Status of the Planar Edgeless Silicon Detectors Gennaro Ruggiero TOTEM Collaboration Meeting 09/11/2005

Results Achieved The Device Electric characterisations and test beams have shown the reliability of our development of planar edgeless detector employing the Current Terminating Structure (CTS) The characterisation of the edge is on the way (see Hubert’s talk on Thursday) The cut at the sensitive edges has been the limit of our development …but has never compromised it!!! We do not have a clear idea on the limit of this development and how close to the physical edge we could still go. The Assembly of the Detector The assembly of detectors on the module has been very poor:  Almost 50% of the sensors employed in the test beam of last year have been found partially or totally unglued or even broken

Plan Very optimistic and tight! Does not take into account possible delays rising for instance from bureaucracy etc…

Pre-Series Run (I) The detectors of the pre-series will have the same sensitive area, pitch adaptation on the device, alignment marks and identification pads of the detectors foreseen for the mass production and can be employed in the experiment. Of the 4 detectors (per wafer) in this pre-series run 1 of them will have a thinner insensitive volume at the edge (34um or 27um) still keeping the same principles of the CTS development Double bonding pads Finding the limit of the CTS The volume of this production is of ~60 devices Insensitive edge of 47um

Pre-Series Run (II)  If this test is satisfactory (in terms of yield and performance) we could still adopt this technique for the mass production Line of the Cut Diamond Diamond saw Dry etching (CNM Barcelona)  “Precise” diamond saw VS dry etching A fraction of this production will be sent to the CNM of Barcelona for the dicing with dry etching 10um 5um

Pre- Series, Mass production & QA tests Yield definition & Optimisation of the QA Tests Strategy on the Pre-Series run Although the acceptance tests on the pre-series leading to the design aimed for the final mass production will be short, further test on these pre-production run will continue leading to the optimal definition of the QA tests that will be employed for the devices from the mass production. QA tests will have to include: Visual Inspection  Rings/Electrodes/Strips Integrity Electric Tests  IVs from CTR, CR and BE and their stability  Single Channel test: Strip current/ oxide quality/ inters trip capacitance Part of these tests require equipments that we are missing so far. The investigation on outsourcing these tests is ongoing. Ian Bohm (Prague) has shown interest Other tests will have to follow once the detector is assemble on the module

Sensor’s Passport Identification History in a Production Database  Data from QA tests need to be stored  The history has to be updated also in the following steps with information on the assembly and following tests with detector bonded to the chips  The information have to be retrieved during the experiment run-time and re-updated if needed Binary Coding

Detector on the module: Alignment Strategy Still missing.. time has come to face this problem Mechanical  Simple procedure but requires precise cuts Optical  Aligning marks on detectors matching marks on the card and on the frame  Might require a complicate machine and/or a very careful operator Other Urgent Matter: storage space for the detectors and modules!!!

In parallel… The “planar edgeless detector” is a very young development and requires furthers studies to ensure us the full understanding. The simulations made so far on these devices have been always assuming a “guessed” boundary condition at the edge. The data so far obtained have clarified many points but not all. Elias, has started a deeper study with more advanced simulation tools. Me and Vladimir are continuously discussing with him the progress of this work. We have submitted an INTAS project to develop radiation hard edgeless detectors. If the project is approved, will allow us to pursue these studies by delegating a good part of them to other institutes who have the facilities for specific measurements that should set a final word on this learning process.