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The new readout chain of the NA62 electromagnetic calorimeter

The new readout chain of the NA62 electromagnetic calorimeter. Aniello Spiezia Student Sessions CERN, August 13 th 2008. The idea behind the experiment. K +  p + nn. BR(K +  p + nn ) = (8.0 1.1) . 10 -11. The rare decay: is a precise test of SM and sensitive to New Physics

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The new readout chain of the NA62 electromagnetic calorimeter

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  1. The new readout chainof the NA62electromagnetic calorimeter Aniello Spiezia Student Sessions CERN, August 13th 2008

  2. The idea behind the experiment K+  p+nn BR(K+  p+nn) = (8.0 1.1) . 10-11 • The rare decay: is a precise test of SM and sensitive to New Physics • The SM prediction is: • The aim of NA62 is to collect about80 eventswith a signal to background ratio of 10:1 • Data taking is foreseen to start in2011-2012

  3. NA62 Layout Detector Calorimeter Structure p+ K+ Beam Particles rate ~ 1 GHz Kaons rate ~ 50 MHz

  4. The Liquid Kripton Calorimeter (LKr) is the only detector from the NA48 experiment that will be used in the new NA62 experiment At the end of 2007 the detector readout was operating with lack of spares for some components (optical link board) The LKr Calorimeter The consolidation of the LKr calorimeter readout isMANDATORY

  5. The SLM (Smart Link Module) is a FPGA based board that gets data from the ADCs and sends them to RACK PCs 54 SLMs and 14 Processor nodes are needed to read the whole LKr Calorimeter that consists of about 13000 channels The Core of the New Readout: SLM

  6. It allows to read the existing ADC modules with the new read-out From ADC to SLM The board converts signal from the ADC in LVDS (Low Voltage Differential Signal)

  7. The SLM and the PC exchange data using Raw Ethernet Protocol The data are attached in packets in which the first 32 bytes are reserved to the header and to control words Each packet has a size of 6176 bytes The communication

  8. The Aim of my Job (I) It is necessary toreduce the size of such output The aim of my job is to increase the performances of the new readout chain Up to now the data are written in a Shared Memory Partition. This requires a final bandwidth for the data of ~ 1.6 GB at 10 kHz trigger rate

  9. The Aim of my Job (II) • For each event all the 13000 cells of the calorimeter send data to the SLMs • But not all the calorimeter is fired by clusters

  10. The Aim of my Job (III) I’m working on an alghoritm to apply a zero suppression to the data coming from the SLM This is done by getting the data that are over a certain threshold only The zero suppression should reduce the initial data by a factor of about 100 This has to be done before the data are stored in the shared memory partition of the PC Then the information is sent to the next element of the readout (online PC-Farm)

  11. The Aim of my Job (IV) • I’m currently testing the zero suppression using pre-recorded data • I’m measuring the time taken by it • The zero suppression takes about 3 seconds per burst (about 100 s each event) • The system will be installed at the experiment in september 2008 11

  12. The Aim of my Job (V) • A shared memory segment is created using: • key = ("/root/newro/fake/procs0.fake", 1); • shmid = shmget(key, shm_size, 0); • shm_ptr = shmat(shm_id, NULL, 0); • The communication and the exchange of data is allowed using: • socket(int domain, int type, int protocol); • sendto(sock, *ptr, length, flags, *dst_addr, dst_len); • recvfrom(sock, *ptr, length, flags, *addr, addr_len);

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