Speaker
Description
A tiny time-projection chamber (Mini TPC) has been developed for tracking beam particles in the active target. CAT-M consists of a large TPC and twelve silicon strip detectors, and which is designed for missing mass spectroscopy using high-intensity ($\sim 10^{6}$ particles per particle) heavy-ion beam inverse kinematics, aim to determine nuclear matter equation of state. Recently a dipole magnet has been introduced inside the field cage of the TPC. Although a large number of delta electrons can be eliminated by the dipole magnet, the beam trajectory cannot be measured with the original structure. The Mini TPC was installed inside the CAT-M chamber, positioned as close as possible to the main TPC to measure beam trajectories precisely.
The Mini TPC, which has an active volume of $42 \times28 \times12 $ mm$^3$, consists of a field cage, THGEM-based amplification stages, and a readout pad array. The field cage, with a total volume of $60 \times 50 \times 28$ mm$^3$, forms a uniform electric field using PCB-mounted electrodes and a three-layer wire configuration. The electric field distortion was confirmed to be less than $0.6$\% through simulation. Ionized electrons are amplified by two stacked THGEMs with $200~\mu$m hole diameter and $500~\mu$m pitch. The readout electrode employs equilateral triangular pads, and position reconstruction is performed using charge-weighted centroids and drift time.
Performance tests were conducted with high-intensity beams exceeding $10^6$ particles per particle. By combining the Mini TPC with SR-PPACs, its position resolution was evaluated, achieving approximately $600~\mu$m in the X-direction and $400~\mu$m in the drift direction. The Mini TPC also enabled the estimation of beam pile-up corrections. In this presentation, we will introduce the design and performance of the Mini TPC developed for high-intensity beam tracking.
| Email address | fumitaka.endo@riken.jp |
|---|---|
| Classification | Instrumentation for radioactive ion beam experiments |
