Report of the_-----------_____ ‘Computing and Readout’ Working Group presented by Adrian Biland / ETH Zurich CTA Meeting Paris, 2. March 2007 Robotics

Report of the_-----------_____ ‘Computing and Readout’

Working Group

presented by

Adrian Biland / ETH Zurich

CTA Meeting

Paris, 2. March 2007

RoboticsReadout

OperationsRoboticsReadout

Paris, 2.3.07 A.Biland, ETHZ IT working group report 2

Active WG Members- Angelo Antonelli (REM)- Adrian Biland (MAGIC)- Thomas Bretz (MAGIC)- Stefano Covino (REM)- Andrii Neronov (ISDC)- Nicolas Produit (ISDC)- Ullrich Schwanke (HESS)- Christian Stegmann(HESS)- Roland Walter (ISDC)

(several more on mailing list)

>50% not fromHESS / MAGIC !!

Lot of experience from- Cherenkov telescopes- Astronomy data formats and interfaces- huge data rates (accelerator experiments)

exists internal draft of a TDR-like paper


two fundamentally different approaches how to operate

- collaboration mode (as in particle physics)

- observatory mode (usual in astronomy)

main differences (simplified, exist mixed modes):

collaboration observatoryfunding: Inst. ask fund. Agency;

build part of experim.

Agencies pay to

‘Consortium’

manpower:

(salaries)

PhD students (ab)used

as workhorses for

construction and

operation

construction:

salaries incl. in cost

operation:

hire staff personal


proposals from collaborators from anybody -> PI

data ownerauthorlist

full collaboration

(huge authorlists)

PI ( and CoIs)

(short authorlists)

dataavailability

kept internally

(often lost at the end)

public domain (delayed)

==> ‘data mining’

‘personal

dedication’extreme cases

start as PhD and stay

until retirement (LHC)

‘My Experiment’

- have an idea- check data archive- write paper- get Nobel Prize (without any contribution done to the experiment)

But usually experimentrenowned not the PI: e.g.‘HUBBLE found...’


doing physicsParticle Physics: (usually) clean, well defined environment

clean, self-consistent theories to check==>predictions

dedicated, 'simple' experiments to test predictions

do EXPERIMENTS ==> collaboration mode ok

Astronomy: no control over environment and 'setup of experiment'

no clean theory; fundamental stuff obscured by complicated

standard-physics processes

usually need many sources and/or many observatories (MWL)

to get conclusive answers

OBSERVATIONS ==> observatory mode, data mining (for MWL)


doing physicsWhat about CTA ? We are in a paradigm-shift:WHIPPLE, HEGRA, CAT, .... : 'source hunting' - proof of concept - invent new fundamental techniques - new source ==> new conference Collaboration mode is ok

H.E.S.S., MAGIC, ...: 'proof VHE important part of Astronomy' - mature technology - surprising richness of VHE sky - impressive results; few conclusive answers - MWL becoming more and more important ===> must incorporate external experts Collaboration mode getting difficult (authorlists !!!)


doing physicsCTA: 'understand physics' (hopefully) - expect ~1000 sources (cannot use a PhD per source) - need automatic data (pre)processing - can do statistical analysis [ compare astrophysics:

learned a lot from statistics of Hertzsprung-Russel Diagram ... ] - MWL becoming extremely important - for steady/periodic sources: data mining - for transients: additionally dedicated MWL campaigns

Final goal: UNDERSTANDING PHYSICS ==> need to incorporate brightest minds (not all of them will be willing to dedicate themself several years to an experiment ...)


doing physics==> CTA better to be operated (part time)

as Observatory (allow guest observers)

and allow data mining (public data access)

details to be discussed/agreed: - how much time for guest observers - how long delay until data become public domain

can make the difference if CTA will be seen as obscure corner or major pillar of astronomy ....


CTA as (open) Observatory- Need well defined procedure how to submit

and process proposals

- Existence and well defined access to data and

analysis programs

...

What is more efficient:

centralized or de-centralized structures ???


‘Array Control Center’ (onsite)tasks: - monitor operation of CTA (goal: automatic/robotic operation;

but having >>10 (100?) telescopes, there will be hardware problems

- ensure safety (nobody within array during operation; what about power failures at sunrise; ....)

- buffer raw-date until shipped to data center (even in case of fast internet connection, we must foresee a buffer in case of

problems) - monitor Quick-look analysis (onsite analysis)

- ....

Most can be done by local technicians(but if we want to send out alarms, need verification by experts)


Operations (center?)- submission and handling of proposals

- plan operation of CTA; scheduling- handle incoming ToO Alarms [GRB: directly to ArrayCtrl]

- control operation of CTA (automatic/robotic operation ==> can also work if there is some downtime in communication)

- control hardware status of CTA (slow control level)

- ...

Needs CTA hardware/physics experts (available/on call)

(could be 12 timezones away ==> no night-shifts ?!)


Data (center?)exist different possible implementations;extreme cases: - data-repository- ‘science support center’

For (open) Observatory:It is less important to have a place wheredisks are located, but to have a dedicatedcontact point for inexperienced users(to be defined on what ‘luxury level’ this has to be: users get raw data vs. users get ‘final plots’)


Data (center?)- receive and store data from CTA - calibration (==> check hardware status)- automatic (pre)processing of data- archive data on different stages: raw, compressed, preprocessed, photon-list, ...(?)

- ensure availability of data to predefined groups PI, CTA consortium, public domain

- make available (and improve) standard analysis tools- offer data analysis training sessions/schools - ...Needs CTA Analysis Experts


General Remark: CTA staff physicists shall be allowed/

encouraged to spend reasonable part of time to do their own physics within CTA (as PI or CoI ...)


Design Studies

On next slides,

topics for design studies are marked in blue


Towards CTA Standard Analysis0) adapt H.E.S.S./MAGIC software to analyze CTA MC for the Hardware Design Studies (partially done)

1) define needs -underlying data format (FITS, root, ...)

-interfaces to external data (for MWL analysis)

-what amount of RAW data must be archived for re-analysis (FADC slices? only Pixels above

threshold?) [might have to archive several PBytes/year]

- ....2) tools survey (what exists and can be re-used)3) start programing (rather early to be ready for first telescope!)

package must be useable by non-experts ==> ‘KISS’


Towards MC Mass ProductionIn hardware design studies (and during operation), need huge amount of MC ==> urgent-tools survey-optimize/speedup programs

GRID: -exists (most probably mature soon)-EU spent €€€€€€€€ ==> success by definition-at the moment, huge amount of unused CPU available

MC easiest to use GRID, can most profit from GRID==> concentrate GRID activities in MC packageAnalysis software shall be GRID aware, but not rely on it


Towards Array Ctrl: ‘robotic’

too complicated system to make fully robotic

hardware must be very(!) reliable

software must be rather simple

(no bells and whistles...)

limited experience, need test environment


Towards Array Ctrl: Slow Ctrl-centralized approach:

powerful central machine controls individual (dumb) telescopes; knows always everything about anything....

-distributed approach:

each ‘intelligent’ telescope runs independent; Central Control just distributes tasks (e.g. schedule changes) and receives status info (but can always request any infos)

-mixed mode

Design study: find optimal solution ...


Towards Array Ctrl: Trigger-most simple approach:

-each telescope has its own local-trigger

-multi-telescope trigger just combines next neighbors local-trigger information

-very ambitious approach:

combine adjacent telescopes on the pixel level

(technically feasible ? any advantage ???)



Towards Array Ctrl: DAQ-centralized approach:

CC receives all raw-data and writes combined ‘CTA events’ containing several telescopes

-distributed approach:

each telescope writes its own data stream (including trigger-info) to local or central file server; combining data of adjacent telescopes done at analysis stage



Towards Operation (center)

probably only few CTA specific requirements

==> need only tools survey (and take decision)


Towards Data (center)

- define needs <== experts from Cherenkov and Astro

- tools survey

- use HEGRA data as playground to proof feasibility of approach

possible extension:

[midterm]: archive H.E.S.S./ MAGIC data in ‘universal’ format for extended tests

[longterm]: allow data mining on old H.E.S.S./ MAGICvery political decisions...; important signal to astro-community...

also analysis package should be tested on old data


Towards Data (center)

is the interface to the astro-community

(data mining !)

basic design might not be crucial for us,

but it should ‘please’ the other users ...


Summary-Exists lot of experience in all needed fields

-Important to combine and synchronize knowledge

-Several decisions to come out of design studies; find ‘optimal’ solutions (probably now show-stopper: ‘wrong’ solution will also work, but less efficient and more expensive)

-Some tasks will need rather long time between design study and final product (e.g. full analysis package); to be ready in time, these design studies must be finished rather soon so that implementation can start ... ( e-center call in 2008 ???)

Documents

Report of the_-----------_____ ‘Computing and Readout’ Working Group presented by Adrian Biland / ETH Zurich CTA Meeting Paris, 2. March 2007 Robotics