LIGO-G9900XX-00-M

LIGO and GriPhyN

Carl Kesselman

Ewa Deelman

Sachin Chouksey

Roy Williams

Peter Shawhan

Albert Lazzarini

Kent Blackburn

Caltech USC/ISI

LIGO Scientific Collaboration 2LIGO-G9900XX-00-M

LIGO Virtual Data Grid

Caltech

MIT

LIGO Livingston

LIGO Hanford

LIGO Scientific Collaboration 3LIGO-G9900XX-00-M

Pictures

LIGO Scientific Collaboration 4LIGO-G9900XX-00-M

LIGO Overview

To detect gravitational waves predicted by Einstein’s theory of relativity.

Waves created from» Rapidly spinning asymmetric compact objects eg. pulsars» Mergers of black holes, neutron stars -- gamma bursts?» Supernova collapse (and post-collapse R-modes)» Starquakes in neutron stars» Primæval GW from early universe

Installation in Louisiana and Washington State» Other projects: Virgo (Italy), GEO (Germany), Tama (Japan)

LIGO Scientific Collaboration 5LIGO-G9900XX-00-M

Physics and Virtual Data

fre

qu

en

cy

Su

per

nov

a Primeval GW Background

Mergers BH/NS

CW (eg pulsar)

MergerRingdowns

time

Each source type has different freq/time charactaristics

different virtual data requirements

LIGO Scientific Collaboration 6LIGO-G9900XX-00-M

LIGO Data

Time series, 16 kHz down to 1 Hz

~1000 channels:» Gravity wave

» seismic, magnetometer, microphone, engineering, … Power spectra, cross spectra, sonogram, … Events

» Each has time and SNR (signal to noise ratio)

» Candidate inspiral events from matched filter

» Other pattern matching

» “Examine the big ones, histogram the small ones”

LIGO Scientific Collaboration 7LIGO-G9900XX-00-M

Processing

Network» NVO is federation, LIGO is coincidence

» In both cases registration is important

LIGO vs NVO vs HEP

detector events

patternmatching

filterreduce

HEP

objects

detector

datacube

events

patternmatching

filterreduce

LIGO, NVO

RDBMS

1D,2D

LIGO Scientific Collaboration 8LIGO-G9900XX-00-M

Data Access

LDAS (Ligo Data Analysis System)» Script (Tcl) based

» Primarily for onsite analysis and archiving

» Talks to local files, Hanford/Livingston

» Has a filtering language– stack-based, like Matlab– functions eg power spectrum, fft, resample

LARS» Can talk to local, HPSS files

» Can do subsetting

» Simple program, simple protocol

LIGO Scientific Collaboration 9LIGO-G9900XX-00-M

Activities

1. Virtual Data» A: Language & Architecture

– Naming is Time/Channel/Transformation

– Smart subsetting

» B: LigoVista web display

– Archive at-a-glance + drill-down

2. Replication» A: Realtime mirror

– Hanford/Livingston/Virgo nternational coincidence study

» B: Fault-tolerant mirror

– from Caltech to UW/Milwaukee

3. Pulsar search» backfill on Condor farms

LIGO Scientific Collaboration 10LIGO-G9900XX-00-M

1A: Virtual Data: Language

Virtual Data:» Times + Channels,

– eg 668371475-668372499 (GPS time, seconds since 1981)– L0: PEM-LVEA_SEIS*, L1:LSC-AS_Q

» Transformations to Virtual Channels– eg. L0:PEM-EX-SEISX- L0:PEM-LVEA-SEISX / resample(L1:LSC-AS_Q, 1, 64)

Use LARS and Globus Replica Catalog For each requested data value, need to

» Determine if it is instantiated; if so, where; if not, how to compute it» Plan data movements and computations required to obtain all results » Execute this plan

LIGO Scientific Collaboration 11LIGO-G9900XX-00-M

1A: Virtual Data: Architecture

existing

in developmentplanned

ConnectivityConnectivity

Request Manager

“local”storage

HPSSat Caltech

OtherRemoteStorage

Replica Catalog

Replica ManagementReplica Selection

LDAP FTPGridFTP

DerivedData

Catalog

Transfor-mationCatalog

LARS Prot.

LIGO Application

Channel, start time, stop time Virtual Data URL

Power spectrum of seismic channels

P. C

harl

ton

LIGO Scientific Collaboration 12LIGO-G9900XX-00-M

1B: Virtual Data: LigoVista

Overview of archive in a web browser» Time based

– month, week, day, hour, ....

» Machine state– lock status, science run, event density, ....

» Drill down to raw data– Transformed data

» Uses Virtual Data framework– compute on the fly and cache

LIGO Scientific Collaboration 13LIGO-G9900XX-00-M

2A: Replication:Realtime

Look for coincidence in Ligo-Virgo data

LIGO Virgo

Interferometer,seismic. etc

Interferometer,seismic. etc

LDASanalysis

eventstream

streamingbidirectionaltransatlanticreplication

LIGO Scientific Collaboration 14LIGO-G9900XX-00-M

2A: Whistlers from Lightning?

LIGO Scientific Collaboration 15LIGO-G9900XX-00-M

2B: Replication: Fault-tolerance

HPSS@Caltech Beowulf@UWiscMilwaukee

Replica Catalog

Replication API

Penn StateUT Brownsville

GridFTP

Master archive replicated at LSC sites• Fault tolerant

LIGO Scientific Collaboration 16LIGO-G9900XX-00-M

3. Pulsar Search

Infinite computation on finite data!» Tiny, precise signals in deep noise» Search on 4D space: sky position, pulsar frequency, spindown,

6 months data

Time (months)

Fre

qu

en

cy (

Hz)

Frequency modulation by Earth movement

UT BrownsvilleUW MilwaukeeCaltech CACRUW Madison

Condor farms0.5 TByte “image”

frequency bins

fre

qu

en

cy

timetime

fre

qu

en

cy

LIGO Scientific Collaboration 17LIGO-G9900XX-00-M

fre

qu

en

cy

timetime

fre

qu

en

cy