Design and construction of a radioactive source XY scanner

1
Design and construction of a radioactive
source X-Y scanner

• B.Satyanarayana
• Department of High Energy Physics,
• Tata Institute of Fundamental Research,
• Mumbai, INDIA

2
The team

• S.Chakrabarti, S.D.Kalmani, N.K.Mondal,
  P.Nagaraj, V.S.Narasimham, L.V.Reddy,
  B.Satyanarayana, P.Verma

3
Plan of the talk

• Introduction
• Design specifications
• Mechanical design
• Radioactive source holder design
• Stepper motor control circuits
• Data readout electronics
• Features of on-line software
• Preliminary results
• Summary

4
Location of HO detector in CMS
5
An HO detector module (Tray)
6
Fully fabricated module
7
Motivation

• An instrument to be used for the quality control
  of HO detector module production.
• Mapping of module response over its entire area.
• Cross-calibration with other QC data.
• Useful for any future detector R D work.

8
Design specifications

• Scanning span 2980 X 530 mm.
• X-Y positioning resolution 1mm.
• Dual stepper motor(40Kg.cm) driven X-drive.
• Twin belt driven X Y drives.
• Radioactive source Cs-137, 10mCi.
• Lead source container acceptable radiation
  levels.
• Current readout resolution 1.5nA.
• Self calibration capability.
• Safety and interlocking facilities.

9
80/20 Industrial Erector Set

• A complete and self sufficient assembly set.
• Made of 6105-T5 aluminum alloy.
• Light weight weighs about a third of iron,
  steel etc.
• Strong and precise beam deflection is about
  0.28mm over a 762mm span with a centered load of
  about 23Kgs.
• Easy to design and fabricate.
• CAD libraries provided.

10
Bill of materials
11
Full view of the scanner
12
A view of X-Y positioning components
13
Demo of tray loading
14
Demo of X-movement
15
Demo of Y-movement
16
Schematics of source holder
17
Cut-away view of source holder
18
View of the source at the garage
19
Radiation levels at the scanner
20
Stepper motor controller specifications

• ISA interface
• User selectable I/O address
• Dual stepper motor control
• Software clock for motors
• Front-end DAQ control
• Limit switch monitoring
• User selectable interrupt generation and control

21
Stepper motor controller
22
Stepper motors driver specifications

• Dual X-motion motor drive.
• Single Y-motion motor drive.
• Max current/coil 10Amps.
• Cooling by four d.c fans.
• Eight (expandable to 16) logic signal
  input/output.
• Five on board limit switch signal circuits.
• One relay driver.

23
Stepper motors driver
24
A view of readout components
25
PMT base circuit for current readout
26
Current-to-Voltage converter
27
ADC board specifications

• Make DMS
• Interface ISA
• Channels 8 single-ended
• Converter IC AD574
• Resolution 12 bits
• Input range Bipolar /- 5V
• Conv. type Success. Approx.
• Conv. Speed 25 micro secs
• Accuracy, linearity /- 1 bit
• Trigger mode Software
• Data transfer Prog. control

28
Features of the on-line software

• On-line display of sources position.
• On-line graphical presentation of data.
• On-line help
• Support of configuration and log files etc.
• Manual, semi-auto and auto operating modes.
• End, legend and (x,y) location positioning
  facility.
• Programmed scan facility.
• X-Y movement tests and demos.
• Support of multiple motor speeds etc.

29
Snapshots of on-line software screens
30
Raw data at an X-Y position
31
Data representation methods
32
X-Scan of a detector tray
33
Y-Scan of a detector tray
34
X-Scan of another detector tray
35
Surface plot of a detector tile
36
Surface plot of an HO detector tray
37
Surface plot of Grapes tile
38
Safety and interlocks etc.

• Limit switches on extreme X-Y positions.
• Limit switch for proper tray mounting.
• Flexible chain link for moving cables.
• Appropriate ventilation and cooling.
• Source holder, lead garage and lead curtain.
• Use of personal TLD badges.
• Interlock for the high voltage supply.

39
Summary

• The instrument meets design specifications.
• Tested and calibrated.
• Is being used in the HO detector production.
• Other applications possible and welcome.
• Possible future work and upgrades.

40
Acknowledgements

• B.S.Acharya, Sudeshna Banerjee, S.R.Dugad,
  M.R.Krishnaswamy, Kajari Mazumdar.
• P.R.Joseph, S.R.Joshi, H.G.Bhujbal, M.Elangovan
  and G.K.Ghodke.
• Florida State University, USA.
• BARC Health Physics Division and BRIT.
• Institutes Central Workshop and Technical
  Services.