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Polarimeter Effective Analyzing Power,


In order to extract the polarization transfer observables it is necessary to know both the polarization of the incident proton and the polarization of the outgoing neutron. The neutron polarization is found by using the analyzing power of the scattering reaction with, primarily, the hydrogen in the front plane of the scintillator. Therefore, the analyzing power, as defined in equation gif, of the detector must be determined before the polarization of the neutrons can be extracted via the formulae:

where is the effective analyzing power of the detector, and and are the ``asymmetries'' corresponding to neutron polarizations in the and directions, respectively. The asymmetries are defined as a difference in the number of polarized particles scattered in one direction versus the opposite direction normalized to the total number of scattered particles. Typically (i.e. in the beamline polarimeters) this is measured by putting one detector to the left of an analyzing target and another to the right and comparing the difference in counts. However, because of the unique design of the INPOL polarimeter, which doesn't have a single small analyzing target, a method called the sector method is used.

Michael A. Lisa
Tue Apr 1 08:52:10 EST 1997