Belle2link - unified data transport to COPPER

Introduction

Belle2link is a unified data transfer system to move data from detector front end to COPPERs through optical fibers.

• COPPERs are originally designed to house digitizers as daughter cards called FINESSE, and analog signals are supposed to be fed into FINESSE cards through copper cables.
• In the recent detector readout including Belle II, the digitizers of front end electronics are normally placed near the detector and the digitized signals are sent to the readout modules through long cables, preferably optical fibers. The method can reduce the number of long cables between detectors and COPPERs and also the noise level in the signal at digitization.
• If the FINESSE card, whose specification is already standard among COPPER users, can be placed near the detector and it can be connected to a COPPER via an optical link, it is the most convenient way.
• Since we already have a long experience with COPPERs in the Belle DAQ system, we decided to develop the data transfer system between detector front end digitizers and COPPERs which satisfy above.
• The transfer system, called "Belle2link" is being developed under the collaboration of IHEP(Beijing), Hawaii U. and KEK, partially supported by JSPS grants-in-aid.

The schematic view of Belle2link is as follows:

Development status

• Three types of receivers are being developed. HSLB by IHEP, DSP_FIN by Hawaii, and MGT FINESSE by KEK. HSLB is supposed to be used for most of Belle2 detectors, and DSP_FIN for the Barrel PID detector which requires a wave form processing at the receiver side. MGT FINESSE is a general purpose receiver card used for various studies of the data link.

The frontend interface is provided as an FPGA core library. A rough definition of the data passing between detector side logic and Belle2link transmitter is shown as below:

-- RyosukeItoh - 22 Nov 2010