LAPPD System Overview


The ANNIE LAPPD modules, to be deployed in the ANNIE tank, will be assembled in two separate packages: The LAPPD Package with its associated readout and power, and The Housing Package with its LVHV slow controls board and attached cabling. The 5 LAPPD modules are then connect to the surface electronics.


LAPPD Package

The LAPPD Package refers to the self-contained system consisting of (1) the LAPPD, mounted in (2) its Ultem Frame, attached to (3) the Analog Pickup Board, by way of (4a) a Passive Bridge Circuit and (4b) an Active Trigger Card (same footprint). Attached to the back of the Analog Pickup Board are (5) two ACDC readout cards. Here is a schematic representation of all of the components:


  • The LAPPDs are the flat-panel, glass photosensor. An inventory of the ANNIE LAPPDs can be found here. Incom test reports can be found here. ANNIE test results can be found here.
  • The Ultem Frame is the plastic frame that holds the LAPPD together with the bridge circuits and Analog Pickup Board. A 3D model of the Ultem Frame can be found here.
  • The Analog Pickup Board is a PCB that directs signals from the LAPPD into Samtech connectors that the ACDC readout cards can plug into.
  • The two Bridge Circuits make contact with the LAPPD anode strips on one side and pads on the Analog Pickup Board on the other. There are two kinds, one passive and one active:
    • The Passive Bridge Circuit just contains RF traces to bring the signals from the LAPPDs to the pickup board
    • The Trigger Card has the same dimensions as the Passive Bridge Circuit, but contains powered components that sense the voltages and make a trigger decision to send to the ACDC cards.
  • The two ACDC cards digitize the LAPPD signals. The design files and details of the ACDC cards can be found here.


Housing Package

The Housing Package refers to the system that comes attached to the waterproof housing, consisting of (1) the waterproof housing with (2) 2 attached waterproof cables, containing (3) an LVHV board soldered to the interior pigtails from the cables. Once the LAPPD Package is cabled to and mounted on to the Housing Package, the waterproof housing is sealed between a (4) UVT acrylic top window and (5) stainless steel back plate. Once ready, the LAPPD package is mounted inside the Housing Package to form a complete LAPPD Module.


Surface Electronics

The Surface Electronics consist of (1) Breakout Boxes (1 per LAPPD) which provide power, communications with the LVHV, and convert from the high density cables to more standard connectors; (2) ANNIE Central Cards (ACCs) which sit in the VME crate X on rack Y, providing consistent clock reference and readout the digitized data from the ACDC cards in the housing; and (3) DAQ interfaces: 3 raspberry pi's which connect to the main ANNIE DAQ computer via Ethernet.

  • The Breakout Boxes serve as the slow controls interface and power conduit for the Water Proof Modules. More details can be found here