Facility upgrade for superheavy-element research at RIKEN

Abstract

The RIKEN Nishina Center (RNC) executed an accelerator upgrade project for the heavy-ion linac (called RILAC). A superconducting RIKEN linear accelerator (SRILAC) and a new superconducting electron-cyclotron-resonance ion source (SC-ECRIS) to boost the final energy and intensity were constructed, aimed at synthesizing a new superheavy element, 119, through a hot fusion reaction. The project included the construction of a gas-filled recoil ion separator (GARIS-III) suitable for detecting the residues of the hot-fusion reaction. To avoid research interruption during the SRILAC construction period (2017–2019) and gain experience in hot-fusion reaction processes, GARIS-II located in the GARIS experimental hall in LINAC building was moved to the E6 experimental hall in Nishina building. Certain exploratory measurements were performed employing the beams accelerated by RILAC2 and the RIKEN ring cyclotron (RRC), which is a part of the existing accelerator complex of the radioactive isotope beam factory (RIBF). Further, commissioning experiments with the upgraded facility (SRILAC and GARIS-III) were performed. The upgrade project and its commissioning results are chronologically described in this article.

Intense vanadium ion beam production for super-heavy element research experiments

“…The long-term production of an intense 51 V 13+ ion beam is required at RIKEN for synthesizing a new element (Z=119) by the fusion reaction of 51 V+Cm. [1] Hence, we constructed the superconducting electron cyclotron resonance (ECR) ion source [2] and successfully produced an intense 51 V 13+ ion beam. [3] As mentioned in ref.…”

Segmented silicon-based solid-state detector with thin dead layer for superheavy element research

“…Nihonium ( 278 Nh, Z = 113) has been produced using the reaction between a 70 Zn beam and a 208 Bi target. [11][12][13] An experiment to synthesize a new element with Z = 119 by the reaction between a 51 V beam and a 248 Cm target using the new GARIS systems [14][15][16] (GARIS-II and GARIS-III) is currently underway.…”