HALL A COLLABORATION MEETING 16 DECEMBER 2009 STATUS OF THE E EXPERIMENT Impulse Approximation limitations to the (e,e’p) reaction on 208 Pb, 209 Bi and 12 C Impulse Approximation limitations to the (e,e’p) reaction on 208 Pb, 209 Bi and 12 C Students: Students: Juan Carlos Cornejo, Joaquin Lopez Herraiz Jlab staff: Jlab staff: Alexandre Camsonne Spokepersons: Spokepersons: K. Aniol, A. Saha, J. M. Udias, G. Urciuoli and the Jefferson Lab Hall A Collaboration

HALL A COLLABORATION MEETING 16 DECEMBER 2009 INDEX MOTIVATION and THEORY DATA ANALYSIS - Checks - Some results on 12 C(e,e’p) and 208 Pb(e,e’p) from J.L.Herraiz, June 2009 Hall A meeting NEW RESULTS FROM MEASURED DATA Bi(e,e’p) SUMMARY

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Nuclear States of interest in E Tl 0.0 3s 1/ d 3/ h 11/ d 5/ g 7/2 MeV 208 Pb MeV ~4.1 1p1h ~5.4 1p1h 209 Bi MeV 0.01h9/2, proton

HALL A COLLABORATION MEETING 16 DECEMBER 2009 x B = 0.18 E. Quint, thesis, 1988, NIKHEF I. Bobeldijk et al., PRL 73 (2684)1994 J. M. Udías et al. PRC 48(2731) 1994 J.M. Udías et al. PRC 51(3246) 1996 If long range correlations are the reason for the small spectroscopic factors, then they should produce a large effect at high missing momentum. An experiment was performed at NIKHEF-K to measure the large momentum region, but the kinematics was far from X B =1. Additional strength was indeed found, but this can be explained either via long- range correlations or by relativistic effects in the mean field model. Long Range Correlations ? Ambiguous Interpretation

HALL A COLLABORATION MEETING 16 DECEMBER 2009 With correlations Without correlations Previous experiment at NIKHEF (Bobeldijk, PRL 1994) found an excess of strength at high p miss in 208 Pb(e,e’p). This was explained by two approaches: (1) Quasiparticle orbits plus non-relativistic DWIA. (2) Relativistic DWIA using independent particle orbit solutions to Dirac equation. Measuring the high p miss region at the quasielastic peak with good statistics will reveal if long-range correlations are needed to describe the data. At X B = 1 both a relativistic and nonrelativistic theoretical treatment agree and excess strength at high p miss is predicted by both approaches if LRC exist. Simulated theoretical calculations Choice of Kinematics 208 Pb(e,e’p)

HALL A COLLABORATION MEETING 16 DECEMBER Bi(e,e'p) 208 Pb is also an interesting study A previous study of electron and photon induced knockout from 209 Bi D. Brandford et al.,PRC (2000) 208 Pb(g.s.) 208 Pb(hole states) (e,e'p) gamma,p (e,e'p)-parallel kinematics, Ee=293,412 MeV, Tp = 100 MeV 110<p miss <290 MeV/c E primary goal here is to isolate the 208 Pb gs by the knockout of the 1h9/2 proton in 209 Bi. The first excited state of 208 Pb is at 2.6 MeV(3 - ) which is weakly excited in (e,e'p) 2 nd goal is to excite the 1p1h Proton configurations in 208 Pb

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Proton orbitals which are important for the low lying states. In 209 Bi, 208 Pb and 207 Tl. 209 Bi – model structure From earlier proton removal experiments and the data of Brandford the strong excitations at 4.1 and 5.4 MeV have proton particle hole configurations given by [1h9/2,(3s1/2) -1 ] [1h9/2,(2d3/2) -1 ] [1h9/2,(1h11/2) -1 ] [1h9/2,(2d5/2) -1 ] There are many states in this energy region which also have large neutron particle-hole configurations(PRC (2006)) but the (e,e'p) reaction is selecting the proton hole configuration.

HALL A COLLABORATION MEETING 16 DECEMBER EXPERIMENT E We measured 208 Pb(e,e’p), 209 Bi(e,e’p) and 12 C(e,e’p) cross sections at true quasielastic kinem. (x B =1, q=1GeV/c, ω=0.433GeV/c) at both sides of q. 1.Determine momentum distributions: 0< p miss < 500MeV/c 2.Determine A TL by measuring cross sections on either side of q 3.Determine the spectroscopic factors dependence with Q 2 (0.81, 1.40, 1.97 GeV 2 ) OBJECTIVES

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Data acquisition:  RUN 1 – (March, 3-26, 2007)  RUN 2 – (January 2008) Additional measurements in Lead in the high p miss region. With thin and thick lead target. 1. EXPERIMENT E Targets: -Diamond/Lead/Diamond -Diamond/Bismuth/Diamond sandwich cryogenic target 0.2mm Pb + 0.3mm Diamond 0.2mm Bi + 0.3mm Diamond (needed for high beam current). Requirements: - Good Energy Resolution - Raster Correction - Normalization Factors - Use 12 C as a reference

HALL A COLLABORATION MEETING 16 DECEMBER DATA ANALYSIS: Emiss Resolution Pmiss = 0-100MeV/c PROTONS

HALL A COLLABORATION MEETING 16 DECEMBER DATA ANALYSIS: Emiss Resolution Two peaks can be separated in this 208 Pb(e,e'p) 207 Tl Emiss spectrum (Pmiss=0). Both of them are composed of two peaks. Thallium Valence states Boron states from 12 C(e,e'p) 11 B Ex= [0-2.5] Ex= [ ]

HALL A COLLABORATION MEETING 16 DECEMBER DATA ANALYSIS: Luminosity and Raster 1 ) 1 ) In order to get Absolute Cross Sections we should know the Luminosity very precisely. 2 ) 2 ) Nevertheless C+Bi+C target had a problem and Bismuth only covered one-half of the target. Furthermore, the raster pattern was not uniform at the edges. 3 ) 3 ) A simple approach (ratio between areas) may not be entirely accurate. To estimate luminosities, we compared the measured cross- section in the region of the target with only diamond foils against the events measured with the graphite target, both with Raster on and off. GRAPHITE DIAMOND X Y

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 209 Bi(e,e’p) 208 Pb Emiss spectrum,p miss = 200 MeV/c Lead g.s. From Bismuth 1h9/2 state boron Ex= [0-3.0] lead hole States

HALL A COLLABORATION MEETING 16 DECEMBER Bi(e,e’p) 208 Pb ground state CROSS-SECTION Integrated over the detector acceptances geant simulation, Coulombs scaled by area of Bismuth to total area in the raster pattern. p miss (MeV/c) exp (nb/MeV/sr 2 ) theory (nb/MeV/sr 2 )       Emiss PRELIMINARY Cross-Section

209 Bi(e,e’p) 208 Pb ground state Independent analysis using MCEEP simulation for kinematic runs at p miss = 100, 200 and 300 MeV/c. Luminosities estimated from the comparison to carbon(graphite) data. PRELIMINARY

HALL A COLLABORATION MEETING 16 DECEMBER 2009 P miss = 200 MeV/c The two spectra have been normalized by the luminosities. The Raster cut has been applied so that the carbon/metal ratios are the same in the two spectra. 11 B states 208 Pb(e,e'p) 207 Tl 208 Pb, g.s. 209 Bi(e,e'p) 208 Pb, hole states Comparison of hole states in 208 Pb and valence states in 207 Tl

Integrated cross section over the particle hole states in 208 Pb PRELIMINARY Luminosities were estimated by comparing the carbon events from the diamond-foils-only region of the target to the same kinematics with the graphite target. The shape of the p miss distribution is fitted well assuming the same proton orbitals are important for the 1p1h states in 208 Pb as the proton orbitals used in

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 208 Pb(e,e’p) RED. CROSS-SECTION (Emiss region –Ex=0..7.5MeV-) SIMULATION DATA PRELIMINARY 207 Tl states

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Results from D. Brandford etal., PRC (2000)

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Summary Analysis is ongoing for the 209 Bi data – extract cross sections on both sides of the three momentum transfer. Theses writing is being finished Papers on the results are being written: - long range correlation implications for 208 Pb(e,e'p) 207 Tl - Q 2 dependence on the spectroscopic factors for 208 Pb(e,e'p) 207 Tl and 12 C(e,e'p) 11 B - A TL dependence on p miss Bi(e,e'p) 208 Pb cross sections

HALL A COLLABORATION MEETING 16 DECEMBER 2009 BACKUP SLIDES

Bismuth 1h9/2 state boron lead hole States DATA SIMULATION p miss = 200MeV/c

KIN 2 KIN 4

HALL A COLLABORATION MEETING 16 DECEMBER 2009 Results from D. Brandford etal., PRC (2000)

HALL A COLLABORATION MEETING 16 DECEMBER 2009

HALL A COLLABORATION MEETING 16 DECEMBER 2009

HALL A COLLABORATION MEETING 16 DECEMBER 2009 HOW MUCH HYDROGEN IS THERE? · LEAD TARGET: NucleiH ~0.12% NucleiPb (.t)H~5.8E-6 (.t)Pb = 1.13E-6 g/cm2 tH ~ 1E-8m · GRAPHITE TARGET (RUN 1): NucleiH ~0.016% NucleiC (.t)H~2.2E-5 (.t)C = 1.9E-6g/cm2 tH ~ 2E-8m

HALL A COLLABORATION MEETING 16 DECEMBER 2009

HALL A COLLABORATION MEETING 16 DECEMBER THEORY AND SIMULATIONS INPUT PARAMETER OPTION BOUND-NUCLEON WAVE FUNCTION NLSH OPTICAL MODELEDAI-C ( 12 C) & EDAD ( 208 Pb, 209 Bi) NUCLEAR SPINOR DISTORTION RELATIVISTIC AND PROJECTED (NON-RELATIVISTIC DYNAMICS) ELECTRON DISTORTIONNONE (yet) KINEMATICSRELATIVISTIC CURRENT OPERATORCC2 NUCLEON FORM FACTORSJ.ARRINGTON (ROSENBLUTH DATA FIT) GAUGECOULOMB RADIATIONSIMULATED BUT NOT UNFOLDED

HALL A COLLABORATION MEETING 16 DECEMBER The first part of the data analysis consisted in: Improving the Optics Database to get 1MeV resolution. Improving the Coincidence Time (resolution  2.5ns). Establishing the Raster Correction (we used a large raster) Normalization factors (Dead-time,Multitracks correction) - This part of the analysis is almost finished and we obtain reasonable good results: 3. DATA ANALYSIS – Calibration Good Coincidence Time RASTER ON RASTER OFF

HALL A COLLABORATION MEETING 16 DECEMBER 2009 For each kinematics, the cross-section is obtained as: 3. DATA ANALYSIS: Cross-Section (e,e’p) Live time and Multitrack corrections Solid anglesElectron Energy Range Luminosity  CC1 - Prescription of De Forest Form Factors from J. Arrington fit of Rosenbluth data. PRC 69, (2004). Using MCEEP we can simulate the Phase-space population and bin the acquired data in (p miss,q, ,  ) Reduced cross-section was obtained as:

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 12 C(e,e’p) REDUCED CROSS-SECTION PRELIMINARY Simulations: RDWIA with and w/o relativistic dynamical effects in the wave function (projected)

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 12 C(e,e’p) REDUCED CROSS-SECTION COMPARATIVE WITH PREVIOUS EXPERIMENTS PRELIMINARY (*)

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 12 C(e,e’p) A TL PRELIMINARY

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: Study of dependence with Q 2 in 12 C Reduced cross-section for the 1p 32 shell (Emiss=[14-23] MeV) in 12 C(e,e’p) are independent of Q 2 SIMULATION DATA No need to adjust simulation for the experiments at different Q 2 within error bars (5%)

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 208 Pb(e,e’p) RED. CROSS-SECTION COMPARATIVE WITH PREVIOUS EXPERIMENTS

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 208 Pb(e,e’p) A TL PRELIMINARY

HALL A COLLABORATION MEETING 16 DECEMBER RESULTS: 208 Pb(e,e’p) Study of dependence with Q 2 in 208Pb Reduced cross-section for the valence states in 208 Pb(e,e’p) are also independent of Q 2 SIMULATION DATA

HALL A COLLABORATION MEETING 16 DECEMBER CONCLUSIONS  Most of the data analysis of E experiment has already been done and preliminary results have been obtained.  In the last few months, we have focused on Bismuth data. CARBON and LEAD:  Results show no significant dependence of spectroscopic factors with Q 2 both in Carbon and Lead.  Simulations obtained from just relativistic mean field calculations (without long-range correlations included) seem to compare fairly well with data at both low and high missing momentum and the A TL has the expected shape.  These results are being checked in more detail. Specially radiative corrections, systematic errors and different theoretical models. BISMUTH:  Cross-section for the state 1h 9/2 has been obtained for different kinematics. These preliminary results are in fairly good agreement with RMF predictions with an occupancy of ~0.7 protons in that shell.

HALL A COLLABORATION MEETING 16 DECEMBER THEORY AND SIMULATIONS With correlations Without correlations Non relativistic dynamics(Projected) Relativistic dynamics Previous experiment at NIKHEF (Bobeldijk, PRL 1994) found an excess of strength at high p miss in 208 Pb(e,e’p). This was explained by two approaches: (1) Quasiparticle orbits plus non-relativistic DWIA. (2) Relativistic DWIA using independent particle orbit solutions to Dirac equation. The A TL is an excellent observable to check both models. Measuring the high p miss region at the quasielastic peak with good statistics will reveal if long-range correlations are needed to describe the data.