EPN 48-2

Préparation du document



europhysicsnews
THE MAGAZINE OF THE EUROPEAN PHYSICAL SOCIETY

Properties of nuclei probed by laser light
Crossing borders: gender diversity in STEM
Ion Coulomb crystals
Nature’s engines: active matter
The Climate machine, a two fluids thermal engine
48/2
2017
Volume 48 • number 2
European Union countries price:
104€ per year (VAT not included)

CONTENTS
europhysicsnews
THE MAGAZINE OF THE EUROPEAN PHYSICAL SOCIETY
Properties of nuclei probed by laser light
Crossing borders: gender diversity in STEM
Ion Coulomb crystals
Nature’s engines: active matter
The Climate machine, a two fluids thermal engine
europhysicsnews
48/2
2017
Volume 48 • number 2
European Union countries price:
104€ per year (VAT not included)
Cover picture: © iStoclPhoto, see p.21 nature’s engines: active matter.
EPS EDITORIAL
03 Scientific and ethical responsibility
C. Rossel
NEWS
04 Historic sites: Piersanti Mattarella, Tower of Thought - Erice, Sicily, Italy
05 International Day of Women and Girls in Science
m PAGE 17
Ion Coulomb
crystals
m PAGE 21
Nature’s engines:
active matter
m PAGE 26
A brief tour of the
climate machine
HIGHLIGHTS
06 How water can split into two liquids below zero
Electronic properties of III-V nanowires unveiled
The Dresden Training for the International nanoCar race
07 Functional Multiplex PageRank: the centrality is a function
How donut-shaped fusion plasmas managed to decrease adverse turbulence
08 Champagne owes its taste to the finely tuned quality of its bubbles
Pattern formation induced by fixed boundary condition
09 Operating regimes in an optical rectenna
Perfect absorption with gap-plasmons enhances elusive belinfante’s spin
100% renewable energy sources require overcapacity
10 Novel plasma jet offshoot phenomenon explains blue atmospheric jets
Accurately evaluating on 40 Ca + optical clock BBR temperature
11 Economics made simple with physics models
100% renewable energy sources require overcapacity
FEATURES
12 Properties of nuclei probed by laser light
R. Neugart
16 Crossing borders: gender diversity in STEM
H.C.W. Beijerinck
17 Ion Coulomb crystals: from quantum technology
to chemistry close to the absolute zero point
O. Dulieu and S. Willitsch
21 Nature’s engines: active matter
J.M. Yeomans
26 A brief tour of the climate machine
1 - The Climate machine, a two fluids thermal engine
J. Poitou
32 Travel with hydrogen
L.J.F. (Jo) Hermans
EPN 48/2 01

EPS EDITORIAL
[EDITORIAL]
Scientific and ethical
responsibility
The different recent statements by President Trump raise
a lot of questions and anxieties in the US but also outside the
country. In his first address to Congress at the end of February
he outlined in his priorities a sharp increase in military spending
at the expense of foreign aid and environmental programmes.
“This budget will be a public safety and national security budget,”
Trump said at the White House and “will put America first”.
Scientists employed or funded
by the US Environmental Protection
Agency (EPA), the National
Institutes of Health (NIH), and
other federal agencies are now awaiting
official words on the proposed
budget cuts, typically 10%, which can
have dramatic effect on environment,
public health, education and science
funding. What else will come up after
the earlier announcement on immigration
restrictions that generated
so many reactions worldwide? An
Open Letter was sent by EuroScience
calling upon European governments
and the European Commission
“to uphold the principles and values
that underpin scientific progress, to
work with their counterparts in the
US administration to maintain a
global science system based on these
principles and to take any measure
at the national and European levels
to preserve and increase the world’s
scientific and research capacity”.
EPS is one of the cosignatories of this
letter. We stated officially that “Science
was and will never be restrained by
physical, cultural and political barriers.
In our globalized world, where international
scientific collaboration (e.g.,
at large-scale facilities such as CERN)
has become the rule, there is no place
for discrimination and censorship. Any
measure that restricts the freedom of
movement and communication of our
US colleagues will have a profound
impact on science and innovation in
Europe and other continents”.
This brings us to the responsibility
of scientists in dealing with policy and
ethical matters, which might be outside
their every day’s concerns but can
have a large impact on their funding
sources and simply the future of their
career. Indeed, it is not excluded that
the budget cuts proposed in the US
can trigger similar developments in
Europe. For these reasons we have to
remain vigilant and willing to come
out of our labs to have our opinions
heard. A good example is the Scientists’
March on Washington that will take
place on April 22 with the expectation
of sister rallies taking place around the
globe. "It is time for scientists, science
enthusiasts, and concerned citizens
to come together to make ourselves
heard!" can be read on the official webpage
of the organizers. The event is "a
celebration of our passion for science
and a call to support and safeguard the
scientific community". The following
weekend, environmentalists are planning
a massive climate change march.
All this happens based on Newton’s
third law stating that for every action
there is an equal and opposite reaction!
© iStockPhoto
Science was
and will never
be restrained
by physical,
cultural and
political
barriers.
It is also interesting to read under the official
link of the Union of Concerned Scientists
www.ucsusa.org that “throughout
its history, UCS has followed the example
set by the scientific community: we share
information, seek the truth, and let our
findings guide our conclusions”. In this
way it was able to build a reputation for
fairness and accuracy and amassed an
impressive history of accomplishments.
Last year EPS was consulted by
ALLEA, the All European Academies,
in its task to review and update the
European Code of Conduct for Research
Integrity. We responded positively
as EPS fully agrees with such
principles as honesty in communication,
impartiality and independence,
objectivity, openness and accessibility,
reliability in performing research, duty
of care and responsibility for future
generations of scientists. Even if these
rules are meant to prevent fraudulent
activities within the scientific community,
it is also our basic responsibility to
provide answers to global challenges,
engage in social and economic debates
and finally guide decisions that shape
our societies. EPS is and should remain
a strong advocate of these ideas.
After two years of an extraordinary
experience as president of the
European Physical Society, it is time
to pass the torch to my successor,
Rüdiger Voss, with all my best wishes
for a successful presidency. n
llChristophe Rossel,
EPS President
EPN 48/2 03
europhysicsnews
2017 • Volume 48 • number 2
Europhysics news is the magazine of the European
physics community. It is owned by the European
Physical Society and produced in cooperation with EDP
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Editor: Victor R. Velasco (SP)
Email: vrvr@icmm.csic.es
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Email: igloi.ferenc@wigner.mta.hu
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Email: david.lee@eps.org
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Email: xavier.dearaujo@eps.org
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Editorial Advisory Board:
Gonçalo Figueira (PT), Guillaume Fiquet (FR),
Zsolt Fülöp (HU), Agnès Henri (FR), Jo Hermans (NL),
Christoph Keller (NL), Robert Klanner (DE),
Peter Liljeroth (FI), Antigone Marino (IT),
Laurence Ramos (FR), Chris Rossel (CH),
Claude Sébenne (FR), Marc Türler (CH)
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ISSN 0531-7479 • ISSN 1432-1092 (electronic edition)
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Legal deposit: March 2017
EPS HISTORIC SITES
Piersanti Mattarella
Tower of Thought
Erice, Sicily, Italy
The EPS Historic Site Award commemorates
places in Europe that have played an important
part in the historical development of Physics. On
August 21 st 2016 the "Piersanti Mattarella Tower
of Thought" at the Ettore Majorana Foundation
and Centre for Scientific Culture (EMFCSC) in
Erice, Sicily, was inaugurated as the 30 th EPS
Historic Site by Prof. Jan Szyszko, Minister of
Environment of the Republic of Poland.
The unveiling of the EPS Historic Site plaque took place at the
base of the tower in the presence of Antonino Zichichi, President
of the EMFCSC, Luisa Cifarelli, President of the Italian Physical
Society and Chair of the EPS Historic Sites Committee, Sergio Bertolucci,
former Director of Research and Scientific Computing at CERN, Horst
Wenninger, past Research-Technical Director at CERN and myself, as
a member of the Blackett Laboratory at Imperial College London. The
ceremony coincided with the 49 th Session of the International Seminars
on Planetary Emergencies whose participants were also in attendance.
The EMFCSC was founded in 1962 by the Italian physicist Antonino
Zichichi, who has served as director of the Centre to the present day.
The Tower of Thought owes its name to the source of inspiration provided
by the study at the top of the tower to visiting scientists including
. The unveiling of the EPS Historic Site plaque. From left to right: H. Wenninger, M.J. Duff,
L. Cifarelli, J. Szyszko, A. Zichichi, S. Bertolucci. (Credits: EMFCSC)
04
EPN 48/2
EPS Historic sites
NEWS
Nobel Laureates Rudolf Mössbauer,
Kenneth Wilson, Richard Feynman,
Georges Charpak, Samuel Ting, Wolfgang
Pauli, Norman Ramsey, Frank
Wilczek, Gerardus 't Hooft, Alex
Müller and Masatoshi Koshiba and
other leading thinkers such as John
Bell. The Tower was also the venue of
the 1982 Erice Statement for a science
without secrets and without frontiers
devised by Paul Dirac, Piotr Kapitza
and Antonino Zichichi.
Piersanti Mattarella, assassinated
by the Mafia in January 1980 while
he held the position of President of
the Regional Government of Sicily,
was a strong advocate for the EM-
FCSC. He was the brother of Sergio
Mattarella, the current President of
the Italian Republic.
Professor Antonino Zichichi was
an extraordinary student of Lord
Patrick Maynard Stuart Blackett. The
current Physics department building
of Imperial College is named the
Blackett Laboratory.
In April 2014 the Blackett Laboratory
was a recipient of the EPS
Historic Site Award and at the Erice
ceremony I took the opportunity to
say few words about the links between
the Blackett Lab and the EMFCSC.
Nino holds Blackett in high regard
and you will find in Erice the Blackett
Lecture theatre where the prizes for
the best students of the Erice Subnuclear
Physics School include the
Blackett Diploma. So we were delighted
when Prof Zichichi accepted
our invitation to the award ceremony
at Imperial College to deliver the distinguished
lecture entitled ‘My testimony
on Lord Patrick M S Blackett.’’
m Piersanti
Mattarella Tower
of Thought.
So I was grateful to Professor
Zichichi for reciprocating the hospitality
and inviting me to this Piersanti
Matarella ceremony to celebrate
Blackett's legacy in both London
and Sicily and in recognition of the
common scientific and cultural interests
of the Blackett Lab and the
EMFCSC. n
llMichael Duff
Emeritus Professor of Physics
and Senior Research Investigator
Blackett Laboratory
INTERNATIONAL DAY OF WOMEN AND GIRLS IN SCIENCE
On 15 December 2015, the United Nations General Assembly
adopted resolution A/RES/70/212 declaring 11 February as
the International Day of Women and Girls in Science. The United
Nations invites all Member States including academia, individuals
and society in general, to observe the International
Day of Women and Girls in Science to promote the full and
equal participation of women and girls in education, training,
employment and decision-making processes in the sciences.
In Spain a group of men and women, researchers, scientific
communicators and teachers, took on the challenge. Some
are members of the “Royal Spanish Physics Society” and other
institutions, although they all participated as individuals to
start the February 11 Initiative. The initiative is based on the
belief that a broad knowledge of the work of women scientists,
past and present, will produce role models for future
women researchers and hence will help close the persistent
gender gap in science. The initiative has attracted further participation
by individuals, associations and organisations and
is already attracting the attention of Spanish media.
The role of the February 11 Initiative is to promote the
organisation of activities for students and for the general
public and to publicise them. This involves the creation of a
webpage 11defebrero.org (in Spanish), gathering information
about the achievements of women scientists, the situation
of girls and women in science, and all the activities that
are being organised mainly in Spain. The initiative is also in
twitter @11defebreroES, facebook @dia11defebrero and instagram
11defebreroes.
The event took place for the first time in 2017 and included
many activities mostly between the 6 th and 19 th of February. The
initiative will hopefully be consolidated in the coming years.
The number of activities is still growing and so far they include
visits and activities in scientific institutions, seminars in secondary
schools, theatre displays, outreach talks in cultural centres
and bars, and TV programs. Anyone in Spain interested in joining
the initiative by organising activities is most welcome to
contact the coordinators. Institutions and organisations across
Europe are also invited to join the celebration of the International
Day of Women and Girls in Science.n
Martine Bosman (IFAE)
EPN 48/2 05
HIGHLIGHTS
Highlights from European journals
LIQUID PHYSICS
How water can split
into two liquids below zero
Theoretical possibility of the coexistence of dual liquid
states of matter in sub-zero water due to the origami-like
stacking behaviour of microscale molecules
dimensions in the range of tens of nanometers and a third
dimension in the micrometre range. The filamentary shape
and nanoscale diameter of NWs have rendered them versatile
and cost-effective components of technological devices.
Moreover, in NWs novel properties arise compared to their
bulk counterparts due to size-dependent effects. A careful determination
of NW properties is thus necessary for achieving
the best design of devices, as well as for explaining fascinating
physical effects in NWs.
m Representation of the diamond lattices formed by the particle studied.
m Geometry of the experiment (left) and optical selection rules in wurtzite
crystals (right).
Did you know that water can still remain liquid below zero degrees
Celsius? It is called supercooled water and is present in
refrigerators. At even smaller temperatures, supercooled water
could exist as a cocktail of two distinct liquids. Unfortunately, the
presence of ice often prevents us from observing this phenomenon.
So physicists had the idea of replicating the tetrahedral
shape of water molecules—using DNA as a scaffold to create
tetrahedral molecules—and thus removing the interference of
ice formation. This approach allowed the authors to confirm that,
in theory, a dual liquid phase is possible in sub-zero water and any
other liquids made of tetrahedral molecules. These results have
been published recently. It is a great tale of how the underlying
microscopic shape determines the overall macroscopic form. n
llS. Ciarella, O. Gang and F. Sciortino,
'Toward the observation of a liquid-liquid phase transition
in patchy origami tetrahedra: a numerical study, Eur. Phys.
J. E 39, 131 (2016)
MATERIAL SCIENCE
Electronic properties
of III-V nanowires unveiled
Semiconductor nanowires (NWs) are technologically relevant
structures in the field of Nanoscience. The name ‘nanowires’
is due to their geometrical characteristics: NWs have two
Since standard absorption spectroscopy is hard to perform
in NWs due to their small volume, we use an alternative technique,
photoluminescence excitation spectroscopy (PLE), to
assess the electronic properties of III-V NWs. Specifically, we
shine light on the debated band structure of wurtzite GaAs and
InP NWs employing polarization-resolved PLE. Moreover, PLE is
used as a statistically-relevant method to identify wurtzite and
zincblende NWs in a same InP sample. Finally, resonant excitonic
effects in the density of states of In x Ga 1-x As/GaAs core/shell NWs
are highlighted by high-resolution PLE. n
llM. De Luca,
'Addressing the electronic properties of III-V nanowires
by photoluminescence excitation spectroscopy',
J. Phys. D: Appl. Phys. 50, 054001 (2017),
APPLIED PHYSICS
The Dresden Training for
the International nanoCar race
To prepare its participation to the first international nano-car
race in Toulouse (France) Spring 2017, the Dresden Team exercised
on the Toulouse LT-UHV 4-STM reconfigured for the race
with 4 independent controllers (one per scanning tunneling
microscope (STM)). An Au(111) surface was prepared over a
full gold substrate. A 90 nm long race track with two turns was
06 EPN 48/2
from european journals
HIGHLIGHTS
m A 3 step driving along the Au(111) track. The black cross indicates the tip
position for the inelastic tunneling excitation of the Dresden molecule-vehicle.
selected on this surface following the rules (www.cemes.fr/
Molecule-car-Race). The Dresden windmill molecule-vehicles
were deposited in ultrahigh vacuum conditions, imaged, and
manipulated by any one of the 4 tips on race track reaching a 5
nm per hour driving speed,-including the STM image recording
after each driving bias voltage pulse. Strategies for a safe and
fast driving were established by the Dresden team along the
Au(111) surface fcc rafter together with the possibility to repair
crashed molecules, for example during the negotiation of a turn.
The teams registered for the nano-car race will benefit from
this atomic-scale, single-molecule-vehicle driving experience
to improve their own driving strategy. n
llF. Eisenhut, C. Durand, F. Moresco, J.-P. Launay
and C. Joachim,
'Training for the 1 st international nano-car race:
the Dresden molecule-vehicle', Eur. Phys. J. Appl. Phys. 76,
10001 (2016).
to different types of connections. For example consider a
multiplex of two layers formed by Lufthansa and British Airways
flights. If we attribute maximum influence to Lufthansa
flights Frankfurt airport is more central than Heathrow airport
while the opposite is true if we attribute maximum influence
to British Airways flights. The Functional Multiplex PageRank
combines this information through a paradigmatic shift: the
centrality of a node is not a single number but an entire function
associated to the relevance given to the different types
of connections. For each node it allows to characterize which
types of connections contribute the most to its centrality. Interestingly
the correlations between the Functional Multiplex
PageRank of different nodes reveal the similarity in the role
of the nodes. n
llJ. Iacovacci, C. Rahmede, A. Arenas and G. Bianconi,
'Functional Multiplex PageRank', EPL 116, 28004 (2016)
PLASMA PHYSICS
How donut-shaped fusion
plasmas managed to decrease
adverse turbulence
Achieving fusion has become more realistic since plasma
flow was identified as regulating turbulence in the 1980s
COMPLEX SYSTEMS
Functional Multiplex PageRank:
the centrality is a function
Multiplex networks are formed by a set of nodes connected
by different types of interactions. The centrality of a node in
a multiplex network depends on the influence one attributes
. Correlations between the Functional Multiplex PageRank of Heathrow, Gatwick,
Frankfurt and Düsseldorf airports in the multiplex network formed by Lufthansa
and British Airways flights.
m Toroidally shaped plasmas of the tokamak type offer a path to low turbulence.
Fusion research has been dominated by the search for a suitable
way of ensuring confinement as part of the research into
using fusion to generate energy. In a recent paper the author
gives a historical perspective outlining how our gradual understanding
of improved confinement regimes for what are
referred to as toroidal fusion plasmas –- confined in a donut
shape using strong magnetic fields-- have developed since the
1980s. He explains the extent to which physicists’ understanding
of the mechanisms governing turbulent transport in such
high-temperature plasmas has been critical in improving the
advances towards harvesting fusion energy. Physicists found
in the 1980s that toroidally shaped plasmas of the tokamak
EPN 48/2 07