Dr. Tobias Flick
The ATLAS Pixel Detector is read out via and optical link. Data to the detector is transmitted via optical fibres from the off-detector side to the on-detector side. And data from the detector is sent vice versa.
On both sides there are optical - electrical converters. The optoboard inside the detector and the Back of Crate card (BOC card) with its optical components on the off-detector side. Data is transmitted to the detector using a BiPhase Mark encoding (BPM) which encodes clock and data signals into one to be transmitted on a single fibre at 40 Mb/s. The signal is then decoded at the optoboard into clock and data to be fed to the detector modules.
These send back their physics data at 40 Mb/s, 80 Mb/s, or 160 Mb/s depending on their location inside the detector. These signals are received on the BOC card and converted into electrical signals again to be sent to the ReadOut Driver and the Highler Level Trigger system for preparation and storage.
The Wuppertal group has taken responsibility about the BOC cards, from the development, the production, the commissioning, up to their operation. This covers the maintenance and tuning of the system as well. We are involved into the operation of the optical link system in terms of providing the software drivers, tuning routines and hardware maintenance. The link is one of the essantial things which have to work in the detector to be able to operate the whole electronics and take data with this part of ATLAS.
Currently investigations about a new laser system for the off-detector hardware is going on. This covers laser testing in the lab in collaboration with international institutes, development of new hardware and testing, as well as work in the detector side (control rooms) to repair broken parts.
My group working in this area consists of several diploma and PhD students as well and Bachelor and Master Students.
The first upgrade of the ATLAS Pixel Detector will be in Phase I the Insertable B-Layer (IBL). A fourth layer will be inserted into the current Pixel Detector. For this the beam pipe radius will be reduced and new electronics mounted on this very close to the pipe surface. This way 14 new staves holding 32 readout chips each are to be controlled and read out.
To adopt for the closer distance and therefore the higher occupancy in the read out chips a new optical link is to be designed and built. The Wuppertal group is participating in developing the off-detector system for the IBL.
We are again designing the BOC card for IBL which will take similar functions as the one in the Pixel Detector, but is based on a modern chip techology to be used.
There will be hardware and software development to be done for this purpose and then the prototyping and series production of the boards itself. This is under way in collaboration with a group of the ZITI Heidelberg (located in Mannheim). And again it is a work with engeneers, students and physicists.
A step further in Phase II upgrade of ATLAS, the inner detector will be renewed completely. For this the optical link needs to be redesigned with new components. We have investigated into a setup to qualify laser diodes to be used inside severe radiation environments. In this test bench, different laser components and packages will be investigated and in combination with irradiations a laser in an optimal package will be chosen for the use in the ATLAS detector for the high luminosity LHC period.