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determination_of_angles_and_momentum [2013/10/18 14:04]
pereira 		determination_of_angles_and_momentum [2013/10/18 14:07]
pereira
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-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. +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 the fast processing of the data as it avoids the tracking of each individual particle in the magnetic fields of the spectrograph. The standard S800 SpecTcl analysis software provides all necessary functions and interfaces to perform these calculations. 
    
 Calculation of the inverse map  Calculation of the inverse map 
 The inverse map relates the coordinates xf, yf, af, bf measured in the focal plane to the coordinates dt,  yt, at, bt at the target position. Since the energy is one of the quantities deduced from the map, the beam position in the dispersive plane at the target cannot be calculated and is assumed to be zero. This assumption implies that the final resolution is obtained by folding the finite size of the beam spot in that direction with the size obtained from the reconstruction, itself depending on the detector resolution and the order to which the calculation is performed (see previous paragraph). Note that this is still the case even when the S800 is operated in dispersion-matched mode, where the incoming beam is momentum dispersed –and therefore rather large--on the target. In that case it is the size at the object location that matters since the entire S800 (analysis line + spectrograph) is achromatic. Because the shapes of the fringe fields vary significantly with the absolute strength of the magnets, inverse maps need to be calculated for each magnetic-rigidity setting of the spectrograph. Users can request these inverse maps for which only the magnet strengths, magnetic rigidity, and the particle (A,Z) are necessary. The calculation of the inverse is not automated (yet!) and therefore a latency of a few days is to be expected before receiving the map file.  The inverse map relates the coordinates xf, yf, af, bf measured in the focal plane to the coordinates dt,  yt, at, bt at the target position. Since the energy is one of the quantities deduced from the map, the beam position in the dispersive plane at the target cannot be calculated and is assumed to be zero. This assumption implies that the final resolution is obtained by folding the finite size of the beam spot in that direction with the size obtained from the reconstruction, itself depending on the detector resolution and the order to which the calculation is performed (see previous paragraph). Note that this is still the case even when the S800 is operated in dispersion-matched mode, where the incoming beam is momentum dispersed –and therefore rather large--on the target. In that case it is the size at the object location that matters since the entire S800 (analysis line + spectrograph) is achromatic. Because the shapes of the fringe fields vary significantly with the absolute strength of the magnets, inverse maps need to be calculated for each magnetic-rigidity setting of the spectrograph. Users can request these inverse maps for which only the magnet strengths, magnetic rigidity, and the particle (A,Z) are necessary. The calculation of the inverse is not automated (yet!) and therefore a latency of a few days is to be expected before receiving the map file. 
  
determination_of_angles_and_momentum.txt · Last modified: 2022/06/09 15:08 by pereira

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