Magnetic colloid for beam adjustment

Technology for preparation of a magnetic colloid for tuning secondary beam channels at accelerators is described. The method is based on the effect of rotation of the light polarization plane by certain colloid solutions, places in a magnetic field of a quadrupole lense, this allows to determine the lense magnetic axis. The colloid is prepared out of a magnetic precipitate obtained from iron chloride salts by introduction into sodium oleate solution simultaneously with a small amount of dodecylamine being used as a stabilizer to prevent colloid particles from growing into larger size particles. The colloid preserves its properties during a year, is stable against precipitating in a magnetic field during 20 min, that allows to carry out the tuning process completely with a good accuracy. The tuning of all particle channels at the JINR synchrotron has been carried out using the colloid described