The first attempt to measure both the longitudinal and transverse
spin-isospin responses was carried out at the High-Resolution
Spectrometer (HRS) at
the Los Alamos Meson Physics Facility (LAMPF) using a 500 MeV polarized
proton beam on 
and 
targets at
q = 1.75 
. The
results are reported in [Car84]. The outgoing protons were momentum
analyzed in the HRS and the polarization observables measured with the use
of a focal plane polarimeter. See [McC84] for details on this
technique.
Figure: Ratio of IVSL to IVST response functions for
at q = 1.75
and 
= 500 MeV.
The dashed
line shows the Alberico et al. calculations [AEM82]
at full nuclear density;
the dotted line, at half nuclear density. [Car84]
The results of the HRS experiment are shown in figure 
. The
ratio (
) is consistent with unity for this
experiment and does not show the enhancement expected from calculations.
For reference the predicted response ratios are shown on figure
for calculations at full- and half- nuclear density.
The prediction for half nuclear density was considered because at 500 MeV
nucleon-nucleus scattering tends to be peaked at the surface of the
nucleus where the nuclear density is decreasing. However, even with the
density
correction the data obviously does not confirm the predictions of Alberico
et al. [AEM82]. This was the first indication from quasifree
nucleon scattering that the nuclear pion field did not show the
enhancement expected. However, the results should be considered with some
skepticism since the 
probe is not the perfect
probe of spin-isospin densities. The interaction has a large
isoscalar component which is not easily separable from the isovector part
of the interaction.