Signals between LHC Signals between LHC Machine & ALICE:Machine & ALICE:

an Updatean Update

David Evans

ALICE TB

23rd February 2006

(with input from Detlef Swoboda)

23/2/2006 D. Evans 2

Update Since DecemberUpdate Since December

13th Dec 05: data exchange requirements presented to ALICE TB

25th Jan 06: meeting at CERN to discuss issues (D. Evans, C. Fabjan, P. Vande Vyvre, L. Jirden, F. Carena.)

6th Feb 06: Leade meeting at CERN to discuss draft LHC document on data exchange. (EDMS: 701510)

23/2/2006 D. Evans 3

Data Interchange ConceptData 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

23/2/2006 D. Evans 4

Experiments Experiments LHC LHC (ATLAS/CMS)(ATLAS/CMS)

Measurement UnitsProduction

Volume (Bytes)

Production Interval (sec)

Data Rate(Bytes/sec)

Total luminosity cm-²s-¹ 4 1 4

Average rates Hz 12 1 12

Luminosity per bunch cm-²s-¹ 14256 60 238

Rates for individual bunches Hz 42768 60 713

Position and size of luminous region (average over all bunches)

cm 24 600 0.04

Total per experiment 966

Minimum data set

23/2/2006 D. Evans 5

Can ALICE Supply this Can ALICE Supply this Information ?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 ?

23/2/2006 D. Evans 6

LHC LHC Experiments ExperimentsProducer Measurement

Data type

Production Volume (Bytes)

Production Speed

Production Rate (kB/s)

Expected Accuracy

Remarks

AB-BDITotal beam

intensityProtons* 8 1 sec 0.008 1% Pb-Ions in prep by R. Jones

AB-BDIIndividual bunch

intensitiesProtons* 28.512 1 min 0.475 5% Pb-Ions in prep by R. Jones

AB-BDIAverage 2D beam size

mm 16 1 sec 0.016 15%For transport to IP will require

knowledge of beta function

AB-BDIAverage bunch

lengthps 8 1 sec 0.008 1%

AB-BDITotal

longitudinal distribution

285.120 1 min 4.752Will be able to detect ghost bunches at the 0.1% level of

nominal

AB-BDIAverage

HOR & VER positions

m 32 1 sec 0.032 50umFrom the BPMs located at Q1

either side of each IP

AB-BDI Luminosity 28.512 10 sec 2.8511%

relative

This is a relative measurement between

bunches

AB-BDIAverage Beam

Loss16 10 sec 0.002

Average of up to 50 selectable BLMs

23/2/2006 D. Evans 7

Data Exchange Dim/DipData 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

Database

23/2/2006 D. Evans 8

Beam Interlock System Beam Interlock System (BIS)(BIS)

H/W link from USER to Beam Dump System: beam dump request.

H/W interface supplied by machineRadiation 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.

23/2/2006 D. Evans 9

Beam Dump RequestBeam 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 email within 24 hours (no

automated system required).

23/2/2006 D. Evans 10

LHC Injection InhibitLHC 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.

23/2/2006 D. Evans 11

Beam Synchronous Timing Beam Synchronous Timing Message (BST)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.

23/2/2006 D. Evans 12

Portion of BST Message for Portion of BST Message for ExperimentsExperiments

Byte Description Beam Data Format Update Rate

1-4 Turn Count Number

1 or 2 32bits (106 hours – reset on injection)

Turn

5 BST Master status

1 or 2 Ring 1 or 2 or SPS, Master status & test bits

Turn

6 Machine mode 1=2 No Beam, Filling, Ramping, Adjusting, Physics, ..

Turn

7-14 GPS Absolute Time

1 or 2 64 bits: UTC format (s since 01/01/1970)

Turn

15-18 LHC fill number

1 = 2 32 bits: integer or UTC time with second resolution

On change

19 Particle type 1 Enumerated Type: proton, Pb, … On change 20 Particle type 2 Enumerated Type: proton, Pb, … On change 21-22 Beam

Momentum 1 = 2 16 bits in GeV/c 10 Hz

23-26 Total intensity 1 4 Bytes: integer x 10e8 charges 10 Hz 27-30 Total intensity 2 4 Bytes: integer x 10e8 charges 10 Hz 31-60 Used exclusively by AB/BDI

23/2/2006 D. Evans 13

BST and ALICEBST 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.

23/2/2006 D. Evans 14

ALICE MagnetsALICE Magnets

CCC to control ALICE magnetsMagnets connected to LHC BISStatus 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.

23/2/2006 D. Evans 15

ZDCZDC

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.

23/2/2006 D. Evans 16

Coordination of LHC-Coordination of LHC-Detector Exchange 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.

23/2/2006 D. Swoboda @ ALI TB 17

LDX ImplementationLDX Implementationby D. Swobodaby 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

23/2/2006 D. Evans 18

Other News from LeadeOther 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