Notes

2013

5 March

Joining: OR, PS, EL, KS, JP, NK

For the asymmetry method, it seems that the target polarization needs to be parallel with the q-vector (virtual gamma). This would probably entail the use of spectrometers, because the setting would rotate some for each kinematic setting and the detectors would need to adjust accordingly. The quantities of interest are A_zz & b_1.

The issue with this is understanding/mitigating the contamination from the various spin observables; g_1,2, A_1,2, b_2,4. These need to be cancelled to a level at/below the b_1 errors (~10^-4). g_2 ~10*b_1 in the higher x_Bj region, which is of interest. One other lever arm for this is to ensure there is minimal beam polarization.

Patricia is going to be looking at the rates for this. She is also going to start with assuming there being no beam polarization and try to include it later.

Regarding magnets, based on Oscar's calculations, a suitable magnet would need an aperture of ± 15 degrees (at least) to accommodate the ~30 degree range of the q-vector. Also, the magnet would need to be able to space for a target length of 3-4 cm.

Please let me know if I missed anything. I know there was also some talk of the Jaffe + friends method, which was in the previously submitted proposal, expect to adjust using asymmetries.