The Module Back-frame
The module back-frame is the element which mechanically supports all the other detector elements and provide gas tightness to the assembly, when the module is mounted in the large prototype. The material used in the production of this element is a stress-relieved, high resistance aluminum alloy. All the design was done at Desy in the FLC group, the production itself at the Hamburg University Workshop which also provided the raw material.
The original idea for the development of the backframe of the DESY GEM Module was to just modify the original design of the backframes for the LP to increase the available surface on the connector side of the readout board. The consulting with the designer of the original device, Dan Peterson from Cornell, gave us confidence that this improvement could infact be done without reducing the functional effectiveness of the backframe.
We designed this first version of the backframe and consulted with the Hamburg University Workshop to actually produce the device. The feedback received from the workshop led to some minor modification to the design. However the HH Uni. Workshop didn't had in its availability the specific alloy previously used for the production of this element nor had the capability to perform the cold shocks required for the stress relief process. We decided anyway to try and produce a first prototype to check whether the lack of these feature will impare the effectiveness of the device.
By the end of Oct. 2009 the first prototype of this backframe has been produced and we proceeded with the surveying of this new device. The surveyed, performed in the Desy Central Workshop showed
The next step will be to survey the produced backframe to check for its conformity with the specification. Once we complete the survey, if the backframe is confirmed to be ok we plan to use it to produce a dummy module for the LPTPC to test the gas tightness and the precision of this component.
To produce the dummy module we need to build the sealing plate for the backframe so that the total thickness will finally be 45 mm. Moreover this sealing plate should have a copper layer on the Drift side to be put at the same voltage level of the other dummy modules. We decided to build this sealing plate with plexiglass, which is cheap, easily available at the HH Uni. Workshop, and easy to machine, with a glued copper layer on top.
Finally to have a working module we also need to build the mounting bracket to fix the module in position and provide the O-Ring to ensure its gas tightness. Both elements were not