X-ray Survey of the ATLAS SCT Hardware Overview Nick Brett and Jim Loken 15-06-05.

X-ray Survey of the ATLAS SCT

Hardware Overview

Nick Brett and Jim Loken 15-06-05

Nick Brett – University of Oxford2

The ATLAS Semi-Conductor Tracker


Alignment Requirements

Alignment should not degrade track parameter measurements by more than 20%

Mis-alignment of SCT must fall within the following tolerances

1220050SCT Forward

1250 100SCT Barrel

Rø(μm)Z(μm)R(μm)


Alignment Techniques

Initial X-Ray Survey

Frequency Scanning Interferometry

Track-Based Alignment Procedures


Aims of The X-Ray Survey Produce a map of the SCT modules

Calibrate the FSI system Module positions can be inferred from shape

of support structure

Compliment Track Alignment Provides an initial geometry Identify otherwise unrecoverable distortions


X-ray Survey Overview


The Scanning Head

Optical strip readerLinear Motion

BM250

Rotary Motion ADR200

X-Ray Assembly


Linear Motion

8 pole induction motor 25:1 ratio gear box Rubber Wheel

Linear Motion BM250

Scanning Head

BM250 motor

Gear Box

Rubber Wheel

Rail


Optical Strip Reader

1.6m Long Scale Strip

RGH25 Read Head

RGB25 Signal Processor

Maximum Spatial resolution of 5μm Resolution 5μm

Signal Period 20μm

RGH25 Read Head


R Measurement

Ø and Z fixed by scanning head

R found through use of stereo angle between X-Ray tubes

Scanning head in calibration stand

SCT barrel X-ray beam


X-rays on silicon

Problems• low Interaction

probability• digital readout

Solutions• Use long integration

window (x-ray mode)• Multiple triggers for

each beam position

strip position (Rø)h

its


Module response

narrow beam

wide beam

strip position (Rø)

hits

Problem Non-uniform response

to x-rays

Solution Use wide beam to

measure response Modulate narrow

beam accordingly


Calibration

X-Ray Beam

Optical Table

SCT Module

(In transport case)

Z Axis


Calibration


Calibration


Summary

Proposed x-ray survey would occur during construction of ATLAS

Data could be used to remove ambiguities in other alignment techniques

Calibration of hardware is proceeding well Actual deployment is unlikely


Backup Slides


Forward Scan

θ

SCT Forward Section

Z Axis

X-Ray Beam

Scanning Head

No need to vary θ continuously, use 2 or 3 fixed angles and vary Z

Simpler and more cost effective

Recent simulation indicates improved accuracy


Support tube and cooling


Module support

X-ray Survey of the ATLAS SCT Hardware Overview Nick Brett and Jim Loken 15-06-05.

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