status of the e06-007 experiment
DESCRIPTION
STATUS OF THE E06-007 EXPERIMENT Impulse Approximation limitations to the (e,e’p) reaction on 208 Pb, 209 Bi and 12 C. Students : Juan Carlos Cornejo, Joaquin Lopez Herraiz Jlab staff: Alexandre Camsonne Spokepersons: K. Aniol, A. Saha, J. M. Udias, G. Urciuoli - PowerPoint PPT PresentationTRANSCRIPT
HALL A COLLABORATION MEETING16 DECEMBER 2009
STATUS OF THE E06-007 EXPERIMENTSTATUS OF THE E06-007 EXPERIMENT Impulse Approximation limitations Impulse Approximation limitations
to the (e,e’p) reaction to the (e,e’p) reaction on on 208208Pb, Pb, 209209Bi Bi and and 1212CC
StudentsStudents:: Juan Carlos Cornejo, Joaquin Lopez HerraizJlab staff:Jlab staff: Alexandre CamsonneSpokepersons:Spokepersons: K. Aniol, A. Saha, J. M. Udias, G. Urciuoli
and the Jefferson Lab Hall A Collaboration
HALL A COLLABORATION MEETING16 DECEMBER 2009
INDEXMOTIVATION and THEORY DATA ANALYSIS
- Checks - Some results on 12C(e,e’p) and 208Pb(e,e’p)
from J.L.Herraiz, June 2009 Hall A meetingNEW RESULTS FROM MEASURED DATA
- 209Bi(e,e’p)SUMMARY
HALL A COLLABORATION MEETING16 DECEMBER 2009
Nuclear States of interest in E06-007
207Tl
0.0 3s1/2
0.351 2d3/2
1.348 1h11/2
1.683 2d5/2
3.470 1g7/2
MeV
208PbMeV
0.0 0+~4.1 1p1h~5.4 1p1h
209Bi
MeV
0.0 1h9/2, proton
HALL A COLLABORATION MEETING16 DECEMBER 2009
xB = 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 XB=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 MEETING16 DECEMBER 2009
With correlations
Without correlations
Previous experiment at NIKHEF (Bobeldijk, PRL 1994) found an excess of strength at high pmiss in 208Pb(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 pmiss region at the quasielastic peak with good statistics will reveal if long-range correlations are needed to describe the data.
At XB = 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
208Pb(e,e’p)
HALL A COLLABORATION MEETING16 DECEMBER 2009
209Bi(e,e'p)208Pb is also an interesting study
A previous study of electron and photon induced knockout from 209Bi
D. Brandford et al.,PRC 63 014310 (2000)
208Pb(g.s.) 208Pb(hole states)
(e,e'p)
gamma,p
(e,e'p)-parallel kinematics, Ee=293,412 MeV, Tp = 100 MeV110<p
miss<290 MeV/c
E06007- primary goal here is to isolate the 208Pb gs by the knockout of the 1h9/2 proton in 209Bi. The first excited state of 208Pb is at 2.6 MeV(3-) which is weakly excited in (e,e'p)
2nd goal is to excite the 1p1hProton configurations in 208Pb
HALL A COLLABORATION MEETING16 DECEMBER 2009
Proton orbitals which are important for the low lying states. In 209Bi, 208Pb and 207Tl.
209Bi – 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 74 034303 (2006)) but the
(e,e'p) reaction is selecting the proton hole configuration.
HALL A COLLABORATION MEETING16 DECEMBER 2009
1. EXPERIMENT E06-007
• We measured 208Pb(e,e’p), 209Bi(e,e’p) and 12C(e,e’p) cross sections at true quasielastic kinem. (xB=1, q=1GeV/c, ω=0.433GeV/c) at both sides of q.
1. Determine momentum
distributions: 0< pmiss< 500MeV/c
2. Determine ATL by measuring cross
sections on either side of q
3. Determine the spectroscopic
factors dependence with Q2
(0.81, 1.40, 1.97 GeV2)
OBJECTIVES
HALL A COLLABORATION MEETING16 DECEMBER 2009
Data acquisition: RUN 1 – (March, 3-26, 2007) RUN 2 – (January 2008) Additional
measurements in Lead in the high pmiss
region. With thin and thick lead target.
1. EXPERIMENT E06-007
Targets:-Diamond/Lead/Diamond -Diamond/Bismuth/Diamondsandwich cryogenic target 0.2mm Pb + 0.3mm Diamond0.2mm Bi + 0.3mm Diamond (needed for high beam current).
Requirements:- Good Energy Resolution
- Raster Correction
- Normalization Factors
- Use 12C as a reference
HALL A COLLABORATION MEETING16 DECEMBER 2009
3. DATA ANALYSIS: Emiss Resolution
Pmiss = 0-100MeV/c
PROTONS
2.13
0.27
0.27
2.68 0.67
HALL A COLLABORATION MEETING16 DECEMBER 2009
3. DATA ANALYSIS: Emiss Resolution
Two peaks can be separated in this 208Pb(e,e'p)207Tl Emiss spectrum (Pmiss=0). Both of them are composed of two peaks.
Thallium
Valence states
Boron states from 12C(e,e'p)11B
Ex=[0-2.5]
Ex=[2.5-7.5]
HALL A COLLABORATION MEETING16 DECEMBER 2009
3. 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 MEETING16 DECEMBER 2009
4. RESULTS: 209Bi(e,e’p)208Pb Emiss spectrum,pmiss = 200 MeV/c
Lead g.s. From Bismuth
1h9/2 state
boron
Ex=[0-3.0]
leadhole States
HALL A COLLABORATION MEETING16 DECEMBER 2009
209Bi(e,e’p)208Pb ground state CROSS-SECTION
Integrated over the detector acceptancesgeant simulation, Coulombs scaled by area of Bismuth to
total area in the raster pattern.
pmiss
(MeV/c)
<>exp
(nb/MeV/sr2)
<>theory
(nb/MeV/sr2)
-0.3 0.038 0.043 0.006
-0.2 0.171 0.065 0.179
-0.1 0.113 0.078 0.060
0.1 0.075 0.039 0.095
0.2 0.362 0.095 0.382
0.3 0.011 0.019 0.026
Emiss
PRELIMIN
ARY
PRELIMIN
ARY
Cro
ss
-Sec
tio
n
209Bi(e,e’p)208Pb ground state
Independent analysis using MCEEP simulation for kinematic runs at pmiss
= 100, 200 and 300 MeV/c. Luminosities estimated from the comparison to carbon(graphite) data.
PRELIMINARY
HALL A COLLABORATION MEETING16 DECEMBER 2009
Pmiss
= 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.
11B states
208Pb(e,e'p)207Tl
208Pb, g.s.
209Bi(e,e'p)208Pb, hole states
Comparison of hole states in 208Pb and valence states in 207Tl
Integrated cross section over the particle hole states in 208Pb
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 pmiss
distribution is fitted well assuming the same proton orbitals are important for the 1p1h states in 208Pb as the proton orbitals used in the 207Tl states
HALL A COLLABORATION MEETING16 DECEMBER 2009
4. RESULTS: 208Pb(e,e’p) RED. CROSS-SECTION(Emiss region –Ex=0..7.5MeV-)
SIMULATION
DATA
PRELIMIN
ARY
PRELIMIN
ARY
207Tl states
HALL A COLLABORATION MEETING16 DECEMBER 2009
Results from D. Brandford etal., PRC 63 014310 (2000)
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Summary
Analysis is ongoing for the 209Bi 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 208Pb(e,e'p)207Tl - Q2 dependence on the spectroscopic factors for 208Pb(e,e'p)207Tl and 12C(e,e'p)11B- A
TL dependence on p
miss
- 209Bi(e,e'p)208Pb cross sections
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BACKUP SLIDES
Bismuth
1h9/2 state
boronlead
hole States
DATA
SIMULATION
pmiss = 200MeV/c
HALL A COLLABORATION MEETING16 DECEMBER 2009
Results from D. Brandford etal., PRC 63 014310 (2000)
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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 MEETING16 DECEMBER 2009
HALL A COLLABORATION MEETING16 DECEMBER 2009
2. THEORY AND SIMULATIONSINPUT PARAMETERINPUT PARAMETER OPTIONOPTION
BOUND-NUCLEON
WAVE FUNCTION
NLSH
OPTICAL MODEL EDAI-C (12C) & EDAD (208Pb, 209Bi)
NUCLEAR SPINOR DISTORTION RELATIVISTIC AND
PROJECTED (NON-RELATIVISTIC DYNAMICS)
ELECTRON DISTORTION NONE (yet)
KINEMATICS RELATIVISTIC
CURRENT OPERATOR CC2
NUCLEON FORM FACTORS J.ARRINGTON (ROSENBLUTH DATA FIT)
GAUGE COULOMB
RADIATION SIMULATED BUT NOT UNFOLDED
HALL A COLLABORATION MEETING16 DECEMBER 2009
- 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 MEETING16 DECEMBER 2009
• For each kinematics, the cross-section is obtained as:
3. DATA ANALYSIS: Cross-Section (e,e’p)
5 _ _ _
e p e p
d Number of counts correctedd d d L
sw w
=W W DW ×DW ×D ×
Live time and
Multitrack corrections
Solid angles Electron Energy Range
Luminosity
5 5
1
1red
e p p p CC e p
d dd d d E P d d d
s sw s w
= ×W W W W
CC1 - Prescription of De Forest Form Factors from J. Arrington
fit of Rosenbluth data. PRC 69, 022201 (2004).
• Using MCEEP we can simulate the Phase-space
population and bin the acquired data in (pmiss,q,,)
• Reduced cross-section was obtained as:
HALL A COLLABORATION MEETING16 DECEMBER 2009
4. RESULTS: 12C(e,e’p) REDUCED CROSS-SECTION
PRELIMINARY
Simulations: RDWIA with and w/o relativistic dynamical
effects in the wave function (projected)
HALL A COLLABORATION MEETING16 DECEMBER 2009
4. RESULTS: 12C(e,e’p) REDUCED CROSS-SECTIONCOMPARATIVE WITH PREVIOUS EXPERIMENTS
PRELIMIN
ARY
PRELIMIN
ARY
(*)
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4. RESULTS: 12C(e,e’p) ATL
PRELIMIN
ARY
PRELIMIN
ARY
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4. RESULTS: Study of dependence with Q2 in 12C
Reduced cross-section for the 1p32 shell (Emiss=[14-23] MeV)in 12C(e,e’p) are independent of
Q2
SIMULATION
DATA
No need to adjust simulation for the experiments at different Q2 within error bars (5%)
HALL A COLLABORATION MEETING16 DECEMBER 2009
4. RESULTS: 208Pb(e,e’p) RED. CROSS-SECTIONCOMPARATIVE WITH PREVIOUS EXPERIMENTS
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4. RESULTS: 208Pb(e,e’p) ATL
PRELIMIN
ARY
PRELIMIN
ARY
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4. RESULTS: 208Pb(e,e’p) Study of dependence with Q2 in 208Pb
Reduced cross-section for the valence states in 208Pb(e,e’p) are also independent of Q2
SIMULATION
DATA
HALL A COLLABORATION MEETING16 DECEMBER 2009
5. CONCLUSIONS Most of the data analysis of E06-007 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 Q2
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 ATL 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 1h9/2 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 MEETING16 DECEMBER 2009
2. 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 pmiss in 208Pb(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 ATL is an excellent observable to check both models.
Measuring the high pmiss region at the quasielastic peak with good statistics will reveal if long-range correlations are needed to describe the data.