determination_of_angles_and_momentum
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determination_of_angles_and_momentum [2013/10/18 11:09]
pereira |
determination_of_angles_and_momentum [2013/10/18 11:13]
pereira |
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| ===== Reconstruction method ===== | ===== Reconstruction method ===== |
| With the exception of the [[Magnets#sextupole in front of the S800 spectrograph and the trim coils, the aberrations—introduced mostly by the fringe fields of the magnets—are calculated and corrected analytically based on measured field maps. This method [3,4] uses the ion optics code COSY Infinity [5] to calculate the transfer matrix S from the target to the focal plane, including aberrations up to 5th order. The matrix is then inverted and applied to the coordinates measured at the focal plane on an event-by-event fashion: | With the exception of the [[Magnets#Spectrograph Sextupole|sextupole]] in front of the S800 spectrograph and the trim coils, the aberrations—introduced mostly by the fringe fields of the magnets—are calculated and corrected analytically based on measured field maps. This method ((Recontruction 1))((Recontruction 2)) uses the ion optics code COSY Infinity ((Ref)) to calculate the transfer matrix //S// from the target to the focal plane, including aberrations up to 5th order. The matrix is then inverted and applied to the coordinates measured at the focal plane on an event-by-event fashion: |
| (at yt bt dt) = S-1 (xt at yt bt) . The subindexes t and f f refer to the positions behind the target and at the focal plane, respectively. The positions measured with the two CRDC are used to determine the coordinates xf and yf and angles af and bt at the focal plane. The scattering angle after the target is determined as φ=a_t Tan[[√(〖Tan(a_t)〗^2+〖Tan(b_t)〗^2 )]. The corrections of the aberrations introduced by the 5th order in the transfer matrix are comparable to the resolution of the position-sensitive detectors in the focal plane. The main advantage of this method is to avoid tracking of each individual particle in the magnetic fields of the spectrograph, and therefore a much faster processing of the data. The standard S800 SpecTcl analysis software provides all necessary functions and interfaces to perform these calculations. | (at yt bt dt) = S-1 (xt at yt bt) . The subindexes t and f f refer to the positions behind the target and at the focal plane, respectively. The positions measured with the two CRDC are used to determine the coordinates xf and yf and angles af and bt at the focal plane. The scattering angle after the target is determined as φ=a_t Tan[[√(〖Tan(a_t)〗^2+〖Tan(b_t)〗^2 )]. The corrections of the aberrations introduced by the 5th order in the transfer matrix are comparable to the resolution of the position-sensitive detectors in the focal plane. The main advantage of this method is to avoid tracking of each individual particle in the magnetic fields of the spectrograph, and therefore a much faster processing of the data. The standard S800 SpecTcl analysis software provides all necessary functions and interfaces to perform these calculations. |
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determination_of_angles_and_momentum.txt · Last modified: 2022/06/09 15:08 by pereira
