STATUS 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

IGEC-1 S hh of IGEC-2 detectors

IGEC-1

burst sensitivity,

rms [Hz

-1 ]

stationary performances: time-frequency plots ALLEGRO

frequency

Mode 1 870 Hz Mode 2 916 Hz

stationary performances: time-frequency plots AURIGA

frequency

Mode 1 866 Hz Mode 2 915 Hz Mode 3 956 Hz

stationary performances: time-frequency plots EXPLORER

frequency

Mode 1 905 Hz Mode 2 927 Hz

stationary performances: time-frequency plots NAUTILUS

frequency

Mode 1 927 Hz Mode 2 942 Hz

•

preliminary duty cycles of detectors in 2005 ALLEGRO: AURIGA: 95% 90% after suspension upgrade (may 19 th 45% before “ “ 2005) 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

GRB

s (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)

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) 149 days upper limit assuming a gaussian pulse  = 0.1 ms

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 least for yr 2006.

may 2004-present

. Observation will continue at

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-1

Scientific coordinator

: G. Prodi;

vice-coordinators

: W.Johnson and M.Visco

Expected performances of IGEC-2

Triple coincidences: 10 6 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 candidates

Double coincidences: lower false alarm rates than for IGEC-1

expected upper limit improvement by IGEC-2

rate [

year –1

]

1 month

IGEC-1 upper limit

dashed region excluded with probability > 90%

1 year

search threshold

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 SNR 4 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) 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 h rss50% this search  2x LIGO only search •

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)

EXPECTED SHORT TERM PROGRESSES: cooling to 0.1 K

NAUTILUS AURIGA T = 0.12K, double gap transducer (11  m and Q=1.5

·10 6 ) double SQUID (L 0 =2.5 H, k=0.7).

T eff ≈ 7  K SQUID noise saturation at 200 mK taken into account.

current Quality factors are assumed increased bias field inside transducer

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

10000 AURIGA Run 1 1000 SQUID energy resolution e ( h ) vs year AURIGA Run 2 — in the detector ● coupled to a LC resonator 100 10 1 1998 two stage LHe T 2000 2002 Year ultracryogenic 2004 2006 AURIGA 0.1 K Detector T eff  4 T n

- 2

Detection efficiency for bursts

Maximum detection efficiency for

transients with flat at the detector frequencies (



900 Hz)

Fourier amplitude

Efficiency of the AURIGA 

matched filter

for

Sine-Gaussian

waveforms :

SNR



SNR SG

100% 98%

SNR

 

matched filter

96% 94%

Q SG

2 5 10 20

SNR SG filter matched to the Sine-Gaussian

computed for the AURIGA detector 92% 90% 800 900 1000 1100

S-G central frequency

[Hz]

- 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

Event counts

EXPLORER NAUTILUS AURIGA 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

50 seconds

EX NA

- 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