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PacSpin 2007, Vancouver, Canada

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1 PacSpin 2007, Vancouver, Canada
The JLab 12 GeV Upgrade Antje Bruell, JLab PacSpin 2007, Vancouver, Canada Upgrade of accelerator and experimental equipment Highlights of the physics 12 GeV Highlights of spin dependent 12 GeV Timelines and schedule

2 Jefferson Lab Today 2000 member international user community engaged in exploring quark-gluon structure of matter Superconducting accelerator provides 100% duty factor beams of unprecedented quality, with energies up to 6 GeV B C A CEBAF’s innovative design allows delivery of beam with unique properties to three experimental halls simultaneously Each of the three halls offers complementary experimental capabilities and allows for large equipment installations to extend scientific reach

3 Jefferson Lab Today A B C
Hall A Hall B Two high-resolution 4 GeV spectrometers Large acceptance spectrometer electron/photon beams Hall C Be brief A B C 7 GeV spectrometer, 1.8 GeV spectrometer, large installation experiments

4 12 11 6 GeV CEBAF Upgrade magnets and power supplies
CHL-2 Upgrade magnets and power supplies help me Enhanced capabilities in existing Halls Lower pass beam energies still available

5 Experimental equipment for 12 GeV
Hall D – exploring origin of confinement by studying exotic mesons Hall B – understanding nucleon structure via generalized parton distributions Hall C – precision determination of valence quark properties in nucleons and nuclei Note BSM not included in project Hall A – short range correlations, form factors, hyper-nuclear physics, future new experiments 5

6 Technical Performance Requirements
Hall D Hall B Hall C Hall A excellent hermeticity luminosity 10 x 1034 energy reach installation space polarized photons hermeticity precision Eg~8.5-9 GeV 11 GeV beamline 108 photons/s target flexibility good momentum/angle resolution excellent momentum resolution high multiplicity reconstruction luminosity up to 1038 particle ID Don’t dwell on this too long, they can read it quickly

7 Physics Experimental Equipment
total project cost: $ 310 M

8 High Energy Scattering
QCD and confinement Asymptotic Freedom Confinement Small Distance High Energy Large Distance Low Energy Perturbative QCD Strong QCD High Energy Scattering Spectroscopy Gluon Jets Observed Gluonic Degrees of Freedom Missing 8

9 Gluonic Excitations Gluonic Excitations predicted by QCD
crucial for understanding confinement quantum numbers of the excited gluonic fields couple to those of the quarks to produce mesons with exotic quantum numbers mass spectra calculated by lattice QCD possibility for experimental search From G. Bali

10 Hybrid mesons and mass predictions
Normal mesons 1 GeV mass difference Hybrid mesons and mass predictions Jpc = 1-+ q Lattice GeV GeV GeV Lowest mass expected to be p1(1−+) at 1.9±0.2 GeV

11 Coherent Bremsstrahlung
GlueX / Hall D Detector 12 GeV electrons collimated Lead Glass Detector Solenoid Coherent Bremsstrahlung Photon Beam Tracking Target Cerenkov Counter Time of Flight Barrel Calorimeter Note that tagger is 80 m upstream of detector Electron Beam from CEBAF

12 Finding an Exotic Wave An exotic wave (JPC = 1-+) was generated at level of 2.5 % with 7 other waves. Events were smeared, accepted, passed to PWA fitter. Output: /- 3 MeV Output: /- 11 MeV Double-blind M. C. exercise Statistics shown here correspond to a few days of running. Mass Input: MeV Width Input: 170 MeV

13 Neutron/Proton Charge Form Factor @12 GeV
(Polarization Experiments only) Here shown as ratio of Pauli & Dirac Form Factors F2 and F1, ln2(Q2/L2)Q2F2/F1  constant when taking orbital angular momentum into account (Ji)

14 Charged Pion Electromagnetic Form Factor
Where does the dynamics of the q-q interaction make a transition from the strong (confinement) to the perturbative (QED-like) QCD regime? It will occur earliest in the simplest systems  the pion form factor Fp(Q2) provides our best chance to determine the relevant distance scale experimentally applicability of pQCD (GPD’s) to exclusive pion production ?

15 with enough luminosity to reach the high-Q2, high-x region!
Access to the DIS 12 GeV with enough luminosity to reach the high-Q2, high-x region! Counts/hour/ (100 MeV)2 (100 MeV2) for L=1035 cm-2 sec-1

16 Extending DIS to High x The Neutron Asymmetry A1
(similar precision for p and d) The Neutron to Proton Structure Function Ratio Hall C: 3H/3He CLAS: tagging spectator proton Add overlay of 6 GeV data obtained to date (need to “stretch” to get on graph properly) 3He(e,e’) 12 GeV will access the valence quark regime (x > 0.3)

17 Flavor decomposition using SIDIS
Valence quarks Ee =11 GeV NH3+He3

18 Flavor decomposition: polarized sea
Large flavor asymmetry in unpolarized sea Asymmetry in polarized sea? First data from HERMES compatible with zero but have large uncertainties Calculations: Instantons (QSM) Pion cloud models ? (Goeke) More data expected from RHIC SSA in future

19 Beyond form factors and quark distributions –
Generalized Parton Distributions (GPDs) 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

20 Kinematics for deeply excl. experiments
no overlap with other existing experiments compete with other experiments

21 DVCS Single-Spin Asymmetry
Q2 = 5.4 GeV2 x = 0.35 -t = 0.3 GeV2 CLAS experiment E0 = 11 GeV Pe = 80% L = 1035 cm-2s-1 Run time: 2000 hrs Many x, Q2 and t values measured simultanously !

22 Projected precision in extraction of GPD H at x = x
Projected results Spatial Image

23 orbital angular momentum carried by quarks : solving the spin puzzle
* q q' p p' e At one value of x only Ingredients: 1) GPD Modeling 2) HERMES 1H(e,e’g)p (transverse target spin asymmetry) 3) Hall A 2H(e,e’gn)p Compared to Lattice QCD For quarks 12 GeV will give final answers

24 Exclusive r0 production on transverse target
2D (Im(AB*))/p T AUT = - A ~ 2Hu + Hd r0 |A|2(1-x2) - |B|2(x2+t/4m2) - Re(AB*)2x2 B ~ 2Eu + Ed AUT A ~ Hu - Hd B ~ Eu - Ed r+ Asymmetry depends linearly on the GPD E, which enters Ji’s sum rule. r0 K. Goeke, M.V. Polyakov, M. Vanderhaeghen, 2001 xB


26 Longitudinally polarized Target SSA for p+
Measurement of kT dependent twist-2 distribution provides an independent test of the Collins fragmentation. Real part of interfe-rence of wave functions with L=0 and L=1 In noncollinear single-hadron fragmentation additional FF H1(z,kT) Efremov et al. p Study the PT – dependence of AULsin2f Study the possible effect of large unfavored Collins function. kT quark

27 Transverse Target SSA @11 GeV
11GeV (NH3) AUT ~ Collins p+ p0 p- f1T┴, requires final state interactions + interference between different helicity states Simultaneous (with pion SIDIS) measurement of, exclusive r,r+,w with a transversely polarized target important to control the background. AUT ~ Sivers

28 Transversity in double pion production
The angular distribution of two hadrons is sensitive to the spin of the quark h1 h2 quark RT “Collinear” dihadron fragmentation described by two functions at leading twist: D1(z,cosqR,Mpp),H1R(z,cosqR,Mpp) Collins et al, Ji, Jaffe et al, Radici et al. relative transverse momentum of the two hadrons replaces the PT in single-pion production (No transverse momentum of the pair center of mass involved ) Dihadron production provides an alternative, “background free” access to transversity

29 Quark Structure of Nuclei: Origin of the EMC Effect
Observation that structure functions are altered in nuclei stunned much of the HEP community 23 years ago ~1000 papers on the topic; BUT more data are needed to uniquely identify the origin: What alters the quark momentum in the nucleus? x JLab 12 Jlab at 12 GeV Precision study of A-dependence Measurements at x>1 “Polarized EMC effect” Flavor-tagged (polarized) structure functions valence vs. sea contributions Explain what the EMC effect is. Point out the three regions and their conventional explanations. Cannot be fully explained by conventional nuclear physics Amazing that we still don’t know the answer after nearly a quarter of a century Coverage extends at least to x=1.5

30 Multi-quark clusters are accessible at large x (>>1) and high Q2
12 GeV gives access to the high-x, high-Q2 kinematics needed to find multi-quark clusters Fe(e,e’) 5 PAC days Need to demonstrate we are in the scaling region here. Errors are the size of the points. Point out the five days. TRANSITION: Now will shift from unpolarized, inclusive experiments to semi-inclusive, where measure final state hadron in addition to electron. These are new experimental approaches for nuclei, made possible by the 12 GeV upgrade: semi-inclusive measurements and polarization. First want to remind about Semi-inclusive Mean field Six-quark bag (4.5% of wave function) Correlated nucleon pair

31 g1(A) – “Polarized EMC Effect”
New calculations indicate larger effect for polarized structure function than for unpolarized: scalar field modifies lower components of Dirac wave function Spin-dependent parton distribution functions for nuclei nearly unknown Can take advantage of modern technology for polarized solid targets to perform systematic studies – Dynamic Nuclear Polarization (polarized EMC effect) Curve follows calculation by W. Bentz, I. Cloet, A. W. Thomas. Explain the curve Mention the effect is >25% in nuclear matter, here scaled to density of valence nucleon in 7Li 31

32 “Polarized EMC Effect” – Flavor Tagging
semi-inclusive DIS on polarized targets, measuring p+ and p-, decompose to extract DuA(x), DdA(x). Challenging measurement, but have new tools: High polarization for a wide variety of targets Large acceptance to constrain syst. errors and tune models x Duv(x) free nucleon + scalar field + Fermi + vector field (total) Ddv(x) DdA(x) Dd(x) Somewhere put nuclear lattice QCD and ChPT? Can eliminate black dotted curve, redraw? TRANSITION: Have discussed five questions whose experimental answers will help us to finally understand the origin of the EMC effect. Up until now, have assumed nuclear fragmentation functions known. Now talk about how to get them. Get delta-U-A from inclusive, delta-U-D from semi-inclusive Ratios DuA(x) Du(x) nuclear matter nuclear matter W. Bentz, I. Cloet, A. W. Thomas

33 APV ~ 8 x 10-5 Q2 APV Measurements 0.1 to 100 ppm
Steady progress in technology part per billion systematic control 1% normalization control JLab now takes the lead New results from HAPPEX Photocathodes Polarimetry Targets Diagnostics Counting Electronics E


35 DOE Generic Project Timeline
We are here DOE CD-2 Reviews Almost half-way between CD1 and CD2 September 2007

36 12 GeV Upgrade: Phases and Schedule
(based on funding guidance provided by DOE-NP in April 2007) Conceptual Design (CDR) - finished Research and Development (R&D) - ongoing 2006 Advanced Conceptual Design (ACD) - finished Project Engineering & Design (PED) - ongoing Construction – starts in ~18 months! Accelerator shutdown start mid 2012 Accelerator commissioning mid 2013 Pre-Ops (beam commissioning) Hall commissioning start late 2013 Now in intensive design phase. Construction begins in two years.

37 Summary The Jlab 12 GeV Upgrade will increase the energy of CEBAF, provide very high luminosities and will thus allow to measure with unprecedented precision: the high x behaviour of (un)polarised structure functions the spin and flavour decomposition in the valence region pion and nucleon form factors at high Q2 single spin asymmetries and kt dependent effects deep exclusive processes in multi-differential form nuclear effects in (semi)-inclusive scattering search for hybrid states parity violating asymmetries as a test of the standard model The ideal laboratory for valence quark physics !


39 Quantum Numbers of Hybrid Mesons
Excited Flux Tube Quarks Hybrid Meson like Exotic Flux tube excitation (and parallel quark spins) lead to exotic JPC like

40 exotic nonets Lattice 1-+ 1.9 GeV 2+- 2.1 GeV 0+- 2.3 GeV 2 + – 2 + +
Radial excitations 1.0 1.5 2.0 2.5 qq Mesons L = 0 1 2 3 4 Meson Map Each box corresponds to 4 nonets (2 for L=0) Mass (GeV) exotic nonets 0 – + 0 + – 1 + + 1 + – 1– + 1 – – 2 – + 2 + – 2 + + 0 + + Glueballs Hybrids Lattice GeV GeV GeV (L = qq angular momentum)

41 Unraveling the Quark WNC Couplings
12 GeV: (2C2u-C2d)=0.01 PDG: ± 0.24 Theory: Vector quark couplings Axial-vector quark couplings

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