Introduction

November 2002

Good News

House Senate

References All of the above can be downloaded from our website Go to Documents - top of left frame:

n n pp Periodic Table

Spectroscopy of the Atom

Discovery of the Hadrons In the 50s and 60s physicists discovered over 100 elementary particles in cosmic ray showers and accelerators. Almost all of these were short-lived and were classified as mesons or baryons. Typical lifetime: s Bubble chamber photo Baryons have half-integer spin and obey Pauli Exclusion Principle (PEP). They are fermions. Mesons have integer spin and do not obey the PEP. They are bosons.

Discovery of Elementary Particles in showers of Cosmic Rays

Spectroscopy of Hadrons neutronprotonπ meson MesonsBaryons

Electromagnetic force explains atoms Electroweak force explains radioactivity Strong Force binds quarks Ordinary Matter Standard Model

Subatomic Sizes

Color

Color Field: Because of self interaction, confining flux tubes form between static color charges No Free Quarks

Lattice Calculations and Flux Tubes From G. Bali: quenched QCD with heavy quarks

Flux Tube Breaking

Exciting the Flux Tube Normal meson: flux tube in ground state There are two degenerate first-excited transverse modes with J=1 – clockwise and counter-clockwise – and their linear combinations lead to J PC = 1 – + or J PC =1 + – for the excited flux-tube Excited flux tube

The Light Quarks and Light Mesons J PC = 0 – – 0 + – 1 – – … Not-allowed: exotic J PC = 0 – – – 1 + – 2 ++ … Allowed combinations Expect to find nine mesons with the same J, P, C - a nonet

Quantum Numbers for Hybrid Mesons Quarks Excited Flux Tube Hybrid Meson Exotic like So only parallel quark spins lead to exotic J PC

QCD and Spectroscopy

Exotic Hybrids Will Be Found More Easily in Photoproduction Production of exotic hybrids favored. Almost no data available There are strong indications from theory that photons will produce exotic hybrid mesons with relatively large cross sections. Quark spins already aligned

flux photon energy (GeV) 12 GeV electrons Coherent Bremsstrahlung This technique provides requisite energy, flux and polarization collimated Incoherent & coherent spectrum tagged with 0.1% resolution 40% polarization in peak electrons in Linearly polarized photons out spectrometer diamond crystal

Tagger Magnet

Aerial View of Jefferson Lab

Linac

Cryomodule

Arcs

Helium Factory

Upgrade Plan

Detector

Magnet arrives in Bloomington Lead Glass Calorimeter & Magnet

Electronics assembly robotics facility to be installed at IU in June PMT Bases: FADCs: Electronics

TOF Prototype $70K from JLab

Magnetic Shielding Helmholtz coils built by undergrads last year - upgraded this year new power supplies

Collaboration Founded in 1998 Workshops (latest in May 2003) 4th Design Report Collaboration meetings Regular conference calls Management plan o Collaboration Board PAC12 Cassel Review APS/DNP Town Meeting NSAC LRP PAC23 Reviews History

Computational Challenge GlueX will collect data at 100 MB/sec or 1 Petabyte/year - comparable to LHC-type experiments. Close collaboration with computer scientists has started and the collaboration is gaining experience with processor farms.

Conclusions The spectroscopy of light quark mesons is on the verge of making important contributions to answering a fundamental question: What is the nature of confinement in QCD? We welcome additional collaborators - theory and experiment and bright, enthusiastic undergrads