E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 1 July, 7 th, 2004 Quasi-elastic 3 He(e,e’p) experiment (E89-044) at Jefferson Lab : study of the 2-bbu parallel kinematics. E. Penel - Nottaris Expérience E de diffusion quasi-élastique sur l’ 3 He au Jefferson Laboratory : analyse des sections efficaces 3 He(e,e’p)d en cinématique parallèle. Hall A collaboration 2 other PhD students : F. Benmokhtar and M. Rvachev

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 2 July, 7 th, 2004 General context Electromagnetic probe - interaction described by QED - electron is a point like particle - small coupling (Z   1) - kinematical flexibility (e,e’p) experiments study the nucleon inside the nucleus - energy and momentum distribution of nucleon - electromagnetic properties of bound proton 3 He nucleus - exact calculations for 3-body systems - ingredients of complex nuclei NN and 3-body forces Short range correlations Relativistic effects

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 3 July, 7 th, 2004 Quasi-elastic scattering on 3 He Plane Wave Impulse Approximation -  absorbed by the detected nucleon - independent particles model for the nucleus - particles described by plane waves.  ep : electron-(off shell) proton elastic cross section Born Approximation : one photon exchange S(E miss, p miss ) : spectral function of 3 He

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 4 July, 7 th, body-break-up : 3 He(e,e  p)d E miss = 5.5 MeV 3-body-break-up : 3 He(e,e  p)pn E miss  7.7 MeV E miss = M p + M recoil – M 3He Missing energy : E miss =  - T p - T r E miss (MeV) Quasi-elastic scattering on 3 He  2.2 MeV energy separation between the 2 processes

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 5 July, 7 th, 2004 Reaction mechanisms beyond PWIA Meson Exchange Currents (MEC) and Isobaric Currents (IC) : Exchange term : Final State Interactions (FSI) : modify the extracted nuclear information involve more general cross- section formulation

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 6 July, 7 th, 2004 Longitudinal and transverse response functions Virtual photon polarization : - h=0 longitudinal polarization - h=  1 transverse polarizations h=0 h=-1 h=+1 interference terms : longitudinal response function  coupling to nuclear charge : transverse response function  coupling to nuclear transverse current

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 7 July, 7 th, 2004 Longitudinal and transverse response functions Parallel kinematics : p miss p’

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 8 July, 7 th, 2004 Experimental settings p miss (MeV/c) q (GeV/c)  Fw -  Bw Extracting the response functions : - forward electron angles :  Fw (  Fw  1) - backward electron angles :  Bw (  Bw  0) at fixed hadronic vertex variables

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 9 July, 7 th, Coincidence experiment => 100% duty cycle - High luminosity (10 38 cm -2 s -1 ) => high beam current and target density -Identification of processes separated by 2.2 MeV at momenta of few GeV => low beam energy dispersion ( ) and high momentum resolution ( ) Jefferson Lab Hall A Basic Equipment

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 10 July, 7 th, 2004 CEBAF Continuous Electron Beam Accelerator Facility Duty cycle100 % Beam energy0.8 – 6 GeV Energy dispersion Beam emittance Beam current 200  A Frequency = 1497 MHz  499 MHz in the halls

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 11 July, 7 th, 2004 Jlab Hall A

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 12 July, 7 th, 2004 Cryogenic 3 He gaseous target High density : T = 6.3 K P  7.6 or 11 atm   = or g.cm -3 Density measurements : - temperature and pressure sensors + state equation of 3 He - elastic electron scattering on 3 He at each beam energy Cylindrical target (tuna can) :  = 10.3 cm Preliminary normalization by density from sensors Systematic error on density from sensors : 7 %

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 13 July, 7 th, He target relative density Luminosity monitoring Target density stability : max. fluctuation < 3% (  0.6 %) corrected for dead time and prescales density of the 1st run density from luminosity monitoring density from P and T sensors run number relative density

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 14 July, 7 th, 2004 High Resolution Spectrometers HRS AcceptanceResolution Momentum± 5 % Horizontal angle  30 mrad 2.0 mrad Vertical angle  65 mrad 6.0 mrad Separates momentum resolution (vertical plane) from vertex position resolution (horizontal plane) 45° vertical deflexion (FWHM)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 15 July, 7 th, 2004 Detectors Set

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 16 July, 7 th, 2004 Electron identification p e > 17 MeV/c p  > 4.8 GeV/c Relative calibration by analysis software Gas Cerenkov detectorShower counters Absolute gains calibration (p e = 3581 MeV/c) preshower and shower counters -- -- e-e- e-e- Cerenkov (channel)preshower + shower (MeV)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 17 July, 7 th, 2004 Scintillators Two planes of 6 scintillator paddles in each arm : S1 and S2 planes Trigger electronics : - Coincidence between the 2 PM of the hit paddle. Single event  S1 & S2 & 45° track Relative calibration by analysis software Coincidence event  Electron event & Hadron event S1 ADC (channel) x rot (m) S1 ADC (channel) x rot (m)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 18 July, 7 th, 2004 Vertex reconstruction VDC tracks  detector variables Spectrometer focal plane variables Spectrometer target variables Vertex variables detector position offsets / focal plane spectrometer absolute position / hall spectrometer optics tensor + beam position In each detection arm :

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 19 July, 7 th, 2004 Transverse position reconstruction z tg y tg beam scattered e -  tg y tg react_z target Transverse position tensor coefficients optimized from vertex position along beam line (react_z) Scattering off 4 targets : - carbon foil at z = 0 - aluminum foils at z = ± 2 cm z = ± 5 cm z = ± 7.5 cm z lab y lab

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 20 July, 7 th, 2004 Transverse position reconstruction beforeafter Low electron momentum High proton momentum hadron react_z (cm) Ph = 2999 MeV/c Ph = 1295 MeV/c electron react_z (cm) Pe = 694 MeV/c Pe = 3850 MeV/c electron react_z (cm) hadron react_z (cm)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 21 July, 7 th, 2004 Momentum reconstruction Momentum tensor coefficients optimized on missing energy spectra : remove dependence on dispersive variables (x fp,  fp ) E miss (MeV) hadron  rot (rad)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 22 July, 7 th, 2004 Spectrometers absolute position - May not point at the hall center - Angle orientation may be different from floor marks  Use scattering off carbon foil at z = 0 electron react_z (mm)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 23 July, 7 th, Background rejection => experimental 3 He(e,e’p) events - 2-bbu and 3-bbu separation - Radiative corrections - Phase space calculation => Monte Carlo Simulation Data Analysis and Simulation => Simulated 3 He(e,e’p) events 3 He(e,e’p)d Cross-sections =>

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 24 July, 7 th, 2004 Background rejection Coincidence events selection Corrected time of coincidence : tc_cor Time of coincidence window width = 12 ns 2 ns beam structure resolution   0.6 ns tc (ns)tc_cor (ns)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 25 July, 7 th, 2004 Background rejection Electrons identification signal in the Cerenkov detector + signal in the showers e-e- -- -- e-e- shower (MeV) preshower (MeV) shower (MeV) preshower (MeV) tc_cor (ns)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 26 July, 7 th, 2004 Target walls rejection : vertex position cuts | react_z | < 4 cm cut on the arm with best resolution on react_z | react_z e arm – react_z h arm | < 2 cm electron react_z (cm)electron react_z - hadron react_z (cm)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 27 July, 7 th, 2004 Background rejection Protons selection p d ++ before cutsafter cuts  No need to remove deuterons or pions hadron  hadron S2 ADC

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 28 July, 7 th, 2004 Parallel kinematics selection p miss  bq  pq Parallel configuration :  Cone aperture = 45 °  bq (°) p miss =+300 MeV/c p miss =0 MeV/c p miss =-300 MeV/c

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 29 July, 7 th, 2004 Accidental coincidences subtraction Subtraction of missing energy spectra : before accidental subtraction after accidental subtraction tc_cor (ns) E miss (MeV)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 30 July, 7 th, 2004 Missing energy spectra E miss (MeV) p miss = 0 MeV/c p miss = +300 MeV/c forward backward forwardbackward

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 31 July, 7 th, 2004 Phase space simulation Limit simulated and experimental phase space to the same volume Optimize statistics by considering maximal phase space volume Cuts on target variables : (same cuts for both arms)  y tg (m)  tg (rad)  tg (rad) (R-function defined by M. Rvachev)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 32 July, 7 th, 2004 Angular and transverse position resolutions Angular resolutions : FWHM  tg = 2 mrad FWHM  tg = 4 mrad Transverse position resolution : fitted from y tg distributions on scattering off carbon foils data  1.4 mm < FWHM y tg < 9.7 mm Carbon foil dataQuasi-elastic 3 He data datasimulation  y tg (mm) electron react_z - hadron react_z (cm)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 33 July, 7 th, 2004 Momentum resolution Adjusted in the simulation to get same resolution on missing energy for 2-bbu as experimental resolution  same momentum resolution for electron and hadron arms. kin # FWHM  kin # FWHM   < FWHM  < datasimulation E miss (MeV)

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 34 July, 7 th, 2004 Extracting 3 He(e,e’p)d cross-sections By fitting simulated missing energy spectrum to experimental data takes into account 3-bbu contribution (1 % systematic error on subtraction) simulates energy losses and radiative effects extracts unradiated cross- section averaged on phase-space Two theoretical models : - unit cross-section - PWIA model E miss (MeV) data simulation

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 35 July, 7 th, 2004 Experimental data analysis shows reliable background control and pretty good transport variables resolutions Simulation reproduces rather well kinematical variables resolutions => used to extract unradiated cross-section averaged on phase-space Possible improvements could come from spectrometer optics optimization, simulated resolutions and absolute normalization by density from elastic data. Systematic error on preliminary cross-sections is 8.8 % (mainly due to target density) Preliminary results

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 36 July, 7 th, 2004 Experimental results : P miss = 0 MeV/c De Forest / Salme PWIA Laget PWIA Laget full calculation p miss (MeV/c) cross-section (  b.MeV -1.sr -2 ) Backward electron angles Forward electron angles

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 37 July, 7 th, 2004 Experimental results: P miss = +300 MeV/c De Forest / Salme PWIA Laget PWIA Laget full calculation P miss (MeV/c) cross-section (  b.MeV -1.sr -2 ) P miss (MeV/c) cross-section (  b.MeV -1.sr -2 ) Salme wave function Urbanna Paris Forward electron angles Backward electron angles

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 38 July, 7 th, 2004 Experimental results: P miss = -300 MeV/c De Forest / Salme PWIA Laget PWIA P miss (MeV/c) cross-section (  b.MeV -1.sr -2 ) P miss (MeV/c) cross-section (  b.MeV -1.sr -2 ) Salme wave function Urbanna Paris Forward electron angles Backward electron angles

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 39 July, 7 th, 2004 Longitudinal and transverse response functions P miss = -300 MeV/c  and q matching for forward and backward kinematics 50 MeV/c p miss bins achieving forward and backward cross-sections De Forest / Salme PWIA Sensitivity to interference terms and imperfect ( , q) matching P miss (MeV/c)  L (  b.sr -2 )  T (  b.sr -2 )

E. Penel-NottarisLaboratoire de Physique Subatomique et de Cosmologie de Grenoble 40 July, 7 th, 2004 Preliminary results show unexpected effects for forward electron angles kinematics at p miss = 0 and rather good agreement for the other kinematics that should constraint theoretical models. Elastic data analysis would allow final cross- sections extraction. Longitudinal and transverse separation looks promising Very interesting results on perpendicular kinematics (2-bbu and 3-bbu) that constrained models. Other experiments at Jlab study few body interactions models through (e,e’p) Overview on E results Parallel kinematics