I have come up with two models for supporting the drift chambers inside the calorimeter.
Pls. refer the details of the model 1 at the site below,
http://www.jlab.org/~ravi/extraction.html
MODEL 1.
The "Inner Dia" of the Barrel Calorimeter is 130 cm
and the
"Outer Dia" of the CDC is 120cm
Hence we have a gap of 10 cm to support the CDC,FDC and would need to have enough space to accommodate the cables being removed from the upstream end of CDC. By incorporating Model 1 into the design, which has a two fiber glass cylinders supporting the CDC/FDC, leaves us with a total space of 5cm and an area of 980 sq cm for the cables to be removed, between the two fiber glass cyliners. The fiber glass cyliners are 1.25 cm thk.
DATA Required:
If I have the exact number of cables which needs to removed from the front end (upstream end) I could modify the dimensions of the fiber glass chambers to suit the space requirement.
MODEL 2.
The highlights of Model 2 is that it does not incorporate the fiber glass chambers to support the CDC,but it would require the plates to be supported by bolting them to the Barrel calorimeter. For a detailed description of the Model 2,pls click the link below and refer the last two slides(19,20) of the presentation.
http://www.jlab.org/~ravi/hall/hallD/gluex.ppt
The support plates are situated at three places around the circumference of the inner surface of the Barrel Calorimeter, the two bottom rails aid in taking the load of the CDC, and the top rail is used for precision alignment. As it can be seen from the slide, the "bottom plate" needs to be bolted to the barrel calorimeter which secures it to the desired position. The rail sitting on top, is bolted to the bottom plate. This completely secures the bottom plate and the rail. Coming over to the top plate, the "top plate" needs to run all the way along the length of the CDC, this plate can be supported from the aluminum plate,which is used in holding the wires of the CDC.
All the components depicted in the models are directly picked from he catalog and represent the exact dimensions.
By incorporating MODEL 2, we gain a lot of space compared to the MODEL 1. and the only drawback I foresee is that the barrel calorimeter needs to have threaded holes to support the bottom plate.
pls. give me your comments, so that I can modify/improve the current 2 models which I have proposed.
Thanks
Ravi
brindza wrote:
GentsRavi has already done this.
He has found commercial rails that can support the drift chambers and do precision positioning.
His presentations from past meeting actually contain the details.
We have also designed a rail support system that does not depend on making holes in the calorimeter.
All of this fits in the present space between the drift chambers and calorimeter.Although it is comforting that you have all reached the same conclusions
you may want to let Ravi continue his design and take a look at his drawings rather than reinventing
the drift chamber support.We can post CAD files and 3D design images for your consideration.
Paul
Elton Smith wrote:
Hi Curtis, Ravi already has shown some ideas for a rail system at our last collaboration meeting which has many of the design criteria you are looking for. We should not try to re-invent this wheel by every group that takes a look at it. Cheers, Elton. On Fri, 12 Mar 2004, Curtis A. Meyer wrote:Dear Eric, Dan and Elton - Gary, Zeb and I started talking about infrastructure for positioning and installing the GlueX chambers yesterday. One of he things that came out of this is that Gary (our technician building the chamber) is very reluctant to have anything like the forward chamber packages "attached" to the front end of the strawtube chambers. He was also very reluctant to have the cable bundles passing over the length of the strawtube chamber. We then started to look discuss that we had thought that this would be the best way to accurately know where the chambers are with respect to each other. We then got to the rail system, and realized that if we had precisely located "stops" on the rails, we could accurately reproduce the chamber positions at least as well as we could do with the packages being attached, and possibly better. Even if we had the forward chamber come out the down stream end of the chamber, and the CDC come out the upstream end. At the moment, we are looking into a rail/positioning system that would allow for this, and allow us to accurately and reproducibly position the chambers inside the magnet. We asre also contacting the Regina group about being able to attach precision rails to the calorimeter. What is coming out of this early discussion is that the current 5cm of space between the chambers and the caloriemters may not be quite enough for the rail system. We may need to look into increasing this to about 7cm or so. Once we get a reasonable estimate on the numbers, we will need to decide with the calorimeter group where this space comes from. Equally spilt, all from DC's or all from calorimeter. curtis