Experiment

GLUEX

HUGS 2011 – Jefferson Laboratory

Hussein Al Ghoul

Department Of Physics

Florida State Universityᵠ

OverviewHUGS 2011 – Jefferson Laboratory

• 12 Gev upgrade

• Hall D

• The physics behind Glue-X

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But first!

HUGS 2011 – Jefferson Laboratory

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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12 Gev UpgradeHUGS 2011 – Jefferson Laboratory

12 GeV upgrade, currently under construction (en.wikipedia.org)

- 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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Hall D

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.

HUGS 2011 – Jefferson Laboratory

Architect’s rendering of Hall D complex (jlab.org)

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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

HUGS 2011 – Jefferson Laboratory

GlueX detector (jlab.org)

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TargetLow-power liquid hydrogen.Specifications:• length: 30cm, diameter: 1 - 3cm

HUGS 2011 – Jefferson Laboratory

Photon TaggerThe 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 solenoidThe 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.

Start CounterThe 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.

Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LABDepartment of Physics, University of Regina, Regina, SK S4S0A2 Canada

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Calorimeter Barrel/ ForwardThe 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.

HUGS 2011 – Jefferson Laboratory

Central Drift ChamberThe purpose of the Central Drift Chamber (CDC) is to accurately measure (r, φ , z) coordinates along charged-particle tracks. (Particle tracking)

Forward Drift ChamberThe forward drift chambers (FDCs) include 4 separate packages of disk-shaped 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-FlightThe purpose of the time-of-flight detector (TOF) is to serve as part of the particle identification system.

Detector SideView Expanded (http://www.phys.uregina.ca)

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The physics behind GLUEXHUGS 2011 – Jefferson Laboratory

Gluonic Excitations

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)

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.

Flux Tubes Excitation HUGS 2011 – Jefferson Laboratory

Flux Tubes Excitation HUGS 2011 – Jefferson Laboratory

A level diagram showing conventional nonets and expected masses of glueballs, hybrids, and meson-meson molecular thresholds. The vertical axis isin 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.

Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LABDepartment of Physics, University of Regina, Regina, SK S4S0A2 Canadaᵠ

Flux Tubes Excitation cont’dHUGS 2011 – Jefferson Laboratory

Zisis Papandreou : THE GLUEX PROJECT AT JEFFERSON LABDepartment of Physics, University of Regina, Regina, SK S4S0A2 Canada

http://www.learner.org

Left: With a π probe the incoming quarks have L = 0 and S = 0. Theexcited flux tube from the scattering results in hybrid mesons with non-exoticquantum numbers. Right: With a photon probe the incoming quarks have L = 0and S = 1. When the flux tube is excited, hybrid mesons with exotic quantumnumbers 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!