A Staged approach to the Super Bigbite Project The Super Bigbite Project is designed to provide precision measurements of the nucleon form factors G E n, G M n and G E p to unprecedented values of Q 2, and to enable a greatly expanded program of DIS experiments. The first stage, for 1.8M, will be comprised of:  Fully approved: G E n (50 days) and G M n (25 days). The second stage is for 2.3M. The second stage will open the door to a large group of Super Bigbite experiments including:  Fully approved: G E p to 15 GeV 2 (45days),  Conditionally approved: SIDIS: Transversity for 3 He(e,e’π/K), high-x u/d ratio using T & 3 He  In planning stages: A 1 n (high Q 2 ), DIS(e,e’ ϕ ), Transversity in (e,e’π o ), PVDIS w 70 msr,, and G E n and F π using a neutron polarimeter. 1

In this presentation we discuss: The excellent quality of the physics that will come out of Stage I. The structure of the project and its budget. The reasons it is so important to move forward quickly 2

The first Hall A gEn experiment First GEn data in the high Q 2 regime where unexpected results were seen for G E p /G M p. Fairly consistent with theoretical explanations of G E p /G M p, thus supporting the importance of quark orbital angular momentum in nucleon structure. Closest agreement is with the Argonne DSE that incorporates dynamic generation of mass, and contains diquark degrees of freedom. 3

Flavor separated dependence for F 1 & F 2 4 With the Hall A results for G E n, the assumption of isospin symmetry, and existing proton results, it is possible to determine F 1 and F 2 separately for u quarks d quarks to high values of Q 2. What is clearly evident is that the ratio drops off markedly for higher values of Q 2, indicating that the d quark is more spatially diffuse than are the u quarks. Shown at left is the ratio of F 1 d and F 1 u for the d and u quarks as they exist in the proton.

The first Hall A g E n experiment enables a more detailed visualization of the neutron 5 Core is positive and “proton like” Core is surrounded by negative pion cloud Naive charge density representing the Fourier transform of the neutron electric form factor Covariant light-front transverse “charge” density in impact- parameter space. After the charge, spin and magnetic moment, the elastic form factors are among the nucleon’s most fundamental properties, telling us their “size and shape”.

Intriguing observation that the ratio F2/F1 is roughly constant over 1 < Q 2 < 3.4 GeV 2  diquark configuration?  An effect of orbital motion? Accurate data at higher Q 2 could reshape our thinking of valence quark structure The first Hall A GEn experiment enabled the flavor decomposition of F 1 and F 2 at high Q F 1,2 u = 2F 1,2 p + F 1,2 n F 1,2 d = F 1,2 p + 2F 1,2 n κ d -1 F 2d / F 1d κ u -1 F 2u / F 1u 6

Stage I of The Super Bigbite program following the 12 GeV upgrade 7

Hall A G E n (E ) will provide dramatic new insight into nucleon structure The dramatic turnover of the Argonne DSE model would be clearly visible. If the turnover is seen, it would provide strong evidence for the importance of diquark degrees of freedom in the nucleon form factors. 8

Hall A G M n (E ) will provide superb accuracy WILL GREATLY IMPROVE THE ACCURACY WITH WHICH G M n KNOWN, AND IS ESSENTIAL FOR EXTRACTING G E n, F 1, F 2 AND DOING FLAVOR DECOMPOSITIONS. WILL GREATLY IMPROVE THE ACCURACY WITH WHICH G M n KNOWN, AND IS ESSENTIAL FOR EXTRACTING G E n, F 1, F 2 AND DOING FLAVOR DECOMPOSITIONS. COMPARED TO HALL B, WILL ACHIEVE superior accuracy IN half the time, WITH INDEPENDENT SYSTEMATIC ERRORS. COMPARED TO HALL B, WILL ACHIEVE superior accuracy IN half the time, WITH INDEPENDENT SYSTEMATIC ERRORS. 9

Projected flavor decomposition using the E data The flavor decomposition of F 1 using G M n /G M p represents a unique opportunity to see deep inside the nucleon. GPD’s will need to be seriously modified to accommodate F 1 d /F 1 u going through zero. 10 Two highest points in planning stage.

The layout of the Super Bigbite apparatus with all components for GEp(5) Scatterin g chamber Vacuu m snout Magnetic shield First tracke r Second tracker Hadron calorimet er Beam line Pb shield 48D48 magn et Third tracker CH2 analyzer Bea m 11

The layout of the Super Bigbite apparatus necessary for the Neutron FFs 48D48 magnet Hadron calorimete r GEM-based “First trackers” Single-axis GEM tracker Magnetic:  beam-line cut, power, support platform  but without new coils, lead shielding Hadron calorimeter GEM-based veto in front of hadron calorimeter. INFN funded GEM-based “First tracker” from SBS BigBite 12

The layout of the Super Bigbite apparatus necessary for the Neutron FFs 48D48 magnet Hadron calorimete r GEM-based “First trackers” Single-axis GEM tracker TOSCA calculation was performed and showed that single coil solution is quite adequate for both G E n and G M n 13

All amounts are in $ k stage I budget for Super Bigbite 14 ItemInstitution Total Magnet, DC power, Beam line and university contracts overhead Jlab Hadron CalorimeterCMU Coordinate detectorUVa Total ,797 ItemSourceAmount SBS Front GEM TrackerINFN1,050 (720 k Euro) Clean room and DAQ electronicsUVa match 50 Readout ChipsUVa on hand 10 Total non-DOE contributions1,110 Non-DOE contributions DOE contributions Jlab Contribution1,797 Non-DOE contributions1,110 Total Stage I Budget2,907

ItemQuantityUnit costContingencyOverheadTotal GEM foil86$1,55020%--$160,000 Readout Boards26$ 38530%--$13,000 Supplies1$ 10,00020%--$ 12,000 Tooling1$ 5,00020%--$6,000 Gas plumbing1$ 2,00020%--$ 2,400 HV distribution1$ 2,75020%--$ 3,300 Support frames2$ 2,50020%--$ 6,000 Readout electronics1$ 129,00020%--$ 154,800 Technician (FTE)2$ 59, %$ 180,000 Total$537,500 ItemCostContingencyTotalNotes Clean room and supplies$14,60020%$17,520Proposed UVa match VME electronics$ 27,00020%$ 32,500Proposed UVa match Readout chips$ 10,000--$ 10,000In hand the coordinate detector at Uva Support from other sources: 15

hadron calorimeter at Carnegie mellon 16 ItemQuantityUnit costContingencyOverheadTotal Shower modules250$ 68030%--$ 221,000 LED Monitoring1$ %--$ 6,630 Tooling1$ 18,00030%--$ 23,400 Transportation1$ 40,00030%--$ 52,000 Total$ 303,030

STage I DOE funds spent at jlab 17 All amounts are in $ k Item Total Magnet DC Power Beam Line Detector Supports0750 university contracts overhead Total

Stage II of The Super Bigbite program following the 12 GeV upgrade 18 The second stage comprising a measurement of G E p and more can be completed for an additional 2.3M USD. The second stage will open the door to a large group of Super Bigbite experiments including:  Fully approved: G E p to 15 GeV 2 (45days)  Conditionally approved: SIDIS: Transversity for 3 He(e,e’π/K), high-x u/d ratio using T & 3 He  In planning stages: A 1 n (high Q 2 ), DIS(e,e’ ϕ ), Transversity in (e,e’π o ), PVDIS w 70 msr,, and G E n and F π using a neutron polarimeter.

The 12 GeV G E p /G M p Experiment The proton form factor, according to the most recent NSAC LRP, “... remains the only source of information about quark distributions at small transverse distance scales." Super Bigbite is the only way to obtain good accuracy at the necessary Q 2 scaling with existing equipment and roughly half the time

Key goals of the 12 GeV program Super Bigbite, together with Bigbite, is the only way to push A1n to x=0.8. Super Bigbite is currently conditionally approved as the basis for the tritium expt.

The 12 GeV A1n Experiment E GeV 8.8 GeV 11 GeV

All amounts are in $ k stage II budget for super bigbite 22 ProjectProject Execution Total New coils for magnet, Beam line, detector supports, and university contracts overhead Jlab Polarimeter GEM chambersUVa GEM ReadoutNSU GEM mechanicsW&M0720 TriggerRutgers Total Jlab contribution5991, ,345

All amounts are in $ k 23 STAGE II DOE FUNDS SPENT AT JLAB Item Total Magnet02120 DC Power0000 Beam Line03050 Detector Supports university contracts overhead Total

All amounts are in $ k Time line of DOE expenditures Stage I + Stage II Total cost to DOE : $ 4,142 k Total non-DOE contributions: $ 1,110 k + Labor

Why it is important to start the Super Bigbite Project now It is important to produce first-rate physics soon after establishing the upgraded beam. To be ready on time, work on the Super Bigbite project must begin now. Of the approved 12 GeV experiments for Hall A, 6 out of 12 require the Super Bigbite apparatus in one form or another. INFN is already moving at full speed to construct their GEM trackers. Delay of Super Bigbite could jeopardize our collaboration. Dubna proposed to build a calorimeter for $0.3M, which is very efficient. UVa has already accumulated experience with small GEM chambers, and has manpower assembled and ready to proceed. 25

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