Session 2WGA: New Detector Technologies for Radioactive Isotope Beam Facilities I

Development of detection systems in the OEDO-SHARAQ beamline for RI beam experiments

The OEDO-SHARAQ beamline has a dual performance of low-energy reaction studies and high-resolution spectroscopy by selecting the suitable ion transportation method. It is characterized by two key pieces of equipment: an energy-degrading system called OEDO, which can slow down the beam to 10 - 50 AMeV; and a high-resolution spectrometer called SHARAQ with a momentum resolution (p/Δp) of 15000.

The OEDO-SHARAQ beamline opens opportunities to explore exotic nuclear reactions and structures in combination with a wide variety of RI beams provided by the BigRIPS fragment separator at RIKEN RI beam factory (RIBF).

 

Since the secondary beams provided by RIBF via fragmentation reactions generally contain many kinds of nuclei with an energy width of several tens of AMeV, not only the spectrometer itself but also the associated beamline must have the ability to clearly identify particles and analyze beam profiles in order to perform high-resolution spectroscopy. Our group, Center for Nuclear Study, the University of Tokyo, has developed the ion transportation method such as the dispersion matching and the beamline detectors: CVD diamond for the timing measurement, low-pressure multi-wire drift chamber for trajectory reconstruction, and strip-readout parallel-plate avalanche counter as low-material position sensitive detector. The detectors are highlighted especially for their performance under high counting rates up to several 10⁵ cps.

In this talk, the developments of high-resolution beamline for the OEDO-SHARAQ system will be summarized with some examples of physics research activities we have recently performed such as direct mass measurement using TOF-Brho technique.   

New detector concepts for heavy-ion physics

Progress in accelerator-based experimental physics has always been linked to detector technology improvement. The unprecedented potential discovery of a modern rare isotope beam facility, such as FRIB, can only be realized by implementing state-of-the-art experimental equipment capable of studying these isotopes at a high beam rate and excellent performance.

I report the development of innovative detector concepts for tracking and particle identification (PID) of heavy ions. In particular, I will describe the development of novel micro-pattern gaseous detector (MPGD) structures capable of stable, high-gain operation at low-pressure, applied as either position-sensitive readout for Time-Projection-Chamber in active-target mode (AT-TPC), or for drift chambers at the focal-plane of large-acceptance spectrographs.

In addition, I will present progress on the design and construction of advanced, innovative instrumentation for highly accurate and efficient identification of the atomic number (Z) of nuclei transmitted to the focal plane of high-resolution spectrographs. The detector concept is based on event-by-event Energy-Loss measurement in a multi-segmented Optical Scintillator System (ELOSS), by recording the scintillation light released by a charged particle along its track. We discuss the optimization of the optical readout configuration based on DUV-sensitive PhotoMultiplier Tubes (PMTs), the expected performance of the novel detector concept, and the overall impact on radiation-detection physics and technology applied to experimental nuclear physics with rare-isotope beams.   

Upgrade of the Detector System in the S800 Spectrograph at the new FRIB

The S800 Spectrograph is one of the main cornerstone instruments in the new Facility for Rare Isotope Beams (FRIB). Besides its use as a recoil tagger, correlating and identifying recoil nuclei detected in its focal plane with light particles and/or photons emitted in the reaction target, the S800 allows for the extraction of relevant kinematical information (momentum and scattering angle) that is necessary for analyzing nuclear reactions.

In order to fulfill the technical demands imposed by the new FRIB experiment program, an upgrade of the S800 (including detector system, analysis techniques, and ion optics) is in progress.

In this presentation, I will discuss the main aspects of the new S800 upgrade and status.