Speaker
Description
The Cooler Storage Ring External-Target Experiment (CEE) requires a high-precision Beam-Particle Monitor (BPM) to track individual heavy-ion beam particles. Reliable detection of lighter ions, such as Carbon, at particle rates up to 1 MHz is essential for precise primary vertex reconstruction and beam diagnostics.
The BPM employs a dual micro-Time Projection Chamber (micro-TPC) architecture operating at atmospheric pressure. It utilizes custom-designed Topmetal-CEEv2 monolithic pixel charge sensors and double-layer Gas Electron Multiplier (GEM) amplification. To evaluate the detector's baseline capabilities, a beam test was conducted using Carbon ions in the absence of a magnetic field. The system utilized an asynchronous, data-driven zero-suppression readout to efficiently record spatial and temporal track coordinates.
The Carbon ion beam test successfully validated the BPM’s high-precision tracking capabilities. Residual analysis demonstrated single-row transverse spatial resolutions of better than 50 µm and arrival time resolutions of approximately 15 ns. By correlating track segments between the orthogonal micro-TPCs, the system achieved an absolute incident time ($t_0$) reconstruction precision of better than 100 ns. Furthermore, the development of offline reconstruction algorithms and calibration procedures, including event reconstruction under non-uniform magnetic fields, space-charge effect corrections, online energy calibration, and pixel time-walk corrections, will also be presented.