E06007, March 3 -> March 26, 2007

208Pb(e,e’p)207Tl, 209Bi(e,e’p)208Pb

Impulse Approximation limitations to the (e,e',p) reaction on 208Pb, identifying correlations and relativistic effects in the nuclear medium

Students:

Juan Carlos Cornejo (CSULA)

Joaquin Lopez (U. Madrid)

x=1, q = 1 GeV/c, w = 0.433 GeV, Q2 = 0.81 to 1.97 (GeV/c)2

Outline

1) Objectives of experiment

2) Optics and raster correction work (Guido Urciuoli, Joaquin Lopez, Juan Carlos Cornejo)

3) Survey of some results and comparison to earlier experiments

4) Plans for upcoming run in January 2008

(I) Long Range Correlations search

a) Measure spectroscopic factors for states near the Fermi level. Spectroscopic factors depend on SRC and LRC.

b) Measure cross sections for these low lying states to 500 MeV/c in pmiss. Excess strength here is theoretically identified as due to LRC.

Objectives

c) Search for Q2 dependence of spectroscopic factors.

207Tl, low lying statesg.s. 3s1/20.351 2d3/21.348 1h11/21.683 2d5/23.470 1g7/2

(II) Identify dynamical relativistic effects in nuclear structure.

Objectives

Measure cross section asymmetry ATL around the three momentum transfer. Relativistic mean field theory predicts an ATL dependence on pmiss< 300 MeV/c due to dynamical enhancement of the lower component of the nucleon wave function. Calculations which do not include the enhancement of the lower component predict a substantially different ATL behavior.

Online data base

HRSR, carbon target 83 mg/cm2 Optics

Progress in data base change

HRSR, carbon target 83 mg/cm2 optics

Run 1231

Raster ON

FWHM ~ 1 MeV

Run 1232

Raster OFF

FWHM ~ 1 MeV

Kin02 Carbon target Raster correcting formula: -1194*ReactPt_L.y -17560*ReactPt_L.y**2

Raster Correction to 2nd order

sm

GEANT simulation using nominal spectrometer resolutions plus data with online optics data base.

12C(e,e’p)11B, small acceptance

815 keV

Cannot expect better than 815 keV resolution

0 3.47

0 8

Data survey

Pb, simulation, pmiss = 300 MeV/c

207Tl, low lying statesg.s. 3s1/20.351 2d3/21.348 1h11/21.683 2d5/23.470 1g7/2

Quint et al. PRL 57, 186 (1986)

Bobeldiik et al., PRL 73, 2864 (1994)

Parallel kinematics,

E0 = 410, 350 MeV

Low pmiss

E0 = 487.3 MeV, xB = 0.18

High pmiss

0 0.351

1.683 5.5

8

207Tl11B

Data survey

GEANT simulation, C with Pb kinematics, pmiss = 0 MeV/c

Pb C11B gs and no 207Tl continuum

dp/p = +- 1.0e-4,

dh = +- 0.3mr,

dv = +- 1.0mr

0

5

209Bi(e,e’p)208Pb

Pmiss = 200 MeV/c

Data survey50 keV/bin

209Bi(e,e’p)208Pb

209Bi(,p)208Pb

D. Branford et al.

PRC 63 014310 (2000)

0

E0 = 293 and 410 MeV,

Parallel kinematics

States at 4.1 and 5.4 MeV are 500 keV wide.

Believed to be configuration mixed states:

p(1h9/2)x(3s1/2)-1

p(1h9/2)x(2d3/2)-1

p(1h9/2)x(1h11/2)-1

p(1h9/2)x(2d5/2)-1

150<pmiss<210 MeV/c

January 2008 run Jan. 20-Jan. 30, E06007 and PREX tests

Measure pmiss = 400 and 500 MeV/c, use 0.5mm tgt

New target design suggested by Bogdan

– maximize contact of diamond and lead

-SRF prepares clean surfaces on diamond and lead in vacuum

- press diamond/Pb/diamond sandwich together under vacuum producing “cold weld”

- E06-007 will be running in close collaboration with the PREX tests

-Request for shift sign-ups coming shortly