1. The 12 GeV Jlab Upgrade Project
Project Overview
Examples of Physics Topics
Gluonic excitations
3D picture of the nucleon
Project Status
Elton S. Smith
Jefferson Lab
PANIC 2008

2. JLab accelerator CEBAF
Continuous Electron Beam
Energy 0.8 ─ 5.7 GeV
200 mA, polarization 75%
1499 MHz operation
Simultaneous delivery 3 halls A B C

3. Upgrade magnets and power supplies
CHL-2
Upgrade magnets and power supplies 12
6 GeV CEBAF
add Hall D
(and beam line)
Enhance equipment in existing halls

4. New Hall D
Hall C (SHMS/HMS)
Hall A (2 HRS + 11 GeV beam for large installations)
Hall B (CLAS12)

5. Normal Mesons – qq color singlet bound states
Spin/angular momentum configurations & radial excitations generate the known spectrum of light quark mesons.
Starting with u - d - s we expect to find mesons grouped in nonets - each
characterized by a given J, P and C.
Spin 0
Spin 1 K0 K+ K* r w f p0 h’ p− p+ h K− K0
JPC = 0– – – 1+ – 2++ …
Allowed combinations
JPC = 0– – 0+ – 1– – …
Not-allowed: exotic

6. Physics goals and key features of GlueX
The physics goal of GlueX is to map the spectrum of hybrid mesons starting with those with the unique signature of exotic JPC .
Identifying JPC requires an amplitude analysis which in turn requires
linearly polarized photons
Breaks azimuthal symmetry
detector with excellent acceptance and resolution
sensitivity to a wide variety of decay modes which include photons and charged particles
This, coupled with a hybrid mass reach up to GeV, requires 9 GeV photons produced using coherent bremsstrahlung from 12 GeV electrons.
Normal mesons:
glue is passive
Hybrid mesons:
glue is excited
See Eugenio in Parallel II: Hadronic structure: form factors

7. Search for QCD exotics 1 1 ’1 b2 h2 h’2 b0 h0 h’0 
The GlueX Detector Design
has been driven by the need
to carry out Amplitude analysis.
1−+
2+−
0+−
Mass scale ~ 2 GeV  p X
,K,g
n,p
h1 → a+1p- → (o+)(-) → +-+-
all charged
h0 → bo1po → (o)gg → +-gggggg
many photons
Photoproduction
h’2 → K+1K− → o K+ K− → +−K+K−
strange particles
Pion production
To certify results, check different decay modes
e.g

8. Linearly Polarized Photon Beam
Rates based on:
12 GeV endpoint
20 mm diamond crystal
300 nA electron beam
diamond – collimator: 76m
collimator diameter: 3.5 mm
Leads to 107 g/s on target
(after the collimator) 4
nominal
tagging
interval
Photon Beam Intensity Spectrum
Design goal is to build an experiment with ultimate rate capability of 108 tagged g/s
on target.
photon energy (GeV)
tagged
dE/E = 0.1%
Pol = 40%

9. Pb-glass detector (Fcal) Superconducting 2 T solenoid
Hall D – GlueX detector
Hermetic detection
of charged and
neutral particles in
solenoid magnet
Pb-glass detector (Fcal)
Barrel
Calorimeter
(Bcal)
Time-
of-flight
(tof)
Target
(LH2)
Initial Flux 107 g/s
18,000 FADCs
4,000 pipeline TDCs
20 KHz L1 trigger
300 MB/s to tape
Future PID
detector
Tagger Spectrometer
(Upstream)
Tracking
Cathode strips
Drift chambers
Straw tubes
Superconducting 2 T solenoid

10. Electronics and trigger (250 MHz)
Front-End Crate
Trigger Distribution Crate
Custom Designed Boards by JLAB
VXS Crate
VXS Crate
Detector
Signals TD TS TS
Fiber Optic Links
Clock/Trigger
62.5MHz
(16)
(12)
(1)
(1)
(1)
(1)
(1)
VXS Crate
Fiber Optic Link
(~100 m)
125 MHz)
( ) – Number in parentheses
refer to number of modules
SSP
GTP
fADC250
(8)
(2)
CTP Crate Trigger Processor
(1)
Copper Ribbon Cable
(~1.5 m)
250 MHz)
Global Trigger Crate
SD Signal Distribution
TI Trigger Interface
Trigger Latency ~ 3 μs
(F1TDC pipeline ~3.9 μs)
VXS Backplane
All detector readout electronics pipelined:
fADC (100 & 250 MHz) and F1TDC

11. Summary of Exotic Hybrid Mesons
The physics goal of GlueX is to map the spectrum of hybrid mesons starting with those with the unique signature of exotic JPC quantum numbers.
Detector designed with high acceptance and efficiency for charge and neutral particles.
Study hybrid mass with masses up to 2.5 GeV
Expected sensitivity to exotic signals is at the level of a few percent of the production of normal hadrons

12. Beyond form factors and quark distributions – Generalized Parton Distributios
X. Ji, D. Mueller, A. Radyushkin ( )
Proton form factors, transverse charge & current densities
Structure functions,
quark longitudinal
momentum & helicity
distributions
Correlated quark momentum
and helicity distributions in
transverse space - GPDs 12

13. DVCS is “golden channel”p g
DVCS
Bethe-Heitler + 2
GPD’s B
dydtd dx d = ( ) BH
DVCS T * 2 + Q e y x 3 1 8 p a f s
Beam Spin Asymmetry ~

14. CLAS12 - DVCS/BH- Beam Asymmetry
Ee = 11 GeV
Q2=5.5GeV2
xB = 0.35
-t = 0.25 GeV2
Luminosity = 720fb-1

15. CLAS12 - DVCS/BH Beam Asymmetry
e p epg
E = 11 GeV
DsLU~sinfIm{F1H+..}df
Selected
Kinematics
L = 1x1035
T = 2000 hrs
DQ2 = 1 GeV2
Dx = 0.05

16. CLAS12 - Detector
CLAS12
Forward Detector
Central
Detector

17. DOE Generic Project Timeline
We are here
Sept 2008
Nov 2007

18. Schedule Hall A commissioning start October 2013
Hall D commissioning start April 2014
Halls B and C commissioning start October 2014

19. 12 GeV Jlab Upgrade Project - Summary
Two major physics thrusts of the 12 GeV project have been touched on in this talk:
Exploration of QCD and confinement: Existence and properties of exotic mesons
3-D View of Nucleon Structure: Generalized Parton Distributions
Tagger Area w/ Electron Beam Dump
Photon Beam Dump N
Hall D
Counting House
Cryo Plant
Service Building
Project is on track with construction starting NOW! 19

20. Backup Slides