S800 Documentation

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====== Modes of Operation ======
The analysis line can be used in two different modes. 

===== Focus Mode =====
In the focus mode, the maximum momentum acceptance is achieved (±2%) by making the analysis line achromatic with a maximum dispersion value 1.5 cm/% reached at the intermediate image plane (see [[Fig. xxx]]). In this mode the coordinates of the fragment at the spectrograph focal plane are sensitive to the momentum of the beam impinging on the target. The momentum of each particle beam must then be tracked, significantly limiting the resolution at the focal plane to about 1 part in 1000 in energy. 

===== Dispersion-matching Mode =====
In the dispersion-matching mode the whole system (analysis line + spectrograph) is achromatic in the focal plane (see [[Fig. xxx]]). The analysis line has a 2D focus (in the dispersive //x// and non-dispersive //y// directions ) in the target point and has a high dispersion of about 11 cm/%, limiting the momentum acceptance to ±0.5%. The intermediate image plane has also a 2D focus and a dispersion of 1.5 cm/%. This mode provides the highest possible energy resolution (1 part in 5000 for a 1-mm wide beam spot), since it does not require momentum tracking. 

===== Monochromatic Mode =====
__The monochromatic mode is still in development stage__. The motivation is the production of low-energy (5-10 MeV) secondary beams from a high-energy fragmentation beam. The implementation of this mode requires the use of a mono-energetic wedged installed in the intermediate image station. The wedge profile must be built  on a case-by-case basis, considering the specific energy and nuclei in the experiment.
S800 Documentation

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