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modes_of_operation [2013/12/24 09:05]
pereira [Focus Mode] |
modes_of_operation [2016/01/19 12:33]
pereira [Focus Mode] |
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| ===== Focus Mode ===== | ===== Focus Mode ===== |
| In the focus mode, the maximum momentum acceptance is achieved (±2%) by making the [[Introduction#Analysis line|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. | In the focus mode, the maximum momentum acceptance is achieved (±2%) by making the [[Introduction#Analysis line|analysis line]] achromatic with a maximum dispersion value 1.5 cm/% reached at the intermediate image plane (see figure below). In this mode the coordinates of the fragment at the [[Introduction#Spectrograph|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. |
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| | {{:wiki:focused.png?750|Ion optics diagram for S800 in focus mode.}} |
| ===== Dispersion-matching Mode ===== | ===== Dispersion-matching Mode ===== |
| In the dispersion-matching mode the whole system ([[Introduction#Analysis Line|analysis line]] + [[Introduction#Spectrograph|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. | In the dispersion-matching mode the whole system ([[Introduction#Analysis Line|analysis line]] + [[Introduction#Spectrograph|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. |
