1. Muon EDR material specification 16/04/20031T.Schneider/LHCb Muon EDR O-ring choice: In the inner part of the Muon system (M2/3 R1/2) we have introduced an O-Ring to close and seal the chambers. Requirements to the O-ring are: Leak tightness High electrical resistance (in range of TΩ) Radiation hardness Chemical resistance to our environment (combination of CF4/electrical field/radiation) Hardness of ~40 Shore A to optimize sealing and number of screws used.

2. Muon EDR material specification 16/04/20032T.Schneider/LHCb Muon EDR O-ring choice: A quite extensive research for commercial O-ring material has been made to identify good candidates. First an electrical test of all available material has been done: A quite large number of so called high technology O-ring material did not fulfill the electrical requirements. Due to the admixture of carbon (makes the O-ring softer and black) the required high electrical resistivity was often not reached.

3. Muon EDR material specification 16/04/20033T.Schneider/LHCb Muon EDR Table of tested O-ring material:

4. Muon EDR material specification 16/04/20034T.Schneider/LHCb Muon EDR O-ring choice: The choice of “soft” (40 shore A) commercial material corresponding to our requirements is limited somehow to natural rubber (NR) and silicone material (MVQ). Silicone would have the advantage that one can get it as soft as needed but the risk of out-gazing Silicone particles made us choosing natural rubber. Therefore natural rubber has been used for all our proto-types. Preliminary aging tests in Gif have given good results (full chamber) A total dose radiation test in Sanita will be performed soon (only O-ring) An additional aging test in Casaccia is foreseen in June/July 2003 (full chamber)

5. Muon EDR material specification 16/04/20035T.Schneider/LHCb Muon EDR Wire specification for gold plated tungsten wire: 30μm gold plated tungston wire with a max tolerance of ±2% in diameter Weight per meter wire: 13.55mg Gold coating thickness: 0.3μm Grade of straightness 1: Free hanging distance /wire length=95/100 Spools of Ø95mm For the preproduction wire has been ordered from LUMA

6. Muon EDR material specification 16/04/20036T.Schneider/LHCb Muon EDR Preliminary test on HV resistors: On 2 sets of 0.25W resistors a spark test has been performed A substantial change of resistor value appears only after many thousands of spark (wire can keep ~1000 sparks?) No resistors were mechanically destroyed For our application (2mm pitch; 2.7KV) we will use 0.4W resistors. (same dimensions as 0.25W) More extensive test will be done as soon we have the 0.4W resistors in hands