Skip to content

Hiroshima TCT Wiki

This wiki explains how to use the laser TCT (Transient Current Technique) scan setup of the Quark Physics Laboratory at Hiroshima University. The setup characterizes AC-LGAD strip sensors for the barrel TOF of the EIC-ePIC experiment by scanning them with an infrared pulsed laser at µm precision.

The goal: with this wiki alone, a first-time user can start up the setup and take data with the control GUI.

日本語版

Use the language menu () at the top right to switch to the Japanese version.

Setup overview

flowchart LR
    LAS["Pulsed laser<br/>PiLAS DX (1064 nm)"] -->|polarization-maintaining fiber| OBJ["Objective 50×"]
    OBJ -->|focused spot| DUT["AC-LGAD<br/>(readout board)"]
    STG["3-axis stage<br/>SHRC-203"] -.moves.- DUT
    DUT -->|C1–C4| OSC["Oscilloscope<br/>LeCroy WavePro 804HD"]
    LAS -->|TRIG OUT| OSC
    PC["Control PC<br/>laser_gui"] --- LAS & STG & OSC
    CAM["Focus camera"] --- PC
  • Everything is controlled with laser_gui (a PySide6 GUI) on the control PC. Without entering the dark room you can go all the way from "positioning the beam → firing the laser → checking and saving waveforms → retrieving data → quick analysis".
  • For the detailed configuration, see Hardware.

First measurement: reading order

  1. Safety — always read this first
  2. Hardware and Sensor and coordinates — what is connected where, and how the coordinates are defined
  3. Control PC and software — installing the GUI, and practicing in simulation mode before touching the real hardware
  4. Measurement overview — checklist from power-on to data taking and shutdown
  5. Details of each step
    1. Startup and connecting the devices
    2. Alignment (origin finding and calibration)
    3. Adjusting the laser intensity (TUNE optimization)
    4. Auto scan
    5. Data retrieval and quick analysis

Start in simulation mode

Starting the GUI with python main.py --simulate turns every device into a simulated one, so you can go through everything from origin finding to scans without the hardware. Do one full practice run before touching the real setup (Control PC and software).

Structure of this wiki

  • Introduction

    An overview of TCT and the safety notes you must read before measuring.

  • Principles

    Signal formation, lasers and illumination methods, and scan types (general).

  • Setup

    The equipment of the Hiroshima setup, sensor geometry and coordinate system, and preparing the control PC.

  • Measurement

    Measurement procedure with the GUI: from startup through origin finding, TUNE optimization and scans to data retrieval.

  • Analysis

    Extracting amplitude and timing information from waveforms.

  • Reference

    Troubleshooting, standard settings, output files, glossary, bibliography and how to edit this wiki.

Contact

The contact person and the laser safety officers are listed on the lab-internal Internal information page (password protected). Ask a lab member for the password.

Sources

The setup-specific content of this wiki is based on the README and source code of the control GUI laser_gui, §3–4 of the analysis note "Laser TCT scan of a 500 µm pitch strip AC-LGAD" (matome), and answers from the people in charge of the setup (2026-11). Items not yet confirmed are marked with "To be confirmed" boxes.