Hadron calorimeter (HCAL) is an essential sub-detector of the baseline detector system for Circular Electron Positron Collider (CEPC). We plan to build an Analog Hadron CALorimeter (AHCAL) prototype based on the Particle Flow Algorithm (PFA). The AHCAL of CEPC uses steel as the absorber and scintillator tiles read out by Silicon Photo-Multipliers (SiPMs) as the sensitive medium. The energy linearity and resolution of the calorimeter depend on the light yield uniformity of the sensitive medium. It is essential to qualify the entire detector production in order to select scintillator tiles with the uniformity of light yield within 10%. An automated batch test platform has been designed with 144 channels and an automated 3D servo motor. The paper summarizes the tests performed on more than 15000 scintillator tiles, and the SiPMs work at 59 V (overvoltage: 5 V). The measured light yield, corrected for the set-up response non-uniformity, is around 12.9 p.e. About 91.6% of scintillators (14219 pieces) are qualified within 10% of the light yield window.

Future electron-positron collider experiments aim at the precise measurement of the Higgs boson, electroweak physics and the top quark. Based on the particle-flow paradigm, a novel highly granular crystal electromagnetic calorimeter (ECAL) is proposed to address major challenges from jet reconstruction and to achieve the optimal EM energy resolution of around 2–3$\%/\sqrt{E\left(\mathrm{GeV}\right)}$ with the homogeneous structure. Extensive R&D efforts have been carried out to evaluate the requirements and potentials of the crystal calorimeter concept from sensitive detection units to a full sub-detector system. The requirements on crystal candidates, photon sensors as well as readout electronics are parameterized and quantified in Geant4 full simulation. Experiments including characterizations of crystals and silicon photomultipliers (SiPMs) are performed to validate and improve the simulation results. The physics performance of the crystal ECAL is been studied with the particle flow algorithm “ArborPFA” which is also being optimized. Furthermore, a small-scale detector module with a crystal matrix and SiPM arrays is under development for future beam tests to study the performance for EM showers.

The high-granularity crystal calorimeter has been proposed for future lepton colliders with an ex-cellent electromagnetic energy resolution. To evaluate the crystal ECAL performance and validate the design specifications from individual units to the entire detector, extensive R&D activities have been performed. Geometry design along with dedicated software development is currently ongoing. Hardware experiments in both laboratory and beam facilities have been conducted, providing reliable data for the crystal ECAL design.

Future electron-positron colliders, or Higgs factories, impose stringent requirements on the energy resolutions of hadrons and jets for the precision physic programs of the Higgs, Z/W bosons and the top quark. Based on the particle-flow paradigm, a novel highly granular crystal electromagnetic calorimeter (ECAL) has been proposed to address major challenges from the jet reconstruction and to achieve the optimal electromagnetic energy resolution of around 2-3%/√E(GeV) with the homogeneous structure. R&D efforts have been carried on to evaluate the requirements on the sensitive detector units and physics potentials of the crystal calorimeter concept within a full detector system. The requirements on crystals, photon sensors as well as readout electronics are parameterized and quantified in a full simulation model based on Geant4. Experiments including characterizations of crystals and silicon photomultipliers (SiPMs) have been followed to validate simulation results and optimize simulation parameters. Physics performance of the crystal ECAL has been studied with Higgs physics benchmarks using the particle-flow algorithm "ArborPFA". Progress has been made on optimizing the ArborPFA algorithm and parameters therein, leading to a significant improvement of the separation efficiency for close-by showers and jet reconstruction performance. For the new detector layout with long crystal bars arranged to be orthogonal to each other in two neighboring layers, a dedicated reconstruction software is also being developed to address major challenges on pattern recognition.

This study investigates the characteristics of Silicon Photomultipliers (SiPMs) with different pixel densities, focusing on their response across a wide dynamic range. Using an experimental setup that combines laser source and photomultiplier tubes (PMTs) for accurate light intensity calibration, we evaluated SiPMs with pixel counts up to 244,719 and pixel sizes down to 6 micrometers. To complement the experimental findings, a "Toy Monte Carlo" was developed to replicate the SiPMs' reponses under different lighting conditions, incorporating essential parameters such as pixel density and photon detection efficiency. The simulations aligned well with the experimental results for laser light, demonstrating similar nonlinearity trends. For BGO scintillation light, the simulations, which included multi-firing effect of pixels, showed significantly higher photon counts compared to the laser simulations. Furthermore, the simulated response derived in this research offer a method to correct for SiPM saturation effect, enabling accurate measurements in high-energy events even with SiPMs having a limited number of pixels.