Why are We Here Today and What are We Trying to Accomplish?

1. Why are We Here Today and What are We Trying to Accomplish? • The entire community has worked to refine the proposed physics program and has also developed new physics opportunities that would become feasible, resulting in a much richer program • The Hall Equipment designs have been refined considerably • In anticipation of CD-0, we must write a pCDR that documents this work, and details the science and how we will realize it • Any such effort needs and deserves the kind of serious scientific review that PAC16 provided for the White Paper – hence the charge to PAC23 for the review of the plans for the pCDR • Important details include: • Hall-specific documents prepared for PAC23 Review • Editorial Board established for the pCDR • 1st Major draft goal is March 2003 • This PAC23 12 GeV session will review the expanded science program and begin the process of evaluating the experimental equipment “fit”

2. The Charge for the PAC23 Review of the pCDR In Progress • Comment on the intellectual framework presented for the 12 GeV pCDR. Is this the best way to present the science case to DOE and to the larger nuclear physics community? Are there flaws or omissions in the framework? • Review the new research programs that are under consideration for being highlighted in the executive summary of the pCDR Do they represent compelling science that must be done to advance our understanding of nuclear physics? At what level should they be included in the executive summary? • Have we omitted any key science initiatives that could be supported by a 12 GeV electron beam? • Is the experimental equipment proposed well matched to the key physics experiments motivating the upgrade? In cases where an experiment or program is proposed for more than one set of equipment, are the differences in capability and physics reach of the equipment essential for getting all of the physics, important for getting as much physics as possible, or simply useful in that, for example, an experiment could be done somewhat faster with one hall equipment compared to another?

3. The Intellectual Framework of the Science Driving CEBAF @ 12 GeV (As Presented to NSAC) The upgrade opens many new scientific opportunities and provides a broad, qualitative enhancement of the present program Key New Physics: • Understanding Confinement (a program of meson spectroscopy) • (defines Emax and requires the addition of “Hall D”) • Detailed Mapping of the Quark and Gluon Wave Functions of the Nucleons via measurements of: • Deep Exclusive Scattering, and • Deep Inelastic Scattering as x 1 for a large range of Q2 (MAD in Hall A, CLAS upgrade to L=1035, SHMS in Hall C) • Extension of the present program of Spin, Hadron and Nuclear Microscopy to higher Q2 • (Higher energies also increase throughput for many experiments now run with 6 GeV beams)

4. Understanding Confinement Theoretical studies of QCD suggest that confinement is due to the formation of “Flux tubes” arising from the self-interaction of the glue, leading to a linear potential (and therefore a constant force) From G. Bali linear potential Experimentally, we want to “pluck” the flux tube and see how it responds

5. CEBAF@ 12 GeV Provides Our First Access to the Generalized Parton Distributions, a Revolutionary New Window on Nucleon Structure Quark distribution q(x) DIS only measures a cut at =0 Antiquark distribution q(x) qq distribution

6. Neutron Asymmetry A1n at Large xBjorken • Study of spin structure functions so far focused on low-x region • A1n behavior for x1 sensitive probe of valence quark wave function: - pure SU(6) : A1n  0 - broken SU(6): A1n  1 • JLab at 12 GeV with its high luminosity is prime facility for measurements at large xBj

7. pCDR Outline • Executive Summary • The Science Motivating the 12 GeV Upgrade • Confinement • Hadron Structure • Valence Quark Structure and Parton Distributions • The GPDs as Accessed via Deep(ly) Exclusive Reactions • Form Factors and Polarizabilities – Constraints on the GPDs • Other Topics in Hadron Structure • Nuclear Structure (was partially under “additional topics…”) • Probing the Limits of the Nucleon-Based Description of Nuclei • The Parton-Hadron Transition in Nuclear Physics • Hadrons in the Nuclear Medium • Additional Topics that Will be Addressed by the 12 GeV Upgrade • Standard Model Tests • Other Topics in Meson Spectroscopy • Spontaneous Symmetry Breaking • Space-time Characteristics of Nuclear Hadronization

8. pCDR Outline (cont.) • The Accelerator • The Experimental Equipment • Hall A • Hall B • Hall C • Hall D • Equipment for Specialized Experiments • Summary and Conclusions

9. Presentations Today and Tomorrow by Editorial Board Members • Executive Summary • Larry Cardman and Frank Close • The Science Motivating the 12 GeV Upgrade • Confinement Curtis Meyer, Alex Dzierba, Ted Barnes, and David Richards • Hadron Structure • Valence Quark Structure and Parton DistributionsZein-Eddine Meziani, Sebastian Kuhn, Oscar Rondon, Wally Melnitchouk • The GPDs as Accessed via Deep(ly) Exclusive ReactionsVolker Burkert, Charles Hyde-Wright, Xiangdong Ji • Form Factors and Polarizabilities – Constraints on the GPDsPaul Stoler, Mark Jones, Bogdan Wojtsekhowski, Anatoly Radyushkin • Other Topics in Hadron StructureGordon Cates, Latifa Elouadrhiri, Thia Keppel, Sabine Jeschonnek

10. Presentations Today and Tomorrow by Editorial Board Members (cont.) • The Science Motivating the 12 GeV Upgrade (cont.) • Nuclear Structure • The Parton-Hadron Transition in Nuclear PhysicsHaiyan Gao, Roy Holt, Carl Carlson • Hadrons in the Nuclear MediumJohn Arrington, Doug Higinbotham, Jean-Marc Laget, Will Brooks • Probing the Limits of the Nucleon-Based Description of NucleiRocco Schiavilla, Larry Weinstein, Paul Ulmer • Additional Topics that Will be Addressed by the 12 GeV Upgrade • Standard Model TestsPaul Reimer, Mike Ramsey-Musolf, Paul Souder, and Dave Mack • Other Topics in Meson SpectroscopyCurtis Meyer, Alex Dzierba, Carlos Salgado, Ted Barnes and David Richards • Spontaneous Symmetry BreakingAron Bernstein, Ashot Gasparian, Jose Goity • Space-time Characteristics of Nuclear HadronizationWill Brooks

11. The Charge for the PAC23 Review of the pCDR In Progress • Comment on the intellectual framework presented for the 12 GeV pCDR. Is this the best way to present the science case to DOE and to the larger nuclear physics community? Are there flaws or omissions in the framework? • Review the new research programs that are under consideration for being highlighted in the executive summary of the pCDR Do they represent compelling science that must be done to advance our understanding of nuclear physics? At what level should they be included in the executive summary? • Have we omitted any key science initiatives that could be supported by a 12 GeV electron beam? • Is the experimental equipment proposed well matched to the key physics experiments motivating the upgrade? In cases where an experiment or program is proposed for more than one set of equipment, are the differences in capability and physics reach of the equipment essential for getting all of the physics, important for getting as much physics as possible, or simply useful in that, for example, an experiment could be done somewhat faster with one hall equipment compared to another?

12. The Experimental Halls Today • Hall C (operational since mid ‘95) L~1038 cm-2s-1 - Two medium-resolution spectrometers HMS and SOS - High-Momentum Spectrometer Short-Orbit Spectrometer • dp/p ~ 10-3 ~ 10-3 • pmax ~ 7 GeV/c ~ 1.5 GeV/c • DW ~ 7 msr ~ 9 msr • Hall A (operational since May ‘97) L~1039 cm-2s-1 - Two identical high-resolution spectrometers (HRS) • dp/p ~ 10-4 • pmax ~ 4 GeV/c • DW ~ 6 msr • Hall B (operational since December ‘97) L~1034 cm-2s-1 - CEBAF Large Acceptance Spectrometer (CLAS) - Based on six-sector superconducting toroidal magnetic field

13. The Three Experimental Halls Hall A (2 HRS) Hall B (CLAS) Hall C (SOS/HMS)

14. CEBAF Upgrade: Experimental Equipment

15. Enhanced Equipment in Halls A, B, & C and a New Hall D A B Medium Acceptance Detector (MAD) at high luminosity and intermediate angles CLAS upgraded to higher (1035) luminosity and coverage C D Super High Momentum Spectrometer (SHMS) at high luminosity and forward angles 9 GeV tagged polarized photons and a 4 hermetic detector

16. Presentations at the Outer Banks by the Editorial Board and Others • The Experimental Equipment (hardware and capabilities): • Hall A: J.-P. Chen, Kees de Jager • Hall B: Volker Burkert • Hall C: Howard Fenker (Rolf Ent) • Hall D: Curtis Meyer and Alex Dzierba (Elton Smith) • Other Equipment for Specialized Experiments: Ashot Gasparian and Paul Reimer

17. The Charge for the PAC23 Review of the pCDR In Progress • Comment on the intellectual framework presented for the 12 GeV pCDR. Is this the best way to present the science case to DOE and to the larger nuclear physics community? Are there flaws or omissions in the framework? • Review the new research programs that are under consideration for being highlighted in the executive summary of the pCDR Do they represent compelling science that must be done to advance our understanding of nuclear physics? At what level should they be included in the executive summary? • Have we omitted any key science initiatives that could be supported by a 12 GeV electron beam? • Is the experimental equipment proposed well matched to the key physics experiments motivating the upgrade? In cases where an experiment or program is proposed for more than one set of equipment, are the differences in capability and physics reach of the equipment essential for getting all of the physics, important for getting as much physics as possible, or simply useful in that, for example, an experiment could be done somewhat faster with one hall equipment compared to another?

18. Summary • This special session of PAC23 will carry out a critical review of the Upgrade plans, providing broad advice on both the physics and our plans for the halls • The science will be presented and discussed in public sessions today and tomorrow • The Hall upgrade plans will be presented in closed sessions at the Outer Banks and there will be an initial pass at reviewing the overlap and orthogonalization of the hall equipment • The PAC will meet in closed sessions (both here and at the Outer Banks) for discussions and development of their report • The report will be a public document and be used as a guide in the preparation of the pCDR