Accelerator Alignment Lab

Survey and alignment team is responsible for precision alignment of accelerator components for accelerator machines and positional relationship among accelerator machines of RRCAT namely Indus-1, Indus-2, microtron and Booster Synchrotron and synchrotron radiation beamlines on Indus-I & II. Apart from this, they also do the precision measurements for other accelerator machines in RRCAT like free electron laser system, Industrial accelerators and their beamline etc. They are also responsible for precision metrology of various large components and assemblies used in accelerators and experimental stations wherever conventional measurement techniques do not work.

Tight tolerances on alignment of accelerators components in their global coordinate system pose a challenge to the survey and alignment team. It demands control over the various sources of errors, use of precision measuring instruments, their proper calibrations, adopting proper survey techniques, accurate measurements and a robust data analysis.

Survey and alignment procedure adopted for different machines varies depending upon their shapes and sizes. The Booster Synchrotron and Indus-I machines are relatively smaller in size so, these machines were aligned using online coordinate determination system based on angle measurements and without use of control networks. However, Indus-2, which has ~ 172.4 m circumference required a network of control points to cover the entire machine for controlling the overall shape and size of the machine. Redundant measurements and least square adjustment to achieve best linear unbiased estimate of coordinates for the control points and ring components has been the approach for computation of misalignment of components and deformation of the machine.

There are precision measuring instruments being used for survey and alignment like total stations, laser tracker, Distinvar® with calibrated invar wire, Laser Interferometer as distance standard etc.

Levelling and elevation: Wild N-3 optical level, Hydrostatic levelling system for online monitoring the elevation change.

An in-house developed software is used for 2-dimensional measurements (planimetric) for survey data collection and their statistical treatment like least square adjustment or alignment error analysis and used the same for on-line coordinate measurements, stake out and resection. Data analysis works like curve fittings, coordinate transformations, etc. were also done in the same software. Vertical measurements and tilt around beam path which are very stringent in accelerator machines were measured, analysed and treated separately. Commercially available softwares were used single or multiple theodolite modes for online 3D-coordinate measurements and analysis whenever needed.

In order to ensure the accuracy of distance measurements by precision distance meters, they are calibrated with distance measured by laser interferometer as standard. A 30 meter long calibration bench has been setup for this purpose. Calibration files are prepared and used for online correction of distances measured at site.

1. Construction and Alignment Experience of Indus-1 SRS in CAT,
   IWAA 1995,
   P.K. Nema, R.K. Sahu, Vijendra Prasad et al.
   
   
2. Review of Alignment Activities for Indus-1 & 2 at CAT,
   IWAA 1999,
   P.K. Nema, R.K. Sahu, Vijendra Prasad et al.
   
   
3. Methodology for Survey & Alignment of Indus-2,
   InPAC-2003,
   R.K. Sahu, Vijendra Prasad et al.
   
   
4. Survey Network Adjustment Programs for adjustment and analysis of alignment data,
   InPAC-2003,
   Vijendra Prasad.
   
   
5. Survey, data adjustment and accuracy computation of Indus-2 alignment control networks,
   InPAC-2005,
   Vijendra Prasad, R.K.Sahu et al.
   
   
6. Precise Survey and Alignment of Synchrotron Radiation Source Indus-2,
   APAC07,
   Vijendra Prasad, R.K.Sahu et al.
   
   
7. Distance calibration at Alignment Lab RRCAT,
   InPAC-2009,
   R.K. Sahu, Vijendra Prasad et al.
   
   
8. Effect of long accurate scales on the accuracy of angle based coordinate determination systems,
   InPAC2018,
   Vikas, R.K. Sahu
   
   
9. Installation of Hydrostatic Levelling System in Indus-2 and Its Preliminary Results,
   InPAC-2019,
   Vikas, P.K. Sharma et al
   
   

1. Shri Rajesh Kumar Sahu, Head IOD
2. Shri Vikas, SOE
3. Shri Dinesh Barapatre, SAG
4. Shri Jagdish Kumar Parate, SAF
5. Shri Jai Singh, SAE
6. Shri C. S. Yadawa, SAE
7. Shri Pankaj Kumar Sharma, SAD1
8. Shri Jasminkumar Dineshbhai Zolpara, DMC
9. Shri Rajendra Mehar, Foreman/C
10. Shri Ram Swaroop Saini, Asst. Foreman
11. Shri Sanat Kar, Techn/B
12. Shri Poonam Kallu, Sr. Wrk. Ast./A
13. Shri Sanjay Kumar, Sr. Wrk. Ast./A