1. January 25, 2005GRETINA 2004 Review1 GRETINA 2004 Annual Review Steve Virostek Lawrence Berkeley National Lab Mechanical System

2. January 25, 2005GRETINA 2004 Review2 Presentation Overview Mechanical system conceptual design Detector mechanical interface Installation site interfaces Mechanical requirements document LN system and target chamber Detector scanning table Prototype detector QC: CMM and X-ray

3. January 25, 2005GRETINA 2004 Review3 Mechanical Conceptual Design

4. January 25, 2005GRETINA 2004 Review4  D1  D2  R2  R1 S  Target Ball Radius Scientific considerations: the effect on the volume available within the ball and the efficiency of data capture Mechanical issues: the quarter sphere detector support radius and the position of the detector mounting flanges Detector Modules Mounted in 2  Structure around Target Ball at Center 2  Structure/Target Ball Size Parameters

5. January 25, 2005GRETINA 2004 Review5 GRETINA Assembly Features Detector module Cap Preamp housing LN dewar Quarter sphere shell Axle bearings Axle Worm and worm gear set Hexapod Railroad car, tracks Flange Wedge plate (under and attached to detector flange)

6. January 25, 2005GRETINA 2004 Review6 Quarter Sphere Structure Large-radius quarter sphere allows space for 17 detector module flanges as well as sufficient material to provide a stiff structure for accurate positioning As the quarter sphere radius increases, the required thickness and weight increase as well – eventually reducing the clearance around GRETINA due to the larger support components Preliminary calculations indicate a shell thickness of 3 to 4” with a quarter sphere radius of 25 to 30”

7. January 25, 2005GRETINA 2004 Review7 Other Design Topics AXLE Design issues include loaded quarter sphere weight and distances to the bearings A larger axle tube size reduces weight but increases the axle bearing cost and impinges on space constraints Preliminary calculations indicate an axle tube of 10” OD and 1/2 to 1” thick wall HEXAPOD The hexapod (or Stewart platform) is a fairly standard octahedral mount using ALS struts The hexapod is very stiff due to the tensile/compressive (no bending) loading of the struts and is finely adjustable over a large range Alignment of a hexapod is non-intuitive, but is easily accomplished using a computer code WEDGE PLATE The absolute error in the shape of the detector caps should be small In order to nest the detectors as closely as possible, the position of the caps must be controlled carefully with the flange mount Since the distance from the cap to flange is not small nor direct (tolerance stack-up), we will correct for the position of each flange with a custom made wedge plate Can accommodate errors of 3 mm in the flange plane, 5 mm out of plane and 1º tilt errors

8. January 25, 2005GRETINA 2004 Review8 Detector Mechanical Interface Module Caps Nest Together with 1mm Nominal Gap Quad Detector Module Wedge Plate 2  Structure + +

9. January 25, 2005GRETINA 2004 Review9 Site Installation Overview TBD

10. January 25, 2005GRETINA 2004 Review10 ANL Installation

11. January 25, 2005GRETINA 2004 Review11 LBNL Installation The 8x8 needs to move in so that its right end is at the centerline

12. January 25, 2005GRETINA 2004 Review12 MSU Installation

13. January 25, 2005GRETINA 2004 Review13 ORNL Installation

14. January 25, 2005GRETINA 2004 Review14 Requirements Document Requirements are for the Mechanical System as defined in the PEP: –Detector Support Structure –Liquid Nitrogen System (interface only) –Target Chamber (interface only) –Detector Installation Tool The LN system (ORNL) and the target chamber (Washington U.) design requirements will be presented in separate documents prepared by their respective developers Purpose of ME Requirements Document –Based on the Functional Requirements in the PEP –Describes mechanical requirements necessary to meet Functional Requirements and physics goals

15. January 25, 2005GRETINA 2004 Review15 Requirements Document (details) Coordinate Systems Tolerances

16. January 25, 2005GRETINA 2004 Review16 Requirements Document (details) 2  Spherical Structure

17. January 25, 2005GRETINA 2004 Review17 Requirements Document (details) Structure and Tracks Translation and Rotation

18. January 25, 2005GRETINA 2004 Review18 Requirements Document (details) Detector Installation Tool Material Issues

19. January 25, 2005GRETINA 2004 Review19 Requirements Document (details) Interfaces Mechanical … Electrical … LN System Target Chamber Transportation

20. January 25, 2005GRETINA 2004 Review20 Requirements Document (details) Interfaces Site Specific … Operating Envelope … Site Requirements …

21. January 25, 2005GRETINA 2004 Review21 LN System and Target Chamber TBD?

22. January 25, 2005GRETINA 2004 Review22 Detector Scanning Table Coincidence scan setup Scanning table Adjunct cart The scanning table may be used with or without the adjunct cart. Horizontal and vertical americium collimators outline surface areas of crystals Vertical cesium collimator… Vertical cesium collimator in conjunction with slit collimators and cloverleaf detectors… Slit collimators with external source….

23. January 25, 2005GRETINA 2004 Review23 Scanning Table Triple-crystal prototype detector module Cloverleaf detectors XY drive for vertical collimator Elevation drive’s tracking rollers Vertical source- collimator on XY drive Horizontal source- collimator on Z drive Detector module rotary table with degree markings Scan cart Cloverleaf elevation drive Adjunct cart Horizontal slits collimator, attached to Z drive

24. January 25, 2005GRETINA 2004 Review24 Scanning Table Details Triple-crystal prototype detector module Slit collimator, attached to Z axis Cloverleaf detectors Cloverleaf elevation drive Americium or cesium vertical collimator Horizontal americium collimator (not visible) on Z drive Detector module rotary table with degree markings XY drive for vertical collimator Elevation drive’s tracking rollers

25. January 25, 2005GRETINA 2004 Review25 Detector CMM Measurement 366 points measured at room and liquid-nitrogen temperatures Results: Deviation from design value = 0.2 mm (RMS) Warm – cold difference = 0.02 mm (RMS)

26. January 25, 2005GRETINA 2004 Review26 Detector X-ray Imaging Crystal positions were determined by X-ray imaging at the UC Berkeley Medical Center The three crystals were positioned with an accuracy of better than 0.5 mm.