BigRIPS separator and ZeroDegree spectrometer at RIKEN RI Beam Factory

Abstract

The BigRIPS in-flight separator, which became operational in March 2007 at the RI Beam Factory (RIBF) at RIKEN Nishina Center, has been used to produce a variety of rare-isotope (RI) beams by using in-flight fission as well as projectile fragmentation. Its major features are large ion-optical acceptances and two-stage structure. Excellent performance in particle identification is also an important feature. Efficient RI-beam production based on the in-flight scheme has been made possible by these features of the BigRIPS separator, allowing us to greatly expand the accessible region of exotic nuclei. An RI-beam delivery line following the BigRIPS separator is designed to work as a forward spectrometer, called ZeroDegree. As a major experimental device at RIBF, the ZeroDegree spectrometer has been used for a variety of reaction studies with RI beams. In this paper, we present an overview of the BigRIPS separator and the ZeroDegree spectrometer, emphasizing the capability and potential of the new-generation RI beam facility, RIBF.

Production cross section measurements of radioactive isotopes by BigRIPS separator at RIKEN RI Beam Factory

“…Since the commissioning of the RIKEN RI Beam Factory (RIBF) [1] in March 2007, a wide variety of RI beams have been produced using the BigRIPS fragment separator [2][3][4], and used for various experiments with exotic nuclei such as secondary reaction measurements, decay measurements, and the search for new isotopes and new isomers.…”

Triaxiality of neutron-rich Ge84,86,88 from low-energy nuclear spectra

“…At the Radioactive Isotope Beam Factory (RIBF), a 238 U beam with an energy of 345 MeV/u impinged on a 3-mm-thick 9 Be target at the entrance of the BigRIPS fragment separator [33]. The isotopes of interest were produced by in-flight fission, selected by the Bρ-E-Bρ method and identified on an event-by-event basis by the time of flight-Bρ-E method in BigRIPS [34], in two different settings.…”

“…The ion's kinetic energy of ∼270 MeV/u was reduced by ∼70 MeV/u while passing the target. Products from secondary (p,2p) or (p,pn) reactions in the LH 2 target were identified by the ZeroDegree spectrometer [33] applying the Bρ-E-Bρ method. Reaction vertices were determined by a time projection chamber (TPC) surrounding the LH 2 target.…”

“…The transition at 556(6) keV has the strongest intensity, indicating a (2 + 1 ) → 0 + 1 transition. The γ ray at 772 (33) keV is assigned to the (4 + 1 ) → (2 + 1 ) transition, and the γ ray at 469 (14) keV is assigned to the (2 + 2 ) → (2 + 1 ) transition from comparison to neighboring 86 Ge and 90 Se [49]. A gate on the 2 + 1 → 0 + 1 transition [see inset of Fig.…”

Status of Beam Line Detectors for the BigRIPS Fragment Separator at RIKEN RI Beam Factory: Issues on High Rates and Resolution

“…Gas detectors, consisting of a multiple sampling ionization chamber (MUSIC) and parallel-plate avalanche counters (PPACs), were installed within the superconducting in-flight separator named BigRIPS [2][3][4] for particle identification of RI beams.…”