Test and start‐up procedures Eva Barbara Holzer, CERN LHC BLM Audit CERN, June 10, 2008

Dependability design of BLM system Calibration Functional test Environmental test Beam energy detector LBDS BIC surface elec. tunnel elec. magnet Particle shower PhD thesis (G. Guaglio, Reliability of the Beam Loss Monitors System for the Large Hadron Collider at CERN, PhDThesis, Universit´e Clermont Ferrand II - Blaise Pascal, 2005.) Fail safe design: “The most probable failure of the component does not generate the worst consequence (= risk to damage a magnet).” Choice of reliable and radiation tolerant components environmental tests of tunnel electronics: Temperature 15 – 50 degree Dose & single event no single event effects observed during tests, dose corresponding to 20 years of operation Redundancy and voting (when single components are not reliable enough) Constant monitoring of availability and drift of readout channels (Functional Tests)

Functional Tests PhD thesis G. Guaglio Detector Tunnel electronics Surface electronics Combiner Functional tests before installation Barcode check (visual, serial numbers) Current source test Radioactive source test HV modulation test Beam inhibit lines tests Threshold table data base comparison 10 pA test Double optical line comparison System component identity check Inspection frequency: Reception Installation and yearly maintenance Before (each) fill Parallel with beam Functional checks – Monitoring of drifts

Leakage Current {M, 5m, T, HWC} (10-BLM P6: LC(offset) w/cable&M-r) Cable identification check (sticker, visual) Cable continuity check; particularly verify if there are no conductors swapped Test of insulation, connection and current limits (bad connection introduces offset current The crate shall be equipped with a test card to record the measurements. Offset current with HV on shall be below 0.5 pA on all channels. MTF recording manually test card in tunnel rack monitor tunnel rack slot

Current Source {M, 5m, T, HWC} (10-BLM P7: Signal via source w/cable) Tests of insulation, correct interconnections and current limits Signal cable disconnected from monitor, current source connected. Correct channel connection checked by observing channel by channel the current signal at the test card In case the measured currents are outside the limits the corresponding cable are changed MTF recording manually test card in tunnel rack cable of monitor tunnel rack slot

ThresholdComparator & Combine&Servey (Combiner) vs DB Comparison {F, 5m, -, HWC QUICK} (60-BLM P1: Threshold/Ch Matrix Test) Before each fill Threshold table, channel parameters (e.g. electronics card number) and channel mapping (matrix for maskable/unmaskable and connected/unconnected) are compared to the one stored in the data base Sequencer, man. (after th. ch.) combiner RBAC TC & combiner ELSA DB

TC to CS (Combiner)Transmission {F, 5m, -, HWC QUICK} (60-BLM P3: UBP Check BLETC to BLECS) Beam permit transmission from all threshold comparators to the last combiner card Before each fill For maskable and un-maskable channels Sequencer (timeout), Expert combiner TC last combiner

CS to CIBU Transmission (responsibility of BIS) {F, 5m, -, HWC QUICK} (60-BLM P4: UBP Check BLECS to CIBU) Technically possible, but not yet foreseen Before each fill For maskable and un-maskable channels Beam permit transmission from last combiner card to the “controls interlock beam user” (the interface to the BIC in the VME crate). Last combiner BLM interface to BIC Toggle of redundant lines BIS last combiner BLM interface to BIC

Remove Beam Permit {F, 5m, -, HWC} (60-BLM P2: TTable User Beam Permit T) Lab test, details not finalized (see talk by Ch. Zamantzas) Tested all 16 channels, all 12 running sums and all 32 energy values of one threshold comparator, each time a new firm ware is installed – test of firmware. On each channels, each running sum and at each energy in the threshold comparator is brought above the abort threshold (increasing the signal and/or lowering the threshold value). Check if firmware correctly identifies the channel above threshold. manually TC

Beam Energy Reception {F, 5m, -, HWC QUICK} (80-BLM) The LHC energy information is sent via the “slow timing” to the CISV (VME card) and from there to the combiner (CS) (which distributes it to all TC in parallel) Continuous check of: Transmission by CRC (cyclic redundancy check) Toggle bit to indicate updates; if timeout -> energy set to max. value continuous combiner CISV

High Voltage Modulation {F, 1m, -, HWC QUICK} (40-BLM) Check the connectivity up to the surface card before every fill The bias current is increased by 100 pA and the 1.3 second running sum is measured and checked. Modulate the high tension with a sine wave Acquire modulated monitor signal, and check MTF recording sequencer (timeout), expert combiner monitor (gas not checked) DB

10 pA Test {F, -, -, HWC CONTINOUS} (30-BLM, P2:10pA/1.3 sec run.sum) Continuous check of the tunnel electronics : each minute the integrated injected current offset is checked The bias current is increased in a control loop(possibility to correct for eventual offset in the electronics – e.g. ageing effects) so that a 10 pA offset is measured. FPGA in CFC verifies signal levels MTF recording continuos analogue tunnel el. FPGA of CFC

Radioactive Source Test {M, 5m, -, HWC} (50-BLM) Functional test of full acquisition chain with Radioactive Source The procedure is described in a dedicated document made in collaboration with TIS. The purpose is to create a signal on the chamber with the RA source and check its presence in the corresponding DAB card channels in the surface electronics and the DB. MTF recording manually TIMBER (DB viewer) monitor DB

EMC Test {F, 2h, -, HWC} (70-BLM) The 40 us and 1.3 s running sum are measured with possible interference sources switched ON and OFF Possible interference sources are: Collimator jaw motors Kicker magnets Injection line magnets manually expert application monitor DB

Double Optical Line comparison Continuous 2 lines with CRC of transmission Decision matrix Continuous TC FPGA of CFC

Channel / Card assignment SW check Continuous Check of software versions (FPGA of TC and CS) Check of electronics serial numbers Continuous FPGA TC & CS TC & CS tunnel el., TC, CS TC, CS

Transmission Time of Beam Permit Disabling During machine checkout For each octant BLM takes away beam permit (by toggle functionality) Measure the delay (by time stamps) between the BLM initiating and the dump system receiving the beam dump request Reporting in MTF manually combiner & LBDS combiner LBDS

Change of Threshold Value with Beam Energy During machine checkout Ramp dipole in 4 sectors and observe DB logging of beam energy values Reporting in MTF manually DB, Manual dipole setting DB

MPS Functionality of BLM (without quenching) Pilot beam of 5109 p+ at 450 GeV Decrease thresholds (trim application) to very low value Create local bump to force a beam dump request with very low level of losses Measure delay between signal over threshold and the beam dump : the whole chain from the chamber to the LBDS, via the LBIS, is tested manually BLM system simulations (magnet + monitor) BLM system & LBDS

Provoked Quench (Transient + Steady State) 43 bunches of 41010 p+ at 450 Gev (below damage limit) Steer the beam in the chosen magnet Check level of losses and BLM readings at the quench level Repeat for MQM, MQTL, MQ and MB If no quench occurs the threshold DB values have to be reduced Test justification and description in Chamonix XV proceedings, 2006, Magnet Quenches with Beam (A. Koschik) A: transient losses and B: steady state losses manually BLM system simulations (magnet + monitor)

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The BIS (Beam Interlock System) Architecture CIBU Three ring-type systems: LHC Beam 1 & Beam 2 SPS Four tree-type systems: LHC injection (Beam 1 & 2) SPS extraction (BA4 & BA6)

Calibration / Threshold determination Number of locally lost beam particles Proton loss locations Hadronic showers Chamber response Hadronic showers (energy deposition in magnet) Deposited energy in the machine component BLM signal Quench and damage levels as function of loss duration (heat flow in magnet) Threshold values Machine component Loss location Detector position Beam energy Loss duration Fraction of quench and damage level of the machine component