Status of the ITS Alignment Monitoring System

First resultsBy

Bjørn S. Nilsen

The Ohio State University

Outline

• ITS and ITSAMS Geometry

• Camera Sport measurements

• Camera Calibration

• ITSAMS raw measurements

• ITS geometry effects?

Camera spot analysis• Camera exposure… set for best image.• 25 images taken in series• Image smoothing to remove intensity

anomalies– Ring centers found for a series of intensity

thresholds.– Remove clearly anomalies centers

• Return Mean center and RMS.• Means & errors computed from all 25

images

Camera ResolutionPixels

• Camera 0, RMSx=7.39±0.18, RMSy=7.48±0.18.

• Camera 1, RMSx=1.91±0.04, RMSy=1.76±0.04.

• Camera 3, RMSx=7.52±0.24, RMSy=5.96±0.19.

Image Centers

Calibration

• Data taken from Test-bench setup

• Image centers used old algorithm

• Still some problems with test-bench setup

Image location

• Data with L3 on in solid markers

• Camera center at 0,0.

1/29/2008 W. Riegler TB Presentation

In order to explain the vertical movement of the front absorber nose by 2.4mm, the top fixation point of the FASS would have to move by d=3.7mm.

It seemed very improbable that the heavy magnet crown, that the FASS is attached to, is moving at all.

L3 Magnet Tests, Frontabsorber Movement

8

1/29/2008 W. Riegler TB Presentation

Beampipe on ITS rail

Lift beampipe (ITS) before TPC movement

Beampipe (ITS) hanging on TPC

+1 TRD, +8 TOF 1.5*9= 14T 2.3mm expected

mm

B-Field tests

0.17 T

0 T

0.17 T

0.5 T

0 T

0.5 T 0.5 T + dipole

0 T +1 TOF

Central Beampipe vs. FA

9

ITSAMS Installed/aligned

ITSAMS Realigned March

Spot position By day

• Clearly spot position shifted when L3 field is on.

• Timing correlation not 100%. images (file dates), Magnet (dcs data base).

Top View Side View

Many Cables

ITSAMS Mirrors

IT’S A-Side

View from Mirror 0

View of Mirror 0 mounting

ITS C-side

Stress free Mounting

ITS mounting

- 3 point mount- Stress Free

Status

• Low Voltage on USB hub improved– Better reliability of camera communications

• Low Voltage IP address conflict fixed• ITSAMS control system still improving

– Automation of image taking and analysis to come– Computation of ITS movement being debugged.

• Wednesday L3 magnet on, run ITSAMS

Spot

Missing Camera 2

Camera 0Camera 1

Camera 3