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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
Tim
e (1
0 ho
urs)
frequency
stationary performances: time-frequency plotsNAUTILUS
Tim
e (1
0 ho
urs) Mode 1
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