1. SAMPLE: Parity Violating Electron Scattering from Hydrogen and Deuterium
Kellogg Radiation Lab, Caltech Pasadena, CA
Nuclear Physics Lab, Univ. of Illinois, Urbana, IL
MIT-Bates Linear Accelerator Center, Middleton, MA
Univ. of Maryland, College Park, MD
Virginia Polytechnic Institute, Blacksburg, VA
Louisiana Tech, Ralston, LA
University of Kentucky, Lexington, KY
College of William and Mary, Williamsburg, VA
Argonne National Laboratory, Argonne, IL
2001: plus MIT, Grenoble

2. Parity Violating Electron Scattering
polarized electrons, unpolarized target
for a proton:
forward angles
backward angles
Beyond 1st order...
electroweak radiative corrections
Z exchange
anapole

3. NUCLEON ANAPOLE MOMENT
Musolf+Holstein, PRD43 (1991) 2956
General electromagnetic coupling:
Anapole
(TRI , PV)
Electric dipole
(TRV, PV)
Modeled by Musolf+Holstein
(1990) using DDH parameters
Recent updates:
Zhu, Puglia, Holstein, Musolf, PRD62 (2000)
Maekawa, Veiga, van Kolck, PLB 488 (2000) 167
D. Riska, NPA 678 (2000) 79

4. SAMPLE Experiment Schematic
Polarized
Injector
Beam position
feedback
Lumi
Beam current
feedback
Wien
Filter
Position,
Angle,
Charge
Halo
SAMPLE
Detector
Beam
Current
K11
Moller
Polarimeter
Accelerator
E = 200 MeV
600 pulses/s
Ipk = 3 mA
Iave = 44 A
PB = 36%
Energy
Fast phase shift
feedback

5. E = 200 MeV
P  36 %

6. SAMPLE 1998/1999 1998: 136 Coulombs delivered
1st use of piezo feedback
after 10 days running
T. Averett, et al., NIM A438, 246 (1999).
D. Spayde et al., PRL 84, 1106 (2000).
1999: 174 Coulombs delivered
R. Hasty et al., Science 290, 2117 (2000).

7. at Q2=0.1 (GeV/c)2

8. Mott Asymmetry in p(e,e’)‘
S. Wells, et al., Phys.Rev. C63 (2001)
transverse beam pol’n + full f-coverage of detector gives access to possible spin dependent terms in elastic cross section.
lowest order is 2-g exchange
1st measurement at “high” energy
no calculations for spin-1/2 target

9. SAMPLE E00-04: D(e,e’) at 125 MeV
spokesperson: T. Ito, Caltech
Q2 = 0.04 (GeV/c)2
Different systematic effects:
A120 = 0.3 A200
s120 = 1.4 s200
background similar, so improved S/B
similar sensitivity to , unique opportunity to measure
other systematic errors comparable
in 2 month run, expect
test run April/May 2001, production run Oct 2001

10. PMT Signal Breakdown “LIGHT”: Cerenkov “non-LIGHT”: EM showers
Scintillation
“non-LIGHT”: EM showers
neutrons
separate w/ pulse counting
“shutter closed”
Dependence of background on beam energy is weak

11. Contributions to the Deuteron Asymmetry
Pollock, PR D42 (1990) 3010.
Musolf + Donnelly, NP A546 (1992) 509.
Elastic and threshold breakup negligible at 200 MeV
may need to consider threshold bkup at 125 MeV

12. PV QUASIELASTIC (e,e’) from DEUTERIUM
“static” approximation:
nuclear model uncertainties small
Hadjimichael, Poulis + Donnelly,
PR C45 (1992) 2666.
meson exchange/two-body currents
Schramm + Horowitz, PRC 49 (1994) 2777
Kuster + Arenhovel, NPA 626 (1997) 911
at SAMPLE kinematics: e.g. q=154
Diaconescu, Schiavilla, and van Kolck,
PRC 63 (2001)
many-body effects are few % at 200 MeV
 energy dependence?

13. SUMMARY
SAMPLE III is unique opportunity to measure
low energy behavior of
125 MeV beam tune has been established
Backgrounds demonstrated to be similar to that at 200 MeV
Will use high polarization crystal if performance is good