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The UCD Nuclear Physics Group . Daniel Cebra. Goal of this talk - to introduce the nuclear physics group and explain what we do and why it is interesting. PS… Check out our web page at http://nuclear.ucdavis.edu. Meet the Group. GRAD STUDENTS: Mike Anderson ( 2001 )

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the ucd nuclear physics group
The UCD Nuclear Physics Group

Daniel Cebra

Goal of this talk - to introduce the nuclear physics group

and explain what we do and why it is interesting

PS… Check out our web page at http://nuclear.ucdavis.edu

Daniel Cebra - Physics 295 Seminar

meet the group
Meet the Group
  • GRAD STUDENTS:
    • Mike Anderson (2001)
    • Jenn Klay (2001)
    • Ian Johnson (2002)
    • Agusta Loftsdottir
    • Clay Bratton
  • UNDERGRADS:
    • Stephenie Ritchey
    • Mark Allen
    • Allen Thoe
    • Stephen Baumgarten
  • FACULTY:
    • Jim Draper (emeritus)
    • Paul Brady
    • Daniel Cebra
    • Ramona Vogt
    • Daniel Ferenc
  • STAFF:
    • Juan Romero
    • Tom Gutierrez

Come visit us on thefifth floor - WEST end

Daniel Cebra - Physics 295 Seminar

recent graduates
Recent Graduates
  • Mike Heffner (2000) Postdoc LLNL
  • Tom Gutierrez (2000) Postdoc UCD
  • Bill Caskey (1999) Z-World, Davis CA
  • Lynn Wood (1998) Z-World, Davis CA
  • Jerry Chance (1997) Postdoc LBNL
  • Doug Mayo (1997) Staff Scientist LANL
  • Jason Dunn (1997) Professor - Idaho Christian
  • Isaac Huang (1997) FunMail.com
  • Jack Osbourn (1995) Professor - Sac State
  • Jessica Kintner (1995) Professor - St. Mary’s

Daniel Cebra - Physics 295 Seminar

what do we do
What Do We Do?

Condensed

Matter

High

Energy

Relativistic

Heavy Ion

Physics

Cosmology

Daniel Cebra - Physics 295 Seminar

cosmic gamma ray astronomy
Cosmic Gamma Ray Astronomy

Ferenc, Bratton, Loftsdottir

Daniel Cebra - Physics 295 Seminar

abstract of research goals
Abstract of Research Goals

The study of collisions between relativistic nuclei will ultimately allow the determination of the properties of nuclear matter over a wide range of temperatures and densities. Without the possibility of direct studies of nuclear matter in bulk (as in neutron stars, supernovae, or the Big Bang), one resorts to the challenging studies of finite and transient systems as provided by nucleus-nucleus collisions. Our experiments search for signatures of the Quark Gluon Plasma (QGP), a phase of matter which dominated the early stages of the Big Bang.

Daniel Cebra - Physics 295 Seminar

basics
Basics

Hadrons =

Made of quarks

Baryon = 3 q

meson = q q

p = uud

n = udd

p+ = ud

K+ = us

Daniel Cebra - Physics 295 Seminar

goals of relativistic heavy ions
Goals of Relativistic Heavy Ions
  • To study the properties of nuclear matter.
  • Specifically to study the Quark-gluon plasma
  • Allows a better understanding of the earliest phase of the universe.

Daniel Cebra - Physics 295 Seminar

nuclear matter phase diagram
Nuclear Matter Phase Diagram

Big

Bang

GQP

Temperature

Heavy Ion

Collision

Hadronic Gas

Neutron Stars

Baryon Density

Daniel Cebra - Physics 295 Seminar

how to make a quark gluon plasma
How to make a Quark-Gluon Plasma
  • Quantum Chromodynamics (QCD) predicts that heavy nuclei collided at ultra relatavistic energies will undergo a phase transition from ordinary hadronic matter to a quark-gluon plasma (QGP).

Daniel Cebra - Physics 295 Seminar

history of the rel heavy ion program
History of the Rel. Heavy-ion Program
  • 76-92 Bevalac, Au @ 0.1 - 1.0 AGeV
  • 86-98 AGS, Au @ 2-10 AGeV
  • 86-00? SPS, Pb @ 40-160 AGeV
  • 91 RHIC approved
  • 00 Colliding beams at RHIC, 130Gev

Daniel Cebra - Physics 295 Seminar

status of the ags sps results
Status of the AGS/SPS Results
  • AGS exps track the Hot Hadron gas region
  • Feb ‘00 - Press release on the observation of QGM at SPS

Daniel Cebra - Physics 295 Seminar

the start of rhic summer 00

The Start of RHIC - Summer 00

Daniel Cebra - Physics 295 Seminar

brief history of the rhic project
Brief History of the RHIC Project
  • 1947 BNL founded
  • 1952 Cosmotron
  • 1960 AGS
  • 1970 Tandem
  • 1979 ISABELLE
  • 1983 CBA canceled
  • 1983 RHIC proposed
  • 1991 RHIC approved
  • 1992 STAR approved
  • 1999 First Beams
  • 2000 First collisions

Daniel Cebra - Physics 295 Seminar

the star experiment plans
The STAR Experiment - Plans

Daniel Cebra - Physics 295 Seminar

star under construction
STAR - Under Construction

Daniel Cebra - Physics 295 Seminar

the detector now
The Detector Now...

Daniel Cebra - Physics 295 Seminar

the first event
The FIRST Event!

Daniel Cebra - Physics 295 Seminar

star peripheral event front
STAR - peripheral event - Front
  • Tracks emerge from common vertex point
  • Grazing collisions produce few tracks
  • Magnetic field bends trajectories into helices - allows measure of momentum
  • Particle ID through gas dE/dx

Daniel Cebra - Physics 295 Seminar

star peripheral event side
STAR - peripheral event - side
  • Determines the z location of the vertex
  • emission angles of the tracks.
  • Demonstrate true 3D tracking

Daniel Cebra - Physics 295 Seminar

star event front view
STAR Event - Front View

Central events have much higher multiplicity of tracks. Up to 2000 charged particles in the TPC’s accpectance

Daniel Cebra - Physics 295 Seminar

star event side view
STAR Event -- Side View

Daniel Cebra - Physics 295 Seminar

star calibration and analysis
STAR Calibration and Analysis
  • Spatial resolution 700 m
  • Tracking - better then 90% efficiency
  • dE/dx resolution = 8%
  • momentum resolution better than 1%

p

K

p

e

Daniel Cebra - Physics 295 Seminar

spectra
Spectra
  • Temperatures are measured in the range expected for a QGP transition
  • Suggestive result, but further analysis is needed

Daniel Cebra - Physics 295 Seminar

how we see strangeness

V0

kink

vertex

How we “see” Strangeness
  • See Strange Hadrons
    • kaon (u or d and s)
    • lambda (uds)
    • Omega (sss)
    • etc...
  • Distinguishing Decay Topologies
    • V0
    • kink

Daniel Cebra - Physics 295 Seminar

slide32

Centrality: Participants vs. Spectators

The collision geometry (i.e. the impact parameter) determines the number of nucleons that participate in the collision

“Spectators”

Only ZDCs measure Npart

Zero-degreeCalorimeter

“Participants”

“Spectators”

  • Many things scale with Npart:
    • Transverse Energy
    • Particle Multiplicity
    • Particle Spectra

Produced Particles

Daniel Cebra - Physics 295 Seminar

slide33

ZeroDegreeCalo as centrality device

  • Only shared detector
    • Rates: luminosity via well-known reference process
    • Timing: substantial background rejection
    • Pulse height: measures centrality
  • Directly confirms monotonic relationship between participants with multiplicity

Daniel Cebra - Physics 295 Seminar

d s dn vs n
ds/dN vs N

Comparison to cascade models demonstrates to collective behavior of nuclear systems

Used to determine centrality of collisions

Daniel Cebra - Physics 295 Seminar

slide35

Shapes of dNch/dh for different Npart

%s

Mean Npart

0-3

Data

HIJING

354

15-20

216

35-40

102

dNch/dh

dNch/dh

Data

HIJING

(dNch/dh)/(½Npart)

(dNch/dh)/(½Npart)

h

Daniel Cebra - Physics 295 Seminar

h

dn d h
dN/dh

Higher multiplicity than comparable p+p collisions indicates collective nature.

Impressive agreement between the exps

STAR

PHENIX

BRAHMS

Daniel Cebra - Physics 295 Seminar

source radii

PHENIX

Source Radii
  • The expected expansion of the outward radius is not seen.
  • Transition may be at lower energy or more subtle.

Daniel Cebra - Physics 295 Seminar

hydrodynamic flow defined
Hydrodynamic Flow - Defined
  • Radial flow
    • Not seen in angular distributions
    • Use HBT, spectra (T = To + m<b2>
  • Directed flow
    • Forward rapidities
    • Not measured yet PHOBOS/STAR
    • Interesting predictions for phase transition…
  • Elliptic flow
    • Early time push, hydrodynamic evolution
    • Strongest at y=0

Daniel Cebra - Physics 295 Seminar

hydrodynamic flow results
Hydrodynamic Flow - Results

The RQMD cascade can not account for the observed flow. Collective behavior is demonstrated.

Daniel Cebra - Physics 295 Seminar

hydrodynamic flow results40
Hydrodynamic Flow - Results

midrapidity : |h| < 1.0

V2

Hydrodynamic model

Preliminary

RQMD

SPS

AGS

Centrality

Daniel Cebra - Physics 295 Seminar

conclusions
Conclusions
  • Summer ‘00 Heavy-ion running was successful - physics results already. But the QGP question is not yet resolved.
  • RHIC should run heavy-ions for 6 months in ‘01 (also 1 month of proton running).
  • Detectors Continue to improve (5-10 years).
  • Future: eRHIC
  • Future: LHC

Daniel Cebra - Physics 295 Seminar

compact muon solenoid
Compact Muon Solenoid

Daniel Cebra - Physics 295 Seminar

advertisements
Advertisements...

Daniel Cebra - Physics 295 Seminar

aps join now
APS - join Now
  • All active physicists should join APS
  • Students memberships a very reasonable
  • Go to meetings, give talks!
  • California Section - next meeting will likely be in Davis

Daniel Cebra - Physics 295 Seminar

intramural sports
Intramural Sports!
  • Basketball
  • Soccer
  • Softball
  • Other sports?

Daniel Cebra - Physics 295 Seminar