolution of stars

Page 12: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 12

Formation of heavy elements(beyond Iron)

Elements beyond iron are not formed in “lighter-element burning” reactions (abundances are too large).

The neutron-rich nuclei in this region are formed via the s-process (n capture) and r-process ( decay).

The proton-rich nuclei in this region are formed via the p-process (p capture).

Need nuclear data far from stability.

Page 13: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 13

Better techniques/facilities =>Better info far from stability

Page 14: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 14

Nucleosynthesis is an ongoing process.

Nuclei are still being synthesized in the Universe.

By measuring life times of unstable nuclei, areas of active nucleosynthesis can be be identified.

For example: 26Al has a lifetime of 730,000

years. 26Al decays by emitting rays. The origin of 26AL rays

reveals the locations of active nucleosynthesis. Data from the GRO satellite

Page 15: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 15

Star Formation:1 x 109 yr after the Big Bang

Molecular clouds of mainly hydrogen molecules are the birthplace of stars:

Dense regions collapse and form “protostars”.

Initially the gravitational energy of the collapsing star is the source of its energy.

Once the density of its central core is large enough, the hydrogen burning process can start, and the star becomes a “main sequence” star.

Page 16: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 16

Big-Bang Problem:Large Scale Structures

The Big-Bang theory predicts that matter is uniformly distributed throughout the universe.

The formation of large-scale structures requires the formation of small fluctuations in density (around 0.5%).

The tiny fluctuations in density can not be produced by gravity.

Page 17: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 17

Cosmic Microwave Background:Fluctuations in early universe

Microwave background is createdwhen hydrogen atoms form (about400,000 years after the Big bang.

Page 18: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 18

Cosmic Microwave Background:Fluctuations in early universe

Observations by COBE have been confirmed by BOOMERANGwith an improved angular resolution (factor of 35).

Page 19: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 19

Formation of light nuclei:Three minutes after the Big Bang

Page 20: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 20

Formation of light nuclei:Three minutes after the Big Bang

Neutrons and protons interact and form deuterium.

Tritium and Helium are subsequently created by neutron and proton capture.

The reaction rates are high enough to ensure that most neutrons will interact before they decay (neutron life time is 10 minutes).

Using measured reaction rates, we can calculate the relative abundance.

Page 21: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 21

Formation of light nuclei:Three minutes after the Big Bang

All deuterium is created during this phase.

The calculated abundances depend critically on the density of baryons (protons and neutrons).

A baryon density of a few percent is required to account for the measured abundances. Data limit the number of light neutrino generations.

Not all dark matter can be baryonic.

Critical density

Page 22: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 22

Formation of Nucleons100 µs after the Big Bang

During the first few seconds after the Big Bang the universe was composed of: Nucleons (protons and neutrons). Any nuclei formed at this

point would not have survived long in this high-temperature environment.

Leptons (electrons, neutrinos, and photons) During this phase baryons, anti-baryons, and photons were in

equilibrium and their abundances were nearly equal. The ratio NB / N observed today is 10-9. This ratio represents the fractional discrepancy between

matter and antimatter during this phase: For every one billion anti-baryons there were one billion

and one baryons.

Page 23: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 23

Unanswered Questions about the Evolution of the Early Universe

Origin of the density fluctuations: Quark-to-Hadron transitions

Matter / anti-matter asymmetry Symmetry breaking

Missing mass: WIMPS Axions Neutrinos

Recreation of the “early universe” mightallow us to address these questions.

Page 24: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 24

Recreating the early universe:relativistic heavy-ion collisions

Page 25: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 25

Production of the QGPRelativistic Heavy-Ion Collisions

Two nuclei approach each other. The nuclei are contracted to thin pancakes

Hard collisions dominate first instants of collision

Produced particles reinteract at hard and soft scales

Final state particles freeze-out and stream towards the detectors…

Page 26: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 26

Phases of Nuclear Matter

Nuclear matter can exist in several phases: At low excitations energies,

nuclear matter may evaporate protons and neutrons.

At high temperatures or densities, a “gas” of nucleons may form.

At extreme conditions, individual nucleons may lose their identities, and the constituents quarks and gluons may form a quark-gluon plasma.

Page 27: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 27

Formation of the Quark-Gluon Plasma (QGP)

Page 28: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 28

Relativistic Heavy-Ion Collider:Scientific Objectives

To create extraordinary states of nuclear matter in density and temperature (similar to matter a few µs after the Big Bang).

To deconfine the quarks and gluons and form a Quark-Gluon Plasma.

Experimental goals @ RHIC

Verify the existence of the Quark-Gluon Plasma.

Explore the properties of this new phase of matter.

Study the transitions from quarks to nucleons (which will provide insight into the physics of the early universe).

Page 29: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 29

From BBC NewsRHIC is not the end of the world!

Page 30: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 30

From ABC NewsThe Doomsday Machine!

Page 31: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 31

Will the world survive the first collisions at RHIC?

Suppose a black hole was formed in a head-on collision between two 100-GeV/A Au ions.

Properties of this black hole (Astronomy 142): The Schwarzschild radius is 2.1 x 10-47 m The black hole evaporates via Hawking radiation in about

2.3 x 10-82 s Before the black hole evaporates, it moves 7 x 10-74 m The black hole can not acquire additional material before it

evaporates.

Yes !!!!!!!!!!!!!!!!!!!!!!!!!!!!! There will be life after RHIC.

Page 32: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 32

Going back in time by travelling across New York State.

Page 33: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 33

Going back in time by travelling across New York State.

Page 34: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 34

The Relativistic Heavy-Ion ColliderBrookhaven National Laboratory

Two 3.8 km-long concentric rings

with 6 interaction regions. Capable of accelerating ions up to Au

(A+A, p+p, and p+A). Maximum beam energy:

Au + Au: 100 GeV/u p + p: 250 GeV

Design luminosity: Au + Au: 2 x 1026 cm-2 s-1

p + p: 1 x 1031 cm-2 s-1

First running period concluded on

9/19/2000 with a luminosity close to

10% of the design luminosity.

Page 35: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 35

Preparing Au ions for injection in RHIC.

1 MeV/u

78 MeV/u

10.8 GeV/u

Page 36: Frank L. H. Wolfs / University of Rochester, Slide 1 Evolution of the Universe Frank L. H. Wolfs Department of Physics and Astronomy University of Rochester.

Frank L. H. Wolfs / University of Rochester, Slide 36

Conclusions

Very different areas of basic physics

and astronomy contribute to our

understanding of the evolution of the

universe. Many unanswered questions may be

understood if we know the properties

of matter under extreme conditions. This new state of matter is produced

for the first time in New York State. First results of experiments at RHIC

will be discussed by Prof. Manly on

10/21 at 3.30 pm.