Скачать презентацию Introduction November 2002 Good News
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Скачать презентацию Introduction November 2002 Good News
Скачать презентацию Introduction November 2002 Good News
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:
Periodic Table n n p p
Spectroscopy of the Atom
Discovery of the Hadrons In the 50’s and 60’s 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. Bubble chamber photo Typical lifetime: 10 -23 s 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 Baryons proton Mesons neutron π meson
Standard Model Electromagnetic force explains atoms Ordinary Matter Strong Force binds quarks Electroweak force explains radioactivity
Subatomic Sizes
Color
No Free Quarks Color Field: Because of self interaction, confining flux tubes form between static color charges
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 Excited flux tube There are two degenerate first-excited transverse modes with J=1 – clockwise and counter-clockwise – and their linear combinations lead to JPC = 1– + or JPC=1+ – for the excited flux-tube
The Light Quarks and Light Mesons JPC = 0– + 0++ 1– – 1+ – 2++ … Allowed combinations JPC = 0– – 0+ – 1– + 2+ – … Not-allowed: exotic Expect to find nine mesons with the same J, P, C - a nonet
Quantum Numbers for Hybrid Mesons Quarks Excited Flux Tube Hybrid Meson like Exotic like So only parallel quark spins lead to exotic JPC
QCD and Spectroscopy
Exotic Hybrids Will Be Found More Easily in Photoproduction Quark spins already aligned There are strong indications from theory that photons will produce exotic hybrid mesons with relatively large cross sections. Production of exotic hybrids favored. Almost no data available
Coherent Bremsstrahlung flux This technique provides requisite energy, flux and polarization 12 Ge. V electrons Incoherent & coherent spectrum 40% polarization in peak Linearly polarized photons out collimated electrons in spectrometer diamond crystal tagged with 0. 1% resolution photon energy (Ge. V)
Tagger Magnet
Aerial View of Jefferson Lab
Linac
Cryomodule
Arcs
Helium Factory
Upgrade Plan
Detector
Lead Glass Calorimeter & Magnet arrives in Bloomington
Electronics PMT Bases: FADCs: Electronics assembly robotics facility to be installed at IU in June
TOF Prototype $70 K from JLab
Magnetic Shielding Helmholtz coils built by undergrads last year - upgraded this year new power supplies
History ü ü ü Collaboration Founded in 1998 Workshops (latest in May 2003) 4 th Design Report Collaboration meetings Regular conference calls Management plan o Collaboration Board Reviews ü ü ü PAC 12 Cassel Review APS/DNP Town Meeting NSAC LRP PAC 23
Computational Challenge • Glue. X 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
Скачать презентацию Introduction November 2002 Good News
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