1. L/T separation in the 3 He(e,ep) reaction Javier R. Vignote and Eric Voutier Laboratoire de Physique Subatomique et de Cosmologie, Grenoble, France Jlab Hall A Collaboration Meeting, January, 4-5 2007

2. L/T separation in the 3He(e,ep) reaction Motivations Quasi-elastic scattering 3 He(e,ep) cross section L/T separation Cross section extraction Monte Carlo simulation Results L/T separation Conclusion and prospects

3. Motivations E89-044 experiment: Previous analyses performed by M.Rvachev, E.Penel, F.Benmokhtar and F.Descamps Free nucleonBound nucleon Change in structure? Study bound nucleon by (e,ep) quasi-elastic scattering Extract electromagnetic response functions for various transfered four- momenta Q (i.e. various probing resolutions).

4. Quasi-elastic scattering: 3 He(e,ep)B Missing momentum : undetected momentum Missing energy : separation energy Leptonic plane Hadronic plane Only e and p are detected Residual system B: Quasi-elastic: Parallel: p m 0 Kinematical regime

5. 2 body break-up peak 2-bbu 3 body break-up threshold 3-bbu Quasi-elastic scattering

6. 3 He(e,ep)d cross section : Nuclear response functions R: Recoil factor σ M : Mott cross section : Kinematic electron coupling coefficients

7. L/T separation: Separation of longitudinal/transverse response functions Interference terms ! 0 if pq ! 0 (parallel kinematics) Averaging over out-of-plane angle: ! 0 Separation using Rosenbluth method: Extraction of the 3 He(e,ep)d cross section at different kinematic settings Keep same hadronic vertex and change leptonic vertex. KIN01 KIN03 change photon polarization 2 points in space

8. Experimental setup

9. d, np Experimental setup

10. 3 Monte Carlo simulation: matrix-method E m Vertex E m Asymptotic Binning in E m V Binning In E m A Radiation effects Resolution effects Weights associated to each vertex bin

11. 3 Monte Carlo simulation: example E m Vertex E m Asymptotic Binning in E m V Binning In E m A Radiation effects Resolution effects Event drawn in 2nd bin Vertex Resolution effect to 1st asymptotic bin Contribution to N 12

12. Monte Carlo simulation: example E m Vertex E m Asymptotic Binning in E m V Binning In E m A Radiation effects Resolution effects Event drawn in 2nd bin Vertex Resolution effect to 1st asymptotic bin Contribution to N 12 Event drawn in 2-bbu bin Vertex (1) Radiation to 3rd asymptotic bin Contribution to N 31

13. Cross section results Kin 03 Kin 01

14. L/T Separation Kin01, Kin03: keep same hadronic vertex ω/q and p m /q phase spaces need to be matched Mean values have to be checked to be equal for Kin01 and Kin03 Extract 2-bbu cross sections for the two kinematics at the average kinematic point. q vs ω for Kin01 and Kin03

15. L/T Separation σ

16. Conclusion and prospects Next steps? Generalization of the matrix-method to deconvolute radiative effects between p m bins Additional binning in Q 2 Cross section extractions and L/T separations for the remaining Q 2 at parallel kinematics Matrix method Results consistent with previous analysis Understanding of the different aspects concerning the separation 3He(e,ep)d Cross section extraction L/T separation