Warsaw Active-Target TPC: A new detector for photonuclear reactions studies at astrophysical energies

An active-target time-projection chamber (TPC) optimised for studying nuclear reactions of astro-physical interest was developed by the University of Warsaw for studying photo-disintegration reactions using intense, monochromatic γ-ray beams. Different reactions can be studied by tuning composition and density of the gaseous target for particular energy of the gamma beam. The Warsaw TPC detector, with its active volume of about 33x20x20 cm3 centred around the beam axis and micro-pattern structures (GEMs) employed to amplify the primary ionisation induced by charged particles produced in reactions in the gaseous target, is characterised by a readout based on signal strips, arranged into 3-coordinate redundant system. The 3D kinematics of charged particles in the event are reconstructed from a total of about 103 channels read out by digitising front-end electronics based on the General Electronics for TPCs (GET). In this paper the principles of detector operation and basic track reconstruction methods are discussed and illustrated by means of preliminary results from pilot measurements conducted in 2021-22.

华沙大学开发了一种主动靶时间投影室（TPC），它针对研究天体物理相关的核反应进行了优化，用于利用强的单色γ射线束研究光致蜕变反应。通过针对特定能量的γ射线束调整气态靶的成分和密度，可以研究不同的反应。华沙TPC探测器的有效体积约为33×20×20立方厘米，以束流轴为中心，并且采用微图案结构（气体电子倍增器，GEMs）来放大气态靶中反应产生的带电粒子所引发的初级电离。它的特点是基于信号条的读出方式，这些信号条排列成三维坐标冗余系统。事件中带电粒子的三维运动学是通过基于时间投影室通用电子学（GET）的数字化前端电子设备读出的总共约10³个通道来重建的。在本文中，探测器的工作原理和基本的径迹重建方法将通过2021 - 2022年进行的试点测量的初步结果进行讨论和说明。