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.