Development of CAT-M for experiments with high-intensity heavy-ion beams*

Gaseous active target based on a time projection chamber (TPC) is a device in which the reaction target itself also acts as a detection device, and enables us to measure low-energy recoil particles without reducing the target thickness. A variety of reactions, such as inelastic scattering, transfer reaction, and other reactions, can be studied by changing the type of gas. 

Our research group has developed and upgraded an active target, CAT-M, which can be used with high-intensity heavy-ion beams. The CAT-M consists of a GEM-TPC with an active volume of 280 (width)$¥times$200 (drift direction of the electron)$¥times$320 (direction of beam) mm$^3$ and 12 silicon detectors. Recently, a dipole magnet has been equipped along the beam path for removing delta rays due to high-intensity heavy-ion beam irradiation, improving the signal-to-noise ratio by two orders of magnitude. Furthermore, a compact TPC has been developed to measure the beam trajectory in the vicinity of the reaction point, which cannot be measured by the large TPC since the dipole magnet masks the beam path.

In terms of physics opportunities, The CAT-M is being used in a project for the systematic ISGMR measurement including unstable nuclei for the determination of the nucleonic matter incompressibility $K_{¥tau}$. The project plans to perform experiments at several facilities, and we have performed ISGMR measurements of $^{132}$Sn, Xe, and Kr isotopes using deuterium gas at 40 kPa in HIMAC and RIBF.

In this talk, the upgrade of CAT-M and the progress of the systematic ISGMR measurement project will be presented.