Design Study for the KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) at RAON

Abstract

The KOBRA (KOrea Broad acceptance Recoil spectrometer and Apparatus) is a multi-purposerecoil spectrometer for low-energy nuclear experiments at the RAON accelerator complex. It isdivided into two stages based on the operational function: the first stage (F0-F3) is an in-flightseparator or beam transport line, and the second stage (F3-F5) is a large acceptance spectrometer. For spectrometers using radioactive ion (RI) beams, high performance, such as high resolutionand large acceptance, are especially required due to the limit of quality of RI beams. In thisrespect, a dispersion-matching technique and a movable magnet system were employed for highresolution and large acceptance, respectively. Reaction spectra at the focal plane for the dispersionmatching mode were obtained and analyzed using a Monte Carlo simulation code. In addition, thegeometrical angular acceptances with respect to the distance between the reaction target and thefirst Q-pole doublet of the second stage were calculated, and the expected maximum solid angle ofthe spectrometer was estimated.