Charge symmetry breaking in np elastic scattering at 347 MeV

Journal Article · Sat Apr 01 04:00:00 EST 1995 · Bulletin of the American Physical Society

OSTI ID:374958

Oers, W T.H. van

Charge symmetry breaking in np elastic scattering has been measured via a non-zero difference of the analyzing powers, {Delta}A{identical_to}A{sub n}{minus}A{sub p}, with the subscripts denoting the polarized nucleon. The non-zero value of {Delta}A reflects the effect of so-called class IV isospin breaking nucleon-nucleon interactions. In the experiment scattering asymmetries were measured with a 347 MeV neutron beam (produced through the D({bar p},{bar n})2p reaction) incident of a frozen spin type proton target. The beam and the target were alternately polarized. Scattered neutrons and recoil protons were detected in coincidence in the center-of-mass angle range from 50{degrees} to 90{degrees} with a mirror symmetric (with respect to the neutron beam axis) detection system. The A{sub n} and A{sub p} measurements were interleaved and executed with the same detection system, the same beam and target properties (except polarization) and frequent flip of the polarization directions. At the zero-crossing angle, where the analyzing powers vanish, all systematic errors except those correlated with spin reversal and background correction were eliminated to at least second order. The experiment determined the difference of the zero-crossing angles to be {Delta}{theta} {identical_to}{theta}{sub n}{minus}{theta}{sub p} =0.438{degrees}{+-}0.054(stat.){+-}0.051(syst.)(c.m.) based on fits of the measured asymmetry curves over the angular range 53.4{le}{theta}{sub cm}{le}86.9{degrees}. Using the experimentally determined slope of the analyzing power dA/d{theta} =({minus}1.35{+-}0.05) x 10{sup {minus}2}deg{sup {minus}1}, the difference of the analyzing powers at the zero-crossing angle is {Delta}A = [59{+-}7(stat.){+-}2(syst.)] x 10{sup {minus}4}. The shape of {Delta}A in the angular range of the experiment was also extracted.

• OSTI ID: 374958
• Report Number(s): CONF-9304297--
• Journal Information: Bulletin of the American Physical Society, Journal Name: Bulletin of the American Physical Society Journal Issue: 2 Vol. 40; ISSN 0003-0503; ISSN BAPSA6
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
ELASTIC SCATTERING
ELECTRIC CHARGES
MEV RANGE 100-1000
POLARIZED BEAMS
POLARIZED TARGETS
PROTON-NEUTRON INTERACTIONS
SYMMETRY BREAKING