HUGS 2011 – Jefferson Laboratory
Experiment
Hussein Al Ghoul
Department Of Physics
Florida State University
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HUGS 2011 – Jefferson Laboratory
Overview
• 12 Gev upgrade
• Hall D
• The physics behind Glue-X
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HUGS 2011 – Jefferson Laboratory
But first!
What are we looking for?
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HUGS 2011 – Jefferson Laboratory
Non-Quark Model Mesons
Exotic Mesons: Quantum numbers violate quark model.
Glueballs: No valence quarks.
Tetraquarks: Two quarks-antiquark pairs.
Hybrid Mesons: A valence quark-antiquark and one or more gluons.
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HUGS 2011 – Jefferson Laboratory
12 Gev Upgrade
- Accelerator portion constructed on the
framework of the existing CEBAF
accelerator.
- Perspective upgrades include:
• Ten high-voltage cryomodules
(maintaining the overall length of original
design)
• Ten new RF stations.
• Double the refrigeration capacity.
• Modifications to the magnets.
• Modifications to the extraction system.
• A tenth arc-beamline.
•New beamline connected Hall D to the
baseline accelerator.
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12 GeV upgrade, currently under construction (en.wikipedia.org)
Hall D
HUGS 2011 – Jefferson Laboratory
Hall D will be located at the
east end of the CEBAF north
linac.
Hall D will use the electron
beam to produce a coherent
bremsstrahlung beam and
house a solenoid detector to
carry out a program in
gluonic spectroscopy to
experimentally test current
understanding of quark
confinement.
Architect’s rendering of Hall D complex (jlab.org)
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HUGS 2011 – Jefferson Laboratory
GlueX Detector
This detector is made up of:
- Liquid H target – 30cm long
- Solenoid: 2.24T
- Tracking (inside solenoid):
• Start counter
• Central Drift Chamber (CDC)
• Forward Drift Chamber (FDC)
- Calorimetry:
• Barrel Calorimeter (BCAL)
• Forward Calorimeter (FCAL)
- Time-of-Flight wall (ToF)
- Custom read-out and trigger
GlueX detector (jlab.org)
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HUGS 2011 – Jefferson Laboratory
Photon Tagger
The purpose of the photon tagging
system is to provide a tagged flux of
up to 108 Hz of linearly polarized
photons from coherent
bremsstrahlung in a thin (20μm),
orientated, diamond crystal.
Superconducting solenoid
The solenoid is the magnetic element
selected to provide momentum
analysis in the tracking chambers. The
solenoid is a 73-inch warm bore super
conducting (SC) device that produces
a nominal maximum central field of
2.2 Tesla at 1800 Amps.
Target
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Low-power liquid hydrogen.
Specifications:
• length: 30cm, diameter: 1 - 3cm
Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LAB
Department of Physics, University of Regina, Regina, SK S4S0A2 Canada
Start Counter
The start counter will be providing a start
signal for time of flight measurements and
to identify the beam pulse associated with
the observed event. It will be located close
to the target in order to be independent of
particle momenta and trajectories.
HUGS 2011 – Jefferson Laboratory
Calorimeter Barrel/ Forward
The purpose of the barrel calorimeter
(BCAL) and the forward calorimeter
(FCAL) is the detection and energy
determination of photons from the
decays of the neutral π o , the η and
other mesons decaying into photons.
Central Drift Chamber
The purpose of the Central Drift
Chamber (CDC) is to accurately measure
(r, φ , z) coordinates along chargedparticle tracks. (Particle tracking)
Detector SideView Expanded (http://www.phys.uregina.ca)
Forward Drift Chamber
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The forward drift chambers (FDCs)
include 4 separate packages of diskshaped horizontal drift chambers to
measure the momentum of all charged
particles emerging from the target at
angles of up to 30o relative to the
photon beam line.(Particle tracking)
Time-of-Flight
The purpose of the time-of-flight detector
(TOF) is to serve as part of the particle
identification system.
HUGS 2011 – Jefferson Laboratory
The physics behind GLUEX
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Gluonic Excitations
Flux tubes are formed between quarks
due to the exchange of virtual gluons. As
these two quarks move apart, the
potential energy between them increases
linearly with the distance separating
them, and eventually becomes equal to
the amount of energy required to form
two new quarks. At that point the flux
tube/string breaks , and two new quarks
are formed and bound together through
the same interaction form.
Conventional mesons are formed when
the flux tube is in the ground state.
However, exciting this tube to the first
excited state will result in exotic mesons.
A Lattice QCD calculation showing that color field
energy is localized in a "flux tube" between separated
quarks. GlueX at Jefferson Lab will search for
excitations of this flux tube.
(Image by D. Leinweber)
HUGS 2011 – Jefferson Laboratory
Flux Tubes Excitation
HUGS 2011 – Jefferson Laboratory
Flux Tubes Excitation
A level diagram showing
conventional nonets and expected
masses of glueballs, hybrids, and
meson-meson molecular
thresholds. The vertical axis is
in units of GeV/c2 . L refers to the
angular momentum between the
quarks and each box with JPC
numbers refers to a nonet of
mesons.
The low-lying glueballs mix with
conventional q¯q mesons, which
complicates their identification. In
contrast, hybrid mesons can
possess JPC numbers not possible
for q¯q and thus are easier to
identify.
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Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LAB
Department of Physics, University of Regina, Regina, SK S4S0A2 Canada
HUGS 2011 – Jefferson Laboratory
Flux Tubes Excitation cont’d
http://www.learner.org
Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LAB
Department of Physics, University of Regina, Regina, SK S4S0A2 Canada
Left: With a π probe the incoming quarks have L = 0 and S = 0. The
excited flux tube from the scattering results in hybrid mesons with non-exotic
quantum numbers. Right: With a photon probe the incoming quarks have L = 0
and S = 1. When the flux tube is excited, hybrid mesons with exotic quantum
numbers are possible.
Here at Jlab, we will be searching for these exotic mesons within project GlueX.
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HUGS 2011 – Jefferson Laboratory
Thank you!