MPSCWG 12/12/ Operational scenario of the BLM system

MPSCWG 12/12/ Addressed questions 1.Strategy for operation of the BLM system 2.Operation with < 4000 channels available? 3.Mobile BLM? 4.Tests with beam?

MPSCWG 12/12/ Introduction Presentation of my understanding of the proposed implementation and thresholds definition The “mechanism” presented is the one anyway needed for the first settings loading, as well as the one which could be used latter on for trimming. I would like to point also some comments/questions at the end of the general strategy. Objectives: find an agreement on general strategy to keep on implementation discuss on few important points within this strategy

MPSCWG 12/12/ Strategy: BLM families For settings generation, BLM are grouped in families A family is defined by the type of element to which the monitor is attached (MQ, MQM, MSD,TCTH…) and the position on this element (entrance, middle, exit, beam 1/2, outside/inside…) We came up with up to 250 different families. BLMs in the arcs (~ 2200 IC) are only 6 families the rest (~1500 IC SEM) is for the quad in the DS, LSS and warm elements One thresholds table is generated by family via an expert application The 32*12 values of this table are assigned as properties of a family in the operational (LSA?) database.

MPSCWG 12/12/ Generation of threshold table 32*12 values table is filled using the dependence of the quench level on beam energy and integration time. The Seed for the parameterization is the 7TeV quench level: Ex: For MQY, the quench level of 5mJ/cm 3 correspond to 3x10 6 point like losses in transient loss Seed includes the ratio between the BLM signal and the deposited energy in the coil for the family and the knowledge of the quench level (J/cm 3 ) The Master Table is derived from this quench levels table by applying a constant factor C : proposed value 5 corresponding to the evaluated uncertainty in simulations. Seed + = Threshold 1 for RS01 … Threshold 32 for RS01 … Threshold 32 for RS 06 … Threshold 32 for RS12

MPSCWG 12/12/ ElementDamage level Master Table Applied table Maskable/ unmaskable Number of monitors MQ, MBSafe beam flag Quench level * C Quench level Maskable2160 LSS quadSafe beam flag Quench level * C Quench level Unmaskable360 DS quadSafe beam flag Quench level * C Quench level Unmaskable480 TCP,TCS%, TDI, TCH, TCLP,TCLI,T CDQ,… ??Damage level Maskable~330 MQW, MBWSafe beam flag Damage level Maskable60 MSI, MSDSafe beam flag Damage level Unmaskable24+60 MBR%Safe beam flag Quench level * C Quench level Unmaskable

MPSCWG 12/12/ ElementDamage level Master Table Applied table Maskable/ unmaskable Number of monitors MKD, MKBSafe beam flag Damage level Unmaskable24 MBXSafe beam flag Damage level Quench level Unmaskable4 TAN,TAS?Damage level Maskable8 XRP?Damage level Unmaskable9 BCM?Damage level Unmaskable BPMSW?Damage level Maskable8

MPSCWG 12/12/ Generation of thresholds table: DB 3 definitions tables are stored within database: BLM_INFO (monitor names, position, channels), BLM_FAMILIES (family factor and conversion factor) and BLM_FAMILY_THRESHOLDS (32x12 values). There are used to generate the MASTER table and the APPLIED table inside the DB. Status of the channel is also in both tables : maskable/unmaskable and connected/not connected Work under development : prototype exists with some 10 families

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MPSCWG 12/12/ Status of the software Expert application for thresholds generation exists (ROOT scripts) and is used to fill the DB. (expert to LSA?) Database : Work in progress, structure defined, prototype exists with some 10 families, still some discussions about history of changes TRIM for operation : Work in progress External tables comparison: to be done, but no major problem

MPSCWG 12/12/ running sums (40 μs to 84 s) to cover the loss duration and 32 energy levels used for filling different buffers: logging: at 1 Hz, max loss rate in each running sums over the last second + corresponding quench levels + error and status from tests Post-Mortem : the last 1.7 s with a 40 μs sample rate (43690 values) + the last 2 min of the logging data + thresholds and masking tables + system status info XPOC : possible to get up to values per channel for the chosen running sum (need to be specified by LBDS) Collimation: on request, 32 consecutive sums of 2,54 ms Study Data: can be triggered by a timing event (to de detailed) BLM system : signals available

MPSCWG 12/12/ Strategy : remarks/questions With this strategy, Master table is not necessarily the damage level table: factor 320 to 1000 between damage level and quench level too much conservative? Thresholds are defined by families: -> There is no “general” family for region like DS, injection… -> Do we need to define OP family? -> Scaling by a family factor F between 0 and 5 It is possible to copy the Master Table and keep it in the flash memory of the BLETC. -> We have to ask for this implementation? -> We can read it back and compare with DB? -> Do we push to get also the internal comparison?

MPSCWG 12/12/ Strategy : remarks/questions The masking is done at the CIBU level: you mask all the channels connected at the same time! -> Is it acceptable from machine protection point of view? For the pair SEM-IC, interlock on the SEM? -> OK for SEM for collimators, but for MSD, MKD…? The maskable/unmaskable status can be defined only at the BLM level, without reconfiguring the BIS? What about reconfiguration of the BIS in case of disconnecting or changing the masking status at the BLM level?

MPSCWG 12/12/ Strategy for BLMS operation Reminder: BLM are part of the machine protection system: The main system to protect LHC from fast losses (between 0.4 and 10 ms) The primary system to prevent quench For slow losses, levels have to be re-evaluated, but less critical because also QPS. Relative loss levels for fast / slow losses 450 GeV7 TeV Damage level320 5 (?) Quench level Dump threshold

MPSCWG 12/12/ Operation with < 4000 channels? (1/2) Reliability of the BLM system: G. Guaglio Ph-D thesis Designed to be SIL 3 level : redundancy when necessary, experience with the SPS… acquire statistic with the existing system on SPS and LHC one as soon as available (150 days of running for the moment) the new software part need to be included in this study?

MPSCWG 12/12/ Operation with < 4000 channels? (2/2) staged approach: how much protection is needed or how much can we relax on it during commissioning with hope to gain operational efficiency? The system need to be fully operational for phase A.5 Minimum system for each phase can/should be defined (MPSCWG) Possibility to change status of channel via the same soft as for the Thresholds masking helps for wrong evaluation of the threshold possibility to change at the BLM level the maskable/unmaskable status

MPSCWG 12/12/ How many channels we can lose?  The loss can be seen by another monitor but need to change the threshold to keep the protection?  Do we have to go through the different loss patterns? (accidental case?)

MPSCWG 12/12/ Mobile BLMs? Mobile BLM Same Ionisation Chambers use the spare channels per card : 2 in the arcs at each quad, a bit more complicated in the LSS because of more elements. electronics is commissioned as for connected channel All the free channels/cards… will be predifined to allow their display without touching the threshold tables Need access to connect the extra chambers Can cover a half-cell every 3-m if 2 chambers per channel No dump thresholds For which use: He leak detection: is it enough? Need some evaluation of the expected pressure dump to evaluate the signal In the LSS?

MPSCWG 12/12/ Simulation : typical result z (cm) Maximum of the shower ~ 1m after impacting point in material increase of the signal in magnet free locations Amplitude/length of the pressure bump?

MPSCWG 12/12/ BLM tests Functional test of full acquisition chain with Radioactive Source The procedure for this test will be 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. Time estimation : 0.5 to 1 hour per front-end station (8 BLMs) Provoked magnet quench possibility to check steady state losses quench limit with circulating beam (part of the MPS commissioning) possibility to check fast losses quench behavior if sector test  What do we lose if we cannot do the tests?

MPSCWG 12/12/ Restricted tests? Testing only a given set of BLMs with the radioactive source? Motivation of the quench test: Verification of the correlation between energy deposition in the coil (= quench level) and BLM signal (= thresholds) Verify or establish „real-life“ quench levels Verify simulated BLM signal and loss patterns => Accurately known quench levels will increase operational efficiency!

MPSCWG 12/12/ Conclusion GO for implementation? Acquire statistics on the reliability of the connections and the applications during the coming dry runs Evaluate the safety of the solution in March and if not satisfactory, close the HW switch! Strategy to run with non-working channels? Action for the MPWG?