GLAST LAT Silicon Tracker

Marcus Ziegler IEEE 2005 1

The Silicon Tracker Readout The Silicon Tracker Readout Electronics of the Gamma-ray Electronics of the Gamma-ray Large Area Space TelescopeLarge Area Space Telescope

Marcus Ziegler

Santa Cruz Institute for Particle PhysicsUniversity of California at Santa Cruz

GLAST LAT Collaboration

ziegler@scipp.ucsc.edu

Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

GLAST LAT Silicon Tracker

Marcus Ziegler IEEE 2005 2

GLAST LAT Tracker OverviewGLAST LAT Tracker Overview

e+ e–

Si Tracker880 000 chanels160 Watts

The LAT Tracker is devided into:

-16 Tracker Towers

each stack is composed out of 19 trays

Tray:

Carbon-composite panel with Si-strip detectors on both sides.

On the bottom side is a tungsten foil bonded

GLAST LAT Silicon Tracker

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TowerTower

GLAST LAT Silicon Tracker

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Electronics PackagingElectronics Packaging

Kapton readout cables.

Tested SSDs procured from Hamamatsu Photonics

19 “trays” stack to form one of 16 Tracker modules.

Electronics and SSDs assembled on composite panels.

4 SSDs bonded in series.

Composite panels, with tungsten foils bonded to the bottom face.

2592

10,368

342

64834218

Carbon composite side panels

Chip-on-board readout electronics modules.

Electronics mount on the tray edges.

“Tray”

GLAST LAT Silicon Tracker

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Detail of an EM MCM, at One EndDetail of an EM MCM, at One End

Nanonics Connector(will be Omnetics)

Pitch-adapter flex circuit90° radius

GTRC ASIC

GTFE ASIC

PolyswitchGrounding screw hole

Shown prior to wire-bond encapsulation and conformal coating.

GLAST LAT Silicon Tracker

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Readout ElectronicsReadout Electronics

GTFE GTFE GTFE GTFE GTFE GTFE

GTRC

GTFE GTFE GTFE GTFE GTFE GTFE

GTRC

GTFE GTFE GTFE GTFE GTFE GTFE

GTRC GTRC

GTRC

GTRC

GLAST LAT Silicon Tracker

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Electronics PackagingElectronics Packaging

Dead area within the tracking volume must be minimized.

Hence the 16 modules must be closely packed.

This is achieved by attaching the electronics to the tray sides.

Flex circuits with 1552 fine traces are bonded to a radius on the PWB to interconnect the detectors and electronics.

Detector signals, 100 V bias, and ground reference are brought around the 90° corner by a Kapton circuit bonded to the PWB.

Composite Panel

High thermal conductivity transfer adhesive

PWB attached by screws

Detector

Readout IC

Machined corner radius with bonded flex circuit.

GLAST LAT Silicon Tracker

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Mechanical StructureMechanical Structure Carbon-fiber composite used for radiation transparency,

stiffness, thermal stability, and thermal conductivity. Honeycomb panels made from machined carbon-carbon

closeouts, graphite/cyanate-ester face sheets, and aluminum cores.

High-performance graphite/cyanate-ester sidewalls carry the electronics heat to the base of the module.

Titanium flexure mounts allow differential thermal expansion between the aluminum base grid and the carbon-fiber tracker.

SSDs Bias Circuits

Tungsten

Panel

MCMFlexure MountsThermal Gasket

Bottom Tray

GLAST LAT Silicon Tracker

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ConclusionsConclusions

Solid-state detector technology and modern electronics enable us to improve on the previous generation gamma-ray telescope by well more than an order of magnitude in sensitivity.

The LAT tracker design uses well-established detector technology but has solved a number of engineering problems related to putting a 900,000 channel silicon-strip system in orbit: Highly reliable SSD design for mass production Very low power fault-tolerant electronics readout Rigid, low-mass structure with passive cooling Compact electronics packaging with minimal dead area

We have validated the design concepts with several prototype cycles and are now approaching the manufacturing stage.

We’re looking forward to a 2007 launch and a decade of exciting GLAST science!