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Transport Issues for EMC Barrel

This article discusses the challenges and considerations for transporting the EMC Barrel as a single structure without disassembly. Topics include the internal structure, module storage and installation, barrel closure, and the options of shipping as a unit or as individual modules.

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Transport Issues for EMC Barrel

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  1. Transport Issues for EMC Barrel Bill Wisniewski, SLAC

  2. The Big Question • Can the EMC Barrel be transported as a single structure without disassembly? • To understand the issues, look at EMC Barrel construction. Bill Wisniewski, SLAC

  3. Internal Structure: Modules • Basic building block: module • There are 40 modules in φ. These are identical in each ring of modules. • There are 7 module ring types in θ. These differ to accommodate the tilt of the crystals as they ‘point’ towards the IP. • Most modules contain 21 crystals arranged as 3 crystals in φ by 7 crystals in θ. The backward most module is 3x6. Bill Wisniewski, SLAC

  4. Internal Structure: Modules Bill Wisniewski, SLAC

  5. Module Storage • The most compact way to store a module is in the barrel structure…. Bill Wisniewski, SLAC

  6. Module Installation • Barrel support cylinder is split in two and loaded from the middle, forward most and backward most modules first. The flange structures at the ends of the barrel preclude loading from the ends. Modules are interlocked in θ, so to remove a module requires removal of all the more central modules in that φ row. Bill Wisniewski, SLAC

  7. Module Installation • Fit out modules with pre-amp electronics/test. Bill Wisniewski, SLAC

  8. Barrel Closure • Add cables, connect to readout crate, add cooling loops, join barrel halves, add cover plates. Bill Wisniewski, SLAC

  9. Barrel Closure • Add inner cylinder and bell housing. ….Install electronics shields at readout ends… Bill Wisniewski, SLAC

  10. Install EMC Barrel in BaBar Bill Wisniewski, SLAC

  11. Install EMC Barrel in BaBar Bill Wisniewski, SLAC

  12. Install EMC Barrel in BaBar Flexible supports limit transmission of energy from the magnet core to the barrel during earthquakes. Bill Wisniewski, SLAC

  13. Barrel Instrumented Bill Wisniewski, SLAC

  14. Ship in Parts • If it proves to be impossible to ship the barrel as a unit, we can expect substantial additional time (and labor) to be needed to disassemble the barrel to the level of modules, ship the modules and support structure, and reassemble the barrel. • Need a dry, temperature controlled disassembly site as in the initial assembly. • Tent and air handlers still exist, will need refurbishment • Racks for storing modules still exist. • Need ‘constant’ temperature shipper for the individual modules. • Necessarily ship modules by air. • Containers are likely to be expensive, so might expect reuse, rather than one per modules. Logistics likely to be worse than the salt procurement saga…. • Note: EMC endcap (John Fry et al) contended successfully with shipping the 20 endcap modules for BaBar this way. The problem is only a bit more than an order of magnitude larger. • Need a dry, temperature controlled assembly site at Tor Vergata. • Will still need to ship some of the fragile large scale structures (inner RF/environmental shield)….not obvious if this is via air or ship. • Need to reestablish all peripherals: much less a ‘turn-key’ operation. Bill Wisniewski, SLAC

  15. Ship as a Unit • Large items such as the magnet coil and cryostat have been shipped via air. The barrel EMC is smaller, but also heavier. Still, it is not as heavy as many tanks which are air-lifted. • May need to carry cooling system to keep it cool. If the flight is swift enough, and the insulation sufficient, active cooling may not be needed. • Dry is less critical for the short term. The crystals are mildly hygroscopic. They lived in a dry environment before module assembly, but during storage and installation into the support structure, the environment was low, but not vanishing, humidity. • A long sea voyage would allow maintenance of temperature with an active cooling system. Low humidity can also be maintained since the barrel calorimeter is reasonably gas tight. Bill Wisniewski, SLAC

  16. Ship as a Unit • What are the concerns, aside from availabilty of aircraft? • The modules are all suspended from the rear. Each can act as a pendulum. CFC is a brittle structure. The ends of the modules extend beyond the ends of the crystals; the unfilled parts of the shells may interact, crack, etc. • A detailed finite element analysis is needed to verify that the frequency spectra encountered in flight (or by sea: intuition says this is likely to be a more complex and higher amplitude driver) do not lead to catastrophic internal vibrations. • Once a spec is in hand for limits on vibrations fed into the loaded barrel structure, a support cradle needs to be designed that would filter harmful driving motions from getting to the barrel, as well as fit securely in aircraft, etc. Bill Wisniewski, SLAC

  17. Ship as a Unit vs. Ship as Modules • The module route will take more time and cost. The problems are soluble. The logistics are a nightmare. • The unit route, if it proves to be possible, requires more engineering; it could be more marginal against failure. Bill Wisniewski, SLAC

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