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Resolution

  The transport matrix obtained from the tracking program can be used to derive the resolution expected from the spectrometers. The horizontal transfer from the vertex to the tex2html_wrap_inline3140 (tex2html_wrap_inline3144) Roman pot is given by Eq. 1.


 equation582

where tex2html_wrap_inline3858 is the horizontal position of the particle in the Q pots, tex2html_wrap_inline3862 is the angle from the Q to S pots, and tex2html_wrap_inline3868 is the initial angle from the interaction point (IP).

The particle's initial conditions at the IP (tex2html_wrap_inline3868 and tex2html_wrap_inline3216) are reconstructed from the detector readings (tex2html_wrap_inline3858 and tex2html_wrap_inline3862) through the equations:


 equation589


 equation595


 equation600

The transfer matrix parameters from the IP to the tex2html_wrap_inline3140(tex2html_wrap_inline3144) pots are given below:

m12=9.47(20.2)

m13=23.5(9.02)

m22=-0.345(-0.220)

m23=3.45(1.57)

tex2html_wrap_inline3898

The detector resolutions can be calculated from these equations using the substitutions tex2html_wrap_inline3900 and tex2html_wrap_inline3902. The following equations for the resolution are obtained:
equation611

equation613
The value of tex2html_wrap_inline3904 depends on the point resolution of the detector and multiple scattering, which are estimated to be about 0.1 mm and 0.04 mm, respectively, for the detector discussed in Sec. 4.2.1. It is also sensitive to the uncertainty in the beam position at the tex2html_wrap_inline3140 location. The average beam position can be measured very well using elastic events, and deviations from this position are expected to be about 0.1 mm [38]. Adding these resolutions in quadrature gives tex2html_wrap_inline3908 mm. This yields estimated resolutions of tex2html_wrap_inline3910 and tex2html_wrap_inline3912. In practice, the |t| resolution is dominated by the 0.06 mrad angular dispersion of the beam, which corresponds to tex2html_wrap_inline3918. These resolutions compare well with the expected dipole spectrometer resolution of tex2html_wrap_inline3920 and tex2html_wrap_inline3922  [35].



Gilvan Alves
Tue Mar 17 12:50:26 GRNLNDST 1998