jefferson lab, newport news, va and the hall a collaboration e06-007 spokepersons: k. aniol, a....
TRANSCRIPT
Jefferson Lab, Newport News, VAand the Hall A Collaboration
E06-007Spokepersons: K. Aniol, A. Saha, J.M. Udías, G. Urciuoli
Students: Juan Carlos Cornejo1, Joaquin Lopez Herraiz2
Hall A: Alexandre Camsonne
Impulse Approximation limitations to the (e,e'p)
reaction on 208Pb and 12C
(1) Now at William and Mary in PhD program
(2) PhD thesis accepted, Universidad Complutense de Madrid
(a) Search for long range correlations at x = 1 for states near the Fermi surface.
(b) Search for possible Q2 dependence on spectroscopic factors.
(c) Using ATL
, search for additional evidence for relativistic effects in nuclear
structure.
STUDY OF THE (e,e’p) STUDY OF THE (e,e’p) QUASIELASTIC REACTIONQUASIELASTIC REACTION
IN COMPLEX NUCLEI: IN COMPLEX NUCLEI: THEORY AND EXPERIMENT THEORY AND EXPERIMENT
Thesis supervisor
Dr. José Manuel Udías Moinelo
Joaquín López Herraiz
Grupo de Física NuclearDepartamento de Física Atómica, Molecular y Nuclear
Universidad Complutense de Madrid
14-May-2010
Experimental Setup:Experimental Setup: 2. – Targets: C+Pb+C 2. – Targets: C+Pb+C
Beam entrance Beam exit
Diamond/Lead/Diamond cryogenic target (for high beam current) 0.2 mm Lead Foil 0.15 mm Diamond Foils
BeO
C
Pb
Pb
Bi
BeO
C
Pb
Pb
Bi
Diamond 0.0465 g/cm2
Lead 0.194 g/cm2
Diamond 0.0395 g/cm2
Target ladder
3
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATION
4 ) DATA ANALISIS5 ) RESULTS 6 ) SUMMARY AND CONCLUSIONS
Emiss (MeV)
ONLINE SPECTRUM
12C
208Pb
- With the optimized database and with the appropriate raster correction, good resolution has been achieved.
- Two peaks can be separated in this 208Pb Emiss spectrum (pmiss=0).
Ex (MeV) Shell
0 3s1/2
0.351 2d3/2
1.348 1h11/2
1.683 2d5/2
3.470 1g7/2 Low lying states in 207Tl
12C
208Pb
OPTIMIZED
SPECTRUM
Emiss (MeV)
4
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS3 ) DESCRIPTION OF THE EXPERIMENTS
5 ) RESULTS 6 ) SUMMARY AND CONCLUSIONS
Spectrometer CalibrationSpectrometer CalibrationOptics Optimization: EnergyOptics Optimization: Energy
Raster position cut – Required in 208Pb to remove those events that hit the frame.
5
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS3 ) DESCRIPTION OF THE EXPERIMENTS 4 ) DATA ANALISIS5 ) RESULTS 6 ) SUMMARY AND CONCLUSIONS
Efficiency correctionsEfficiency corrections
1212C(e,e’p) EC(e,e’p) Emissmiss
6
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS4 ) DATA ANALISIS5 ) RESULTS 6 ) SUMMARY AND CONCLUSIONS
Pmiss = 0-100MeV/c
7
Spec. factor = 0.85 0.05
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS
6 ) SUMMARY AND CONCLUSIONS
1212C(e,e’p) – 1pC(e,e’p) – 1p3/23/2 shell shell
Reduced Cross SectionReduced Cross Section
8
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS4 ) DATA AN
1212C(e,e’p) - 1pC(e,e’p) - 1p3/23/2 shell shell
AATLTL
chi2DOF =1.59 (Rel.)
chi2DOF =2.09 (No Rel.)
9
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS4 ) DATA ANAL 6 ) SUMMARY AND CONCLUSIONS
208208Pb(e,e’p) – Valence States Pb(e,e’p) – Valence States Reduced Cross SectionReduced Cross Section
Experimental 208Pb(e,e'p) reduced cross section (for the aggregate of valence states) together with the results from relativistic DWIA for the contributions from individual shells.
3s1/2, 0.52(6)
2d3/2, 0.59(6)
1h11/2, 0.65(6)
2d5/2, 0.52(6)
Relativistic DWIA mean field calculations
10
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS4 ) DATA ANAL 6 ) SUMMARY AND CONCLUSIONS
208208Pb(e,e’p) – Valence States Pb(e,e’p) – Valence States Reduced Cross SectionReduced Cross Section
11
1 ) QUASIELASTIC (e,e’p) REACTION 2 ) SIMULATIONS 3 ) DESCRIPTION OF THE EXPERIMENTS4 ) DATA ANALIS6 ) SUMMARY AND CONCLUSIONS
208208Pb(e,e’p) - Valence StatesPb(e,e’p) - Valence StatesAATLTL
chi2DOF = 1.13 (Rel.)chi2DOF = 2.65 (No Rel.)
nucleu
s
shell spec.fac
t
12C 1p1/2 0.85(5)
208Pb 3s1/2 0.52(6)
2d3/2 0.59(6)
1h11/2 0.65(6)
2d5/2 0.52(6)
Spectroscopic factors at
Q2 = 0.8 GeV2
Spectroscopic factors vs Q2
-100 MeV/c<pmiss
<+100 MeV/c
From PhD thesis of Joaquin Lopez Herraiz
Some Target Issues – A tough neighborhood for experimenters!
Run 1 (March 2007) – First exposure to data taking with heavy metal
targets at high currents.
We want to look at the LHRS momentum spectrum as a luminosity
monitor. We have carbon data which we can subtract from the
diamond/lead/diamond spectra.
Raster pattern for carbon The morphology of the
heavy metal targets
changes during the
exposures.
A stable total trigger rate
is not a reliable measure
of a stable target.
Raster pattern selected avoids the frame.
R1207, Pb/Q =259.6
R1208, Pb/Q = 255.8
After several hours at 50uA.
Target is 0.17mm thick.
R1209, Pb/Q = 255.6
R1210, Pb/Q = 247.4
R1211, Pb/Q = 244.1
Visual Inspections of targets from run 2
(January 2008) – E06007 tgts at 30 deg.
0.5 mm, 208Pb
0.17mm, 208Pb
0.2mm 209Bi
A better design than for run 1.
Migration of lead – target gave bad
emiss
spectrum.
Thin lead and bismuth targets
look to be in good shape.
Analysis is continuing.
Close ups of thick lead and thin lead from run 2.
We are looking for the target ladder from run1.
Alexandre is setting up a system, x-ray and/or laser, to measure target thicknesses
and uniformity.