A large area 100 channel Picosec Micromegas detector with sub 20 ps time resolution

Abstract: The PICOSEC Micromegas precise timing detector is based on a Cherenkov radiator coupled to a semi-transparent photocathode and a Micromegas amplification structure. The first proof of concept single-channel small area prototype was able to achieve time resolution below 25 ps. One of the crucial aspects in the development of the precise timing gaseous detectors applicable in high-energy physics experiments is a modular design that enables large area coverage. The first 19-channel multi-pad prototype with an active area of approximately 10 cm$<sup>2$ suffered from degraded timing resolution due to the non-uniformity of the preamplification gap. A new 100 cm$<sup>2$ detector module with 100 channels based on a rigid hybrid ceramic/FR4 Micromegas board for improved drift gap uniformity was developed. Initial measurements with 80 GeV/c muons showed improvements in timing response over measured pads and a time resolution below 25 ps. More recent measurements with a new thinner drift gap detector module and newly developed RF pulse amplifiers show that the resolution can be enhanced to a level of 17~ps. This work will present the development of the detector from structural simulations, design, and beam test commissioning with a focus on the timing performance of a thinner drift gap detector module in combination with new electronics using an automated timing scan method.

• The paper demonstrates the development of a 100-channel Picosec Micromegas detector achieving sub-20 ps timing resolution in high-energy physics experiments.
• It introduces a robust design using a hybrid ceramic/FR4 board to ensure drift gap uniformity within 10 μm, minimizing mechanical deformation.
• Rigorous testing with 80 GeV/c muons and grid-based calibration validates the detector's uniform signal arrival time and simplifies global time-walk correction.

Overview of a Large Area 100 Channel Picosec Micromegas Detector with Sub 20 ps Time Resolution

The paper in focus details the development and performance evaluation of a large area 100 channel Picosec Micromegas detector, prominently designed for applications requiring precise timing in high-energy physics experiments. The authors address intricate challenges associated with timing detectors, aiming to achieve significant advancements in time resolution and uniformity across an extensive detector surface.

Detector Design and Structural Improvements

The work presents a refined detector prototype incorporating a 100 channel design within a substantial 100 cm² area. The primary objective revolved around enhancing drift gap uniformity, a critical factor influencing timing resolution. Prior attempts with a 19-channel prototype, as cited, exhibited limitations due to drift field non-uniformity, leading to suboptimal timing outcomes. To confront this issue, the new design integrates a hybrid ceramic/FR4 Micromegas board, selected for its superior rigidity and planarity, reaching tolerances within 10 μm. Such structural improvements, coupled with mechanical isolation of active components, aim to mitigate bending and deformation risks, preserving timing precision.

Performance Evaluation of the 100 Channel Prototype

Upon development, the 100 channel detector underwent rigorous testing using 80 GeV/c muons at the CERN SPS secondary beamline to assess its timing characteristics. Impressively, the device achieved sub-25 ps time resolution over individual pads, matching or surpassing previous single channel benchmark performances. Noteworthy is the demonstration of consistent SAT (Signal Arrival Time) across various pads, upholding uniform time response. The uniformity further ensures the feasibility of implementing a singular global time-walk correction algorithm, enhancing operational simplicity for extensive detector arrays.

Methodology Innovations for Timing Characterization

The challenge of accurately characterizing timing performance over a large detector area necessitated innovative measurement methodologies. The proposed approach involved leveraging a grid-based scan using a reference MCP detector, ensuring precise localized calibration and reliability of timing data independent of reference detector biases. By focusing on the well-performing central regions of the MCP for timing reference and applying a systematic spatial scan, meaningful data was obtained over extensive DUT areas while reducing tracking demands and potential non-uniform biases.

Advances in Drift Gap Design and Electronics

Further enhancements in performance were achieved by reducing the drift gap to 180 μm, corroborated by custom RF amplifiers providing robust signal processing capabilities. Tests with this configuration reported remarkable timing resolutions averaging 17 ps across multiple pads, suggesting both the efficacy of reduced drift gaps and the uniformity of the detector apparatus in sustaining high temporal accuracy.

Implications and Future Directions

The successful realization of a 100 channel Picosec Micromegas detector with these characteristics holds profound implications for high-precision timing applications. Such enhancements in time resolution are pivotal in various domains, including particle identification and collision event analysis within extensive high-energy physics research frameworks. Future efforts are poised towards augmenting the detector's stability and robustness, along with sculpture development of a complete readout chain utilizing multi-channel SAMPIC digitizers, ushering advanced instrumentation towards practical deployment.

Overall, this work significantly contributes to the development of precise timing detectors, optimally combining novel materials, innovative design strategies, and performance-centric methodologies, thereby supporting the progressive demands of contemporary high-energy physics experiments.