This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Cameron, J.M.

Ni, B.

The, I.

English

IUScholarWorks

ELECTROMAGNETIC PROCESSES 
ANALYSIS OF DATA FOR DEUTERON TENSOR POLARIZATION 
IN ELECTRON-DEUTERON SCATTERING 
J.M. Cameron and B. Ni 
Indiana University Cyclotron Facility, Bloomington, Indiana 4 7405 
I. The 
MIT- bate^, Cambridge, Massachu~etts 02199 
A high efficiency deuteron polarimeter devel- 
oped at the University of Alberta and calibrated 
- BONN E 
at the Laboratoire National Saturne was used to 
measure the tensor polarization of recoil deuterons 
in electron-deuteron scattering at the MIT-Bates 
Lab in 1987-88.' Data were taken at incident elec- 
tron energies of 650,750, and 850 MeV and consti- 
tute by far the highest Q2 measurements to date. 
Several on-line modifications necessitated by the 
hostile radiation environment have made analysis 
of this data much more complicated than origi- 
nally anticipated. Additional shielding added at 
the higher two energies required a relocation of 
some of the polarimeter detectors. In addition the 
deuteron energies incident on the polaximeter at 
Bates were midway between calibration points. A 
Monte Carlo simulation program was developed 
- 1 . 5  
and calibrated using the LNS data. This was then 
s 
0 2 4 6 8 1 0  
- 
used to make the adjustments necessaxy to predict q [: f m " 1  
the polarimeter response. Analysis of the data are 
now essentially complete. Work continues to de- 
termine the systematic errors due to Monte Carlo 
modeling and to various software cuts on the Bates 
data. These systematic errors axe tentatively es- 
timated to be between 0.1 and 0.15. The prelim- 
inary results at the three energies are shown in 
Fig. 1. The data clearly indicate that the tensor 
analyzing power is not at its perturbative QCD 
expectation value of -JZ and that the prediction 
of the full Bonn potential2 including meson ex- 
change corrections and relativistic effects give a 
good account of the deuteron structure. 
Figure 1. Deuteron tensor po- 
larization data. The results 
of the present experiment are 
shown as solid dots. The er- 
ror baxs include only statis- 
tical uncertainties. The cal- 
culations are for three ver- 
sions of the Bonn Potential 
and include both meson ex- 
change current and relativistic 
 effect^.^ 
1. M. Garcon et al. in Spin Observable~ of  Nuclear Probes, 1988 edited by C.J. Horowitz, 
C.D. Goodman, and G.E. Walker (Plenum Press, 1988) p.357. 
2. J. Pauschenwein, L. Mathelitsch and W. Plessas, Nucl. Phys. A508 (1990) 253c. 
DIELECTRONIC RECOMBINATION IN HE+ IONS* 
J. A.  Tanis, E. M. Bernstein, 
W e ~ t e r n  Michigan University, Kalamazoo, Michigan 49008 
S. Chantrenne, M. W. Clark, D. Schneider 
Lawrence Livermore Laboratory, Livermore, California 94550 
T. Ellison, C. C. Foster, W. W. Jacobs, T. Rinckel, A. Ross 
Indiana University Cyclotron Facility, Bloomington, Indiana 47405 
W. G. Graham 
Queen's U n i v e r ~ i t y ,  Belfast B T7 I N N ,  United Kingdom 
J .  R. Mowak 
North Carolina State University, Raleigh, North Carolina 27695 
M. P. Stockli 
K a n s a ~  State University, Manhattan, Kansas 66506 
Dielectronic recombination (DR) is an atomic collision process which involves electron 
capture accompanied by simultaneous ionic excitation, i.e., an inverse Auger transition. 
We have investigated DR for Is --+ ~lln'l' transitions in He+ + e- collisions1 at IUCF using 
the ion storage ring and the electron Cooler in a "single pass" mode, i.e., the ions circled 
the magnet, arid then are collected in a Faranday cup. A beam of 44 MeV 3Het ions (current 
-- 300 nA) was merged with the electron cooling beam (current - 0.2 A) over an interaction 
length of -- 2.8 m. Events resulting in DR were detected by observing neutral He atoms 
produced in the electron Cooler. These atoms, which exited through a O0 port followi~ig 
the cooler region, were observed with solid-state detectors in a dE/dx arrangement thereby 
allowing pa.rticle identificakion to separate the He atoms from background events. 
For He+ (Is)  ions DR is expected to occur for relakive energies of 33-39 eV between the 
ion and electron. By ramping the relative electron energy from -50 eV 5 Erel < +- 50 eV, 
DR maxima, were observed for electron velocities less and grea,ter than the ion beam ve- 
locity, respectively. Between these DR maxima, a peak due to radiative re~ombina~tion 
(inverse phototelectric effect) was observed for Erel = 0. A typical spectrum is shown in 
Fig. 1. Maximum counting rates at the DR maxima were about 10 Hz and the signal 
to noise ratio was about 18:l. Due to a hardware problem, the electron beam energy 
resolution (about 20 eV in the projectile frame) was insufficient to resolve individual tran- 
sitions due to DR. New measrlrements are planned with this problem corrected, and it is 
anticipated that the resolution will be sufficient to observe these individual transitions. 


Analysis of Data for Deuteron Tensor Polarization in Electron-Deuteron Scattering

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Analysis of Data for Deuteron Tensor Polarization in Electron-Deuteron Scattering

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