Identification and separation of radioactive isotope beams by the BigRIPS separator at the RIKEN RI Beam Factory

[摘要] We have developed a method for achieving excellent resolving power in in-flight particle identification of radioactive isotope (RI) beams at the BigRIPS fragment separator at the RIKEN Nishina Center RI Beam Factory (RIBF). In the BigRIPS separator, RI beams are identified by their atomic number Z and mass-to-charge ratio A/Q which are deduced from the measurements of time of flight (TOF), magnetic rigidity (Bp) and energy loss (Delta E), and delivered as tagged RI beams to a variety of experiments including secondary reaction measurements. High A/Q resolution is an essential requirement for this scheme, because the charge state Q of RI beams has to be identified at RIBF energies such as 200-300 MeV/nucleon. By precisely determining the B rho and TOF values, we have achieved relative A/Q resolution as good as 0.034% (root-mean-square value). The achieved AIQ resolution is high enough to clearly identify the charge state Q in the Z versus AIQ particle identification plot, where fully-stripped and hydrogen-like peaks are very closely located. The precise B rho determination is achieved by refined particle trajectory reconstruction, while a slew correction is performed to precisely determine the TOF value. Furthermore background events are thoroughly removed to improve reliability of the particle identification. In the present paper we present the details of the particle identification scheme in the BigRIPS separator. The isotope separation in the BigRIPS separator is also briefly introduced. (C) 2013 Elsevier B.V. All rights reserved.

[发布日期] 2013-12-15

[效力级别]  Proceedings Paper

[关键词] Fragment separator;Radioactive isotope beam;Particle identification;Trajectory reconstruction