Speaker
Description
Finding the answers to the long-standing questions, such as, emergence of mass and spin of the proton from partons, saturation of gluon density, and gluon momentum distribution inside the proton and nuclei, motivated the EIC [1] under construction at Brookhaven National Laboratory, USA. The first EIC detector, ePIC (electron Proton-Ion Collision experiment), consists of a central barrel detector, as well as extensive beamline detectors in the outgoing electron (far-backward) and hadron (far-forward) beam directions. The far-forward (FF) detectors include Roman pots, which are placed inside vacuum and are intended to detect protons and ions scattered at very small angles (~ 5 mrad) in the forward direction, at ~30 m downstream from the interaction point. The main goal of the FF detectors is to tag exclusive and diffractive events and to reconstruct their transverse momentum with a resolution of ~ 10 MeV/c. This is obtained relying on a new generation of 4D tracking sensors, pixelated AC-LGADs (capacitively-coupled Low-Gain Avalanche Diode, pixel of 500x500 $\mu$m$^2$) [2][3] capable of providing the required spatial (less than 50 $\mu$m from charge sharing among neighboring pixels) and timing (~ 30 ps) resolutions. To read-out these novel LGADs exploiting their charge sharing capability, an optimized read-out large scale chip, EICROC (32x32 pads), is being designed at OMEGA. The first ASIC prototype, EICROC0_v0 (4x4 pads) [5], is a system-on-chip with analog and digital processing including for each of the 16 channels a fast low-noise trans-impedance preamplifier, followed by two paths: a fast path with a discriminator connected to a 10-bit Time-to-Digital Converter (CEA/Irfu) for time measurement (ToA) with a 25 ps accuracy; and a slow path with shaper connected to an 8-bit 40 MHz successive approximation Analog-to-Digital Converter (AGH Krakow) providing amplitudes. The performance results obtained at IJCLab with pixelated AC-LGAD sensors read out by the EICROC0_v0 ASIC, including preamplifier response and digital data from the TDC and ADC, will be presented. These results rely on measurements performed using the internal charge injection system, a beta source, and an infrared laser. Special emphasis will be placed on quantifying the charge-sharing ratio between adjacent pixels, together with evaluating the timing and spatial resolutions achievable with the EICROC0_v0 ASIC
Acknowledgement:
This work is benefitting from support from the French Agence Nationale de la Recherche (ANR), under grant ANR-24-CE31-5571 (project ROAD_4_EIC).
References:
[1] R. Abdul Khalek et al., “Science Requirements and Detector Concepts for the Electron-Ion Collider: EIC Yellow Report”, Nucl. Phys. A 1026 (2022).
[2] G. Giacomini et al., “Fabrication and performance of AC-coupled LGADs”, JINST 14 (2019), P09004.
[3] S. Kita et al., “Optimization of capacitively coupled Low Gain Avalanche Diode (AC-LGAD) sensors for precise time and spatial resolution”, NIM A 1048 (2023) 168009.
[4] A. Verplancke et al., “EICROC: an ASIC to read-out the AC-LGAD sensors for the Electron-Ion Collider (EIC)”, contribution to the proceedings of the Topical Workshop on Electronics for Particle Physics, Sept. 30th – Oct. 04th, 2024, Glasgow, UK, JINST 20 C04014.
