wsr1 sensitivity c7 sensitivity - public.virgo-gw.eu

WSR1 sensitivity

C7 sensitivity

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C O N T E N T S

“h - The Gravitational Voice” is an internalpublication of the European GravitationalObservatory (EGO) and the VirgoCollaboration.

The content of this newsletter does notnecessarily represent the opinion of themanagement.

Editor: Carlo Bradaschia

Editorial Staff:Angela Di VirgilioGary HemmingPaolo La PennaBernhard LopezFilippo MenzingerFlavio Nocera

Design: Bernhard Lopez

Published in electronic format on the EGOWeb:www.ego-gw.it

C O N T E N T S

NEWS FROM THE SITE 2WSR1: Done!EGO Council and STAC Meetings OutcomeThe Summer Collaboration MeetingsMore Room and Cooling for the Computing System

NEWS FROM THE WORLD 811th Marcel Grossmann MeetingEPS Meeting in Kiev

SCIENCE & TECHNOLOGY 9Wind, Sun and Hydrogen around EGOSolar Cells: How do they Work?

EVENTS & SOCIAL LIFE 13Sidereus NunciusDates to Keep an Eye on

OUT & ABOUT 15How to Get to EGO by Bicycle

PEOPLE 17

THE GRAVITATIONAL VOICE - OCTOBER 2006

N E W S F R O M T H E S I T E

We are glad to report onadvancements a t the s i te ,reproducing the letter recentlyaddressed to the EGO Council bythe Virgo spokesman, Benoit Mours:

"Virgo is proud to announce thattoday we successfully completedour first Weekly Science Run(WSR1). This is the beginning ofthe transition phase we announcedduring the last council where we aremixing commissioning activitiesduring the week and science datataking during the week-end.

The start of this new period has beenmade possible by the progress of

the commissioning of Virgo, whichis now able to operate with a goodduty cycle (90% of science modeduring WSR1) and sensitivity similarto the LIGO detectors at highfrequency. This turns Virgo to acompetitive instrument for sourcesemitting into this frequency band.

(…) We expect additional progressesfor the sensitivity in the wholefrequency band during the upcoming months. The ramping up ofthe analysis of these and the futurescience data is also taking place withthe wish of starting soon our jointactivities with LIGO.

This success is the achievement ofa very long process of design,construction and commissioning ofVirgo made possible by the steadyeffort of all the Virgo groups andEGO.

We look forward to presenting theseand future progresses during the nextSTAC and EGO council meetings."

This announcement triggered ashower of congratulation messagesfrom all over the world. Let usconsider that as an omen for longlasting scientific runs to start soon.

C. BRADASCHIAFRONTCOVER: VIRGO SENSITIVITY

CURVE AS FROM WWW.VIRGO.INFN.IT,PREPARED BY G. HEMMING

WSR1: Done!The first Weekly Science Run

performed last September 8-11 has been successful

The Council meeting wassubdivided into two sections, onefor formal matters of the Consortiumand the second part devoted to theconsideration of the developmentsboth for EGO and for the Virgocollaboration.

In the formal part the 2005 accountswere closed and approved and themandate of the present EGO directorwas extended till the end ofSeptember 2007.

In the second part the Councilconsidered several reports, thelaunch of the new R&D programwas examined and a first discussionon the preparation of the 2007budget proposal was also held.

EGO director's report

The EGO director reported on thedevelopments achieved in thevarious departments since thepreceding Council meeting, notingin particular on the personnel sidethat six new staff members havejoined EGO in the months since theprevious Counci l meet ing.Moreover, three conventions havebeen drawn up (respectively, at NiceOCA, at Annecy LAPP, at Florence-

Urbino) to support commissioningfellowships c/o Virgo laboratories.The resulting staff evolution at EGOis depicted in the graph below.

It was also noted that EGO in thelast three years has supported 34fellowships in different laboratoriesfor a total of 70 man-years with atotal cost of 2.1 M€ to support theGravitational Waves community.They have been given underdifferent headings: 12 fellowshipsin the R&D program, 4 fellowshipsin non-R&D support to individuallaboratories, 11 fellowships in VESFprogram, 7 Virgo commissioningfellowships.

The Director provided, for theCouncil, a summary of the highlightsof his written report. He underlinedthe developments for Virgo upgradesa n d Vi rg o + , t h e s m o o t hadvancement in the works for thenew building, the completion of theVirgo+ and R&D laboratories in theWest intermediate building, thecompletion of the works for the newcomputer room, the realization ofthe injection bench from project toconstruction, the participation tomost of the commissioning

activities, forwhich EGO alsoprovides the fullteam of operators.He also noted theadvancementsmade by theelectronics, SW,suspension andvacuum groups.For computing heunderlined thecompletion of thestorage farm, nowwith 120 TBcapacity.

He also presented an update of thedeployment, within EGO, ofprojects, which are temporary inter-departmental structures crossinghorizontally through the verticaldepartmental structure of EGO tofulfil specific activities, as, fore x a m p l e , t h e P r o j e c t o nCommissioning and the EnergySaving Project, which has beenestablished with the view to containor possibly reduce the cost of energyat EGO.

Reports from the Virgo collaboration

The Virgo spokesman presented thehighlights of his report. Reports werethen given by: the commissioningcoordinator, Matteo Barsuglia, oncommissioning status and plans; thecoordinator for data analysis, AndreaViceré, on data analysis status; thecoordinator for outreach, CarloBradaschia, on outreach; the detectorcoordinator, Michele Punturo onVirgo upgrades. These reports areavailable on the Virgo collaborationweb site.

The Council quite appreciated thea d v a n c e m e n t s i n Vi r g oc o m m i s s i o n i n g a n d t h edevelopments of the data analysis,in particular positively evaluatingthe increasing level of collaborationwith LIGO.

The Council also could appreciatethe positive developments in thearea of upgrading Virgo andpreparing for Virgo+.

Carlo Bradaschia presented toCouncil the development of theoutreach activities, including thequarterly on-line news bulletin, "h-the gravitational voice", of EGO andVirgo.

3THE GRAVITATIONAL VOICE - OCTOBER 2006


EGO Council and STAC Meetings OutcomeOutcome of the June 2006 meetings of

EGO Council and of its Scientific and Technical Advisory Committee (STAC)

Report from the STAC chairman

The first day of the STAC meetingwas dedicated to discussion of thereports from the laboratories thathave participated to the first R&Dprogram launched by EGO andcarried out over the period 2003-2006. Results obtained in the 18projects that were part of the R&Dprogram were reported. From thereport to Council of the STACchairman, David Shoemaker,several considerations may beunderlined. Among them was thatthe R&D funds of the first EGOprogramme have been veryproductively used.

The prospects of launching a newEGO R&D programme were thenconsidered and it was noted thatthe new R&D program is crucial tosetting the scope, and thendetailing, the Advanced Virgoupgrade; the STAC recommendsgiving highest funding priority tothose R&D programs that haveimmediate relevance to theplanned Virgo upgrades.

Regarding the reports by EGO, itwas noted that the scope ofactivities of EGO is impressive:helping to grow the VESF,strategically funding R&D,managing fel lowships , andbuilding up the infrastructure, inaddition to scientific and technicalcontributions, while the continuedstrength of the commissioningcontribution was notable.

Regarding the reports by the Virgocollaboration, it was consideredthat, among several things, thevery recent achievement of lockingwas the crucial point of inflectionpost-intervention, allowing studyof a linear system and incrementalimprovements. Also i t wasconsidered that the studies to datewith the higher circulating powerwere very encouraging and theSTAC was impressed with the

focus, organization, and progressof the commissioning.

C o n s i d e r i n g t h a t t h ecommissioning plan proposes tofocus for the near term on the high-frequency regime, followed by aScience Run I of 3-6 months at asensitivity of 15 Mpc for NSNSbinaries, optimized for directionand polarization, while thefollowing commissioning stage isdesigned to address low-frequencyissues, followed by a Science RunII of 3-6 months at a sensitivity of30 Mpc for NSNS binaries,optimized for direction andpolarization, the STAC supportedthis approach to defining the scopefor Science Run I and II.

Hearing about progress for Virgo+,the STAC considered that thisupgrade is well defined, has fewtechnical challenges, and gives aremarkable improvement inperformance for a moderateamount of effort.

Then, considering that EGO andVirgo wish to start intervention in2011 for Advanced Virgo, theSTAC noted that for this it isimportant to be timely, in order tokeep pace with other developmentsin the field (Advanced LIGO,LCGT, GEO-HF), while i ta p p e a r e d t h a t E G O / Vi rg oinfrastructure are very well poisedto be upgraded at minimal cost,although the project organization,and the engineering design must bebrought forward now to allow costestimates, funding decisions, andscope adjustment to be made.

Report on VESF (Virgo-EGOScientific Forum)

The report was presented by theVESF coordinator, FrancescoFidecaro. It contained a résumé ofthe activities carried out since lastNovember, the most relevant oneshaving been: the conclusion of 11conventions between EGO and

proponents of VESF fellowships;the 1st VESF School for GW atEGO last May which was attendedby 38 students coming from 9countries; the joint GWADW(Gravitational Waves AdvancedDetectors Workshop)-VESFmeeting at Elba island last May.There were 114 participants fromall over the world, with all mainGW actors represented.

Three new groups have applied for,and been accepted to, VESFmembership: the MTA-KFKI-RMKI Group, from Budapest,Hungary, the Geneva UniversityGroup, Switzerland and theInstitute of Cosmology andG r a v i t a t i o n g r o u p , f r o mPortsmouth (UK). There are now43 VESF groups from the 10European countries: France,Germany, Greece, Hungary, Italy,P o l a n d , R u s s i a , S p a i n ,Switzerland, UK.

The 2007 draft budget proposal

The director presented the firstdraft of the 2007 budget, the mainscope of which is, on one side, thefunctioning and maintenance ofthe interferometer and of the wholesite with its infrastructures and itscomputing centre, and, on theinvestment side, the completion ofthe new main building and itsoutfitting, the completion of theacquisitions for the approvedprogram of the present Virgoupgrades and of the upgrades forVirgo+.

The Council considered the overallbudget proposal as acceptable forthe time being. The final financialenvelope of the 2007 budget willbe defined in consultation with themember Institutions in view of thefinal budget proposal to bediscussed and approved byCouncil in its autumn meeting.

F. MENZINGER



The SummerCollaboration

Meetings

Amsterdam in July

This summer, for the first time, theVirgo collaboration meeting washeld in the NIKHEF UniversityCentre in Amsterdam, which madea welcome change to the monthlyVirgo week routine. The meetingtook place between the third andfifth of July, and was quite wellattended, with more than 50registered people.

The Commissioning status outcomewas quite satisfactory with respectto previous meetings. In the lastmonth much progress had beenmade: problems in the injectionbench had been fixed (inparticular the contactbetween filter 7 and themarionetta), the lockingacquisition was becomingfast and repeatable, longerlocking stretches wereavai lable , the h igherfrequency sensitivity wasbetter than C7, thermaleffects were in the processof being better understood,and several monitor devices,such as the scanning Fabry-Perot on the dark fringe,were giving more information andconfirmation of heating of the inputmirrors (the simulation of which isthe object of several people, someof them from the NIKHEF group).In addition, automatic alignmentwas being closed on more degreesof freedom (five degrees of freedomon automatic alignment, six on driftcontrol, only BS on local controls).

Even if C7 sensitivity curve was notyet reached, it was clear that theinterferometer was going to worksoon in the same conditions as C7,in terms of both sensitivity and

reliability, which was quite nicenews. It was proposed to startweekly science runs duringweekends as soon as the C7sensitivity curve was attained.

Some discussion went on in boththe plenary session and in the dataanalysis meeting about the startingof data exchange with LIGO. In theDetector meeting a lot of discussionwas within the framework ofthermal effects in the interferometer.The discussions on the phasecamera, scanning Fabry-Perot,sidebands thermal drifts, andthermal compensation, were alltriggered by the evidence of thethermal effects in the mirrors, whichwere being confirmed by themeasurements and the simulations.Even if there was general agreementon the utility of the scanning Fabry-

Perot, so that an additional one onB2 (interferometer reflection) wasdecided, no final decision was takenon the shape that the phase camerashould have, even if its utility isrecognised.

Other particular events of noteincluded: the presentation of theRoma II group, having recentlyjoined the collaboration; well wishesto Romain Gouaty, who has left fora post doc in LIGO; and theappointment of Giovanni Losurdoas Advanced Virgo coordinator,which is both deserved recognition

for Giovanni and a milestone in thestarting of the organization ofactivity towards Advanced Virgo.

Globally, in particular after the May-June fears of insuperable problemscaused by thermal effects, thegeneral impression was ofconfidence in near-future progress.Overall, the collaboration meetingof Amsterdam should (and will) besurely remembered for the warmreception and organization of theNIKHEF group.

The NIKHEF (Nationaal Institutvoor Kernifysica en Hoge-Energiefysica) is located in theAmsterdam Science Park, in theeastern outskirts of Amsterdam, andis very well connected to the centreof town by bus and underground.

The Science Park and its buildingsare quite new, and graciouslysurrounded by green, whichmakes a very nice impressionto the visitor (at least insummer, and when it doesn'train). The seminar hall, wherewe met for the first two days,is wide and receptive, maybewith just the small remark thatthere is no electrical powerconnection directly to eachseat: but this is surely meantintentionally, so that peoplecannot switch on their laptopsinstead of listening to the

speaker (even if everybodysucceeded in bypassing theproblem). Of particular interest arethe scientific apparatus on show inthe hall of the NIKHEF institute.

The reception by the Dutch groupwas very warm. The lunches wereessential and quick, allowing us toget back to work soon, so that it waspossible to finish the meeting earlier,and have some free time to wanderaround Amsterdam, which is sucha lovely town, especially with thesurprisingly hot weather weencountered.





Besides, if the lunch was moderate,the dinner offered us by the NIKHEFgroup on the first day was reallysurprising: we met at the "Lovers"dock, where a long boat was waitingto escort us along the channels ofthe city while we were dining. Thatwas really an unusual experiencefor those who had the chance to bethere.

So, we think we should again thankNIKHEF for the way in which thismeeting was organised andmanaged, and, as a personal thankyou, one of us would like to takethe opportunity to express hisgratitude to all the secretaries ofNIKHEF (Mrs. Dekkar, Mrs.Schram-Post, Mr. Bulten), for thehelp they gave in solving anunfortunate accident that occurred,clear evidence of their problem-solving capacity.

Last but not least, how could it beforgotten that on the Tuesday nightthe Italy-Germany World Cup matchtook place, and Italy won, amonggreat happiness, at least from theItalian side of the collaboration?

Cascina in September

The hints for coming commissioningprogress, contained in the seeds ofdetector comprehension announcedand discussed at the NIKHEF VirgoWeek, sprouted vigorously in thefollowing weeks. The results wereannounced and discussed in the nextCollaboration meeting, held in earlySeptember and on-site, when a newsensitivity curve was shown - muchimproved with respect to C7.

We are convinced that this was alsoa long-term beneficent effect of thehealing Amsterdam atmosphere onseveral Virgo members. Notsurprisingly, since we saw severaldistinguished commissioningscientists attending those pharmacies(curiously called "Coffee Shops")selling herbal inhalation medication,so helpful for mind welfare andsharpness.

The positive slope continued in thefollowing weeks, allowing theperformance of a very satisfactoryfirst Weekly Science Run (WSR1),mentioned also in another part ofthis h issue.

Several hardware interventions havebeen decided and scheduled in theSeptember Virgo week: studyingand possibly overcoming theapparently poor Faraday isolatorperformance, installing the acousticisolation box in the Laser Lab,building the "phase camera",studying wider Brewster windowsthat do not cut the beam tails.

We can announce that the first goalhas already been successfullyachieved. After a few days of workinside the injection tower, it wasdiscovered that, as suspected, theFaraday isolator malfunctioning wasactually due to magnetic fielddeformation. What was not expectedis that the origin of the deformationwas a small steel "Allen" key (seephoto above), that had been suckedinside the magnet surrounding theFaraday crystal. This time, the doorto success was opened by extractingthe key, instead of plugging it intothe right lock.

Other highlights of the SeptemberVirgo Week were: the kick-offmeeting forAdvanced Virgoactivities, the proposal by MichelePunturo of a "Virgo+ White Book"

and the decision and plan for theWeekly Science Runs.

Finally, Francesco Fidecaroproposed to produce a "YellowBook" (the name borrowed from thegood old Yellow Book on LEPphysics) on the physics ofphenomena accessible with Virgoand on methods to analyse them. Inorder to profit from all of theknowledge and experience existingin VESF, LSC and the wholescientific community, it will be a"WikiBook", that is a sort of "opencontent textbook", where everybodywill have the possibility tocontribute.

P. LA PENNA, C. BRADASCHIAPHOTO: C. BRADASCHIA

More Room andCooling for the

Computing System

Computing and storage capacityhas increased constantly since theconstruction of the Virgo buildingsin 1998. Now it includes 23 racks

with more than 120 TB of on-diskstorage and the so-called "300GFlops" computing farm (1 TB -(Terabyte) corresponds to 1000Gigabytes. 1 GFlops corresponds tothe computing power of a processorable to perform 1 billion operationsper second, with floating pointnumbers).

The farm will be completed in thenext few months, when other 128AMD CPU wi l l t ake thecomputing power to more than 400KSpecInt2000 (see figure). Tohave an idea of what this means,think to 400 PC at 2.8 GHznetworked to exchange data at aspeed of 1 Gigabit per second.

The large disk storage area isnecessary to enable the on siteprocessing of several months ofrough data. The computing farm isnecessary in the search forcoalescing binary events "in time",that is keeping pace with the dataacquisition.

Computing Infrastructure facilitieshave hardly kept pace with thegrowing needs of Virgo. The flooroccupancy changed from the initial20 m2 to 45 m2 by eating nearbyrooms and the cooling system wasextended in 2003; but there was nohope of cooling the new farm andeverything else (including theoffices): existing cold water pipesfrom the refrigerator buildingcannot sustain a flow of more than40 kW, the false floor is also toolow for the needed airflow. Thinkof a rack of 80 CPU and it will eatup more than 10 kW, and the wholefarm alone will amount to 30 kW.

Therefore the computer room wasre-thought according to the coolingneeds. This was one of the mainreasons to move the Control Roomto the g round f loor. Thedisplacement left an additional 45m2 space alongside the currentcomputer room to install the newcooling system and racks withoutimpacting upon Virgo activity.

The refrigerating fluid chosen is agas mixture (no danger of waterdripping on the Virgo operatorsd o w n s t a i r s . . . ) . T h e h e a texchangers have been mounted onthe Control Building roof, whichhas been transformed for thepurpose. Inside the room twosystems work together: the firstcools globally, with 4 refrigeratorand venting units forcing the airthrough the floor in the coldcorridors removing 50 kW of heat(for all the Virgo servers, the EGOservers and the storage farm); thesecond is made of 3 units hangingfrom the ceiling over the corridorwhere 10 kW of heat per rack mustbe extracted, for a net coolingpower of another 30 kW.

Of course the possible failure of 1unit must be overcome, thereforethe units are oversized with anominal total power of 120 kW.

The system was put to work onJuly 5th with all the needednetwork and power, but still inhard conditions: in order tominimize the down time of theinterferometer.

Only the computing farm wasmoved into the new room, all theother servers were kept in the oldone and cooled with the newsystem by el iminat ing theseparating wall.

This is not the final setup, but atleast people in the ControlBuilding could enjoy the return ofair conditioning in the offices,which had to be dropped duringsummer heat peaks!

The next step will be saved for thenext interferometer shutdown,foreseen in 2007: the old room willbe cleared, the network cablingwill be untangled and the serversmoved into the final places.

And then? If needed, besidessqueezing in other computingnodes and storage, using part of theredundancy, higher densities willcall for more powerful coolingsolutions able to extract 20 kW perrack.

S. CORTESE, EGOPHOTO: C. FABOZZI/B. LOPEZ



11th MarcelGrossmann

Meeting

The 11th Marcel Grossmannmeeting took place in Berlin, last July,from the 24th to the 29th. It is one of thelargest meetings inside the GeneralRelativity Community: more than 900physicists were there, astrophysicists,mathematicians, string theorists and"alternative theorists"!

The current status of GravitationalWave antennae were reported withplenary talks on the 26th and, each day,a parallel section was dedicated to GWresearch: Operating GW Detectors,Advanced GW Detectors, Space andThird Generation GW Detectors, GWData Analysis. It is nice to see that thereis so much room for our field inside theGR community. I was there, but ofcourse to summarize a meeting of thiscomplexity is very difficult; allinformation about it can be found on theweb at: http://www.icra.it/MG; videolive streams of the plenary sessions arealso available by choosing "Conference

Lifestream" in the main page menu.Proceedings will come out quite a bitlater, in 2007.

At MG11 no striking news wasannounced: unfortunately the darkmatter discovery claim by Chandra X-ray Observatory was diffused twoweeks later, on August 14.

A. DI VIRGILIOPHOTO: WWW.ICRA.IT/MG

EPS Meeting in Kiev

Last June I was in Kiev for ameeting of the European PhysicalSociety, it was my first time thereand my first time inside an EPSmeeting - in April I was appointedto be one of the eleven members ofthe EPS Executive Committee. Theorganization, headed by ProfessorLitovchenko, was simple, butextremely efficient and rich inhumanity.At the airport a young student waswaiting for me, very patient sincemy airplane had been delayed byseveral hours, and then with a taxiwe went to the hotel. The highwayaround Kiev is very large and wellconstructed, the traffic is heavy, andthe cars, quite old I must say, runrather fast. The church S. Sofia, veryold and beautiful, is the onlymonument left. The metro is veryconvenient, and runs very fast, muchfaster than the ones we are used to.Old ladies sell flowers on the cornersof the streets.The meeting was devoted todiscussing the situation of physicsin Ukraine, and to the annual"Journée de reflection" of theExecutive Committee. The mainpoint of reflection of the EPSrestricted meeting was based uponthe European Ins t i tu te o fTechnology. It is a European Unionproject aiming to create, insideEurope, a flagship project forexcellence in higher education,research and innovation. The EPS

president Ove Pulsen pointed outthe importance of carefullyfollowing the progress of this project- anyone interested on this point canread the editorial in the last issue ofEurophysics News.The current status of the EPS journalEurophysics Letters was reviewed:the Society is very proud to see thatit is going very well and will do itsbest in order to provide a Europeanalternative to Physical ReviewLetters.The hospitality of the Ukrainianphysicists was extremely warm andkind. A large effort was made andall representatives of the UkrainianUniversity were there, as well asrepresentatives of neighbouringcountries. The vice minister ofeducation, a physicist, was presentas well. From the talks it was evidentthat physics is alive and well inUkraine. Unfortunately they havevery little income, the structures areold, but they are very talented inphysics, and they use this talent topublish a lot of papers - the averageis six papers per year per physicist.Young people are attracted byscience and each university hasseveral thousand students in physics.However, they cannot afford PhDlevel courses; and on this issue helpfrom Western countries would bevery welcome.We were very impressed by the storyon how the Ukrainian PhysicalSociety was born and later kept alive,during the break down of the SovietUnion. Students are constantlymotivated with Olympiads andcompetitions, which clearly showthat most of the old Soviet Uniontradition has not been lost; we shouldremember how important that schoolof physics has been. My impressionwas that they are smart people, witha lot of good sense, really willing toemerge, and do their best ineverything, with very little. It wasalso clear to me that they look atEurope, aiming to be betterintegrated into it as soon as possible.

A. DI VIRGILIO

8

N E W S F R O M T H E W O R L D

THE GRAVITATIONAL VOICE - OCTOBER 2006

Wind, Sun andHydrogen around

EGO

The interest in alternative energysources sprouted recently in andaround the Cascina site. It may bea coincidence or, more likely, it isdue to the increasing importance ofthe energy issue in today's world.This is testified by a "web focus",on the web site of Nature, were youcan find a long list of articlespublished on Nature about all theproblems and the advancements onenergy saving and production(http://www.nature.com/nature/focus/energy/index.html).

The events, in roughly chronologicalorder: two companies proposed toinstall aeolian generators in thevicinity of EGO, to produce cleanelectricity; EGO and Virgo startedconsidering the possibility ofinstalling photovoltaic generatorson tunnel roofs; ENI (the Italianstate oil company) inaugurated, onthe highway station of Grecciano,the first Italian hydrogen pump.

First commercial Hydrogen pumpin Grecciano

Let us start from the last event, evenif it is close to us only from ageographical point of view. Itinvolves, in the same place, manyunusual power sources. What makesthe Grecciano station unique inEurope, and in the world, is the factthat the sold hydrogen is locallyproduced through water electrolysis,by renewable power sources.

This explains the purpose of thethree small windmills (20 kW each)that have been raising our curiosityfor a while when going for lunch atthe restaurant "Le Colline". But thisis not all: more clean energy comesfrom silicon photovoltaic panels,covering the roof of the station.

In Grecciano the only fuel not soldis alcohol (wine is available at thebar); all the others are there: besideshydrogen, there are gasoline, dieseloil (containing some vegetal oil),methane and LPG.

The H2 production capacity will besufficient to cover a total of 40,000km per year, by a fleet of twoMultipla and two Doblo', modifiedby ILT Technology (Ponsacco), toburn either gasoline or hydrogen.The double fuel cars have 20%reduced performances, usinghydrogen, and an autonomy of 380+ 120 km (gasoline + H2).

Jules Verne anticipation (L'ilemysterieuse, 1874: "Je crois qu'unjour l'eau servira de carburant, quel'hydrogène et l'oxygène qui laconstituent, ...") is becoming reality?

Windmi l l s : f r i ends to theenvironment, are they enemies toVirgo?

Pushing for high sensitivity, werealized that the Cascina plain is arelatively windy place: according tothe anemometer on top of the CentralBuilding, 45% of the time there arewinds blowing faster than 10 km/h,reaching peak values of 70 km/h.

Other qualities, such as being distantfrom urban areas, close to Pontederaindustrial site and to be of residualnegligible naturalistic value, make

the Cascina site a candidate locationfor wind energy production plants("windmills").

To comply with the requests of theKyoto Protocol for the reduction ofpolluting emissions, the Tuscanyregional energy plan (PER: PianoEnergetico Regionale) set the targetto produce 300 MW of wind powerby the year 2010.

As part of PER, two wind parkshave been proposed for installationin the EGO neighborhood. The firstone to start operations (next spring)is managed by the Italian ASA(Azienda Servizi Ambientali,Livorno). It consists of four 2.3 MWwind turbines placed East of EGO,between 5.5 and 6 km from theCentral Building.

The second one, managed by theGerman Windwaerts, is still in thedesign phase. According to the lastagreed layout, it will consist of four2.0 MW turbines located between5.1 and 6.1 km South West from theVirgo West Building (Vicarello).

The two chosen locations are theresult of long diplomatic andscientific work performed to protectVirgo from the not good vibrationsproduced by windmills.

Latest generation windmills arehuge: the steel tower is about 100m high and supports a nacelle anda 3-blade rotor with a diameter of90 m, that is about 100 tons of totalweight and tall as a 40-storeyskyscraper. A close view reveals thatthe nacelle is as large as a big truck!

The chosen models are optimizedfor a moderate wind speed, between2.5 and 25 m/s (9 - 90 km/h). Theyare endowed with a feedback controlsystem of the rotor speed (typicalvalue of the rotor revolution periodis T = 5-6 s) acting on the bladespitch angle; the nacelle rotates inthe horizontal plane to follow thewind direction.


S C I E N C E & T E C H N O L O G Y

Although modern turbines havebeen optimized to be acousticallyquiet (less than 50 dB at 100 mdistance), not much work has beend e d i c a t e d t o m a k e t h e m"seismically quiet". In fact weexpect them to produce notnegligible ground vibrations. Thelow frequency seismic emission(below 10 Hz) from the two windparks is obviously a concern forVirgo: both because they couldcause a significant increase of thenoise background at the site, andparticularly because the productionof low frequency monochromaticseismic waves can excite criticalresonances of interferometercomponen ts , fo r example ,mechanical modes of mirrorsuspensions.However, we are not alone: theGEO600 site has an 8-turbine windpark at about 1.5 km from its Northarm, and LIGO (Hanford) had todeal with two proposals for theinstallation of large wind parks ini ts close neighborhood. R.Schofield from LIGO firstperformed a study of the seismicemission from a wind park, withthe aim of predicting its spectralcomposition and intensity at theLIGO site. The wind park next toGEO600 gave the optimum chanceto study the properties of theseismic wave field in a soft soil,made of lime and sand, which issimilar to that of the EGO site; andat the same time to investigatep o s s i b l e e f f e c t s o n t h einterferometer.Sponsored by ILIAS, we paid avisit to our German colleagues andperformed a study of the seismicemission of the wind park next toGEO600. We (Lara Giordano,Federico Paoletti and Irene Fiori onthe EGO/Virgo side; Gillian Mayerand Stefan Hild on the GEO side;and Emanuele Marchetti from theGeophysics Dept. of FirenzeUniversity) performed a mappingof the seismic wave field around

GEO600 using a pair of lowfrequency portable seismic stationsoperated in coincidence (with GPSantennae): one station deployed ata fixed location close to onewindmill, and the second onemoved to many locations atincreasing distances (5m to 5km).One microphone was used to lookfor the presence of a component ofseismic low frequency vibrationpropagating through the air. Oneanemometer measured wind speedand direction. Measurements wereperformed over four days, thuscovering different conditions: lowand intense wind, periods withwindmills stopped, day and nighttime.

The spectral analysis revealed thatthe windmills seismic signalcontains intense low frequency (0.1to 10 Hz) components whoseintensity increases with winds p e e d . P e a k f r e q u e n c i e scorrespond to the rotor frequencyand to its third harmonic, and toresonant modes of the tower. Wemeasured a re la t ively fas tattenuation of the seismic wavefield with distance. Precisely, asexpected in presence of soildispersion effects, RMS noisedecays exponentially with distance,such that a few km away the signalis of the same amplitude as the

s e i s m i c e n v i r o n m e n t a lbackground.The final purpose was to elaboratea model of windmill seismic signaland derive the "safety distance"from the Virgo buildings, such thatwindmill spectral noise does notexceed the env i ronmenta lbackground. This constraint hasbeen discussed with ASA andWindwaerts who could producemodif ied layout so lu t ions ,complying with Virgo needs, inaddition to those imposed by urbanand environmental constraints (i.e.distance from roads, houses, urbansites).We now anxiously wait for the firstof the two wind parks to startoperations (this should happenright in the middle of our firstscience run) hoping to see ourpredictions confirmed!Will sun power help EGO?The idea to use the huge amount ofenergy shined by the sun on ourtunnel roofs has been turning in ourminds for a long time; but westarted to consider it seriously, as asilent alternative more compatiblewith gravitational wave detection,with respect to the proposedwindmills. I t must be saidi m m e d i a t e l y t h a t t o d a yphotovoltaic electricity productionis not intrinsically economic, dueto the high cost of silicon panels.The business becomes somewhatconvenient thanks to the fact thatENEL (the Italian electricalcompany) is forced by law to buythe excess produced clean energyat about four times the marketprice.We are convinced, anyway, thatthis operation would be stronglypositive for the image of EGO andVirgo, on a local scale, and ofCNRS and INFN, at national andinternational level. It would showhow we are in favor of renewableenergy sources and that we havepushed the windmills a little awayfrom the site uniquely for scientificreasons.



Let us give a few orders of magnitude(http://en.wikipedia.org/wiki/Photovoltaic_array):1 kW/m2 is the specific solar powerreaching the earth surface at theEquator, at noon170 W/m2 is the specific solar powerat our latitude, averaged on thewhole year, clouds included0.6 kWh/m2/day is the energy outputof a 1 m2 panel with a goodconversion efficiency of 15%

The simple practical solution beingconsidered is to cover only the best-oriented part of the West tunnel roof,that is the lap looking South. In thisway we could reach the nominal1MW peak power, the maximumpermitted by law to access thepromotional price. A computationperformed by a professionaldesigner, on a proposed surface of2750x2.7=7425 m2, gives an averageproduction of 1,276,000 kWh peryear, for at least 20 years, takinginto account all the possibleinefficiencies due to temporaryfailures and maintenance.

Even if at present the total yearlyconsumption of EGO is of the orderof 3 Millions kWh, that is three timesthe possible solar production, at leastduring the day, in summer, therewould be an excess of power. In factthe average power used by EGO isabout 400 kW, with peaks of up to700 kW - below the photovoltaicpeak power of 1 MW. In practice,the compensation would not be donelocally; EGO will continue to getpower through the usual power lines,while the produced power would befed into the power network throughan independent connection. Thecompensation would be computeda posteriori, with an appropriatealgorithm, taking into account theenergy flow in both directions.

The real issue is the cost of thesystem. The overall estimatedbudget, including silicon panels,

support structure, assembly on site,DC/AC converters and cabling isabout 5.5 MEuros. According to thedesigner computation, the operationis anyway economically positive. Incase the needed budget is madeavailable by the EGO Council(which is unlikely), the first severalyears of operation would benecessary to recover the spentmoney, then there should be realprofit. In case the budget is givenon loan by a financing company theprofit is expected start a few yearslater.

Luckily all around Italy there arepublic agencies devoted topromoting renewable power sources.The EGO Director has recentlysigned an agreement with theAgenzia Energetica di Pisa, that willprepare the preliminary project tobe submitted and eventuallyaccepted by ENEL. The Agencyhelp will be very important also infinding financial and industrialpartners to set up joint ventures tobuild the system. More flexibilitymay be obtained by a stagedprogram to equip 1 km of tunnelroof every 2-3 years.

As in the case of windmills, a wordof caution about noise is alsonecessary. Photovoltaic generatorshave no moving parts; on the otherhand the converters from DCcurrent, produced by solar cells, toAC current fed into the network mayproduce electromagnetic noise,being based on oscillators.Moreover, the best converters workat higher frequency, which mayimply higher noise pick-up. As soonas a preliminary design is available,noise measurements will beperformed on the chosen devices.

The previous pictures showwindmills at the GEO site andFederico Paoletti installing aseismometer at the base of awindmill tower.

I. FIORI, C. BRADASCHIA

Solar Cells: How dothey Work?

The principle, the photovoltaiceffect, comes from the properties ofsemiconductors; we will try toexplain the matter in a simple,intuitive way, not to be taken as arigorous treatise (1).

A semiconductor is a material,usually crystalline, containingelectrons weekly bound to theiratomic nuclei, hence relatively freeto move inside the crystal lattice.Semiconductors allow the passageof electric current, but not as easilyas metals (conductors), where thereare electrons completely free tomove around, inside the material.

In a semiconductor, a movingelectron leaves behind a "hole", thatis a missing electron. It is amazingto see from the equations that a holemoves exactly as if it was a realpositive charged particle (the runaway electron has a negative charge).

To increase the conductivity we dopesemiconductors; there are no sportlaws prohibiting this practice!Typical semiconductors are siliconand germanium, elements with 4valence electrons in the outer shell;every atom is bound to the foursurrounding ones, saturating all thepossible bonds. If we replace hereand there in a silicon crystal oneatom with one of arsenic, a "donor"atom, having a valence of 5, we will



have an extra electron free to goaround (the overall electric chargeis zero, since the extra electronnegative charge is compensated byan extra positive proton in thearsenic nucleus). More availableelectrons give higher conductivity.A semiconductor doped with donorimpurities is called of "n-type",having a majority of negativecarriers. In semiconductors thesame effect can be obtainedincreasing the density of holes,with positive charge. Very simple:instead of doping with arsenic, wecan use an "acceptor" atom, likealuminum. Having a valence of 3,aluminum is not able to bind itselfto all the 4 surrounding silicons andleaves out a free place: a positivehole, free to move as we said. Thiswill be a "p-type" semiconductor.

Imagine a slice of silicon (a"wafer"), doped for ½ of itsthickness with donor atoms and forthe other half with acceptor atoms.In the two half slices, respectivelyelectrons and holes are moreabundant and move freely around.Electrons and holes diffuse also inthe other type of material, werethei r charge is not moreequilibrated by the charge of theoriginal atomic nuclei. The excessof electrons diffused in p-typematerial and of holes diffused in n-type material produces a smallvoltage difference between the twolayers of the wafer. This recallswhat happens at the contact surfacebetween zinc and copper in aclassical battery: the Volta "pile".The carrier diffusion continuesuntil when the extra + and - chargeaccumulated on the n-side and onthe p-side, respectively, of theseparation surface ("junction")create an electric field stopping thecharge migration. With a copperwire (or with semiconductor slabs)we can put in electrical contact thetwo faces of the wafer, in the hopeto ge t a usab le cur ren t .Unfortunately at the additional

contact interfaces introduced in thecircuit, similar carrier diffusionmechanisms create voltagedifferences exactly balancing theone at the junction.

Let us now shine a strong light onone wafer face. Photons, hittingatoms, will kick off electrons andgenerate many more + and - carrierpairs. If the wafer is thin enough,electron/hole pairs are generatedclose to the junction (in the socalled depletion zone) and cansustain charge carrier diffusionacross it. The current flowing inour copper wire is now there andcan be used.

Solar cells have been used initiallyto power satellites, emergencyphones along the highways andpocket calculators. Nowadays theyhave hundreds of applications.

Commercial photovoltaic panelsappear as 1 m2 aluminum frames;but, under the glass, instead of apicture, the surface is covered bysilicon wafers, very similar inwidth and thickness to blackish,squared CDs. Cutting edgedevelopments are leading to thecreation of panels of amorphous(non crystalline) silicon, depositedon plastic film, to be attached aswallpaper, or photovoltaic tiles tobe integrated on houses from thestart.

Notes

(1) We encourage the interestedreader to consult Wikipedia todiscover more on this subject:

http://en.wikipedia.org/wiki/Semiconductor

http://en.wikipedia.org/wiki/Solar_cells

We suggest also The FeynmanLectures on Physics, Vol. 3 -Quantum Mechanics. In spite ofthe frightful title, we are convincedthat also the non-physicist readerwill profit of the incredible telltalecapability of Richard Feynman.

Chapter 14, on semiconductors,contains only fourteen simpleequat ions over 20 pages!Feynman's chair at Caltech is todayheld by Kip Thorne.

C. BRADASCHIA



PERSONNEL MOVEMENTS01 June - 31 August 2006

ARRIVALS

Staff

Fabio GherardiniTechnical assistant for theoperation of the interferometer,Interferometer Operation(Operations)

Michele NassiTechnical assistant for theoperation of the interferometer,Interferometer Operation(Operations)

FabioTerenziComputer technician,Computing

Collaborators

Daniel SentenacCommissioning Project

Matthew EvansCommissioning Project

DEPARTURES

Staff

Mehdi GacemTechnical assistant for theoperation of the interferometer,Interferometer Operation(Operations)

Roberto SpagnoliTechnical assistant for theoperation of the interferometer,Interferometer Operation(Operations)

Christophe MoinsSoftware Engineer,Interferometer Operation

Sidereus Nuncius

Not everybody knows that duringthe past months, besides the usualscientific collaborations all aroundthe word, EGO also participated tothe creation of a European artisticproject: Sidereus Nuncius -Narrazioni tra arte, fede e Scienza(Sidereus Nuncius, narrationsbetween art, faith and Science), aEuropean project in honour ofGalileo Galilei, with the aim ofpromoting dialogue between rationaland religious thinking (1).

Virgo participated actively to therealisation of the project. The artistsinvolved, namely Paolo Pierazzini,Isabel Preuilh, Eraldo Bernocchi(http://www.myspace.com/eraldobernocchi) , AlainWergifosse, Alvaro Una Resa,Juan Coll Soler and others,came to the Virgo site, speakingwith scientists, making videosa n d p h o t o s o f t h einterferometer, and mainlylistening to real and simulatedVirgo signals. When they left,they had their USB keys fullof digitalized cracks, pops,hisses and chirps of variousorigin.

The material collected wasused first to teach electroniccomposition in a workshopattended by students fromvarious European countriesand, ultimately, as a basis forthe creation of an interactiveevent, Virgo Ma 49-100/04(http://www.fabbricaeuropa.com/index.php?id=736). The premieretook place on May 20th in Florence,during the Fabbrica Europa Festival,which takes place every year at theLeopolda Station.

Carlo Bradaschia, Paolo La Penna(with daughters) and myself had thepleasure of attending: we were taken,together with the rest of the

audience, inside a large roomcompletely filled with sound, where,from time to time, you couldrecognize some of the Virgo signals;screens were hanging from all thewalls, showing the images capturedfrom video cameras placed allaround. Mime artists in white suits(2) mixed with the audience, actingso as to focus our attention to oneplace or another in the room, andinvited us to mimic faces andgestures in front of the cameras, thusbecoming part of the show: later,people were encouraged to makemusic themselves, plucking steelropes stretched from the ceiling tothe floor, or even knocking hard onthe head of one of the artists (luckilyprotected by a motorcyclist helmet).

The performance went on in acrescendo of noise, sounds andimages, until it ceased abruptly,leaving us almost relieved. A finallong cheerful applause greeted theartists.

The performance of Virgo Ma 49-100/04 was preceded by theprojection of Gravitational Psalms,an audio visual work by the physicistAndrea Ferrara, a researcher active

in the field of general relativity(SISSA, Trieste), and composer ofthe group Tempo Reale, founded byL u c i a n o B e r i o(http://www.centrotemporeale.it/index.php?lang=en&sez=home&sub=0). A video of the work has beenkindly given to us by Andrea (3).The Florentine performance wasrepeated during Ipse dixit, themultimedial event which closedSidereus Nuncius, and which washeld in Pisa on September 24 and 25(http://www.sidereusnuncius.net/sidereus/index.html).Ipse Dixit was a two day event,organised as a hypertext, which tookplace in various places of the town,at different times. Both days openedwith Co-stellazioni, a true treasure

-hunt, which led people fromplace to place following thesteps of Galilei. Wirelessantennae had been installedto allow the use of notebooks,while walking around.After that, at sunset, insidethe Botanical Garden (4)actresses, playing nymphs ofthe waters, were reading themost poetic passages fromGalileo's fairy tale works.They were accompanied bymusicians, hidden in theshadow of the ancient trees,playing primitive and ethnicali n s t r u m e n t s ( c i t h a r a ,didjeridoo, xylophone, drum).The fabulous atmosphere wasperfectly evocative.

Then in Piazza Dei Miracoli,inside the Battistero, people

could listen to SiderisVox, a workby Leonello Tarabella, composerand information technologyresearcher at CNR in Pisa, whichfully exploited the extraordinaryacoustic capabilities of thismonument (think only that thereverberation time exceeds 15 s!).In the meantime, the people insidethe Camposanto monument couldfollow the life of Suor Maria Celeste,


E V E N T S & S O C I A L L I F E

Galileo's daughter, through the lettersshe exchanged with her illustriousfather (to see the whole play, go tohttp://www-serra.unipi.it/webtv/galileo.html).

In the same hours, the "VecchiM a c e l l i " ( t h e o l d P i s aslaughterhouse), hosted two otherevents: in the old cowshed, thecompany “I Sacchi di Sabbia”performed a play entitled “Le leggidi gravità (Gravity laws)”; after that,the former pigsty, which now hoststhe "Museo degli strumenti diCalcolo" offered a new stage to areduced, still impressive, version ofVirgo Ma 49-100/04.

The two days were completed byexhibitions and installationsscattered all around the town.

Notes

(1) Sidereus Nuncius (SiderealMessenger), published in 1610 byGalileo Galilei. Written in Latin, itis the first scientific book based onobservations made through atelescope. It describes the Moon,the stars, and claims the existenceof moons orbiting around Jupiter.

(2) Used clean room overalls andovershoes supplied by EGO.

(3)Andrea Ferrara ([email protected])

Gravitational Psalms - Video/audiotrack of the performance, premieredat the festival “Fabbrica Europa”,Firenze, May 19, 2006.2006#009 PRODUCTION@Ongaku S tud ios , Crea t iveC o m m o n s , S a m p l e c l i p :http://www.ego-gw.it/public/hletter/clip_issue2.aviFull performance, compressed:http://www.ego-gw.it/public/hletter/video_issue2.avi(4) Founded in 1544, it is the oldestuniversity botanical garden in theworld - http://www.horti.unimore.it/CD/Pisa/Pisahome.html.

I. FERRANTEUNIVERSITA DEGLI STUDI DI PISA

Dates to Keep anEye on

August 5, 1906

One century ago Ettore Majoranawas born, one of the most brilliantphysicists of the past century. Hewas a member of the Fermi team inRoma, known as "i ragazzi di viaPanisperna", from the street werethe Physics Institute was located atthat time.

Majorana, in his very short scientificlife, performed several precursoryinvestigations on relevant issues ofthat nascent branch of science thatwe now call elementary particlephysics. In particular, Majoranaundertook fundamental theoreticalwork on particle symmetry, whichturned out to be the cornerstone ofneutrino mass studies, currently avery active subject of research.

Giuseppe Cocconi reported thefollowing sentence, pronounced byFermi in 1938: "Because, you see,in the world there are variouscategories of scientists: people of asecondary or tertiary standing, whodo their best but do not go very far.

There are also those of high standing,who come to discoveries of greatimportance, fundamental for thedevelopment of science (and here Ihad the impression that he placedhimself in that category). But thenthere are geniuses like Galileo andNewton. Well, Ettore was one ofthem. Majorana had what no oneelse in the world had (...)"

Our colleague, Ettore Majorana, thenephew of this homonymous uncle,provided the photograph for theexclusive use of "h".

September 11, 2006

It is the fifth anniversary of a sadevent. But it is also the date of aEuropean success: on this day aneutrino beam, produced by theaccelerator complex of CERN, inGeneva, reached the Gran Sasso


E V E N T S & S O C I A L L I F E

Laboratory of INFN, in Italy. Theneutrino beam, originated at CERN,with a cross-section of less than 1cm2, reached the goal covering a 1km2 area, after traveling more than700 km underground, in 2.5milliseconds.

Neutrinos are continuously producedin nuclear reactions within the stars,and they are the most abundantparticles in the Universe afterphotons. Our planet is constantlytraversed by their flux: each second,60 billion neutrinos go through aspace the size of a fingertip. Theyinteract so weakly with otherparticles that they can go throughany form of matter without leavinga trace.

The new beam could shed light onthe neutrino mass problem, veryclose to Majorana's studies(http://public.web.cern.ch/Public/Content/Chapters/Spotlight/SpotlightCNGS-en.html).

We wish the best of success to theOpera and Icarus detectors at GranSasso, built in order to detect andstudy the long travelling neutrinobeam. Our wishes are even warmer,since the present director of the GranSasso Laboratory is Eugenio Coccia,gravitational wave hunter fordecades and member of the RomaII group, recently joining the VirgoCollaboration.

November 30

On this day, every year since 2000,the Festa della Toscana is celebrated.We are proud to note that this datehas been chosen to honour the sameday of 220 years ago. On November30, 1786 the grand duke of Tuscany(1765-1790) Peter Leopold ofLorraine published new laws for hisstate, including the definitiveabolishment of the sentence to death,for the first time in Europe and inthe world. In 1790, with the nameLeopold II, he became Holy RomanEmperor till his death, in 1792.

C. BRADASCHIA

How to Get to EGOby Bicycle

With the intention of providing afew alternative means of getting toEGO and also exploring a little ofthe surrounding area, this is the firstin a series on interesting diversionsin and around Virgo. Titled 'How toget to EGO by bicycle' maybe it canprovide a bit of encouragement tothose considering alternatives tohigh fuel prices, traffic jams,expensive taxis etc.

Route 1: Pisa - EGO

Distance: 18km, Duration: 1 hour

(A map can be found on thefollowing page)

We begin our journey from the southside of Ponte della Vittoria (1) andcycle the complete length ofLungarno Guadalongo. When thecar park finishes, the road veers tothe right. However, we go left (2)and join the cycle path, which runsparallel to the River Arno. We takethis for approximately 4km, untilthe cycle path stops abruptly - mindthe gap! - and descend to street-levelon the right-hand side (3).

Having descended from the bicyclepath, we take a right down a smallstreet between two rows of houses(Via Enrico Malatesta) (4), then takethe second left for Piazza Leone XIIIand then an immediate right on toVia Piastroni. After roughly 150metres, this becomes Via VecchiaFiorentina, which will take us almostall of the way to the Via Tosco-Romagnola.

At half way along the Fiorentina theBadia di San Savino can be seen onthe left-hand side. A small churchand quiet courtyard are still to befound inside, while the ex-dormitorywindows can be seen on the hillsideas you pass by from the road.

After a couple of km on theFiorentina we take a right onto Viadi Quarto (5), which brings usbriskly to the Via Tosco-Romagnola- normally very busy so keep youreyes peeled! Here we take a left sothat we are on the main road forapproximately 50 metres, beforeleaving it by taking a right onto ViaMoggi. This takes us under therailway line and into a thankfullyquieter area.

After passing beneath the railwayline and overcoming the shortsubsequent climb, take a left ontoVia di Pratale. We shortly encounter


O U T & A B O U T

a staggered crossroads; here, gostraight on and take Via Ivan Rocchi.

At the T-junction (6), we go rightonto Via Visignano and then takethe left-hand turn that brings us tothe first, and only, roundabout ofour journey. We go straight over thisand onto Via Oristano, which thenmerges onto Via Nugolaio, whichpasses in front of a couple of bigNavacchio retail outlets (Desio eRobe etc.) and is the ugliest part ofthe journey.

After around 200 metres we take aleft onto Via Fosso Vecchio (7) andinto the pleasanter climes that theArno plain has to offer.

The Fosso Vecchio is accompaniedby the ditch (dry in summer), whichgives it its name, and can be hard-going on windier days. It also makesup approximately 4km of ourjourney.

We leave it at the fourth availableright-hand turning over the parallelmain road (the FI-PI-LI) and crossthe tallest bridge of the ride (8). Weare now on Via Macerata, a coupleof km in length and a nice changefrom the hard work of the FossoVecchio. Don't worry, we are nowalmost there and can see the NorthEnd of Virgo for the first time!

The Via Macerata brings us to

Chiesanuova and the Via Arnaccio(9). Take care when crossing hereas the traffic is often moving at highspeed. Going straight over wecontinue on the Macerata for 3kmbefore we taking the final left turnonto Via Amaldi (10) and one lastfight against the wind before arrivingat the gates of EGO.

Please feel free to contributeinformation, possibilities orsuggestions on the various routesavailable in the surrounding area.

G. HEMMINGPHOTO: WWW.CERN.CH

MAP: WWW.GOOGLE.COM


O U T & A B O U T

SUMMER STUDENTSAT EGO

This year once again several summerstudents have been received at EGO.They have collaborated withdifferent projects from softwaredevelopment to data analysis. Hereis an extract of their impressions.

Jessica Democles from France, incollaboration with the Universitàdegli Studi di Pisa: "The task ofcontrol l ing theinterferometer isreally impressivesince you have tomake models topredict the expectedbehaviour, take dataand then analyze it,and find what couldbe wrong whenresults do not fit.The purpose of thiskind of internship isto get the head outof academic study,where you knowwhat you shoulde x p e c t , a n deverything worksbecause i t hasalready been proventhousands of times.So I think that, bym a k i n g m ycontribution to VIRGO on theanalysis of the "Scanning Fabry-Perot", and by following some ofthe other act ivi t ies of theinterferometer, I have learned a lotof things."

Jaime Junell from USA, incollaboration with INFN Roma: "Myshort stay at the VIRGO site hasbrought me many wonderfulexperiences. The program itself wasnot very organized or prepared toreceive me; however, everyone hasbeen extremely kind and a fewpeople have put forth great effort tohelp make this a valuable learning

experience. (…) The variety of workthat I have done has allowed me tosee how several different fieldsoverlap each other. Technicians,engineers, secretaries, computertechnicians, physicists, andprogrammers all must work as agroup. I have seen inventiveness,resourcefulness, hard work, andingenuity working together towardsone goal. I'm very happy with myexperience here at VIRGO."

Edward Greve from USA, incollaboration with INFN Roma:"The work I have done here inCascina was divided into twosections, first a small section onworking with software programmingfor data collection devices to be usedin VIRGO, and second on workingwith the Gravitational WaveStochast ic Background viamathematical modelling andcomputer simulation. (…) We wereable to test the equations withsimulated data, and then went ontrying to determine how to maximizethe performance of the detectors."

Geoffrey Guilbon from France, EGOinternship: "Working at EGO was avery nice experience. I applied herefor a four month training so as towork together with the SoftwareGroup. It was very interestingbecause it has been an occasion forme to learn a lot about softwareengineering inside a research centreand the way in which one has towork to make it possible for thewhole structure to be successful overa long time period. (…) It was also

the first time Iworked and livedon my own in aforeign country,and I was reallyamazed to seehow much peoplehelp each other,because at somepoint they havebeen in a similarsituation. I'll leaveEGO in a fewdays, at the endof September, andwill have verygood memoriesof my stay here inItaly among verynice people, andI'm pretty surethat I 'll comeback in the next

years."

Encouraged by the positivecomments, the Summer StudentProgram should be repeated also inthe coming years; the "researcherapprentices" staying with us for aperiod, may become PhD studentsor collaborators in the future.

From their comments we also thinkto understand that a little more ofpreparation and organization of theirwork would make the program evenmore successful.

B. LOPEZ, C. BRADASCHIAPHOTO: E. GREVE


P E O P L E

wsr1 sensitivity c7 sensitivity - public.virgo-gw.eu

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