STATUS of BAR DETECTORSSTATUS of BAR DETECTORS

G.A.Prodi - INFN and University of Trento

International Gravitational Event Collaboration - 2

ALLEGRO– AURIGA – ROG (EXPLORER-NAUTILUS)

outline

• updates on performances of detectors• current organization of IGEC-2• recent and current observations• plans for future joint observations• target performances of detector upgrades

burst sensitivity,rms [Hz -1]

IGEC-1

Shh of IGEC-2 detectorsIGEC-1

Mode 1870 Hz

Mode 2916 Hz

frequency

stationary performances: time-frequency plotsALLEGRO

Tim

e (1

0 ho

urs)

frequency

stationary performances: time-frequency plotsAURIGA

Tim

e (1

0 ho

urs) Mode 1

866 HzMode 2915 Hz

Mode 3956 Hz

Mode 1905 Hz

Mode 2927 Hz

frequency

stationary performances: time-frequency plotsEXPLORER

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0 ho

urs)

frequency

stationary performances: time-frequency plotsNAUTILUS

Tim

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0 ho

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927 HzMode 2942 Hz

• preliminary duty cycles of detectors in 2005

ALLEGRO: 95%AURIGA: 90% after suspension upgrade (may 19th 2005)

45% before “ “EXPLORER: 83%NAUTILUS: 90%

epoch vetoes are still being defined…

the IGEC-2 observatory have been in at least three-fold coincidence operation for most of 2005

- tests show that detectors are affected by a very low rate of noise outliers- work in progress on comparison and cross-validation of the detectors results, based on raw data exchange:talk by Francesco Salemi in “Detector Characterization”

TRIGGERED SEARCHES by Gamma events

• Search for bursts in coincidence with 387 GRBs (BeppoSAX and BATSE):

cumulative upper bound of h = 2.5 · 10-19 in a time window of 10s

P.Astone et al. (ROG Collaboration), Phys. Rev. D 71, 042001 (2005)

- Search for gw ringdown in coincidence with the Dec 27 2004 giant flare

from SGR 1806-20:

upper limit which invades

part of the parameters’

region of existing models

in the AURIGA bandwidth

Baggio et al. (AURIGA collaboration), Phys.Rev.Letters 95, 081103 (2005)

149 days

upper limit assuming

a gaussian pulse

= 0.1 ms

ROG: BURST SEARCH on 2003 data

time coincidence analysis per sidereal hour on 2003 data of EXPLORER and

NAUTILUS excluded the rate-amplitude region formerly indicated by a similar

analysis on 2001 data

P.Astone et al. (ROG Collaboration), Proc. Amaldi 6, (2005)

IGEC-2 coordination of observation times:

- IGEC-2 groups are planning the interruptions of the observation time to

maximize the time coverage (i.e. to keep at least 3 out of the 4 detectors in

coincidence operation at all times).

see our schedule: https://sam.phys.lsu.edu > IGEC2 calendar

IGEC-2 run coordinators: W.Johnson (chair), V.Fafone (deputy), L.Taffarello

- IGEC-2 provides real time information on detectors status to other

experiments. AURIGA and ROG basic information can be automatically

queried via web pages .

see for instance: www.auriga.lnl.infn.it > present status

in the near future, we plan to add real time information on the achieved

sensitivity to standard transient signal waveforms

- investigation started on the feasibility and effectiveness of an Early

Warning System (in the footpath of SNEWS)

see poster by R.Terenzi and R.Sturani

IGEC-2 search for bursts• data are available since may 2004-present. Observation will continue at

least for yr 2006.

priority to the anaIysis of the last semester (May.-Nov.2005), since

AURIGA improved its duty cycle and up to the start of LIGO S5. Data

exchange is planned by end of 2005.

• New: blind data exchange for a blind data analysis:

Rigid time shifts has been secretly added by each group and will be circulated only when the analysis procedure is agreed in detail

• Network analysis based on IGEC-1 experience: use a priori information to improve the network search (signal template, testing source locations, common search thresholds on amplitudes, etc.)– Nfold-time coincidence search with adapting order N – a priori control of false dismissal (conservative bound). – Data selection, time coincidence search and accidental coincidence

estimation in the footpath of IGEC-1Scientific coordinator: G. Prodi; vice-coordinators: W.Johnson and M.Visco

Expected performances of IGEC-2

Triple coincidences: 106 time shifts, no accidentals on 9.3 days false alarm rate < 10-4 / yr for H> 10-21/Hz

high statistical significance in case of gw candidatesDouble coincidences:

lower false alarm rates than for IGEC-1

rate[year –1]

search threshold

dashed region excluded with probability

> 90%

expected upper limit improvement by IGEC-2

1 month

1 year

IGEC-1 upper limit

STOCHASTIC BACKGROUND SEARCHES by BARS & INTERFEROMETERS

- ALLEGRO & LIGO S4: first stochastic results from a hybrid observatory

see talk by John Whelan et al. (LSC) in “Stochastic searches”

- VIRGO & INFN BARs: playground h(t) data exchange using VIRGO C6

and C7 commissioning runs to test analysis procedures on real data

see poster by G.Guidi, G.Cella et al. (AURIGA, ROG & VIRGO)

Expected SNR4

per unit bandwidth,

integration time

and gw

BURST SEARCHES by BARS & INTERFEROMETERS

• AURIGA & LIGO S3: first burst analysis from a hybrid observatory. Mainly

of methodological relevance, based on a cross-correlation search on LIGO

data triggered by AURIGA candidate events. Tuning phase completed.

see poster by F.Salemi et al. (AURIGA & LSC)

• VIRGO & INFN BARs: characterization of network efficiency and

comparison of coincidence search methods on real data (VIRGO C6 & C7)

see poster by G.Guidi et al. (AURIGA, ROG & VIRGO)

efficiency for cos-gaussian 900Hz Q9

uniform polarization and sky distribution

AURIGA&H1&H2 coincident operation: 74 hr

estimated false rate 0.5 Hz

AURIGA sets overall efficiency

hrss50% this search 2x LIGO only search

T = 0.12K,

double gap transducer (11 m and Q=1.5·106)

double SQUID (L0=2.5 H, k=0.7).

Teff ≈ 7K

SQUID noise saturation at 200 mK taken into account.

current Quality factors are assumed

increased bias field inside transducer

AURIGA

NAUTILUS

EXPECTED SHORT TERM PROGRESSES:cooling to 0.1 K

FINAL REMARKS

• growth of the efforts towards joint observation between bars and

interferometers;

The hybrid observatory is useful when aiming at a gw detection.

Benefits:

- improved the time coverage in burst searches

- improved statistical significance of a gw candidate

(if it falls within the reach out of bar detectors)

- increased physical information on the gw

direction from arrival times

additional amplitude information

solution of the inverse problem

- more discrimination against disturbances

Limits: lower reach out of bar detectors

good opportunities in the medium term with ultracryogenic resonant detectors

extra slides

SQUID energy resolution () vs year

— in the detector

● coupled to a LC resonator

1998 2000 2002 2004 20061

10

100

1000

10000

AURIGA Run 2

AURIGA Run 1

Ene

rgy

reso

lutio

n (

)

Year

two stageLHe T

ultracryogenic

AURIGA 0.1 K

Detector Teff 4 Tn

Detection efficiency for burstsMaximum detection efficiency for transients with flat Fourier amplitude

at the detector frequencies (900 Hz)

Efficiency of the AURIGA matched filter for Sine-Gaussian waveforms:

90%

92%

94%

96%

98%

100%

800 900 1000 1100

2

5

10

20

S-G central frequency [Hz]

SNR matched filter

SNRSG filter matched to the Sine-Gaussian

computed for the AURIGA detector

QSG

SG

SNR

SNR

- 2

Arrival time estimation

AURIGA arrival time estimation

for signals

by Monte Carlo injections of

software signals

• IGEC-2 is not yet able to measure light time delays among detectors

- 2

Exchanged candidate events

amplitude histograms of exchanged events

EXPLORERNAUTILUSAURIGA

Event counts

Event amplitude H [Hz]

- 2

Self correlograms of exchanged events

• Histograms of the time lags among events of the same detector:

much more “Poissonian”than in IGEC-1

AU

EX NA

50 seconds

- 2

cross correlograms of exchanged events

• Histograms of the time lags among all events from two different detectors:

Poisson model as in IGEC-1

AU-EX

AU-NA EX-NA

- 2