1. Limited Streamer Tubes
Mechanical Design Review
William Sands , Princeton University,

2. Overview
The Limited Streamer Tube (LST) has been used in experiments around the world with great success as a particle detector. This is not a new technology and it’s proven effectiveness in other experiments was a leading reason for the LST being chosen for RPC replacement in BaBar.
The individual LST will be referred to as a tube and an assembled set of two or more will be referred to as a module.
The tube will be built at Pol Hi Tech in Italy and after extensive testing will be sent to the U.S. for assembly at Ohio State University and Princeton University.
It will take 1164 tubes to make 564 modules to populate the needed layers in all sextants.

3. Basic LST Components

4. Basic Handling
The tubes and modules will always be handled out of boxes and fixtures with there x-axis vertical for greatly increased strength against deflection. Although they are very long and made of PVC they are quite robust especially as a module.

5. Assembly of Modules
Modules will be assembled in fixtures such as shown here. The individual parts will be bonded with a 2 part epoxy made by Shell ,using Epon resin 815C and Epi-Cure 3140 as the hardening agent.

6. Assembly Procedure Diagram
The PHI strip is placed in the fixture and epoxy is applied, then epoxy is applied to the inner sides of the tubes and rib prior to being set on the PHI strip and hold downs placed on. After curing the fixture is pivoted vertical for module removal.
The stainless rib is placed in the module to assist in the rigidity of the module when the x-axis is in the horizontal position in the magnet. The rib will help overcome any anomalies in the magnet steel.

7. Shipping ,Testing and Installation Box
From the gluing fixture the module is moved to a specialized box deemed the H-box because of it’s shape. The box will be constructed in Italy and shipped to the U.S. with tubes inside and then be able to accept modules for testing and shipping.

8. H-Box Properties
As long as only the top is removed the H-Box remains very resistant to deflection and prop twist. After testing one side the top is replaced and the box is flipped to access the other side. The aluminum foil is in place for testing purposes.

9. Conclusion
Spare tubes and modules will be built but with extensive testing and quality control these should be at a minimum.
The overall structure of the tubes and the modules are simple and robust making them a reliable detector for BaBar.