1.3.4 N5: Gravitational Wave Antenna (GWA)
Coordinator: R. Flaminio (CNRS/IN2P3/LMA and EGO)
Deputy Coordinator: K. Danzmann (MPI/Hannover)
The objective of this network is to increase the level of European coordination in the field of gravitational wave research in order to maximize the return on the large investment already made, to enhance the performance of the existing detectors, and to prepare the future of this discipline in Europe. The network is used to exchange information on subjects of common interest such as commissioning and operation of existing detectors, to foster the development of common methodologies for joint observations, and to support the elaboration of a common strategy for future gravitational wave detectors in Europe.
Several institutions, participating in ILIAS, are active in this network. The participation of contractors in terms of persons-months is given in Table 1. A single contractor, namely the European Gravitational Observatory (EGO), ensure the financial management of this network.
The GWA network activity is progressing as foreseen. The network includes three Working Groups: WG1 on antenna commissioning and characterization, WG2 on joint operation of antennas, and WG3 defining a European strategy for future detectors. All the working groups are holding meeting on a regular bases. The list of meetings organized since April 1st 2007 is given in Table 3. All the documentation concerning this network is available on the WEB at http://www.ego-it/ILIAS-GW/
N5 – Table 1a: Participants institutes.
Participant number / 2 / 3 / 9 / 13 / 14 / 15 / 19Participant short name / CNRS / INFN / MPIK / IFN / EGO / Leiden / U.Glasgow
Person-months / 6 / 16.5 / 9.5 / 0 / 9 / 0 / 3.5
N5 – Table 1b: Other entities.
Institution / Country / Participation inFriedrich Schiller University Jena / Germany / Annual general meeting, WG3
Laser Zentrum Hannover / Germany / WG3
CNR IFSI-Frascati / Italy / WG1, WG2
Polish Academy of Sciences Warsaw / Poland / WG2
Universidad de les Illes Balears / Spain / WG2
Cardiff University / U.K / WG2, WG3
University of Birmingham / U.K. / WG2, WG3
Imperial College London / U.K. / Annual general meeting
N5 – Table 2: Deliverables.
Deliverable/ Milestone No / Deliverable/Milestone Name / Workpackage/Task No / Lead Contractor(s) / Planned
(in months) / Achieved (in months)
1 / WG1 annual report / WP1 / EGO (14)
INFN (3)
MPI (9)
CNRS (2) / 48 / 48
3 / WG2 annual report / WP2 / EGO (14)
INFN (3)
CNRS (2)
Glasgow (19) / 48 / 48
5 / WG3 annual report / WP3 / EGO (14)
INFN (3)
MPI (9)
Glasgow (19) / 48 / 48
N5 – Table 3: Workshops/Meetings.
Date / Title/subject of meeting /workshop / Location / Number of attendees / Website address19/06/07
20/06/07 / Working group 1 meeting / Cascina, Italy / 11 / http://www.ego-gw.it/ILIAS-GW/N5-WP1_19Jun2007.html
22/10/07
25/10/07 / Working group 1 meeting / Hannover, Germany / 21 / http://www.ego-gw.it/ILIAS-GW/N5-WP1_23Oct2007.html
05/03/08
06/03/08 / Working group 1 meeting / Cascina, Italy / 15 / http://www.ego-gw.it/ILIAS-GW/N5-WP1_5Mar2008.html
26/02/08 / WG2: GRB-GW workshop / Rome, Italy / 16 / http://www.ego-gw.it/ILIAS-GW/N5-WP2Rome26Feb08.html
02/04/07
03/04/07 / WG3: Design study and Virgo+ review / Cascina, Italy / 8 / http://www.ego-gw.it/ILIAS-GW/FP7-Cascina-Apr02/index.html
13-18-19-20-23-26/04/08 / WG3: Strategy definition for 3rd generation GW detector / Phono-conference / 11
2/05/08
9/05/08 / WG3: Strategy definition for 3rd generation GW detector / Phono - conference / 9
7/06/08 / WG3: Strategy definition for 3rd generation GW detector / Phono-conference / 9
24/08/08
31/08/08 / WG3: Strategy definition for 3rd generation GW detector / Phono-conference / 6
16/10/07
17/10/07 / WG3: Virgo+ review / Cascina, Italy / 14 / http://wwwcascina.virgo.infn.it/collmeetings/DMwebpages/secondVirgoplusReview.html
09/01/08
10/01/08 / WG3: Virgo+ review / Cascina, Italy / 9 / http://wwwcascina.virgo.infn.it/collmeetings/DMwebpages/EGOVirgoplusReview-Jan08.html
28/01/08
30/01/08 / WG3: Advanced Virgo design / Cascina, Italy / 5 / https://workarea.ego-gw.it/ego2/virgo/collaboration-meetings/2008-agendas/2008-January_28th-30th
10/10/07 / 2nd joint ENTApP – GWA meeting / Tubingen, Germany / 44 / http://www.tat.physik.uni-tuebingen.de/ENTApP/
08/10/06
09/10/06 / 4th ILIAS-GWA Annual general meeting / Tubingen, Germany / 65 / http://www.ego-gw.it/ILIAS-GW/ILIASGW4/
N5 – Table 4 : Role of participant contractors
Deliverable/ Milestone No / Deliverable/Milestone Name / Workpackage/Task No / Contractor(s) / Role
1 / WG1 annual report / WP1 / EGO (14) / Management and reimbursement of all travel expenses
Participation to all WG1 meetings
Hosting of meetings
Writing of annual report
INFN (3) / Coordination of WG1 activity
Organization of meetings
Participation to all WG1 meetings
Writing of annual report
Preparation of next 12 months plan
MPI (9) / Coordination of WG1 activity
Organization of meetings
Participation to all WG1 meetings
Writing of annual report
Hosting of meetings
Preparation of next 12 months plan
CNRS (2) / Participation to all WG1 meeting
2 / WG2 annual report / WP2 / EGO (14) / Management and reimbursement of all travel expenses
Writing of annual report.
CNRS (2) / Participation to WG2 meetings
INFN (3) / Coordination of WG2 activity
Organization and participation to WG2 meetings
Writing of annual report
Preparation of next 12 months plan
MPI (9) / Participation to WG2 meetings
Glasgow (19) / Coordination of WG2 activity
Organization and participation to WG2 meetings
Writing of annual report
Preparation of next 12 months plan
3 / WG3 annual report / WP3 / EGO (14) / Management and reimbursement of all travel expenses
Writing of annual report
Participation to all WG3 meetings
Hosting of meetings
INFN (3) / Coordination of WG3 activity
Organization of meetings
Participation to all WG3 meetings
Writing of annual report
MPI (9) / Coordination of WG3 activity
Organization of meetings
Participation to all WG3 meetings
Writing of annual report
CNRS (2) / Participation to all WG3 meetings
Glasgow (19) / Participation to all WG3 meetings
Activity of working group #1: Antenna commissioning and characterisation
Working group #1 is devoted to the commissioning and characterization of existing antennas. The focus of the working group activity is the commissioning of the two large interferometers operating in Europe, Virgo in Italy and GEO in Germany. The working group composition is given in the corresponding report. All the participants are deeply involved in the commissioning of existing antennas.
Since April 2007 the group has held three face-to-face meetings. The minutes of the meetings and all the slides presented are available on the web at http://www.ego-gw.it/ILIAS-GW/N5-WP1_meetings.html.
As in the years before, the comparison of noise sources of the GEO and Virgo detectors has been very fruitful for both sides. Both detectors are still in a phase, where the sensitivites are limited by non-fundamental noise sources for some fractions of the detection band, and therefore exchange on the methods to mitigate these noise sources is important for a rapid progress. Over the last year, GEO has been taking science data in the LSC- S5 frame up to October 2007. During this time the detector was operated in the so called night and weekend mode, acquiring science data at nights and weekends, and providing commissioning time during day-time working hours. Virgo has held its first long science run (VSR1), overlapped with S5 from May 18th to Oct 1st 2007. After the run a new phase of commissioning has started, leading to important sensitivity improvements.
Also this year the focus of the discussion within this working group has been the analysis and comparison of the main noise sources limiting the sensitivity of Virgo and GEO. One of the main subject has been the identification and the reduction of control noises. Important progresses were made both at GEO and Virgo and shared within the working group. Another important point was the identification and the reduction of noises due to unwanted diffused light. Methodologies to conduct these investigations were developed at Virgo and at GEO and shared within the working group. In addition important progresses were made in the study of the effect of magnetic noise at Virgo.
The second parameter which describes the performance of these detectors is their duty cycle. Since this year both Virgo and GEO underwent long data taking periods it was possible to study accurately their long term behaviour. The main result regarding the noise sources from running GEO and Virgo over extended periods of time is the fact that in general the noise sources are very stationary, if there are no uncontrolled parameters of the system left. Regarding the stability of the locked state, both detectors can be described as very stable by now. It turned out that both detectors were able to reach duty cycle larger than 80% with locking periods as long as a day or more.
Characterization methodologies were also compared and shared. Thanks to a rich exchange of good practices, to date, both projects run automated scripts computing the band-limited-rms sensitivities in different frequency bands. Results are documented per unit time and made accessible to the commissioners for further analysis. The procedure to automatically calculate the detector noise budget was also re-discussed.
This working group also discussed and shared the automation and operation procedures. Due to its maturity, the GEO automation and operation procedures have been essentially the same for the last year. The detector is left unattended over nights, and can recover full lock automatically in most cases, where the lock was lost. Important progresses were made at Virgo which now also have an automatic relocking procedure used routinely during nights and weekends when the interferometer is left unattended.
Finally the working group has issued recommendations for one of the future upgrades foreseen at GEO (that had already been implemented at Virgo) and one of the future upgrades foreseen at Virgo (that had already been implemented at GEO). This kind of exchanges are of course very useful to anticipate any problem one may encounter when these upgrades are implemented.
Activity of working group #2: Joint operation of antennas and network data analysis
Working group #2 is devoted to the joint operation and data analysis of the existing European gravitational wave antenna. The aim is to promote discussions among European gravitational wave data analysts and to study network data analysis methodologies for gravitational wave searches; in particular for those involving European detectors. All the members of the working group are deeply involved in the analysis of the data produced by the experiment they are involved in (AURIGA, GEO, MiniGRAIL, Nautilus and Virgo).
Since April 2007 the group organized two face-to-face meetings and one workshop. Slides and agenda of the meetings are available on the ILIAS-GWA web site (http://www.ego-gw.it/ILIAS-GW/N5-WP2_meetings.html ). During the last year the activity of the working group proceeded according to the plan.
Over the past year, GWA-WG2 has continued its efforts to promote discussion between the European gravitational wave (GW) data analysis community. The implementation plan has laid out efforts focusing on exchanging knowledge between members of the gravitational wave community and other communities (namely observational astronomers and theoretical astrophysicists). This focus allowed members of GWA-WG2 to develop new searches or extend pre-existing ones for GW in conjunction with observations in the electromagnetic spectrum. We have continued to support ongoing collaborative analyses between the LIGO Scientific Collaboration (LSC) and the Virgo collaboration which involve many members of GWA-WG2. This joint analysis has produced two publications reporting on the results of initial investigations into a joint LSC-Virgo analysis for burst and inspiral GW sources (see WP2 technical report for the references), in addition to several other papers related to GW searches performed within the LSC and Virgo collaborations. Moreover, the LSC-Virgo stochastic code developed with support from GWA-WG2 is now being applied to data jointly acquired during the LSC S5 run and the Virgo VSR1 run. There has also been joint analysis work between the AURIGA and Virgo collaborations, performing a search for GW bursts. This analysis has now produced a paper which has been submitted and is pending publication.
Our efforts to increase the interaction between GW data analysts and theoretical astronomers have led us to organize a second ENTApP-GWA joint meeting in Tubingen on the 10th of October, 2007. This meeting brought together theoretical astrophysicists from ENTApP with data analysts from GWA to exchange knowledge and discuss details of research performed on different sources of GW. For the GW data analysts, obtaining more information about their signal parameter space is a crucial step in making efficient, effective searches. For the ENTApP members, it was important to get details of GW searches to so as to tailor their models and simulations to prove data analysts with a better scientific picture of their targeted GW source. There has also been a workshop organised to discuss the implications of gamma-ray burst observations on GW searches. This workshop was held in Rome on the 26th of February, 2008.
Finally the scientific case for a future gravitational interferometer was further developed. The focus during the last year was put on the capabilities of a detector that, like the envisaged Einstein Telescope, would reach a spectral sensitivity in the range of 10-25. In particular a study was started on the physics program one could perform thanks to the detection of low frequency gravitational waves emitted by the coalescence of binary black holes.
Activity of working group #3: A European strategy for future detectors
Working group #3 is devoted to the elaboration of a strategy for the future development of gravitational wave detectors in Europe.
The activity during the last year progressed as foreseen. Since April 2007 the group organized four face-to-face meeting and several teleconferences. All the presentations are available on the web at http://www.ego-gw.it/ILIAS-GW/N5-WP3_meetings.html. At each meeting appropriate experts external to the working group were invited according to the agenda of the meeting.
The main activities supported since April 2007 were 1) the review of the Virgo+ project, 2) the preparation of a conceptual design for Advanced Virgo and 3) the preparation of a work plan for the design of a new European infrastructure devoted to gravitational wave detection.
Three reviews of the Virgo+ project took place during the last year. Members of WG3 external to the Virgo collaboration were involved in the technical review of the first upgrade of the Virgo detector called Virgo+. The funds made available by ILIAS were also used to support the participation of physicists not directly involved in GW detection to the review of the Virgo+ project. The implementation of the Virgo+ upgrade is starting in this period and should last until the end of the summer 2008.