Brho Settings

The Brho of the segments 6 and 7 (analysis beam line) will be set during the secondary-beam tuning in cooperation with the A1900 group. The energy loss in all detector systems operating in this beam line has to be considered for the Brho setting (object scintillator, object PIN, tracking PPACs). In the course of secondary-beam tuning, a scintillating target ("viewer") and camera setup at the target position of the S800 might be requested by the A1900 group.

The Brho of segment 8 - the spectrograph - has to be chosen by the experimenter according to the objectives of the experiment. Please coordinate all required Brho changes of the spectrograph beam line (segment 8) with the S800 group as early as possible. The segment 8 Brho can roughly be estimated by assuming the segment 7 Brho (analysis beam line) and correcting for the energy loss of the desired fragment/particle in the reaction target. The "physical calculator" of the program LISE is well suited for this purpose. The final Brho of segment 8 will later be fine-tuned to achieve the desired setting in the S800 focal plane (fragment of interest centered, for example).

We strongly recommend Barney printouts after every change of the spectrograph. This not only provides a paper copy of all magnet settings from segment 0 to segment 8 but also saves this information in ascii format on disk (accessible via the A1900 web site under "Beam Line Savesets"). If an inverse map is desired for the tracking of the particles in the spectrograph, segment 8 Brho and the magnet currents of the dipoles and quadrupoles are needed to determine important input parameters for the calculation of the inverse map.