CNN-based Position Reconstruction for the T0 Detector in the HIRFL-CSR External-target Experiment
Abstract
The T0 detector provides the event start time for the HIRFL-CSR external-target experiment, and its multi-channel readout signals also contain 2D position information of incident particles. In the CEE experiment, the dedicated beam-profile detector has a rate capability of only ~1 kHz, far below the beam event rate of up to 1 MHz, so it cannot provide real-time beam-spot monitoring under high-rate data-taking or an event time reference. To fill this gap, this work studies a CNN-based position reconstruction method that enables the T0 detector to provide both start time and beam-spot information. The over-threshold times and time-over-threshold (TOT) values from 32 SiPM channels are reorganized into a geometry-preserving input tensor. Time features are corrected by event-wise mean-time subtraction, and TOT features are normalized by an event-wise trimmed mean before feature standardization. A customized CNN directly regresses the incident coordinates. Training and validation samples are built with Geant4 simulation and waveform digitization, and the method is evaluated using a pulsed-laser scanning data set with known position labels. On independent test sets, the residual standard deviations for uniformly distributed planar simulation data are about 1.11 and 1.04 mm in x and y. For the discrete laser-scanning geometry, the resolutions are about 2.36 and 1.34 mm in simulation and 2.42 and 1.41 mm in experiment. The trained model is applied to CEE zero-field beam data collected at the Institute of Modern Physics, Lanzhou, in January 2026, and a 2D beam-spot distribution is reconstructed. These results show the T0 detector's potential as a high-rate beam-spot monitor while retaining its role as an event start-time detector.
Related
- The detector system of the SHiP/NA67 experiment at CERN
- Impact of the position effects in the energy calibration of the BULLKID detector
- Analysis of mixed radiation fields at the MoEDAL experiment based on real-time data from a Timepix detector network
- Commissioning and Performance of the Time-of-Flight Detector for the T2K Neutrino Oscillation Experiment
- ARGUS: an experiment-agnostic framework for detector-health monitoring in particle physics
BibTeX
@misc{lv2026cnnbased,
title = {{CNN-based Position Reconstruction for the T0 Detector in the HIRFL-CSR External-target Experiment}},
author = {Shuai-Ke Lv and D Hu and M Shao and Yingjie Zhou and Yiding Zhao},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.12969},
eprint = {2610.12969},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.12969},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - CNN-based Position Reconstruction for the T0 Detector in the HIRFL-CSR External-target Experiment
AU - Shuai-Ke Lv
AU - D Hu
AU - M Shao
AU - Yingjie Zhou
AU - Yiding Zhao
PY - 2026
DA - 2026/10/09
PB - arXiv
DO - 10.48550/arxiv.2610.12969
UR - https://arxiv.org/abs/2610.12969
AB - The T0 detector provides the event start time for the HIRFL-CSR external-target experiment, and its multi-channel readout signals also contain 2D position information of incident particles. In the CEE experiment, the dedicated beam-profile detector has a rate capability of only ~1 kHz, far below the beam event rate of up to 1 MHz, so it cannot provide real-time beam-spot monitoring under high-rate data-taking or an event time reference. To fill this gap, this work studies a CNN-based position reconstruction method that enables the T0 detector to provide both start time and beam-spot information. The over-threshold times and time-over-threshold (TOT) values from 32 SiPM channels are reorganized into a geometry-preserving input tensor. Time features are corrected by event-wise mean-time subtraction, and TOT features are normalized by an event-wise trimmed mean before feature standardization. A customized CNN directly regresses the incident coordinates. Training and validation samples are built with Geant4 simulation and waveform digitization, and the method is evaluated using a pulsed-laser scanning data set with known position labels. On independent test sets, the residual standard deviations for uniformly distributed planar simulation data are about 1.11 and 1.04 mm in x and y. For the discrete laser-scanning geometry, the resolutions are about 2.36 and 1.34 mm in simulation and 2.42 and 1.41 mm in experiment. The trained model is applied to CEE zero-field beam data collected at the Institute of Modern Physics, Lanzhou, in January 2026, and a 2D beam-spot distribution is reconstructed. These results show the T0 detector's potential as a high-rate beam-spot monitor while retaining its role as an event start-time detector.
ER -