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# White Rabbit Newsletter, May 2017
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## CERN
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## Tsinghua University
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We have adapted WR technology for a pre-clinical Positron Emission
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tomographic Instrument. The PET ring consists of 8 detector modules,
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each containing 6 LYSO arrays coupled to a 8\*8 SiPM matrix. The signals
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from the SiPM are processed by a dedicated ASIC and then digitized and
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time-tagged with a commercial ADC and FPGA-based TDC respectively. Each
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module acts as a White Rabbit slave node to synchronize the time
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reference of the TDC. The extracted list mode data is also transmitted
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via the WR link. A standard WR switch collects the data from all 8
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detector modules, but the firmware has been modified. The list mode data
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packages from each module are extracted while other packages enter the
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switching matrix as normal. The list mode data are then processed by
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dedicated timestamp coincidence logic. The outcomes are then re-packeted
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and send out via a separate port to a reconstruction PC. The scheme
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greatly simplifies the PET design by replacing traditional off ring
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electronics with a standard White Rabbit switch.
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The design of dual-port Cute-WR mezzinine has been released. It can act
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as a slave with a redundant connection to improve the reliability or in
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daisy chain mode to support a cascade topology. We have verified the WR
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functionality on each port for both master/slave. The daisy chain for
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PTP transmission has been verified, and the routing of data frames is
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still under development. With the dual port mezzanine, we are also
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designing a portable calibration node which can play an important role
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in a WR auto-calibration procedure, WR array deployment and validating
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the synchronization accuracy, bringing the advantage of higher
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integration, more convenience and lower human workload
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(http://ieeexplore.ieee.org/document/7820218/).
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A prototype array of 100 detector nodes are running in Tibet. For quite
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a long period, we suffered some instabilities, randomly losing nodes
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during power up and normal operation. The new released WRPC 4.0 has
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greatly improved the situation. The LHAASO project has been finally
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approved and more than 500 WRS and 7000 WR nodes will be deployed at an
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altitude of 4300m asl. At the end of 2018,a quarter of the full array is
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foreseen to operate.
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## Nikhef and Vrije Universiteit Amsterdam
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## EPFL
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