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LIGO and GriPhyN. Caltech. USC/ISI. Carl Kesselman Ewa Deelman Sachin Chouksey. Roy Williams Peter Shawhan Albert Lazzarini Kent Blackburn. LIGO Virtual Data Grid. LIGO Hanford. MIT. LIGO Livingston. Caltech. Pictures. LIGO Overview.

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Ligo and griphyn

LIGO and GriPhyN

Caltech

USC/ISI

Carl Kesselman

Ewa Deelman

Sachin Chouksey

Roy Williams

Peter Shawhan

Albert Lazzarini

Kent Blackburn


Ligo virtual data grid
LIGO Virtual Data Grid

LIGO Hanford

MIT

LIGO Livingston

Caltech

LIGO Scientific Collaboration


Pictures
Pictures

LIGO Scientific Collaboration


Ligo overview
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


Physics and virtual data

time

Merger

Ringdowns

Primeval GW Background

Supernova

frequency

CW (eg pulsar)

Mergers BH/NS

Physics and Virtual Data

Each source type has different freq/time charactaristics

 different virtual data requirements

LIGO Scientific Collaboration


Ligo data
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


detector

filter

reduce

events

objects

pattern

matching

HEP

LIGO vs NVO vs HEP

  • Processing

  • Network

    • NVO is federation, LIGO is coincidence

    • In both cases registration is important

detector

filter

reduce

events

RDBMS

datacube

pattern

matching

LIGO, NVO

1D,2D

LIGO Scientific Collaboration


Data access
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


Activities
Activities

  • Virtual Data

    • A: Language & Architecture

      • Naming is Time/Channel/Transformation

      • Smart subsetting

    • B: LigoVista web display

      • Archive at-a-glance + drill-down

  • Replication

    • A: Realtime mirror

      • Hanford/Livingston/Virgo nternational coincidence study

    • B: Fault-tolerant mirror

      • from Caltech to UW/Milwaukee

  • Pulsar search

    • backfill on Condor farms

LIGO Scientific Collaboration


1a virtual data language
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


1a virtual data architecture

LIGO Application

Channel, start time, stop time

Virtual Data URL

Request Manager

Replica Selection

Replica Management

existing

in development

LARS Prot.

LDAP

GridFTP

FTP

planned

Connectivity

HPSS

at Caltech

Other

Remote

Storage

Replica

Catalog

Transfor-

mation

Catalog

Derived

Data

Catalog

“local”

storage

1A: Virtual Data: Architecture

Power spectrum of seismic channels

P. Charlton

LIGO Scientific Collaboration


1b virtual data ligovista
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


2a replication realtime
2A: Replication:Realtime

  • Look for coincidence in Ligo-Virgo data

LDAS

analysis

event

stream

Interferometer,

seismic. etc

Interferometer,

seismic. etc

streaming

bidirectional

transatlantic

replication

Virgo

LIGO

LIGO Scientific Collaboration


2a whistlers from lightning
2A: Whistlers from Lightning?

LIGO Scientific Collaboration


2b replication fault tolerance
2B: Replication: Fault-tolerance

  • Master archive replicated at LSC sites

  • Fault tolerant

GridFTP

HPSS@Caltech

Beowulf@UWiscMilwaukee

Replication API

Replica Catalog

Penn State

UT Brownsville

LIGO Scientific Collaboration


3 pulsar search
3. Pulsar Search

Frequency modulation by Earth movement

  • Infinite computation on finite data!

    • Tiny, precise signals in deep noise

    • Search on 4D space: sky position, pulsar frequency, spindown,

0.5 TByte “image”

Condor farms

6 months data

UT Brownsville

UW Milwaukee

Caltech CACR

UW Madison

frequency bins

Frequency (Hz)

Time (months)

frequency

frequency

time

LIGO Scientific Collaboration

time


frequency

frequency

time

time

LIGO Scientific Collaboration


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