1. CLIC DETECTOR PAC RING SHIELDING CONCEPT Jerome Axensalva BE/OP16/12/2011 MDI meeting1

2. Introduction 1: At its both ends, the CLIC detectors must be shielded to avoid radiation leaks in the experimental cavern, this can be achieved by filling the gap between the detector and the cavern walls with dedicated material. Jerome Axensalva BE/OP General Layout. Drawing by Nicolas Siegrist 16/12/2011 MDI meeting2

3. Introduction 2: To allow the detectors to be moved in and out the cavern and to insure the maximum tightness against radiations (no gap between the cavern wall and the detectors), it is foreseen that this radiation shielding can be extended and retracted. Jerome Axensalva BE/OP Shielding layout. Drawings by Nicolas Siegrist 16/12/2011 MDI meeting3

4. Constraints we have around the demanded shielding: - The first 100 mm of depth of the yoke material. - 4 fixed concentric coil rings. - Cavern wall (not shown). - If any other, please specify…! Jerome Axensalva BE/OP16/12/2011 MDI meeting4

5. What is required : A Moveable Shielding System Between the Coil Rings to Fill the 50 mm Gap. Jerome Axensalva BE/OP16/12/2011 MDI meeting5 Shielding in extended position Shielding in retracted position

6. What is proposed 1: We need a supporting system for the moveable shielding rings -> screwed sliding pins in the yoke… Jerome Axensalva BE/OP16/12/2011 MDI meeting6 Shielding supporting pins

7. What is proposed 2: …to guide and support the shielding rings… Jerome Axensalva BE/OP16/12/2011 MDI meeting7 Shielding support

8. What is Proposed 3: … and finally a translation equipment to perform the 50 mm In and Out stroke -> double effect hydraulic cylinders. ! Note, that, at this point, grooving's in the yoke are needed to run the hydraulic piping to the inner shielding rings. Jerome Axensalva BE/OP16/12/2011 MDI meeting8 Yoke grooving and hydraulic equipment

9. What is Proposed 4: Note that the shielding rings are also grooved to house the hydraulic cylinders. Low friction material is in place at the interface between the sliding pins and the shield to minimize the risk of jamming. Jerome Axensalva BE/OP16/12/2011 MDI meeting9 Shielding viewed from backward with yoke material hidden

10. Manufacturing consideration: The rings are difficult to manufacture and transport in one single piece (Ø max ~ 11 m)… A reasonable solution is to split them into 3 equal sectors and re-assemble them once on the detectors. Jerome Axensalva BE/OP16/12/2011 MDI meeting10

11. Test Bench: Preliminary tests are proposed on a prototype system to validate the hydraulic and sliding systems… Jerome Axensalva BE/OP16/12/2011 MDI meeting11 Test bench assembly

12. Test Bench: …and we also need to perform endurance tests on components: hydraulics, low friction pads, motion sensors, etc… Jerome Axensalva BE/OP16/12/2011 MDI meeting12 Test bench assembly

13. Test Bench: View from the bottom, grooves for hydraulic piping Jerome Axensalva BE/OP16/12/2011 MDI meeting13 Test bench: grooves in the dummy shield part and hydraulic piping

14. Test Bench: Hydraulic cylinders. Jerome Axensalva BE/OP16/12/2011 MDI meeting14 Test budget: ~ 15.000 kCHF

15. Questions: Is this concept compatible with the yoke’s magnetic field (Threads, Grooves, Piping fixes, … ) ? Do we really have 100 mm of the yoke’s material available ? Can we anticipate a clearance between the fixed coils rings and the moveable shield rings of 5 mm ? Need to evaluate the stress and deformations of the yoke around the sliding pins threads -> need to know the exact yoke material. Radiation levels compatible with the hydraulic components ? (piston rings of the hydraulic cylinders are made of synthetic material). Failure mode(s) ? Redundancy ? Seismic constraints ? Cavern wall movements transmitted to the detectors ? (hydraulic circuits opened/relieved or not during operation) ? … Jerome Axensalva BE/OP16/12/2011 MDI meeting15