L/T separation in the 3 He(e,e’p) reaction at parallel kinematics Freija Descamps Supervisors: Ron Gilman Eric Voutier Co-supervisor: Jean Mougey

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report Conclusion and prospects

Motivations E experiment: December 1999! April 2000 Free nucleonBound nucleon Change in structure? Study bound nucleon by (e,e’p) quasi-elastic scattering Extract electromagnetic response functions for various transfered four- momenta Q (i.e. various probing resolutions). High Q 2 : unexplored domain Variable Q 2 High precision measurements

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report Conclusion and prospects

Quasi-elastic scattering: 3 He(e,e’p)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

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

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

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,e’p)d cross section at different kinematic settings Keep same hadronic vertex and change leptonic vertex. KIN01≠ KIN03 change photon polarization 2 points in space 

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report Conclusion and prospects

Experimental setup Jefferson Laboratory (CEBAF, Newport News, USA), continuous electron beam : Beam Energy up to 6 GeV Beam Intensity up to 200  A Recirculation arcs 0.6 GeV LINAC 67 MeV injector 3 experimental areas Extraction elements

Experimental setup

d, np Experimental setup

Electron ArmHadron Arm TOF p 0 Electron ArmHadron Arm TrackingVertical Drift Chamber (2 planes) TriggersS1, S2 scintillator planes (Čerenkov)S1, S2 scintillator planes (S0) PIDČerenkov, Shower counters S1, S2 ! TOF S0 S1, S2 ! TOF

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report Conclusion and prospects

Experimental data 1 Raw Data Coincidence events Real coincidence events Filter Background rejection Accidental coincidence rejection Experimental Yield In p m and E m bins

1 Experimental Data: Background rejection Some examples... Electron ArmHadron and Electron Arm Events that are not reconstructed at the same point by each spectrometer Pion contamination Demand |z labh -z labe | < 0.02.Demand hit in Čerenkov counter.

1 Experimental Data: Accidental coincidences Bin experimental data in p m Per p m bin: bin in E m First bin in E m = 2-bbu bin Substract flat background: Bin in E m Experimental yield per p m, E m bin Accidental coincidences

Luminosity 2 Raw Data All events Detector Efficiencies Efficiency study total deadtime target density Normalization factor

2 Luminosity: Scintillator efficiency study Scintillator efficiency study Kin 03: S1-study in Hadron arm Start losing ‘good events’!

2 Luminosity: target density monitoring Target density monitoring: Single rates Kin 03: Single rates vs. Run number Increase in target density

Monte Carlo simulation 3 Experimental conditions Input Raw simulated events Resolutions, Offsets, Target density Monte Carlo Acceptance cuts Simulated Yield In p m and E m bins

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

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

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 Event drawn in 2-bbu bin Vertex (1) Radiation to 3rd asymptotic bin Contribution to N 31

Cross section results Kin 03 Kin 01 Previous Analysis Current Analysis

Cross section results Kin 01 Previous Analysis Current Analysis Why this difference?  Bq  pq  Bq > 90°  Bq < 90° Current analysis: no angle selection

Cross section results Previous Analysis Current Analysis  pq  Bq P m >0( 135°)  pq <2°

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report Conclusion and prospects

L/T Separation: status report 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

L/T Separation: status report σ

L/T separation in the 3He(e,e’p) reaction at parallel kinematics Motivations Quasi-elastic scattering 3 He(e,e’p) cross section L/T separation Experimental setup Cross section extraction Experimental data Normalization Monte Carlo simulation Results L/T separation Status report 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 Good understanding of efficiencies Optimization of good-event-selection Matrix method Gain in statistics Iteration of matrix method Results consistent with previous analysis Understanding of the different aspects concerning the separation First results seem reasonable Detector in-beam efficiency study 3He(e,e’p)d Cross section extraction Preliminary L/T separation