Signals between LHC Machine & ALICE: an Update David Evans ALICE TB 23 rd February 2006 (with input from Detlef Swoboda)

23/2/2006D. Evans2 Update Since December 13 th Dec 05: data exchange requirements presented to ALICE TB 25 th Jan 06: meeting at CERN to discuss issues (D. Evans, C. Fabjan, P. Vande Vyvre, L. Jirden, F. Carena.) 6 th Feb 06: Leade meeting at CERN to discuss draft LHC document on data exchange. (EDMS: )

23/2/2006D. Evans3 Data Interchange Concept DIP/DIM (data interchange protocol) Publish/Subscriber paradigm All data with UTC time stamp 250 kBytes & 100 messages/s –Dominated by LHC Cryo  Machine bandwidth Latency about 1 s

23/2/2006D. Evans4 Experiments  LHC (ATLAS/CMS) MeasurementUnits Production Volume (Bytes) Production Interval (sec) Data Rate (Bytes/sec) Total luminositycm-²s-¹414 Average ratesHz121 Luminosity per bunchcm-²s-¹ Rates for individual bunchesHz Position and size of luminous region (average over all bunches) cm Total per experiment966 Minimum data set

23/2/2006D. Evans5 Can ALICE Supply this Information ? Luminosity –Can we get an estimate from T0, V0, CTP interaction rate ? Position and size of luminous region –Can we get these data from V0 online ?

23/2/2006D. Evans6 LHC  Experiments ProducerMeasurement Data type Production Volume (Bytes) Production Speed Production Rate (kB/s) Expected Accuracy Remarks AB-BDI Total beam intensity Protons*81 sec0.0081% Pb-Ions in prep by R. Jones AB-BDI Individual bunch intensities Protons* min0.4755% Pb-Ions in prep by R. Jones AB-BDI Average 2D beam size mm161 sec % For transport to IP will require knowledge of beta function AB-BDI Average bunch length ps81 sec0.0081% AB-BDI Total longitudinal distribution min4.752 Will be able to detect ghost bunches at the 0.1% level of nominal AB-BDI Average HOR & VER positions mm 321 sec um From the BPMs located at Q1 either side of each IP AB-BDILuminosity sec % relative This is a relative measurement between bunches AB-BDI Average Beam Loss 1610 sec0.002 Average of up to 50 selectable BLMs

23/2/2006D. Evans7 Data Exchange Dim/Dip DCS already uses DIM/DIP concept so LHC data exchange already fits into this system. DCS to take care of data exchange and software interlocks. N.B. S/W interlocks not for Beam Dump. Data written to database so no need for special end- of-run event to store these data. LHC Data S/W Interlocks Sub-dets DCS Data base

23/2/2006D. Evans8 Beam Interlock System (BIS) H/W link from USER to Beam Dump System: beam dump request. H/W interface supplied by machine Radiation monitors and connection to H/W interface to be supplied by ALICE –Use ATLAS/CMS radiation detectors Marc Tavet to coordinate this. ALICE to find resources.

23/2/2006D. Evans9 Beam Dump Request ALICE Beam monitors (for Beam Dump interlock) must send their status to CCC via DIP. –E.g. on a scale: 1 (safe)  5 (abort) Post-Mortem needs to be sent to CCC after beam dump request. –Can be sent via within 24 hours (no automated system required).

23/2/2006D. Evans10 LHC Injection Inhibit No solution yet –H/W solution safest but requires machine to find resources and design system. Also ALICE would have to produce extra hardware. –S/W solution easiest if safe solution can be found i.e. exps have to continually submit signal in case of network problems. Probably best solution.

23/2/2006D. Evans11 Beam Synchronous Timing Message (BST) BST uses the TTC technology, to send messages over channel B of TTC. Machine supplies optical cable but NOT interface. Message mainly used by LHC instrumentation etc. Some messages maybe of interest to experiments.

23/2/2006D. Evans12 Portion of BST Message for Experiments

23/2/2006D. Evans13 BST and ALICE BST message not guaranteed when no beam No hardware available to take BST data. Not possible to stamp events with data without major upgrade of trigger and all sub-detector front-end electronics. All important information also send via other means (DIP/DIM, Safe LHC Parameter system (SLP). CTP, DAQ consider system is not needed. –Optical cables installed, however, in case we want it in the future.

23/2/2006D. Evans14 ALICE Magnets CCC to control ALICE magnets Magnets connected to LHC BIS Status of magnets monitored by CCC and sent via DIP data exchange. ALICE has requested ability to control our magnets after beam is dumped. –Control passed back to CCC prior to ramping.

23/2/2006D. Evans15 ZDC ZDC to be moved out during beam injection stage. –ZDC has its own H/W interlock. ZDC to be moved in & out of data taking position from ALICE Control Room (Not CCC). Status of ZDC to be sent to CCC via DIP.

23/2/2006D. Evans16 Coordination of LHC- Detector Exchange Detlef Swoboda has agreed to coordinate these exchange issues between the machine and experiments (thanks to Chris Fabjan’s proposal). This means each detector will only have to talk to one person rather than many. Detlef has already put forward a strategy.

23/2/2006D. ALI TB17 LDX Implementation by D. Swoboda Proposed Strategy – Nominate contact Experiment LHC machine (actually will be several for machine!) – Prioritize parameter list in order to have at least the compulsory systems ready at LHC start up – Identify equipment required + equipment supplier – Define WPs for implementation Experiment LHC machine – Assign required resources

23/2/2006D. Evans18 Other News from Leade LHC physics will begin with 75ns bunch crossing rate – can’t say how long, weeks ? Experiments request they go to 25ns asap. –To minimise pile-up in detectors. Collision rate monitors for ALICE agreed –Use ionisation chambers