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Drawings describing the muon identifier assembly for the Muon Identifier Preliminary Design Review are available on the WWW. The drawings show the design of the muon identifier mechanics for PHENIX. There are views of the (north) muon identifier from the front, top, and side. The side view shows how the panels are hung from above using Unistrut hardware. These drawings contain great detail but are insufficient for detailed fabrication issues. These are the preliminary design drawings.
Complete Autocad fabrication drawings of the full-scale muon identifier prototype are available. These drawings are the actual drawings used to build the panel and contain almost all details. The files are named m212000x.dwg (where x=3,4). The only type of details missing are those such as rivet hole locations which were decided in situ for the prototype. We have not yet made actual fabrication drawings for the entire PHENIX muon identifier mechanics system. Such drawings would of course specify in advance all details (including rivet hole positions).
The present design calls for 6 panels per gap and requires that panels above and below the beam pipe have the same height (except for gap 6). The panels in one gap are labelled as follows:
| A | B | C |
| F | G | H |
The number of Iarocci tubes and their dimensions for gaps 1-5 are:
| Panel | Horizontal | Length | Vertical | Length | Total tubes |
|---|---|---|---|---|---|
| A,C,F,H | 118H | 5200 mm | 128V | 5010 mm | 246 |
| B,G | 90H | 2504 mm | 52V | 3821 mm | 142 |
The number of Iarocci tubes and their dimensions for gap 6 are:
| Panel | Horizontal | Length | Vertical | Length | Total tubes |
|---|---|---|---|---|---|
| A',C' | 100H | 5200 mm | 128V | 4263 mm | 228 |
| F',H' | 118H | 5200 mm | 128V | 5010 mm | 246 |
| B' | 76H | 2504 mm | 52V | 3243 mm | 128 |
| G' | 90H | 2504 mm | 52V | 3821 mm | 142 |
The resultant global figures are:
| Quantity | Value |
|---|---|
| panels/gap | 6 |
| panels/arm | 36 |
| tubes/gap | 1268 for gaps 1-5 |
| tubes/gap | 1218 for gap 6 |
| tubes/arm | 7558 |
| area/gap | 13.1 m x 10.7 m |
Tubes are loaded into the panel as follows. A tube is placed against a positioning bar on a lab table. Double-sided adhesive tape is applied to the top of the tube. A second tube is placed on top. The positioning bar ensures that the tubes are staggered by precisely 5 mm along the entire length. The industrial tape developed for the automobile industry is used in truck assembly and is known to adhere for many years. The internal panel design is a sufficiently tight package that even if the tape did come loose over a portion of the panel, the tubes would have (almost) nowhere to go. Please, note that every panel has a top and bottom cover plate that makes it a sealed box (except for entrances for services).
There are places where there is no vertical coverage for horizontal tubes and no horizontal coverage for vertical tubes. The following diagram shows the dimensions of the region in a gap for which the gap is fully efficient with both x and y coverage. The aluminum frame and the rails lie outside of this region. In the drawing below (not to scale), the active area is located between the outer rectangle and the inner square. (The inner square is due to the square hole for the beam tube.)
332,10185----------------------------------------12774,10185 | | | | | | | | | | | 5411,6305--------7696,6305 | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 5411,4159--------7696,4159 | | | | | | | | | | | 332,458--------------------------------------12774,458In this drawing the nominal beam line is located at 6553, 5232.
There are alternate designs which have been considered which involve features such as having only 5 intrumented gaps per arm. These designs are not discussed here so that it is clear which design this document addresses.
Each HV channel services 18 to 26 tubes via an HV daisy chain inside the panel. The cable between the panel and the supply is the PHENIX 8-conductor HV cable. The supplies will have a rated maximum voltage of 5 kV. The HV connector is block connector at the supply end. The HV channels correspond to tubes as follows (where primes denote gap 6):
| Panel | Horizontal | Vertical | HV channels per panel | Number of tubes in each circuit |
|---|---|---|---|---|
| A,C,F,H,F',H' | 6H | 6V | 12 | H:20+20+20+20+19+19 V:22+22+22+22+20+20 |
| B,G,G' | 4H | 2V | 6 | H:23+23+22+22 V:26+26 |
| A',C' | 4H | 6V | 10 | H:26+26+24+24 V:22+22+22+22+20+20 |
| B' | 4H | 2V | 6 | H:20+20+18+18 V:26+26 |
There are 4 x 12 + 2 x 6 = 60 HV channels per gap for gaps 1-5. There are 2 x 10 + 2 x 12 + 2 x 6 = 56 HV channels for gap 6. For two arms, there are a total of 10 x 60 + 2 x 56 = 712 high voltage channels.
Each set of 18 to 26 tubes is an independent ``circuit''. So, there is one gas inlet line and one gas outlet line per circuit. There is an internal gas tubing daisy chain that connects the tubes in a given circuit inside the panel. Note that a pair of tubes staggered by half a cell are connected to different HV channels and separate gas inlets and outlets. Because of edge effects, the number of tubes per circuit varies from 18 to 26 tubes in a group that share the same HV and gas. All internal gas tubing is 1/4" polyethylene plastic tubing. Since the long external gas tubing will dominate the impedance, the varying number tubes per circuit is not expected to present too large a range of mechanical gas flow impedances to accomodate.
For panel A, there are twelve 1/4" inlet lines and twelve 1/4" outlet lines per panel. There are 12 HV conductors (requiring 2 PHENIX 8-conductor HV cables). There are 8 round-flat cables for signals.
For panel B, there are six 1/4" inlet lines and six 1/4" outlet lines per panel. There are six HV conductors (requiring 1 PHENIX 8-conductor HV cable). There are 5 round-flat cables for signals.
There are 18 motherboards located in crate(s) on the west side of the arm and 18 motherboards located in crate(s) on the east side of the arm.
There is insufficient room in front, between, or behind the panels for services to exit from the top of panels A, B, or C due to the supporting rails. Therefore, all services exit their panel by going either directly east or west through holes in the side of the panel and head toward the nearest side (east or west) of the muon arm.