Speaker
Description
Low-pressure time projection chambers (TPCs) are essential for precision measurements of low-cross-section nuclear reactions in nuclear astrophysics, as they enable excellent tracking, particle identification, and background suppression. However, conventional TPCs face challenges under low-pressure and high-rate conditions, including insufficient gain, severe ion backflow (IBF), and space-charge distortion. To address these issues, we developed a double micro-mesh (DMM) detector integrated into a low-pressure TPC for the direct measurement of 12C+12C reaction at stellar energies. The two-stage amplification structure achieves high gas gain while strongly suppressing IBF ratio under low-pressure operation.
Prototypes with a sensitive area of 13 cm × 23 cm have been fabricated. Systematic X-ray characterization demonstrates stable gain performance in both He-based and Kr-based gas mixtures at around 90 mbar. An IBF ratio of 6 × 10-4 is achieved with optimized mesh configurations, maintaining the gain-IBF product below 5 under typical experimental conditions. Studies of high beam intensities at about 30 p𝜇A show that substantial X-rays are generated by beam interaction on the carbon target and the resulting challenge of large space charge distortions is successfully resolved by using DMM-TPC in the He/Ar working gas. In the 12C+12C measurement at Ec.m. < 3 MeV with a current of 50 p𝜇A, the detector enables clear 3D track reconstruction and efficient particle identification for protons and α particles. The DMM-TPC exhibits long-term stability, high rate capability, and low IBF, making it a promising solution for precision measurements of low-cross-section astrophysical fusion reactions.
| Name of the speaker | Zhiyong Zhang |
|---|---|
| Eligible for the Georges Charpak Young Scientist Award. | no |