Skip to main content

FIT

  • A 64-channel multihit TDC developed by Baba-san.
  • Although it uses the VME form factor, it is dedicated to MPV. MOCO is not required.

External view of FIT.

I/O​

  • 64ch LVDS inputs (32ch KEL x2)
    • DO NOT USE ECL!
  • LVDS I/O
    • Trigger Input
    • Trigger Output (Through)
    • Test Input
    • Test Output (Through)
  • An LVDS trigger can be output from the MPV controller (FW 2.21 or later). By daisy-chaining two-pin cables, a fanout module for trigger-signal distribution is no longer required.

Firmware​

  • FITLL
    • FIT Low-resolution Low-frequency
    • Prototype firmware for functional testing
    • 1 MHz/ch
    • 1 LSB = 312.25 ps
  • FITL
    • FIT Low-resolution
    • Firmware with improved rate capability by reading out data in parallel in four-channel groups.
    • 1 LSB = 312.25 ps
    • 64 MHit/s for 4 ch group
    • 8 MHz/ch
    • 20 MHz (when only one channel in a four-channel group has hits)
    • Deadtime ~ 0.18 us/hit
    • A geometry header was added.

FITM (1 LSB = 250 ps) and FITH (1 LSB = 125 ps) are planned as future extensions.

Dataformat​

FITLL​

  • Err: 1bit
    • Do not analyze data with the error bit set.
  • Trg: 1bit
    • Trigger-channel flag (currently unnecessary)
  • Channel: 8bit
    • 0-63 = leading
    • 128-191 = trailing
    • 64 = trigger
    • 68-70 timestamp (currently unnecessary)
  • Data: 20bit

FITL​

  • Trigger number: 16bit
  • Geometry: 12bit
  • Err: 1bit
    • Do not analyze data with the error bit set.
  • Trg: 1bit
    • Trigger-channel flag (currently unnecessary)
  • Channel: 8bit
    • 0-63 = leading
    • 128-191 = trailing
    • 64 = trigger
    • 68-70 timestamp (currently unnecessary)
  • Data: 20bit