An Astronomy Park around Virgo! - ego-gw.it · I was surprised to read such sharp opinions in such a widely diffused and normally “soft” magazine. ... such as a guitar string,

An Astronomy Park

around Virgo!

2

C O N T E N T S

NEWS FROM THE COLLABORATION 3Squeezing light to catch gravitational waves

FROM THE WORLD 6The Japanese Large-scale GW Telescope: KAGRALISA PathfinderAn Astronomy Park

NEWS FROM THE SITE 13The 2012 VESF SchoolThe new EGO optics laboratoryThe Biathlon 2012

OUT & ABOUT 16Copenhagen, a drama

LETTERS TO THE EDITOR 20

THE GRAVITATIONAL VOICE - FEBRUARY 2012

�h - The Gravitational Voice� is an internal

publication of the European Gravitational

Observatory (EGO) and the Virgo

Collaboration.

The content of this newsletter does not

necessarily represent the opinion of the

management.

Editor: Carlo Bradaschia

Editorial Staff:

Henrich Heitmann

Gary Hemming

Martin Mohan

Séverine Perus

Frédéric Richard

Production:

Séverine Perus

Published in electronic format on the EGO

Web:

www.ego-gw.it

E D I T O R I A L

While reading the following two articles on wind turbines in the April issue of Europhysics News:C. le Pair, F. Udo and K. de Groot: Wind turbines as yet unsuitable as electricity providers.http://dx.doi.org/10.1051/epn/2012204andP.J. Eecen, H.A. Bijleveld and B. Sanderse: Wind energy research - development of advanced design tools.http://dx.doi.org/10.1051/epn/2012203

I was surprised to read such sharp opinions in such a widely diffused and normally �soft� magazine.Hence, I thought it would be interesting to hear the reactions of the EGO and Virgo folk and, as such, I advertisedthe two articles by e-mail.

We publish in this issue of h, in the column �Letters to the Editor�, a subsequent exchange of letters and wemention the fact, upon the suggestion of Andrea Vicere�, that EPS and SIF are organising a school dedicated tothe theme: http://en.sif.it/activities/energy_school/2012 with �energy storage� being one of the central topics.We will be happy to receive and publish further comments on this hot subject.

C. BRADASCHIAEditor-in-Chief

http://www.europhysicsnews.org/index.php?option=com_article&access=doi&doi=10.1051/epn/2012204&Itemid=129

http://dx.doi.org/10.1051/epn/2012203

http://en.sif.it/activities/energy_school/2012

3THE GRAVITATIONAL VOICE - JULY 2012

N E W S F R O M T H E C O L L A B O R A T I O N

Squeezing light to catch

gravitational waves

That the expected amplitude of agravitational wave is quite small isa fact familiar to readers of h. So itshould not come as a surprise thatcatching a gravitational wave is adifficult task. It is mainly a struggleagainst various noises which do theirbest to mask the expected effect, adistance change between twosuspended mirrors.

Due to the smallness of the quantitiesinvolved, measuring the position ofa mirror with a ruler is out ofquestion and the VIRGO way to dothat is by using interference. In anutshell, a light wave (the laserbeam) is sent to a far away mirror,and the reflected wave is observed. The information about the mirror�sposition is contained in how manytimes the wave oscillates beforecoming back.

Obviously the mirror moves for alot of reasons unrelated to thepresence of gravitational waves, andcurrently the fundamental limitation

for the VIRGO sensitivity is thermalmotion. But let us suppose that in anot too far future thermal noise willbe reduced by a large factor. Thenwe will find that there is a kind ofnoise which is linked in a veryintimate way with the measurementprocedure used. We can call it opticalnoise or, for reasons that will bediscussed in the following, quantumnoise.

The surprising point about quantumnoise is that it could seem that itgives a limit to the sensitivity thatcannot be evaded for fundamentalreasons, no matter how smart weare. This is called Standard QuantumLimit (SQL).

When we think about a wave, weimagine something which is similarto the picture sketched in Figure 1.There is something which canoscillate, such as a guitar string, andthe �position� and the �velocity� ofa given piece of the string is well

defined at any time. The trouble with

this picture is that it is a classical

one. It does not take into accountthe fact that guitar strings (or theelectromagnetic field constituting alaser light wave) follow the rules ofquantum mechanics.

A quantum oscillator behaves in aquite peculiar way. We cannotdetermine exactly its �position� andits �velocity� at the same time:accordingly with the so-calledHeisenberg uncertainty relation theproduct of the indeterminacy of thesetwo quantities cannot be smallerthan a value proportional to afundamental physical constant calledh. This has interesting consequencesthat I will try to illustrate with someexamples.

In Figure 2 I represented the possiblepositions of a small �quantum ball�oscillating inside a valley as afunction of time. In drawing thepicture I supposed that initially theball was found with pretty goodaccuracy displaced in the positivedirection from the bottom of thevalley. The initial ball velocity isthus uncertain, this uncertaintybecoming larger and larger with theprecision of our knowledge of theinitial position. Several initialvelocities will be possible, and for

Figure 1. The VIRGO way to measure the position of a mirror. The light sentto the mirror (in red) is reflected back (in green) to the observer.

Figure 2 � The behavior of aquantum ball oscillating at thebottom of a valley. The oscillationis along the blue axis, while timeincreases along the red one. Eachcolor corresponds to a possibleclassical motion which starts at thesame position with a different initialvelocity.

THE GRAVITATIONAL VOICE - JULY 2012 4

each of them the position of the ballwill change in the following in adifferent way. The uncertainty aboutthe position will grow reaching amaximum after a quarter of theoscillation period, and then it willstart to decrease and so on,continuously oscillating between amaximum and a minimum.

This �quantum ball� behaves quitestrangely, but maybe I set it up inthe wrong way. If we want to obtaina more �classical� ball it is better toavoid a too accurate initial positionmeasurement, which unavoidablytriggers a large increase of theuncertainty afterwards.

The knowledge about the positionof a classical oscillator can be perfectin principle and it does not changewith time. The most similar quantumoscillation we can construct is theso-called coherent state, which isactually a quite accurate model fora laser beam. In this case the positionindeterminacy is not zero, but atleast it is time independent. This isshowed pictorially in Figure 3: inthe case we are interested in, theplot could represent the value of thelaser field at a given point as afunction of the time. The two colorscorrespond to two waves withdifferent amplitudes, and at a givent ime the indeterminacy isrepresented by the thickness of thecurve.

We should keep in mind that thereis no such thing as a �real� classicaltrajectory followed by the oscillatorbut hidden by our ignorance: at agiven time the oscillator is in aquantum superposition of positions.I will not discuss here the fascinatingsubject of the meaning of thisquantum superposition concept,which is a severe challenge for thecommon sense (1).

From our point of view we can seea quantum superposition as a noisesource: when we measure somethingabout the oscillator we will find aresult selected randomly among all

the possibilities. As we are interestedin measuring the displacement ofthe wave (that is, its phase), ameasurement will select one of theclassical oscillations compatible withthe given indeterminacy. By lookingat Figure 2 we see that there areseveral different phases which cancome out after the measurement,evidenced as classical curves withdifferent colors. In other words wehave a qu i te l a rge phaseindeterminacy.

For the coherent states in Figure 3things go somewhat better. Onceagain the phase is not completelydetermined, but its indeterminacy ismuch less than before. I plotted twoextreme possibilities for each wave(thin gray lines): this is an estimateof the limit on the sensitivity to theposition of the mirror.

By looking carefully at Figure 3 werealize an important point: the phaseindeterminacy of the orange curveis lower than the green curve�s one.This seems to suggest a simple wayto reduce phase noise: we couldsimply increase the field amplitude,by buying a more powerful laser.

Up to some extent this certainly

works. However increasing the laserpower is not a painless option, as itleads to several issues which are noteasy to deal with. But let us supposethat these could be solved: still wefind that quantum noise cannot bereduced arbitrarily in this way.

The reason is simple to understand:as it is clear from Figure 3, acoherent oscillator fluctuates bothin phase and in amplitude. Whenthe laser is reflected by the mirrorit acts on it with a pressureproportional to the square of itsamplitude. If the amplitudefluctuates the pressure will also andthe mirror will be displaced from itsoriginal position in an unpredictableway, changing the phase of thereflected beam anyway. When thelaser power is low this effect willbe small, but the intrinsic phaseindeterminacy of the coherent statewill be large. On the other handwhen the laser power is increasedthe intrinsic phase indeterminacywill decrease, but the phaseindeterminacy induced by the shakenmirror will increase. There will bean optimal intermediate power thatwil l give the lower phaseindeterminacy obtainable, which isthe Standard Quantum Limitmentioned before.


Figure 3. In a coherent state the knowledge we have about the amplitude ofthe laser field does not change with time, and it is the better we can get withthis constraint. This is the best approximation we can have of our intuitive(classical) concept of a wave.



Figure 4 - The state of a quantum oscillator can be changed. On the left sidefour different states for an incoming laser beam are depicted. The beamsreflected by a suspended mirror are described by new states, which arerepresented on the right side. Some classical oscillations compatible with theindeterminacy are superimposed in each case.

It seems that there is no way to escapefrom this, but this is not true. A hintabout a possible way out comes fromthe �strange� quantum oscillation wesaw in Figure 2, which is a memberof a family called �squeezed states�.This particular �squeezed state� isno better than a coherent one as itsphase noise is larger, but maybe withsome exploration it is possible to

find something useful.

The first option could be to use asqueezed state with less phase noisecompared with the one of a coherentstate. An object of this kind in factexists; it is appropriately called a�phase squeezed� state and isrepresented in the second row ofFigure 4, above.

But this solution does not work. Asthere�s no such thing as a free lunch,we see that together with a reducedphase noise there is an increasedamplitude one (2). When a laser beamin this �phase squeezed state� isreflected on a mirror, it shakes it alot, and the reflected beam (on theright side in Figure 4) is in a statewith an increased phase noise. Thisis the same effect that leads to theStandard Quantum Limit (see the firstrow of Figure 4) but worsened.

On the other hand if we try to use an�amplitude squeezed state� like theone which is represented in the thirdrow of Figure 4, this will be reflectedby the mirror without shaking it a lot.However a large phase noise will bepresent in the beam since thebeginning: this is not a good optioneither.

The simplest options do not seem towork well, but there is a large classof possible �squeezed states�. In the�phase squeezed� and �amplitudesqueezed� states I described so farthe probability of having a phasefluctuations is independent from theprobability of having an amplitudeone. In the general case we canintroduce correlations between thetwo.

And it turns out that doing this in aclever way we can obtain a �squeezedstate� that, after being reflected bythe mirror, has a phase noise reducedcompared with the one of a �coherentstate�. An example is represented inthe last row of Figure 4.

This opens the door to severalinteresting possibilities of evadingthe Standard Quantum Limit. In thelast decade these have beenextensively studied theoretically andtested experimentally. The level ofnoise reduction is continuouslyincreasing, and the key issue here isthe ability of generating laser beamswith large squeezing (3).

Squeezed light will be applied in thenext generation of advancedgravitational waves detectors. It willbecome in the future a more and

more important aspect in the designof gravitational wave observatories.

G. CELLA, Pisa Group

(1) For those who are interested to anon technical but careful introductionI cannot resist the temptation ofsuggesting a book: G. Ghirardi,Sneaking a Look at God's Cards,Princeton University (2007). It requiressome effort, but it is worth of it.

(2) This is a general consequence ofthe Heisenberg uncertainty relation,which can be rephrased by saying thatthe product of the position error at agiven time and after a quarter of periodis constant, so if we reduce the first weshould increase the second. I encourageyou to verify this on all the oscillationsin Figure 4.

(3) I will not discuss here in detail howa squeezed beam can be generated. Thisis done routinely today in opticallaboratories. I want only to remark thatwhen we reflect a coherent state on amirror, the reflected beam will be in asqueezed state, as shown in the firstrow of Figure 4.

After long and arduous efforts theJapanese Large-scale Gravitationalwave Telescope (LCGT) was finallyapproved by the Ministry ofEducation, Culture, Sports, Scienceand Technology in June of 2010.Although a significant amount ofdelay was caused by the TohokuEarthquake and its aftermath, theexcavation of the tunnel at theKamioka mine was finally startedon May 22, 2012. Meanwhile,

KAGRA was selected as the newnickname for LCGT, which isassociated with the KamiokaGravitational wave detector, and anew logo (see Fig. 1) was chosensubsequently. In Japanese, the wordkagura means music and dance inhonor of Japanese gods. In thisarticle I will briefly explain theobjectives, design, preparation,schedule, and organization ofKAGRA.

The objectives of KAGRA are todetect gravitational waves and toestablish a new astronomy -gravitational wave astronomy -together with Virgo, LIGO, andGEO in the context of the worldwidenetwork. We are especially interestedin detecting gravitational wavescoming from neutron star binarycoalescences. These detectionstogether with simultaneous gamma-ray observations will, for instance,allow us to determine whetherneutron star binary coalescences aretruly an engine of short gamma-raybursts. We also expect to detectgravitational waves coming fromblack hole binary coalescences,supernovae, pulsars, etc., althoughthe expected detection rate for suchevents is not well established.

KAGRA consists of a 3km longResonant Sideband Extraction (RSE)interferometer with the cryogenicmirrors suspended from the SeismicAttenuation System (SAS). Thedetector will be built undergroundin the Kamioka mine, 200m belowthe surface, as illustrated in Fig. 2.The vibration level at the site is afactor of 100 smallerthan the surface, whichtogether with the SAS,reduces the seismically-originated mirror motiondrastically. The SASwas developed based onthe Vi rgo Super-attenuator technologies,and in collaboration withLIGO. As shown in Fig.

3, the SAS consists ofan inverted pendulumand a mul t i -s tage

pendulum. Each stage also acts as avery low-resonant-frequency vertical

isolator with the help of geometricanti-spring effect, invented byRiccardo DeSalvo. The mirrors ofthe arm cavities are cooled to 20Kin order to reduce the thermal noise.For this purpose, sapphire substratesand fibers will be used because ofthe material�s excellent mechanicaland thermal properties. The lowerstages of the SAS are set up in acryostat (see Fig. 4), and are cooledby a pulse tube cryocooler via softheat links to the intermediate masses.The cryogenic thermal shield aroundthe masses and inside the beam tube(up to 20 meters from the masses)prevents the masses from beingexposed to the thermal radiationfrom the room temperature vacuumchamber and beam tubes. Thetopology of a power-recycled Fabry-Perot Michelson interferometer,which is used for most of the 1st-generation detectors, such as Virgo,LIGO and TAMA300, will beenhanced by an RSE configuration,for which an additional mirror isplaced at the anti-symmetric port.


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

The JapaneseLarge-scaleGravitational

Wave Telescope: KAGRA

Fig. 1. Logo of KAGRA

Fig. 2. Illustration of KAGRA locatedunderground in the Kamioka mine.

This configuration allows us tooptimize the quantum noise, that iscomposed of shot noise and radiationpressure noise, with regard to thechirp signal expected from acompact-star binary coalescence.

KAGRA is required to detectgravitational waves coming fromneutron star binary coalescencesmore than once a year withprobability of higher than 90%. Tosatisfy this requirement, the dutyfactor of KAGRA must exceed 80%

and the observation range must belarger than ~180 Mpc. Here, asignal-to-noise ratio of 8 forgravitational waves incident normalonto the detector is assumed. Thespectrum of the sensitivity limit ofKAGRA is shown in Fig. 5, whichgives an observation range of ~280Mpc. In reality, however, weanticipate that various practicaldeviations from the ideal designcould impair this sensitivity limit.

In Japan we started research anddevelopment for the detection ofgravitational waves with a laserinterferometer around 25 years agowith the 10m and, later, the 100mdelay-line prototypes at Institute ofSpace and Astronautical Science(ISAS), and then with the 20mFabry-Perot prototype at NationalAstronomical Observatory of Japan(NAOJ). Encouraged by thesuccessful results on thoseprototypes, we proceeded to realizeTAMA300 at NAOJ and CLIO atthe Kamioka mine facility of theInstitute for Cosmic Ray Research(ICRR), University of Tokyo.TAMA300 is a power-recycledF a b r y - P e r o t M i c h e l s o ninterferometer, where a simplerversion of SAS was installed and itsperformances were successfully



Fig. 3. Seismic Attenuation Systemfor KAGRA. The upper and thelower parts are separated by solidrock.

Fig. 4. Sketch of the cryostat and cryocoolers designed for KAGRA.

Fig. 5. Sensitivity limit of KAGRA.


verified. CLIO, the 100m cryogenicprototype interferometer, was builtto demonstrate the cryogenictechnologies required for KAGRA.At room temperature CLIO hasachieved a sensitivity limited byboth the suspension thermal noiseand the mirror thermal noise. By

cooling of the two front mirrors areduction of thermal noise couldsuccessfully be demonstrated (seeFig. 6). This was a crucial milestonefor the success of KAGRA.

After the tunnel is completed, whichis expected to happen in March of2014, we plan to build KAGRA intwo stages: initial KAGRA(iKAGRA) and baseline KAGRA(bKAGRA). iKAGRA is a simpleF a b r y - P e r o t M i c h e l s o ninterferometer with a modestvibration isolation system and fusedsil ica test masses at roomtemperature. We decided to startwith iKAGRA to gain some usefulexper ience for a km-classinterferometer and also to learntechnical challenges for bKAGRA.We plan to conduct a short

observation run in 2015 to checkthe data acquisition system andanalyze the obtained data. We hopethat we can achieve a sensitivitygood enough to join the worldwidenetwork of gravitational wavedetection. Then we will proceed tobKAGRA.

It is an RSE interferometer with afull SAS and sapphire mirrors atcryogenic temperature. We hope tof inish the instal la t ion andcommissioning to start an obser-vation run around 2017 - 2018.

The KAGRA project is hosted byICRR with strong support from theHigh Energy Accelerator ResearchOrganization (KEK) and NAOJ, aswell as from more than twentydomestic and more than teninternational institutes/universities.KAGRA is led by PrincipalInvestigator, Takaaki Kajita, who isalso the director of ICRR and theExecutive Office (EO). The EOmanages fourteen subsystem groupswith the help of the ProjectManagement Support (PMS) groupand mostly through the Systems

Engineering Office (SEO). KAGRAcouncil consisting of the directorsof ICRR, KEK, and NAOJ and otherimportant members determinescritical issues on the project.KAGRA also has Program AdvisoryBoard (PAB) and External ReviewBoard (ERB). PAB consisting ofsenior members in the GW andneighboring field (includingEuropean members: Benoit Moursand Bernard Schutz) reviews mainlythe management aspects ofKAGRA, while ERB consisting ofresearchers with high expertise inthe GW field (including Europeanmembers: currently RaffaeleFlaminio, Andreas Freise, RobertoPassaquieti, and Benno Willke, andformerly Alessandro Bertolini)reviews mainly the technical aspectsof KAGRA.

KAGRA employs the undergroundlocation and cryogenic mirrors,which are key technologies for the3rd-generation gravitational wavedetectors, such as the EinsteinTelescope (ET). Therefore, KAGRAis not only one of the 2nd-generationdetectors, aiming for the first directdetection of gravitational waves, butalso plays an important role forfuture generations to further developgravitational wave astronomy.H e n c e , w e a r e n a t u r a l l ycollaborating with the ET projectby exchanging young scientists withthe ET-LCGT interferometricTelescope Exchange of Scientists(ELiTES) program led by MichelePunturo on the ET side and with thestudent fellowships on the KAGRAside (we also plan to submit aproposal equivalent to ELiTES).

KAGRA is still in the initial stageof the project, but we truly hope thatwe can achieve a good sensitivityas soon as possible to join the worldnetwork of gravitational wavedetection.

Professor Seiji KawamuraInstitute for Cosmic Ray Research

University of TokyoSubproject manager of KAGRA

Member of GWIC


Fig. 6. Sensitivity of CLIO operated with the two front mirrors at room(grey trace) and cryogenic (red trace) temperature. (Takashi Uchiyama,et al., Phys. Rev. Lett. 108 (2012) 141101)

LISA Pathfinder: achieving near-perfect

free-fall for gravitational wave astronomy


A gravitational wave is �felt� asa tidal effect, a position-dependentacceleration that stretches andcontracts, just as the gravitationalfield of the sun and moon isobserved in the swelling of the oceanat opposite sides of the Earth. Agravitational wave detector�s simple,but difficult, task is that of measuringthe minute tidal deformation that apassing gravitational wave produceson a constellation of free-falling testparticles.

In terrestrial laser interferometerdetectors like VIRGO and LIGO,aimed at sensitivity in the range of10 Hz to audio frequencies, the testparticles are suspended end mirrorsseveral km apart, which are in free-fall except for calibrated suspensionand control forces. For ultra-lowfrequencies, from nano to microHz,several dozen neutron star pulsarsscattered across the Milky Way canserve as test masses, withgravitational wave strain detectablein the Doppler-shifted arrival of theirradio beacon �clock� pulses atearthbound radio telescopes. Forgravitational wave detection in theintermediate 0.1 to 100 mHz band,the LISA � Laser InterferometerSpace Antenna � mission conceptforesees roughly-kg test massesorbiting around the sun in a nearlyequilateral triangle with severalmillion km side length.

These detection techniques are allforms of differential accelerometry. The gravitationally-induced relativeacceleration of the free-falling testbodies is measurable, but it is indirect competition with two mainnoise sources: first, the fake effective

acceleration caused by noise of thedetector as a displacement sensor,and, second, any true residualacceleration of the test particlescaused by spurious forces unrelatedto the gravitational wave. For thissecond reason, the free-falling testparticles are also known as�geodesic reference� test masses, asthey ideally serve as references ofpurely gravitat ional orbits .

For LISA, the maximum tolerabledeviation from perfect free-fall isquantified by a residual accelerationnoise with a noise power spectraldensity below 3 10

-15/s

2/Hz

1/2. This

translates to a background ofspurious acceleration low enoughto allow, in several hours time,resolution of a gravitationaldifferential acceleration withamplitude 10

-17 g � where g = 9.81

m/s2 is the well known acceleration

due to gravity at the Earth�s surface� with oscillation periods from 5minutes to severa l hours .Coincidentally, this requirement forlow acceleration noise is similar tothat needed, around 10 Hz, forAdvanced VIRGO.

LISA will observe binary systemsof compact objects � solar massblack holes, neutron stars, and whitedwarfs � at a point in their evolutionmillions of years before their orbitalfrequency reaches the audiofrequencies range detectable byVIRGO, minutes before their finalmerger. More unique to LISA aregravitational waves from compactobjects falling into the massive blackholes at the centers of galaxies andcoalescences of the massive blackholes themselves, binary systems

with millions of solar masses thatmerge at frequencies far below theterrestrial observation band.Achieving � or not achieving � thetarget acceleration noise floordetermines the LISA resolution atand below several mHz, and thusalso the number of astrophysicalsources that we can observe, to whatdistance, for what length ofobservation time, and how well wewill know their sky positions.

Given the impact that free-fall willhave on gravitational wave science,it is reasonable to ask � can wereally use an apple-sized test massas a reference of pure free-fall withsuch precision, well below a femto-g (�femto� means 10

-15)? Probably

yes, according to analysis and earth-based measurements of the smallforces that can perturb the test massorbit. However, a complete answerto this question awaits the results ofLISA Pathfinder, the �Einsteingeodesic explorer� mission.

LISA Pathfinder

LISA Pathfinder (LPF) is aEuropean Space Agency (ESA)-ledmission aimed at achieving, andmeasuring, sub-femto-g free-fallwith the core hardware that will beused for LISA. It will launch in2014, from French Guyana, into the1

st Lagrange point roughly 1.5

million km toward the sun, with theaim of guaranteeing the differentialaccelerometry resolution that isneeded to open the window of space-b a s e d g r a v i t a t i o n a l w a v eastrophysical observation in the nextdecade.


Free-fall and gravitational wave detection


Space allows much larger testparticle separation than the km-sizedinterferometry arms possible onearth. It eliminates the force noiseintroduced by suspending the testmass in 1 g � indeed it eliminatesthe need to touch the test mass atall � and radically extends the timescale over which the test mass canbe considered in free-fall. It alsoallows us to safely distance the testmasses from the Earth�s locallynoisy gravitational field frommoving water, rock, air, and life.These are the reasons why we needto go into space to detectgravitational waves at frequenciesbelow 1 Hz.

Space does not remove, however,the residual interaction with the co-orbiting satellite and the localenvironment around the test mass. Additionally, the LISA accelerationnoise goals are three orders ofmagnitude beyond what is currentlyachieved by the best spaced i f f e r en t i a l a cce l e rome t ryexperiments, such as the GOCEmission, which measures spatial and

temporal variations in the Earth�sgravity. As both the sensitivity leveland low frequencies required aredifficult to reach in an Earthboundlaboratory, an in-orbit experimentl ike LPF i s necessary toconvincingly demonstrate themeasurement science needed forspace-based gravitational waveastrophysics.

The idea of LPF is to drasticallyshrink a single LISA arm to fit intoa single spacecraft, with two free-falling test masses separated by 40cm, and then perform a laserinterferometer measurement of theresidual relative accelerationbetween the two test masses. Thesensitivity to gravitational waves islost in the factor 10

9 reduction of the

test particle separation, but therelevant noise sources for the strayTM acceleration remain and will bedetected at the femto-m/s

2-level.

The co-orbiting satellite, in additionto housing interferometry hardware,shields a LISA or LISA Pathfindertest mass from the fluctuating solar

radiation pressure that wouldotherwise dominate its residualacceleration. The remaining sourcesof force noise relevant at the femto-g level include cosmic ray chargingof the test mass and strayelectrostatic fields; test massmagnetic impurities and theinterplanetary and spacecraftmagnetic fields; Brownian motionfrom residual gas impacts;fluctuations in nanoNewton-levelapplied electrostatic control forces;spacecraft self-gravity fluctuations.

All of these noise sources, andothers, will be tested on LISAPathfinder. The most threateningsources are those acting on the testmass surface due to the surroundingelectrostatic, magnetic, vacuum, andthermal environment; these sourcescan be well-characterized on groundw i t h t o r s i o n p e n d u l u mmeasurements of small forces withsuspended LISA-like test massesinside of the relevant flighthardware. Finally, Brownian noise,stray electrostatic fields, noisycontrol forces and other sourcestargeted by LPF are relevant to abroad class of experiments withreference test masses, includingVirgo. Thus, the LPF investigationsbuild a physical model of the limitsto achieving perfect geodesic motionfor experimental gravitation.

Figure 2 shows a conservativeprediction for the LPF accelerationnoise performance, based onextensive ground testing of both theinterferometry sensitivity and forcenoise sources. In addition toimproving upon the official missiongoal, the expected performancemeets the LISA acceleration noisegoal at all frequencies above 1 mHz. In so doing, LPF should guaranteethe core LISA scientific return,including high precision observationof gravitational waves from anumber of known white dwarfbinary systems in our galaxy. Alsoshown are current upper limits tosurface forces acting on the testmasses, based on torsion pendulummeasurements with prototype flighthardware, indicating that LISA


Figure 1 Illustration of the LISA Pathfinder science payload, featuring the two2-kg Au/Pt test masses, separated by a Zerodur optical bench with interferometryhardware to allow a relative acceleration measurement.

THE GRAVITATIONAL VOICE - JULY 2012 11

would allow gravitational waveobservation, even if the flightperformance were no better than thatalready demonstrated with our moremodest ground instruments.

Challenging economic times andevolving science programs insideboth ESA and NASA have increasedthe error bars relevant to the launchdate of LISA and have reopeneddiscussion of many aspects of themission � including the orbits, theoptimal size and number of laserlinks for the available budget, thenature of the collaboration betweendifferent agencies, even the use ofthe name �LISA� itself. Theastrophysical science case andperformance requirements remainunchanged, however, as does themeasurement technique and keyhardware. LISA Pathfinder isfinanced to fly, and it represents, inVi r g o t e r m i n o l o g y, t h ecommissioning phase for the finals p a c e g r a v i t a t i o n a l w a v eobservatory, whether or not it isnamed LISA. We hope to providean update, with data from theorbiting LPF spacecraft, in just acouple of years!

William Joseph WeberUniversità di Trento

19 June 2012


I live in Santo Stefano a Macerata,in the vicinity of EGO. My thesis toobtain the �architect� degree at theUniversity of Florence was inspiredby two outstanding structures in theterritory. One is EGO and the otheris the remaining structure ofDecoindustria. We already knowabout EGO but what about

Decoindustria? Decoindustria, whichis situated between Chiesanova andthe Virgo North End Building, was

a plant devoted to the treatment ofcontaminated liquids. It was closedby the Italian magistracy for illegalAn Astronomy

Park

by Sara Baglini

Figure 2 Expected performance for the LPF acceleration noise upper limit(black) compared with the LPF and LISA mission specifications. Also shownare the acceleration noise levels required to observe gravitational waves froma number of known galactic white dwarf binary systems and torsion pendulumupper limits on the contribution from test mass surface forces. [Presented atthe Marcel Grossmann 12 Conference in July, 2012]

For more information on LISA Pathfinder, see:http://www.rssd.esa.int/index.php?project=LISAPATHFINDER&page=Indexandhttp://www.esa.int/esaSC/120397_index_0_m.html.

For the evolving LISA concept, see: http://elisa-ngo.org/.

http://www.rssd.esa.int/index.php?project=LISAPATHFINDER&page=Index

http://www.esa.int/esaSC/120397_index_0_html

http://elisa-ngo.org


management of poisonous waste.

The idea took shape of convertingthe industrial plant to somethingnice and useful for the community.Virgo was the inspiration for theproposal to create a national SciencePark dedicated mainly to astronomy.Virgo would play a strong role inattracting people while theattendance would be enhanced bythe location along the linearmetropolitan area, which is expectedin the future to connect Pisa withFlorence.

The idea has been endorsed by theCascina County Council which isalready engaged in the challengingd e c o n t a m i n a t i o n o f t h eDecoindustria site. It has become areal design by the architects SaraBaglini and Danilo Gentili. For therealization it will be necessary toobtain funds at regional, nationaland European level.

Designing the Park

�Gira.sole Luoghi diScienza�The original landscape wascharacterized by the horizontal linesof fields, interrupted by cypress rowsand a few farm houses. The newlandscape will be dominated by theexistence of the EGO observatoryand by the large industrial complexesconverted for public use.The needs of students, researchersand tourists will be taken intoaccount within the framework of ascience oriented developmentstimulated by local universities,research institutions and hightechnology spin off industries.

In addition to a Planetarium and anAstronomy Museum the AstronomyPark will include a Hostel for visitingclasses and a Guest House forresearchers temporarily working atEGO.The Hostel and the Guest Housewill be designed reproducing thearchitecture of old country houseswith common wide yards to be used

by students and researchers. Atground level all the commonutilities: kitchen, library, readinghall, pub. On the upper floor roomsand small apartments will beavailable for longer stays.

The Planetarium and the Museumwill preserve the size and the shapeof the two largest tanks of the oldindustrial plant. Their puregeometrical shape corresponds verywell with the new safe technologywhich replaces the dangerousoriginal. In the Planetarium,equipped with I-Max technology,there will be room for projectionsand science inspired shows. In theMuseum there will be laboratoriesfor hand-on experimental activity.The large instrument prototypes andthe free fall demonstrator presentlyhosted at EGO will be moved to thegarden outside.

The four natural elements can bediscerned in this natural science site:� Fire: the stars projected in



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

the Planetarium cupola

� Air: the central open spacein the Museum building

� Earth: the garden soil andthe lining coating the cylindricalbuildings

� Water: the fountain basin inthe central court.

The PlanetariumThe entrance is through a classicaldromos (entrance to ancient Greektombs) s lowly descendingunderground. The visitor will beguided from the obscurity ofignorance to the virtue of wisdomalong a spiral slope surrounding the75 seat Planetarium. The outside ofthe cupola, a full sphere, willreproduce the Earth�s surface,transforming the walk to the entranceof the Planetarium into a �journeyaround the world�.

The Astronomy MuseumThe wide central space is partlyoccupied by a large crystal spherecontaining a tree sprouting from awater basin. It is a symbol of naturepenetrating the building, an outsidesymbol contained inside a shell. Atground level there will be a bookshop, a media center, a bar and otherservices. Astronomical exhibits, skypictures and videos will be exhibitedon the two upper floors.

The 2012 VESFSchool

In the week of June the 18th tothe 22nd, EGO hosted the first VESFSchool on Gravitational Wave (GW)Advanced Detectors.

In the year when work on AdvancedVirgo and Advanced LIGO haskicked off, the VESF Executive

Board has proposed a topical school,for the first time focused onexperimental issues related to thedesign and construction of AdvancedInterferometers: this has turned outto be good intuition, as the numbersconfirmed: we had 18 participants,mostly PhD students (and some post-docs). They represented 9 differentnationalities over two continents(France, Germany, Great Britain,Greece, India, Italy, Poland, Spainand Ukraine), and they arrived from13 different institutions, from 7countries and 2 continents: Siena,Camerino, Pisa, Roma 1 and 2,AEI, Glasgow, IEES, Artemis, LAL,Leiden, Warsaw and MIT.

One striking feature was the highnumber of women participating: 7,a record for any VESF School! Allthe students were well prepared andmotivated: many of them are alreadyactive in the Virgo collaboration,some might join in the future, othersare involved with GEO or even withLISA.

The course was held by 14 lecturersof high profile, recruited in 5different countries (+ EGO). Mostof them are actively working onAdvanced Virgo, but we also had 2representatives from the LSC. Thelectures, spread over 5 days, rangedover topics from sources tosuspensions, from lasers to cavities,

from controls to diffuse light andthermal noise, covering most of theissues that characterise the upgradeto Advanced interferometer.Overall, the students were subjectedto an amazing 996 slides in 27 hours!Also for this reason, the guided tourof the Virgo facili t ies wasparticularly appreciated, and raiseda lot of interest and curiosity.

A nice dinner topped the socialprogramme and strengthenedfriendship ties: rumour has it thatthe after dinner socialisation lastedtill late into the night (or should wesay early morning?!). Logistics was,as usual, quite efficient and effective,despite the concurrent meeting ofthe EGO Council that absorbed mostof the energies and time of the EGOstaff. Our thanks to EGO and itsDirector, to the computing peopleand to the secretariat, for a smoothand trouble-free school!

In summary, an experimental school,both in the sense of a newprogramme and of a syllabusfocused on the experiment, whichturned out to be a success!

M. BASSAN

Picture below: school participants withMassimo Bassan (school co-director)and Stefan Hild (lecturer).

The �old� EGO Optics Lab wascreated in September 2007 in thenew building to cope with thegrowing needs of on-site testing andprototyping of new optical systemsfor the maintenance and upgrade ofVirgo.

The main part of the lab wasspecifically dedicated to thecompletion of the R&D for the HighPower Input Optics (HPIO) toprepare for AdV. Figure 1 shows theenclosure hosting the 200W lasersource and the dedicated high poweroptical setup. In addition to R&Dstudies, the setup was intensivelyused to develop recent Virgo+upgrades such as improvement ofthe SIB Faraday isolator, realisationof high power in-vacuum beamdumps for the detection system,study of high power diaphragms�

A second part of the lab (see Figure2) was used for all other activitieswi th s e tups ded i ca t ed t omeasurements such as diffusion,reflectivity, absorption, polarisation�and some more exotic activitiessuch as the development of a newadaptive optics system for GW

detectors, the TDM. (ThermallyDeformable Mirror). Since itscreation, the amount of activities inthe lab has constantly increased,reaching complete saturation. Inaddition to the permanent opticalsetups installed in the facility, the43 m2 of the lab were also used tostore various optical materials,devices and spares, leaving no roomfor new setups or space formounting, cleaning and inspectionof optics.

Besides, new activities are foreseenin the next few years since the EGOOptics Group is in charge of the INJsubsystem for AdV, which means inparticular the development of 2 largeoptical benches. The HPIO R&Dsetups have to be maintained overthe next 2 years as the final FaradayIsolator and other components willbe built and characterised beforeintegration into AdV.

It was therefore decided in 2011 toenlarge the lab by �absorbing� thespace dedicated to the electronicslaboratory that moved to Building

1. Plans of the new lab can be seenin Figure 3.

The two rooms, Optics Labs 1 and2, correspond to the old laboratory.The addition of two new roomsdoubles the total space of the lab:Optics Lab 3 hosts three new opticaltables and will be devoted to themost demanding applications interms of cleanliness, Optics Lab 4will be used for storage and somespace will be devoted to noisestudies with, for example, a setupd e d i c a t e d t o m e c h a n i c a lcharacterisation of optical mounts.

The most important modificationsof the infrastructures are linked tocleanliness issues. Indeed, the �old�laboratory was created in a spacethat was supposed to host someoffices, and the materials used wherefar from adapted to a cleanenvironment. Despite all efforts tomaintain the old lab �as clean aspossible�, Figure 4 shows the stateof an optic exposed for a few daysto its hostile conditions.

Figure 4: A few days of dust expositionin the old lab.



Figure 1: High power room of the �old�optics lab

Figure 2.

Figure 3: Plan of thenew laboratory

The new EGOoptics

laboratory

Therefore, considerable effort wasmade to modify rooms 1, 2, 3 inorder to limit this issue. More indetail, the ceiling, originally madeof plaster, was replaced with plasticplates. Then, the walls were paintedwith a special paint and a PVC floorwas installed. In addition, theexisting air conditioning wasmodified to control the temperatureof rooms 1 to 3 and clean filterswhere installed on different ACoutlets.

Figure 5: A view of one of the newrooms, Optics Lab 3.

Infrastructure works started inFebruary 2012 and finished last May.First impressions of the new lab arevery good and people find it for themoment a very convenient place towork. Figure 5 shows a view of thenew room Optics Lab 3 where somesetups for AdV, such as BMSi m p r o v e m e n t a n d R F Ccharacterization, were alreadyinstalled. As one can see from thisfigure, in only one month, this newroom already starts to be crowded...

B. CANUEL

EGO Optics group

With respect to past years (in 2011it rained shortly after everybody hadmoved to the canteen), this year theBiathlon took place during aparticularly hot period.

This might have deterreda few potential athletesfrom participating, butnevertheless four teamswere formed, ready top a r t i c i p a t e i n t h ecompetition.

The table below shows themeasured times after halfthe Biathlon (athletesreturning from the Northa r m ,grey)

and the finaltimes (white).

The winningteam was thenewly createdPartenoPisa; butbeing a blend ofthe traditionallyv i c t o r i o u sNapoli (poetic:Partenope) andLocking teams,its victory wasn o t a r e a lsurprise. For the

second to fourth places, the arrivalsequence changed quite a lotbetween the first half (the athletescoming back from the North Arm)and the final result.

Despite the difficult weatherconditions, the winning time wascomparable with that of past years(2011: 35�13��; 2010: 36�29��).

H. HEITMANN

h Reporter



The Biathlon2012

Heading for the final leg of the run,after receiving the baton from thecyclist.

Photo courtesy of Marc van der Sluys.

In this issue we use the productionof the play 'Copenhagen' by MichaelFrayn at the Church of San Zeno inPisa on the 15 of June, which wassupported and promoted by EGO,along with the Foundation Pisa andthe Comune di Pisa, as a springboardto look at the event on which theplay is based, its author and thesetting in which the performancewas given.

The Bohr-Heisenbergmeeting

The play itself is based on a meetingthat took place in occupied Denmarkin September 1941 between thephysicists Niels Bohr (1885-1962)and Werner Heisenberg (1901-1976), while the latter visitedCopenhagen with fellow physicistCarl Friedrich von Weizsäcker. Whatactually took place at that meetingwill probably always be lost in themists of time, but, in subsequentyears it has been possible toformulate a general idea � perhaps'ideas' is a more precise way ofputting it � of what was discussed.The issue of the content of thediscussion first emerged with thepublication of the book 'Brighterthan a thousand suns: A personalhistory of the atomic scientists',which contains the first publishedaccount of the Manhattan Projectand the German atomic bombproject, by Robert Jungk (1913-1994) in German in 1956. Jungk,who was born into a Jewish familyin Berlin and was studying at itsuniversity when Hitler came topower, emigrated to Paris andstudied at the Sorbonne in 1933,before spending the period 1936-1938 in Prague, publishing an anti-fascist paper. From '38, with theentrance of the Nazis into Prague,he fled to Switzerland, where heremained until the end of the war in1945 [2]. He described himself as a'scientific journalist' [1] andproduced a considerable volume of

literature in relation to thedevelopment and production of bothnuclear energy and weapons. Hewas also keenly involved in thethemes of peace, the future and anti-nuclear activity, publishing, amongnumerous other titles, a critique ofthe nuclear industry with 'TheNuclear State' in 1970 and evenstanding as Green Party candidatein the Austrian presidential electionsof 1992, eventually won by ThomasKlestil. Following the 1956publication he was contacted directlyby Heisenberg, who wished toclarify a handful of points thatemerged following the latter'sreading of the text during a periodof short illness [3]. It is from thisexchange of letters, which took placebetween November of '56 andJanuary of '57, and subsequentevents that the dynamic of the affairemerges.

Heisenberg's original letter coversan array of different issues, from thepolitical convictions of a colleagueto discussions on the 'Uraniamproblem', and the concept of activeresistance within a totalitariandictatorship. He even goes as far asto note that he has actually readalmost all of the works by theEnglish novelist Anthony Trollope,rather than Tobias Smollet, as hadbeen reported by Jungk in his text.However, it is his subsequent letter,motivated by a request for furtherinformation solicited by Jungk inreply to the original correspondence,that the Copenhagen meeting isaddressed.

In his reply, Heisenberg describeshow the physicists in, what he terms,their 'Uranium Club' had reachedthe conclusion that not only wouldit be possible to produce energy froma uranium and heavy water reactor,but also that a decay product of 239-uranium would be produced whichcould be used as an explosive in anatomic bomb. However, theyperceived the technical resources

required to achieve an objective ofthis kind to be 'enormous'. Hecontinues by explaining how thiswas actually a useful situation:

�This situation seemed to us to bean especially favorable preconditionas it enabled the physicists toinfluence further developments. For,had the production of atomic bombsbeen impossible, the problem wouldnot have arisen at all; but had itbeen easy, then the physicistsdefinitely could not have preventedtheir production...The actual givensof the situation, however, gave thephysicists at that moment in time adecisive amount of influence overthe subsequent events..� [3]

In this context, Heisenberg statesthat they, note the fact that the letteruses 'we', rather than 'I', thought thata discussion with Bohr 'might be ofvalue'. During that meetingHeisenberg states that he asked Bohrwhether he thought it justifiable thatscientists work on the 'Uraniumproblem' dur ing war- t ime,considering the grave consequencessuch work might imply. Hecontinues by saying that Bohr'immediately grasped the meaningof the question' and describes hisresponse as being 'startled'. He thensays that Bohr immediatelydemanded:

�Do you really believe one canutilize Uranium fission for theconstruction of weapons?� [3]

Heisenberg then becomes a littlemore coy, stating that he 'may' havereplied that 'I know' that, at least inprinciple, it is possible. He thendescribes how Bohr was so 'shocked'at what he had heard and that theexplanation for this reaction musthave been that Bohr believedHeisenberg was trying to tell himthat Germany had made great stridestowards the manufacture of thebomb.This letter certainly gives rise to a


O U T & A B O U T

Copenhagen, a drama

sense of frustration on the part ofH e i s e n b e r g ; a s e n s e o finconclusiveness; of an unfinishedpiece of business. He puts this downto the fact that he knew that Bohrwas being closely monitored by whathe terms 'German poli t icaloperatives' and as a result, he wasforced to be circumspect in hisstatements:

�I tried to keep the conversation ata level of allusions that would notimmediately endanger my life...Inmy subsequent attempt to correctthis false impression I must not havewholly succeeded in winning Bohr'strust, especially because I only daredto speak in very cautious allusions(which definitely was a mistake onmy part) out of fear that later on aparticular choice of words could beheld against me.� [3]

He felt that this impossibility tocommunicate fully was at the rootof the misunderstanding. Certainly,he was correct in believing that Bohrwas under surveillance. At the endof September 1943, Bohr, whosemother was Jewish, receivedwarning of his imminent arrest bythe Gestapo as part of a planneddeportation of all of the Jews inDenmark. He and his wifesubsequently fled to Sweden by sea[4] as part of what has becomeknown as the 'Rescue of the DanishJews' � an historic event in whichthe Modstandsbevægelsen (DanishResistance Movement) with the helpof many ordinary Danish citizens,evacuated the vast majority of thecountry's Jewish population by boatsof varying sea-worthiness toSweden. As a result of these actions,8,000 people's lives were saved. Atthe end of the war, 99% ofDenmark's Jewish population hadsurvived the Holocaust. [5] Beforelong he was taken by militaryaeroplane to Britain, where he wasintroduced to the secret atomic bombproject, before being transferred tothe Los Alomos base in the UnitedStates, where he worked on theManhattan Project under thepseudonym 'Nicholas Baker' forsecurity reasons. [6] Interestingly,

Bohr frequently expressed concernabout the development of atomicweapons and is even quoted ashaving later said, �That is why Iwent to America. They didn't needmy help in making the atom bomb.�[7] Following a meeting withOppenheimer, in which it wasapparently decided to send Bohr tospeak to Roosevelt about thepossibility of sharing informationwith the Russians, in order to speedup work, Roosevelt seeminglyproposed that Bohr should discussthe idea with Churchill, to gainBritish agreement. Churchill,however, of course not renownedfor his overtly friendly sentimenttowards the communist system,recorded �It seems to me Bohr oughtto be confined or at any rate madeto see that he is very near the edgeof mortal crimes.� [8]

The remainder of the letter dedicatedto the meeting deals with what tookplace in a less distinct manner,exploring rather issues in relation tothe state of developments inGermany and the USA at the time.It is interesting however, to noteh o w H e i s e n b e rg g o e s t oconsiderable lengths to stress thathe is uncertain of all that he recallsowing to the passage of time �remember this was 15 years afterthe event - and to a conscience ofan unspoken sub-text to the meeting,which rendered it difficult to clarifyprecisely what took place:

�Everything I am writing here is ina sense an after the fact analysis ofa very complicated psychologicalsituation, where it is unlikely thatevery point can be accurate. - Imyself was very unhappy over thisconversation...Even now, as I amwriting this conversation down, Ihave no good feeling, since thewording of the various statementscan certainly not be accurateanymore, and it would require allthe fine nuances to accuratelyrecount the actual content of theconversation in its psychologicalshading.� [3]

An extract of Heisenberg's letter was

included in the Danish languageversion of the text, also publishedin 1956, which was apparently takenout of its original context and gavethe impression that Heisenberg hadused his meeting with Bohr to claimthat, for moral reasons, he hadsabotaged the German atomic bombproject. [9] Bohr, upon reading thetext, took exception to thisdescription of events and, as a result,proceeded to write a series of letters,most of which were never sent, toHeisenberg, in order to express hisdisagreement. These letters � elevendocuments in all � are available viathe Niels Bohr Archive, the websiteof which states that, �The documentssupplement and confirm previouslypublished statements of Bohr'srecollections of the meeting,especially those of his son, AageBohr.� and that they were releasedin their entirety on the 6th ofFebruary 2002, �in order to avoidpossible misunderstandings�. [10]The documents had been subject toa clause proscribing their releaseuntil fifty years after the death ofBohr, which means that they shouldnot have been released before 2012.However, this clause was revoked,in agreement with Bohr's family,given the intense interest in theHeisenberg meeting provoked byFrayn's play. [11]

All but one of the eleven documentsin the archive are either drafts �sometimes incomplete - or notesand are even sometimes in the hand-writing of Margrethe � Bohr's wife- or Aage Bohr, rather than Bohrhimself. The remaining documentis in the form of a telegram, sent byHeisenberg in response to 60thbirthday greeting from Bohr. TheDirector of the Niels Bohr Archive,Finn Aaserud, notes in theintroduction to the documents thatthey are to be treated with caution,all being written at least sixteenyears after the event. In addition,they have all been translated intoEnglish, which means that, �As withany translation, the precise choiceof corresponding words and phraseshas been difficult�; a difficultyaccentuated by the fact that the


O U T & A B O U T

documents are drafts, notes and oftenunfinished. [11]

Rather than offer an interpretationof the letters here, which is obviouslythe axis on which this story pivots,and making a vain attempt to reacha conclusion that is perhaps un-reachable and un-knowable, it isperhaps more advised to simplypoint the reader in the direction ofthe documents themselves. They canbe found within the pages of theNiels Bohr Archive website and area v a i l a b l e h e r e �http://www.nba.nbi.dk/papers/introduction.htm. Regardless of theextent to which the documentsactually clarify the issue, they dogive the impression of a wish toaddress or render clearer exactlywhat happened on that evening backin 1941.

One further piece of interestinginformation is provided through asummary of events by Bohr's son,Aage, quoted in the book, NielsBohr: His life and work as seen byhis friends and colleagues, editedby Stefan Rozental and released in1967, in which he addresses themeeting directly:

�In the book �Brighter than aThousand Suns� by Robert Jungk itis asserted that the Germanphysicists submitted a secret planto my father, aimed at preventingthe development of atomic weaponsthrough a mutual agreement withcolleagues in the allied countries.This account has no basis in theactual events, since there was nomention of any such plan eitherduring Heisenberg�s visit, or duringa later visit to Copenhagen � alsomentioned by Jungk � of the Germanphysicist Hans J.D. Jensen. On thecontrary, the very scanty contactwith the German physicists duringthe occupation contributed � asalready mentioned � to strengthenthe impression that the Germanauthorities attributed great militaryimportance to atomic energy.� [12]

And with that, we return to thebeginning. The evidence has been

presented, but the conclusionremains the same � indecisive. Giventhe lack of conclusive proof, it ispossible only to read and re-read theavailable documents, looking forsuggestions, building hypothesesand loading more or less significanceonto statements that may or may notreally be of any import. This reallydoes seem to be an area of historyof which we will never really beable to know precisely whatoccurred. The issue was, however,further clouded in March 2006,following the intervention of theCroat physicist and philosopher,Ivan Supek (1915-2007), who hadbeen a friend and student ofHeisenberg. Supek claimed thatMargrethe Bohr had informed him,in confidence, that von Weizsäcker,rather than Heisenberg had actuallybeen the protaganist in the meeting:

�Heisenberg and von Weizsäckercame to Bohr in German armyuniforms. Von Weizsäcker's idea,probably originating from his fatherwho was Ribbentrop's deputy, wasto persuade Bohr to mediate forpeace between Great Britain andGermany.� [13]

So, 65 years after the event, yetanother alley opens up down whichone might potentially lose oneself.Enter Michael Frayn - stage left, oneis tempted to say - and the words heputs into the mouth of hisHeisenberg:

�No one understands my trip toCopenhagen. Time and time againI�ve explained it. To Bohr himself,and Margrethe. To interrogators andintelligence officers, to journalistsand historians. The more I�veexplained, the deeper the uncertaintyhas become. Well, I shall be happyto make one more attempt.� [14]

G. HEMMING

1. J. Calder, Obituary: Robert Jungk,The Independent (http:/ /www.independent.co.uk/news/people/obituary-robert-jungk-1414618.html), 18July 1994.

2. The Right Livelihood Award,http://www.rightlivelihood.org/jungk.html.

3. Two Letters from WernerHeisenberg to Robert Jungk, the authorof "Brighter Than a Thousand Suns"[+ a reply by Jungk] (Englisht r a n s l a t i o n ) , h t t p : / / w e r n e r -heisenberg.unh.edu/Jungk.htm.

4. C o p e n h a g e n ( p l a y ) ,http://en.wikipedia.org/wiki/Copenhagen_%28play%29, 2012.

5. Rescue of the Danish Jews,http://en.wikipedia.org/wiki/Rescue_of_the_Danish_Jews, 2012.

6. Pais, Abraham, Niels Bohr'sTimes, In Physics, Philosophy andPolity, Oxford: Clarendon Press. ISBN0-19-852049-2, 1991.

7. Long, Doug, The atomic bomband beyond, http://www.doug-long.com/bohr.htm.

8. Rhodes, Richard, The Makingof the Atomic Bomb. New York: Simonand Schuster. ISBN 0-671-44133-7,1986.

9. N i e l s B o h r ,http://en.wikipedia.org/wiki/Niels_Bohr, 2012.

10. Niels Bohr Archive, Releaseof documents relating to 1941 Bohr-H e i s e n b e r g m e e t i n g ,http://nba.nbi.dk/release.html, 2002.

11. Aaserud, Finn, Release ofdocuments relating to 1941 Bohr-Heisenberg meeting. Introductoryc o m m e n t s ,http://www.nba.nbi.dk/papers/introduction.htm, 2002.

12. Bohr, Aage, �The War Yearsand the Prospects Raised by the AtomicWeapons,� pp. 191�214 in StefanRozental (ed.): Niels Bohr: His life andwork as seen by his friends andcolleagues, Amsterdam: North-HollandPublishing Company, p. 193, 1967.

13. http://jutarnji.hr/clanak/art-2006,3,19,supek_intervju,17440.jl?artpg=1, in Wikipedia, Ivan Supek,http://en.wikipedia.org/wiki/Ivan_Supek, 2012.

14. Frayn, Michael. Copenhagen.New York, New York. Anchor Books:


O U T & A B O U T

http://www.nba.nbi.dk/papers/introduction.htm


http://www.rightlivelihood.org/jungk.html

http://werner-heisenberg.unh.edu/Jungk.htm

http://en.wikipedia.org/wiki/Copenhagen_%28play%29

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

http://www.doug-long.com/bohr.htm

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

http://nba.nbi.dk/release.html


http://www.jutarnji.hr/moj-zivot-s-nobelovcima-20--stoljeca/23289/

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

Random House, Inc. 2000.

Michael Frayn

Michael Frayn was born in Mill Hill,London in 1933, grew up in Ewell,Surrey and was educated at KingstonGrammar School. His father, a deafasbestos salesman, would bringhome samples of the material, withwhich the young Michael wouldplay, hammering nails into them andso on, completely oblivious of itstoxicity. Frayn's sister, Jill, wouldlater prematurely pass awaysuffering from a lymphoma,probably caused as a result of thisearly and sustained exposure toasbestos dust. His mother, havingsurvived the War, died of a heartattack in November 1945.

He was idealogical as a schoolboyand, while at school, set up anindependent communist cell with aclassmate. Following school, helearned Russian, while on a two yearmilitary service, and then studied atCambridge, where he read MoralSciences (Philosophy) at EmmanuelCollege. While at the university he,along with a group of Russian-speaking friends, set up what hebelieves was the first studentexchange programme with Moscow,although this brought him intocontact with the intelligence serviceswhich, as he wished to maintain hisindependence, caused him towithdraw. His earlier communisttendencies soon wore off, however.He states that he learned Russian tostudy Russia better, but that �Theinterest in Russia remained, thecommunism wore off prettyquickly�.

Upon graduation, he began to workas a reporter for the ManchesterGuardian and has since commentedthat �Newspapers were where I feltmost at home�. Having worked forboth the Guardian and the Observer,Frayn began to write fiction, whichhe describes as being not unlike'industrial management' � citing theneed to strike a balance with thecharacters of a play or book in order

to get them to do what the authorwants them to do, while stillallowing them to have their ownlives as well. He has written bothdrama and prose and been successfulin both, while his work ranges fromfarce - the writing of which hedescribes as being 'particularlydifficult' - to philosophical, often inthe same play. His most famousproductions have been Noises Off,a farce about a play within a play,Copenhagen and Democracy, adrama about the end of WillyBrandt's chancellorship of WestGermany and the unmasking of hissecretary, Gunter Guillaume, as aspy.

In relation to Copenhagen, he saysthat he �worked very hard to findout everything that was known...I'vetried to respect the historical record,in so far as it exists, but then whatI've tried to do is imagine what wasin the heads of the two.� With regardto the potential pitfalls of thisapproach, he recounts an interestinganecdote in relation to the openingnight of the play in New York, initself a tense evening, followingwhich he met one of the audience - Werner Heisenberg's son - whoinformed him that his � Frayn's �Heisenberg was nothing like hisfather, who never expressed feelingsfor anything other than music, butthat, however, he understood how aplay requires characters to be moreforthcoming in order to functionproperly.

As well as his own fiction, Fraynhas translated work by both Chekhovand Tolstoy into English and saysthat one of the aspects of Chekhov'swork that he most admires is hismodesty, in the sense that he isabsent from it. In this context, thenearest Frayn has come to writingabout himself is in 'My Father'sFortune, A Life', a memoir about thelife of his father, written to satisfythe curiosity of his daughter abouther antecedents, in which he ofcourse appears as a significant partof his father's life.

So, playwright, novelist, reporter,

columnist and screenwriter, thebibliography is considerable. Butone thing in particular stands outfrom the various available sources� interviews, reviews and so on -for an article such as this, and thatis the fact that, as he says in his ownwords, �I very much like laughing�.

The Church of San Zeno,Pisa

The setting for the production ofMichael Frayn's Copenhagen wasthe deconsecrated Church of SanZeno in Pisa. One of the oldestchurches in the city, the abbey wasre-opened in October of 2000,following a protracted restorationand is now used for exhibitions,concerts and the occasional play. Itcan be found on Via San Zeno, nearto Piazza Santa Caterina and is nearto the homonymous doorway to theold town, which gives onto theintersection between Via delBrennero and Via Vittorio Veneto.Dated as far back as 1029, the churchwas part of a monastery complexand also hosted a hospital until the15th century. The church passed tothe order of the Camaldolese monksin the 12th century.


O U T & A B O U T

PERSONNEL MOVEMENTS

Departure

Gaelle Parguez

Engineer left the Vacuum team endof June 2012.

The e-mail from Gilles BogaertHi Carlo,about wind turbines as electricityproviders,http://en.wikipedia.org/wiki/File:Wind_in_Denmark_1977_2011_large.pngWikipedia explains to me thatDanish wind turbines providealready 28% of the 2011 electricityproduction (and the goal of theDanish government is 50% in2020).It is suprising that for the case ofDanish wind, the authors ofEurophysics News refer to a 2009report which has been heavilycriticized.Gilles Bogaert, Nice, 8.06.2012

The answer by Michele PunturoDear Bogaert, Dear Carlo,I believe that THE solution for theenergy problem doesn�t exist, butonly components of a globalstrategy. I found very interesting thereading of a book, freely availableon web, written by a physicist: DavidJC MacKay and titled �SustainableEnergy - without the hot air�(http://www.withouthotair.com).It is interesting because it makes theattempt to compute an energy budget(consumed energy vs producedenergy). As suggested by the title,the author tries to demonstrate howit is possible to use �green� energies,but being a physicist and usingnumbers and not adjectives, it has ahard job to fill the gap betweenavailable �green� energy and theneeds of our modern society (theconclusion, if there is a conclusion,is that we have to reduce drasticallyour energy needs� or, even if it iswell hidden in the text, use nuclearenergy). There is an interestingevaluation of the energy producedthrough wind turbines in Ireland(with some reference to the Danishsituation); they obviously producea lot of energy, but to have a relevantrole with respect to the needs of acountry with the population densityof the UK, comparable to the EUaverage (and not obviously toDenmark), you need to cover a hugefraction (~the entire surface ofWales) of the country with windturbines plants. Note that the UK

has strong winds and this �solution�is not possible for the Mediterraneancountries, where the winds areusually weaker than 4m/s (forexample see the European wind mapin Fig. 49 of the ET design study:https://tds.ego-gw.it/ql/?c=7954).Furthermore, if you see Fig. 26.2 ofthe above-cited book, thefluctuations of the Energy producedby wind in Ireland aren�t mitigatedby the country-size plants, and thenexpensive smart grids are needed tofill the energy holes or to redistributethe peakproduction. This ismainly done byenergy-exchangewith neighboringcountries (asDenmark does)that produceenergy through aneasily tunablesource (likenatural gas, oil,carbon and hydro-electric).Regards,Michele Punturo,Perugia 11.06.2012

A comment from Andrea Vicere�Hi Michele,that's right and I believe in fact thatnuclear energy is the only sourcewhich could allow in the mid term(the next 20 years) to keep thecurrent level of energy supply whilereducing dramatically the CO2 footprint. However, also nuclear energyisn't a solution in the long termbecause we will run out of cheapuranium sooner or later, and nuclearfusion isn't round the corner. So asyou said a mix is necessary, and inthe long term one could expect thatthe storage of energy will be a crucialcomponent of the grid, much morethan it is now, in order to increasethe capacity factor of wind or solarfarms.Cheers, Andrea15.06.2012

An answer by Michele PunturoLet us define �capacity factor� asthe ratio between the energyproduced by a plant in a period oftime and the amount of energy itcould have produced at continuous

full power operation during the sameperiod. According to the datadelivered by the NEI (NuclearEnergy Institute, a policyorganization of the nuclear energyand technologies worlds-wideindustry, certainly not anindependent institution), in a sevenyear period (2000-2007) the wholenuclear plant system in the USA hada capacity factor of 87%. In thefigure the overall trend in the USAin the last 40 years is reported.

One more answer by MichelePunturoHi Andrea,I fully agree that smart grids andenergy storage are crucialtechnologies to be developed in thefuture. Just to quantify the problemof energy storage, in order tostrengthen what was stated at thebeginning of the discussion on �windturbines as a sustainable energysource� let�s make a simplecomputation.A European citizen consumes, onaverage, 689W (an American1363W!!!). Let�s consider a countrywith 60M citizens (like Italy or theUK): the average powerconsumption is ~41GW. Let�ssuppose that you want to produce¼of that energy with wind turbines,without accessing energy producedby other countries in an easilytunable way. Hence about 10GW ofthe energy is produced with windturbines (corresponding to 30-40GWof installed power). If you look atwind availability, in a windy country,such as Ireland or the UK, there areperiods of 10 days without wind.Let�s be optimistic and limit


L E T T E R S T O T HE E D I T O R

http://www.withouthotair.com

http://en.wikipedia.org/wiki/File:Wind_in_Denmark_1977_2011_large.png

https://tds.ego-gw.it/ql/?c=7954

ourselves to 5 days without wind.Hence you need to store10GW x 24 x 5 = 1240GWh ofenergy.Currently, the only serious way wehave to store that energy is usingthe so called �pumped storage�(hydro-electric plants used inreversed mode). To produce 100GWh using such a plant you haveto store 210M cubic meters of waterand let it fall from a height of 200m(considering an efficiency of 90%).This is a lake 10m deep and 21km^2in surface, about 3 times the lake ofMontedoglio, that caused so muchtrouble to the population inValtiberina. Then, you need 12 ofthese (3xMontedoglio) lakes just tocover ¼ of the energy needs for 5days in Italy! Possible, but quitedifficult! Another possibility is usingbatteries �. Better solution�Let�s jump to Uranium availability.The known conventional reservesin the ground of Uranium are (in theWorld) 4.7Mtons, the Uranium inthe Phosphate deposit (moreexpensive) are 22Mtons and in theOceans 4500Mtons (2005 data).Let�s use just the easiest and smallestsource of Uranium. According towhat is stated in the above-citedbook, this is enough for about 1000years of energy production with the(2005) rate of usage. Instead, if eachinhabitant of the Earth reaches anenergy consumption comparable tothe European one, the reserves willbe enough for about 160 years.Obviously there could be the usualfactor 2 error in the computation,but the once-through nuclear reactoris not the only available technology.Fast breeder reactors could producea factor 60 more power with thesame amount of excavated Uranium;they exist (http://en.wikipedia.org/wiki/Breeder_reactor) but thetechnology is still not fully undercontrol �or better, is quite risky.But 60x160 years of energyavailability is quite appealing.Finally, there is also Thorium. Indiahas the capability to use Thoriumand their reserves are estimated tobe enough for 1000 years.

(Andrea found an error in thecomputation)Ciao Andrea,

Thanks for your email; it is alwaysuseful to cross-check the numbers.I used the numbers and thestatements in page 162 of thepreviously-cited book. I cross-checked the references used in thatbook and I found a series ofinteresting info. When economicsenters into evaluations, numbers aremore difficult and unstable. First ofall the global known reserves areincreased (2009 data) to 5.5Mtons,but it depends on the extraction cost.An indicative plot is reported herehttp://www.world-nuclear.org/info/inf75.html.According to the IAEA there are anadditional 5 Mtons available, but itdepends on the extraction cost. Whatremains true (in your email, andwrong in mine) is that the directlyavailable reserves are enough for~80 years (160 considering theadditional reserves stated by theIAEA, but with the current rate ofusage!). I found confirmed theincrease of performance (x 60) givenby fast breeder.It is always useful to discuss theseinteresting subjects. Ciao, Michele

A short commentHi,An additional comment, about theauthors, De Groot actually,I am surprised to see he was formerlyappointed by the Shell Dutchcompany:www.clepair.net/windsecret.htmlGilles Bogaert, 18.06.2012

Jo van den Brand, 24.06.2012:Windmills in HollandThis contribution was triggered byCarlo Bradaschia, who noticed apaper on wind energy by C. le Pair,F. Udo and K. de Groot inEuroPhysicsNews 43/2 2012. Keesle Pair was director of the Dutchfunding agency STW (whichsupports technical sciences) and FredUdo was a senior scientist at Nikhefand is now retired. These authorsquestion the rational of placingmulti-gigawatt windparks offshorewithout a good buffer and storagesystem. I happen to agree with themand recently had the pleasure toexplain this on Dutch nationaltelevision (in a debate with thenumber one person in the

Netherlands active in sustainableenergy - this after having leftGreenPeace and working with theIPCC). Below I give you a briefimpression of the Dutch approachto wind energy.It is well-known that there is a longtradition of windmills in TheNetherlands. The Dutch have beenbuilding windmills for centuries andwith these windmills part of thecountry itself was built. Besides landdrainage, mills were used forindustrial purposes, such as cornmilling and sawing. As a nation wehave a strong emotional connectionto windmills and we are proud toshow them to tourists. While 1194of these historical windmills are stillin operation, the vast majority ofthem has disappeared (the Dutchdatabase lists 15914 of historicalwindmills). However, recentlywindmills started a comeback,mainly driven by the quest forsustainable energy. At present thereare about 1900 turbines installed on-shore with a capacity of 2.0 GW.Since the power of a wind turbineis given by the kinetic energy of theair incident per unit of time (and

thus proportional to ½ Av it isquite sensitive to windspeed. It would make sense to placewindmills in areas with high windspeed, e.g. along the coast, but inpractice they are placed in-land inremote areas. This is motivated bywhat is called the �perception of theincorporation in the landscape�which is Dutch-speak for�minimizing the number of peoplecomplaining�. The consequence isthat in reality this 2 GW capacityhas an efficiency of not more than18%. To ensure that sufficient energyis available during the other 82% ofthe time, we are now building 3 largecoal-fired power plants. In 2010 theDutch approach to realizing windenergy became quite aggressive byallocating a subsidy of 5.4 billionEuro (4,395.8 million Euro is alreadycommitted) for the construction ofoffshore wind farms. While thisnicely appeals to sentiments onDutch history of windmills, and thesea, it is worthwhile to question theeconomic value of such aninvestment in times of crisis. Thepromise is a capacity of 700 MW.


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http://www.clepair.net/windsecret.html

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