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COMPASS Experiment at CERN

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COMPASS, a “COmmon Muon and Proton Apparatus for Structure and Spectroscopy”, is a high-energy physics experiment at the Super Proton Synchrotron (SPS) at CERN in Geneva, Switzerland. Nearly 240 researches from 11 countries and 28 institutions work in COMPASS. The purpose of this experiment is the study of hadron structure and hadron spectroscopy with high-rate muon and hadron beams. 

The MLab group has designed and implemented the Reconfigurable COMPASS RICH-1 Read-Out System for the 83000 channels Ring Imaging CHerencov (RICH) Detector of the experiment. The system can steadily work up to a trigger rate of 75 kHz with maximum channel occupancy of 20%. At these conditions, the data acquisition rate is 7.77 Gbytes/s and the data transmission rate is 5.13Gbytes/s.

 

COMPASS RICH-1 Read-Out System

rich boards

The reconfigurable COMPASS RICH-1 Read-Out system is based on 192 identical large front-end boards (BORA board). BORA was designed for acquiring, digitizing, threshold subtracting and transmitting event data. The overall operation of the board is controlled and supervised by a DSP tightly interacting with an FPGA that acts as a parallel co-processor. The DSP allows characterizing each analog channel by locally calculating noise and pedestal. Each BORA communicates with the outside world through two optical fibers and through a dedicated DSP network. One optical fiber is used to receive event triggers, and the other one is used to transmit event data to subsequent processing stages of the acquisition system. The DSP network allows reconfiguring and reprogramming the DSPs and FPGAs as well as acquiring sample events to visualize the overall operation of the system. The whole RICH has eight DSP networks working in parallel. These networks are handled by DOLINA, a PC resident multiprocessor board containing eight DSPs. Each network is formed by 24 BORA DSPs and 1 DOLINA DSP.

The read-out system can steadily work up to a trigger rate of 75 kHz with maximum channel occupancy of 20%. At these conditions, the data acquisition rate is 7.77 Gbytes/s and the data transmission rate is 5.13Gbytes/s.

The DSP-FPGA combination in the BORA board, with its intrinsic parallelism, largely determines the high performance of the system. The local data processing capability in BORA allows on-line threshold subtraction, as well as carrying out extensive statistical studies on all 83000 channels in a reasonable time.

The required flexibility of the system, designed for adaptation to different experimental conditions or requirements has been achieved by the use of reprogrammable elements such as DSPs and FPGAs. The DSP networks allow reconfiguring and reprogramming these elements, as well as providing the communication between BORAs and the RICH Control PC. These networks handled by DOLINA board provide the mean to manage and monitor the whole RICH-1 readout system.  


For more details about the COMPASS RICH-1 Read-Out System:
 

  1. Baum, G. et al. “The COMPASS RICH-1 read-out system”. Nuclear Instruments & Methods in Physics Research (NIM-A). Section A 502 (2003) 246-250

  2. Baum, G. et al. “BORA: a Front End Board, with local intelligence, for the RICH Detector of the COMPASS Collaboration”. Nuclear Instruments & Methods in Physics Research (NIM-A). Section A 433 (1999) 426-431.

  3. old webpage
  4. M. L. Crespo, Data Aquisition and Processing System for the RICH-1 of the COMPASS experiment (in Spanish), ICTP-INFN Laboratory, Trieste, Italy and National University of San Luis, San Luis, Argentina.


For more details about COMPASS Experiment please go to: http://wwwcompass.cern.ch/

 Click to see some of our Publications.

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