Real time performance estimates of the LHC BPM and BLM system SL/BI

29/03/2000SLTCJJG - SL/BI - 2 Contents BLM/BPM System Layout. BLM/BPM Functionality Requested. BLM/BPM Real Time Behavior. First Conclusions. Open Issues.

29/03/2000SLTCJJG - SL/BI - 3 The Beam Position Monitors (BPM) (cf. LHC BI Conceptual Design Report)  For each transfer line 26 H and 27 V  106 monitors.  For the main rings about 1000 monitors (H & V).  The specifications for the rings and transfer lines beam position systems are very similar  a common approach for the readout electronics and for the calibration system is planned.  TI8 BPMs and CO Infrastructure (Timing, Network, Middleware…) have to be ready in TI8 for February 2004 injection test.  A prototype digital acquisition board (DAB) is in development at TRIUMF (part of Canadian contribution to LHC funded until May 2000). It will be delivered and tested in the SPS (BA4) this summer.

29/03/2000SLTCJJG - SL/BI - 4 The Beam Loss Monitors (BLM) (cf. LHC BI Conceptual Design Report)  The beam halos will be cleaned by means of multiple collimators in the two insertions at IP3 and IP7. The dedicated BLMs will NOT be housed in the BPM crates.  The tertiary halo which will escape from the cleaning insertions will be concentrated around the quadrupoles BLMs will be located close to the quadrupoles and housed in the BPM crates.  All BLMs will be permanently surveyed in order to dump the beam to prevent magnet quenches.

29/03/2000SLTCJJG - SL/BI - 5 BPM/BLM System Layout (1/2) BPM ~ 500 PUs (H and V) distributed around each ring. Housed in 250 crates around tunnel  4 PUs per crate with their 40 MHz processing electronics (analogue and digital). To ensure enough bandwidth to readout non RT data-sets (multi-turn data, post mortem data, etc.), a standard 10 Mbit/s Ethernet connection for each station via ATM gateways to the PCR has been proposed. BLM 6 detectors per QD/QF quadrupole pair ( 3 detecting losses from each ring) Those share the 250 BPM crates  12 detectors per crate with their electronics measuring loss rates individually for each of the 12 batches. 1 Mbits/s WorldFIP segments (each handling up to 6 crates) are considered for transmitting the RT data-flow via the ATM gateways to the PCR.

29/03/2000SLTCJJG - SL/BI - 6 BLM/BPM System Layout (2/2) Ethernet: General purpose (Mass data retrieval, setting...). ATM : RT communications between PCR and US/UJ/RE. WorldFIP: - 10Hz RT Orbit Correction (Front End->US/UJ). - Beam Loss Monitoring (Front End->US/UJ). BST: - 11kHz. Turn clock (Main Signal) - All Synchronization signals. (fast timing 40 MHz) - All Synchronous commands. Ring (* 250) -> Up to 6 crates per Wfip Bus, 4 BPMs & 16 BLMs per crate BLM/BPM Crate... R.Reboot R.Console Network Switch (10 Mbits/s) US/UJ/RE (* 24) Local BST Drivers Ctrl Station (PPC) BI WorldFIP Master * 2 PCR WorkStation/PPC (HPUX, LinuX, NT…) Network Switch (GigaEth) PCR Remote Reboot Remote Console BST Master (? TTC ?) Network Switch (ATM)

29/03/2000SLTCJJG - SL/BI - 7 BI Crate Layout (if VME is chosen)

29/03/2000SLTCJJG - SL/BI - 8 BLM/BPM VME Crate (if VME is chosen)

29/03/2000SLTCJJG - SL/BI - 9 Beam Orbit Measurement Functionality For the global orbit feedback with closed loop bandwidth of 1 Hz a readout of average orbit data at 10 Hz is foreseen. For the other applications (1000 turns, Optic Measurements…) it will be possible to trigger on request the acquisition of N consecutive turns of any M bunches, where N x M may not exceed For the post mortem (frozen by beam dump), the circular storage in the DAB of about the last second of orbit data is currently considered.

29/03/2000SLTCJJG - SL/BI - 10 Beam Loss Monitors Functionality To prevent magnet quenches, the BLM electronics will measure loss rates individually for each of the 12 batches integrated over 10 ms  100 Hz measurement rate. If data has to be concentrated to apply beam abort algorithm, we will need to transmit to PCR at least beam average rates at 100 Hz. For the post mortem (frozen by beam dump), we could maintain locally parallel circular buffers at 100 Hz and 1 Hz (e.g. could have last 256 s every 1 s and 2.56 s every 10 ms for each detector and batch).

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29/03/2000SLTCJJG - SL/BI - 12 First Conclusions Every single piece of the puzzle is feasible, BUT we must keep in mind that the assembly, tuning and commissioning of the entire system will be a very difficult task that will need time, collaboration, competence and experience. We need the TI8 BPM system to be ready for February Due to this, we have to define and chose the HW (VME, Wfip 2.5Mb/s, ATM, Optic Fiber,…) and SW (PPC, LynxOS,...) development platform this summer and stick to it. We need answers to the open issues in the coming months....

29/03/2000SLTCJJG - SL/BI - 13 Why So Early Radiation qualification problems may induce long delays. People availability. We will have to deal with a very complicated system.

29/03/2000SLTCJJG - SL/BI - 14 Open Issues LHC Front End Platform... Beam Dump… (When, How…) Post Mortem… (When, What...) BLM/BPM acquisition RT transmission… Optic Fiber in the Tunnel... BST … (What, How…) BLM/BPM/WorldFIP/ATM synchronization… Absolute time stamp...