VI. RNC ACTIVITIESRIKEN Accel. Prog. Rep. 55 (2022)

Research Facility Development Division
Instrumentation Development Group
1. Abstract
This group develops the core-experimental instruments at the RI Beam Factory. Four projects are currently going on. SLOWRI
is an experimental instrument to provide low and cold ion beam. The high energy RI beam is stopped by a gas catcher system andre-accelerated to several tens of keV to deliver a high-quality cold RI beam to the user. SCRIT is the world’s ﬁrst experimental facilityfor electron scattering of unstable nuclei and was constructed oﬀ the main beamline of RIBF. The ﬁrst physic result was demonstrated
in 2017, and the electron scattering experiment for radioactive isotopes has been started in this year. An upgrade of the electron beam
power that drives RI beam production is currently underway. The Rare-RI Ring is an event-by-event-operated heavy ion storage ringfor precise mass measurement of extremely rare exotic nuclei. It is currently accepting applications for experimental proposals andhas already conducted PAC-approved experiments and published its ﬁrst physics results. Improvements are currently underway toachieve more precise mass measurements. The compact heavy-ion storage ring RUNBA is an R&D machine for the development ofbeam recycling techniques for nuclear reaction research on rare elements. This is currently under construction and some of the criticalcomponents of the ring are currently undergoing technical development. All instrumentations is designed to maximize the researchpotential of the world’s most intense RI beams, and dedicated RI Beam Factory equipment makes the experimental challenge possible.
The experimental technique and experience accumulated in this group provide opportunities for new experimental challenges and form
the basis for the future development of the RIBF.

2. Major Research Subjects
(1)
(2)
(3)
(4)

SCRIT Project
SLOWRI Project
Rear RI Ring Project
RUNBA project (Beam recycling development)

3. Summary of Research Activity
We are developing beam manipulation techniques to carry out the above projects. These are high-quality slow RI beam generation
technology (SCRIT, SLOWRI), beam cooling and stopping technology (SCRIT, SLOWRI) and beam accumulation technology in astorage ring (Rare RI Ring, RUNBA). The technical know-how accumulated in the project will play a major role in the next generationof RIBF. The current status and future plans for each project are described in the respective sections. We have successfully measured
electron elastic scattering from 132 Xe isotopes and obtained nuclear charge density distributions in SCRIT. Recently, we have started
electron scattering experiment for unstable nuclei. That will be the world’s ﬁrst electron-RI collision experiment. We are in the processof power upgrading of the electron beam from the RTM, which is the driving for RI production, and expanding the nuclei that can beaccessed. The Rare RI Ring is an event-by-event based mass measurement system, designed speciﬁcally for extremely low-producing
isotopes. We carried out PAC-approved experiments and successfully measured the masses of 74, 76 Ni, 122 Rh, 123, 124 Pd and 125 Ag
for the ﬁrst time. To improve mass resolution and eﬃciency, the ﬁrst-response kicker system and optical tuning system are being
improved. Test experiments are currently underway at SLOWRI to establish slow RI beam generation using two diﬀerent type of gascells. PALIS has been commissioned from 2015, and basic functions such as, the RI-beam stopping in Ar gas cell, the extraction
from the gas cell and laser ionization have beam evaluated. Movable mass spectrometer combining RF carpet gas cells (RPGC) andmultiple reﬂection time-of-ﬂight (MRTOF) are in operation at facilities such as Zero Degree and GARIS. The combination of RFGCand MRTOF has been used successfully to measure the mass of 74, 75 Ni isotopes.
According to the future plans of Nishina center, a beam re-cycling technique is under development. Beam recycling technology
allows the circulation of RI beams to be maintained in a storage ring with a thin internal target until a nuclear reaction occurs. Inorder to establish beam recirculation, the increase in energy width and emittance needs to be compensated for using a fast feedbacksystem. We have demonstrated the possibility of compensation in an analytical way and found the properties of EDC and ADC
devices necessary for compensation. To develop these new technologies, a compact heavy ion storage ring (RUNBA) connected toISOL (ERIS) is under construction at the SCRIT facility. Under a research cooperation agreement with ICR in Kyoto University,
technical development of the main components required for RUNBA i.e. the charge breeder, energy dispersion corrector, angular
diﬀusion corrector and internal target system are underway.

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MembersDirector
Masanori WAKASUGIContract Researcher
Ryo OGAWARA
Visiting Scientists
Akira OZAWA (Tsukuba Univ.)
Fumi SUZAKI (JAEA)

Kyo TSUKADA (Kyoto Univ.)

Student Trainee
Yoshiki MAEHARA (Kyoto Univ.)
Part-time Worker
Midori TAKEMON (Administrative Part-time Worker I)

List of Publications & Presentations
Publications and presentations for each project team are listed in subsections.

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