Alignment systems for GlueX

GlueX Collaboration Meeting

Bloomington, Indiana

May 20-22, 2004

Courtesy of Dimos Sampsonidis, Aristotle University of Thessaloniki

Presented by Zisis Papandreou, University of Regina

NIKHEF Web Page

Pattern used to measure

x- and y-axis, size for z-axis

Range of several cm

with accuracy less than 1m

•Three point relative alignment measurement systems (RASNIK) with accuracy ± 1μm.

Y

X

The main element used in chamber alignment

and QA/QC during chamber construction

The infrastructure - RASNIK systems

Original system used a bright dot

Lens adapted to layout

CCD camera 400000 pixels

pixel size 7x7μm2Mask and light source

Performance, in terms ofImage Position on Sensor:

x = 0.05 µm

y = 0.05 µm

scale = 2 x 10-5

RotZ = 20 µrad

Coded Mask

Y

X

RASNIK specs

Alignment information from image pattern

recognition

InfraredLED

Online Quality AssuranceTemperature variation Effect on RASNIK monitoring

for tube layer position (z coordinate)

Temperature variation at Stiffback

Temperature variation at Rasnik Tower

The height of the clean room is limited (2,65 m).

The stiffback is heated from the lights while it is suspended.

6m shift of stiffback visible!

What’s required

• RasNik components: camera, mask, lens• PC with FrameGrabber: data translation• Rasmux: a custom multiplexer

– For use with camera and mask– Suitable cables

• Software: free from NIKHEF• AUTH will contact NIKHEF for a system

or could participate in system development

BCAM: another option

• Boston CCD Angle Monitor

• ATLAS forward muon chambers

• Camera electronics is radiation resistant

• 10 mrad field view

• At 16m 3rad accuracy

• Minimum effect of turbulence on resolution