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HFT

Wieman 11/6/2004

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Outline

Development Status MIMOSTAR pixel detectors MIMOSA5 Electronic Readout Ladder mechanics Beam pipe

Interface issues External tracking requirements Mechanical interface Calibration concept

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MIMOSTAR1 back from foundry

Prototype 128X128 30 m pixels (640X640 for the full size with 4 ms frame read time)

Final design features such as JTAG controlled internal biasing levels and multiple testing modes

Received chip from foundry in October 04, testing to start at LEPSI/IReS

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LEPSI/IReS MIMOSA V testing at LBNL

Developing readout skills at LBNL with a single MIMOSA V chip

MIMOSA V is an earlier device developed at LEPSI/IReS prior to the STAR work

Noise and leakage currents as previously measured by the Strasburg developers

Design in progress for a multi-chip ladder using the MIMOSA V

Leakage Current by Section

Bottom LeftTop LeftBottom RightTop Right0

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4

6

8

10

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Section

Leak

age

Cur

rent

(fA

)

Leakage at 27 degCLeakage at 24.5 degCStrasbourg Leak (-5 degC)

Lara PierpointFabrice RetiereFred BieserRobin Gareus Howard MatisLeo Greiner

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Electronic/Mechanical Ladder Work – MIMOSA V

Multi chip design Readout with Off ladder ADCs Low mass mechanical development

0.010" Kapton cable

50 micron Si

0.004" carbon fiber

RVC0.004" carbon fiber

differential analog drivers/amplifiers

buffer

Carrier structure and cable are significantly wider for electronic performance test ladder.MIMOSA 5 MIMOSA 5

differential analog drivers/amplifiers

buffer

Top View

End View

Leo Greiner

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Ladder structure and X0 budget

Unidirectional carbon fiber skins separated by reticulated vitreous carbon (RVC) foam.

Very stiff Foam separation gives large

moment of inertia with little added mass

Carbon provides large Young’s modulus with low Z

With single end support expected to have < 10 m gravitational deflection

Ladder mass 2.7gm (a sheet of copier paper weighs 4.7 gm)

Carbon ladder structure 0.12% X0

Cable = 0.10%

50µm Si Detector = 0.053 %

Carrier (flat with RVC) = 0.12 %

Total for single ladder = 0.27%*

(500µm beam pipe = 0.142%)

*RDO chip will add another 0.053% if in final design.

More information on cable design/constraints at http://www.lbnl.leog.org/cable_constraints.htm

More information on material radiation length at http://www.lbnl.leog.org/pixel_rad_length.pdf

Leo Greiner

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Beam pipe concept required for HFT, discussions started with Brush Wellman

mm

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Beam pipe concept required for HFT, central region

Beam pipe supports attach here

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Ghost Tracks – pointing accuracy – hit density

Ghosts tracks, i.e. connecting the wrong hit to a track depends on Hit density on the tracking layer Track projection uncertainty to

the layer

P fs

s 1

Associate the closest hit to the track and the probability of a false association is:

where

s 2 2

Pfs

s 1

Eugene Yamamoto’s plot

This is not an efficiency – ghost trade off unless you set a limiting window

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Mechanical Interface

3 point kinematic connection to support structure

Two roll in rails

Kinematic structure concept to replace earlier arm design

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Alignment and spatial calibration procedure

Map all detector surfaces for each 4 ladder arm assembly with the vision coordinate machine

Assemble the 6 arm assemblies and map their relative positions

Install in STAR preserving all relative positions

If outside tracker alignment is fully known use a few tracks to determine the 6 parameters defining position of HFT within the outer tracker

If the outside tracker is not spatially calibrated do it with tracking through the HFT

BarBar vertex detector in the vision coordinate measuring machine

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Kinematic assembly – constrained to repeatedly assemble to same the same location

Allows assembly in vision coordinate machine to be the same as in the installed position

Ball in cylinder pair kinematic mounts

6 mount points used in assembly around beam pipe

3 mount points for each arm