The IMPix-S, a Silicon Pixel Sensor for Gaseous Detector at HIRFL and HIAF

The heavy ion research facility in Lanzhou (HIRFL) and the high-intensity heavy-ion accelerator facility (HIAF) are advanced heavy-ion accelerators that play a critical role in pursuing a deeper understanding of nuclear physics. The development of high-performance gaseous detectors at HIRFL and HIAF poses broad requirements on silicon pixel sensors. Hence, we have designed the IMPix-S, a silicon pixel sensor that can collect charge directly from its surrounding media. It has 64 rows <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 120$ </tex-math></inline-formula> columns of square pixels, with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$37~\mu $ </tex-math></inline-formula>m <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times 37~\mu $ </tex-math></inline-formula>m. Each pixel can measure the position, energy, and time of arrival. Laboratory test results show that energy measurement achieves an integral nonlinearity (INL) of better than 1% and an equivalent noise charge (ENC) of ~50–145 e<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-}$ </tex-math></inline-formula> with a dynamic range of up to 18.3 ke<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{-}$ </tex-math></inline-formula>. The accuracy in the time measurement path is around 300–500 ns with an effective range of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10~\mu $ </tex-math></inline-formula>s. In addition, the IMPix-S achieves a spatial resolution of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 2.6~\mu $ </tex-math></inline-formula>m in measuring the laser beam and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 1.836~\mu $ </tex-math></inline-formula>m in measuring 181Ta35+ tracks. This article will discuss the design and performance of this IMPix-S silicon pixel sensor.