12 February 2007/draft 3
Strategy document subatomic physics
Overview
Particle physics sketches a magnificent perspective on the elementary constituents of
matter and their interactions. At the smallest length scales investigated a rich spectrum of
phenomena is observed. This includes strong, weak and electromagnetic interactions
(collectively referred to as the Standard Model), each with their own intermediary
particles: gluons, W- and Z-bosons and photons. Further ingredients of the theory include:
the existence of three families of quarks with and leptons without colour charges,
condensation of quark pairs in the vacuum, and confinement of quarks and gluons in the
proton and other hadrons. Moreover, the included gauge interactions grow weaker at
smaller particle separation and higher momentum transfer, transitions between quarks
and neutrinos belonging to different families are possible, and asymmetries in the
interactions of matter and anti-matter occur. Measurements at the largest length scales
show this Standard Model to be incomplete. Anisotropies in the cosmic microwave
background radiation, catalogues of supernovae, large galaxy red-shift surveys and
collisions between galaxy clusters indicate the Universe to consist of 4% ordinary matter,
22% dark matter and 74% dark energy. Nevertheless, these and other astrophysical data
yield a remarkable quantitative understanding of the evolution of the Universe from the
Big Bang to its present state 13.7 billion years later.
The Large Hadron Collider (LHC) currently nearing completion at the CERN laboratory will
provide first direct information on particle physics at the next distance or energy scale. It
will revolutionise our understanding of matter, forces and space. The discovery of the
Higgs particle, assumed to be responsible for all Standard Model particle masses, will have
tremendous implications, as this mechanism of dynamical mass generation implies new
forms of matter, with potentially important implications for cosmology. The observation of
extra spatial dimensions will have profound influence on attempts to reconcile gravity with
quantum mechanics. The observation of new particles not predicted by the Standard Model
could elucidate the nature of dark matter in the Universe. Physics beyond the Standard
Model could furthermore manifest itself in precision measurements of CP-violation effects
in heavy quark interactions at the LHC or in low-energy small-scale precision
measurements of the permanent electric dipole moment of particles (e.g. the TRIP
programme at the KVI laboratory). Finally, heavy ion collisions in LHC will yield detailed
measurements on a state of matter assumed to have filled the Universe directly after the
Big Bang: a plasma of free quarks and gluons at extremely high temperatures.
Next to advances in the important field of accelerator-based experiments there is a
worldwide and growing interest for studies at the interface of particle physics and
astrophysics, combined into the field of astroparticle physics. New experimental directions
emerge which make use of particle-physics techniques and instrumentation. E.g., recently
the ANTARES neutrino telescope, the Pierre Auger high energy cosmic ray observatory and
the VIRGO gravitational wave antenna started operation. With such detectors hitherto
unexplored phenomena in the Universe can be studied, and we get access to particles with
energies beyond those available with accelerators.
In particle and astroparticle physics theoretical developments are indispensable for both
the formulation of research questions and the analysis and interpretation of experimental
data. The Standard Model has become the solid basis for the whole field. Theoretical work
on unification of the interactions, supersymmetry and gravity provides input for the search
for physics beyond the Standard Model. These models address important problems in their
own right and have a large impact on cosmology.
1
Theoretical physics
Theoretical particle physics deals with the conceptual underpinnings of particle and
astroparticle physics in the broadest sense, on the one hand exploring new concepts and
ideas related to the elementary constituents of matter and force, and on the other hand,
inspiring experimental verifications of these ideas thus enabling the detailed comparison
between theoretical concepts and real measurements. Central themes in present-day
research are the physics of the Standard Model and what lies beyond, unification of gravity
and quantum mechanics, and the origin and evolution of the Universe. This research is
covered by two FOM programmes.
The community, two research institutes (KVI and NIKHEF) and six university groups (in
Amsterdam, Groningen, Leiden, Nijmegen and Utrecht), has set up the FOM network
Theoretical High Energy Physics. In 2006 this network has prepared a strategic plan [1]
with three central research themes:
1. Phenomenology;
2. Theoretical cosmology;
3. String theory and quantum gravity.
These themes are chosen for their scientific promises as well as their interconnected ideas
and goals, and are in line with current and foreseen research ambitions in the international
arena. Furthermore, it is natural that phenomenologists and experimenters have a
mutually fruitful cooperation. Theoretical cosmologists are well acquainted with the
experimental astroparticle physics community. String theorists encourage LHC
experimentalists to speculate about revolutionary discoveries: e.g. the existence of extra
dimensions or the observation of mini black holes.
Phenomenology
Phenomenology is the interface between theoretical and experimental physics. From the
confrontation of theoretical ideas with data a bi-directional dynamics emerges: intriguing
data can inspire theoretical innovations while compelling ideas can stimulate new
experiments. For example, the comparison of precise data from the LEP experiments at
the CERN laboratory with higher-order calculations within the Standard Model narrowed
the allowed range of the top-quark and Higgs-boson mass -- the top quark was soon after
discovered at the Tevatron in the predicted mass range.
In the next decade opportunities in phenomenology are particularly exciting, because the
LHC is about to come online, accessing a new, unexplored energy regime. A host of
tantalising analyses (identification of the Higgs particle, searches for new particles and/or
phenomena like the formation of a quark-gluon plasma or the existence of extra
dimensions) crucially depend on precise determinations of signal and background rates for
a large variety of observables explored in the LHC experiments. Physics beyond the
Standard Model could also manifest itself indirectly at low-energy experiments, through
virtual contributions, such as minute CP-violating effects as predicted by supersymmetric
models. In both areas, the Netherlands is able to continue the strong track record set
already in the past with LEP and Tevatron related phenomenology.
Theoretical cosmology
Cosmology aims to describe the temporal and spatial evolution of the Universe from its
origin, the Big Bang, to the large-scale structures as we observe them now. Based on
experimental data and intellectual ingenuity, cosmologists have put forward revolutionary
concepts such as the existence of dark matter, dark energy and inflation, an epoch of
highly accelerated expansion in the early Universe. The focal point of theoretical
cosmology in the Netherlands is to develop cosmological models that include inflation, and
that are supported by particle physics and well motivated within supergravity and string
theory. Comparisons with data like the cosmic microwave background by the WMAP- and
in the future Planck-satellite and eventually the detection of primordial gravitational waves
2
with the LISA laser interferometer in space will restrict inflationary scenarios. These
models can be narrowed down further through the study of relic particles and cosmic
defects which in turn are constrained by the limits set by observations of ultra-high energy
cosmic rays and neutrinos with the Pierre Auger and ANTARES/KM3NeT observatories,
respectively. Because of several recent strategic appointments, because of historical
strengths in phenomenology, string theory and quantum gravity, and because of close ties
with experimentalists, Dutch cosmologists can make a real impact in this field.
String theory and quantum gravity
About two decades ago string theory emerged as a candidate for a unified description of
all the forces. Since then it has developed into a broad framework that connects a wealth
of topics ranging from high-energy physics to cosmology, from condensed matter to
quantum gravity. String theory distinguishes four promising directions for future research
that are strongly cross linked: the foundations of string theory, quantum gravity and black
holes, string phenomenology, and string cosmology. String theory suggests exciting
possibilities, such as the discovery of ‘large’ extra dimensions and the production and
subsequent evaporation of mini black holes in forthcoming proton-proton interactions at
the LHC. String theory also has promising connections to cosmology. Ill-understood
cosmological phenomena such as inflation, dark matter, dark energy and trans-Planckian
effects in the cosmic microwave background spectrum can be naturally addressed, and
possibly clarified from a string-theory perspective.
String theory and quantum gravity are worldwide the hottest research direction in
theoretical physics. In spite of being represented by a relatively small number of theorists
in this global setting, the Netherlands has a disproportionately large impact e.g. in blackhole physics, holography, string phenomenology, topological strings and non-pertubative
approaches to quantum gravity. This also explains why the annual Amsterdam Strings
summer workshop is considered to be one of the most prestigious gatherings of the string
community.
Particle physics
The backbone of particle physics in the Netherlands lies in accelerator-based experiments.
The main focus hereof is the exploration of the high-energy frontier using the LHC (ALICE,
ATLAS and LHCb programmes) at the CERN laboratory for which the NIKHEF collaboration,
comprising the NIKHEF research institute and four university groups in Amsterdam,
Nijmegen and Utrecht, coordinates the Dutch participation. The complementary approach,
to search for new physics through low-energy precision experiments (TRIP programme),
is pursued by KVI of the University of Groningen.
Large Hadron Collider (ALICE, ATLAS and LHCb)
During the past decade, NIKHEF has made significant investments in the construction of
the ALICE, ATLAS and LHCb detectors. Within a year’s time these experiments will go
online to record and analyze LHC’s proton-proton collisions. This will reveal a physics
bonanza for many years to come. The highlights hereof are listed below.
Whereas the electromagnetic and the strong interactions are mediated by massless gauge
bosons (photons and gluons, respectively), the weak interactions are mediated by the
massive W+, W and Z0 gauge bosons. These non-zero masses are an indication of broken
gauge symmetries. In the Standard Model this is explained by the interaction of the Wand Z-bosons with a condensate of scalar fields. The theory then predicts the existence of
a degree of freedom, most simply manifesting itself as a massive neutral spin-0 particle,
the Higgs boson. Thus far this particle -- of which the mass is not predicted by theory -has not turned up in any experiment. The proof of its existence is necessary to complete
the experimental confirmation of the Standard Model, and thereby elucidate the origin of
symmetry breaking and mass generation for weakly interacting particles. The search for
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the Higgs boson is the most important single research topic in the field of particle physics
in the coming years and is the cornerstone of the ATLAS programme.
If the Higgs boson is not discovered at the LHC, the origin of symmetry breaking should be
sought for beyond the Standard Model. Strong arguments in favour of the incompleteness
of the Standard Model are: it does not contain a candidate particle to explain the
apparently large amounts of dark matter in the Universe; it does not incorporate gravity;
it introduces 28 apparently arbitrary parameters (outside the field usually referred to as
fundamental constants and particle masses), the values of which can not be explained
within the Standard Model. A plethora of theories beyond the Standard Model have been
proposed. Their predictions range from the existence of new particles (e.g.
supersymmetric particles or new heavy gauge bosons) to the occurrence of new
interactions or the existence of extra spatial dimensions. Any discovery of physics beyond
the Standard Model is likely to revolutionise our understanding of nature. ATLAS is well
positioned to study these speculations and in particular ATLAS will either observe
supersymmetric particles or, if not, refute the theory of supersymmetry.
In the daily world it is taken for granted that processes can proceed equally well when
mirror imaged i.e. by interchanging left and right. In weak interactions, however, this is
not the case. Indeed, the W-bosons couple only to left-handed spinning particles, and not
to their right-handed spinning mirror imaged counterparts. This phenomenon is known as
parity violation. In addition to parity violation there is a more subtle effect, known as CPviolation. This effect distinguishes between matter and anti-matter, and is widely believed
to be at the root of the asymmetry in abundance of matter over anti-matter observed in
the Universe. A small amount of CP-violation is present in the Standard Model of particle
physics, but it is an open question as to whether it suffices to explain the observed
imbalance between baryons and anti-baryons in the Universe. As a result studies of CPviolation can provide a window on physics beyond the Standard Model. This is the focus of
the LHCb programme. B-mesons, and hence b-quarks, are copiously produced in LHC’s
proton-proton collisions. Through online selection of B-mesons LHCb will be able to study
CP-violating effects in the b-quark sector, thereby confirming the Standard Model or
discovering signatures of physics beyond the Standard Model.
The theory of strong interactions provides a good description of small-scale phenomena in
collision experiments in high-energy physics. The much more frequent phenomena at large
distances, most notably the confinement of quarks and gluons inside hadrons are difficult
to treat. Analytical and numerical approaches to such non-perturbative problems, in
particular to the thermodynamics of quarks and gluons at finite temperature and density,
indicate that at high temperature a new phase of matter can exist, in which quarks and
gluons are no longer confined inside hadrons like the proton. This phase is called the
quark-gluon plasma. Cosmologists conjecture that all strongly interacting matter went
through such a phase in the very early Universe, a fraction of a second after the Big Bang.
With the colliding beams of heavy ions, instead of protons, in the LHC, the ALICE
experiment plans to study the details of the quark-gluon plasma, which is the earliest
thermodynamic state of the universe that we may be able to create in the laboratory.
TRIP
A complementary approach to the exploration of parity and CP-violation in the subatomic
world is provided by low-energy, small-scale precision measurements. The discovery
potential of these measurements is large and in some cases exceeds that of direct
searches. Within the Netherlands, research in the field of low-energy precision
measurements is performed at KVI in Groningen within the framework of the programme
Trapped Radioactive Isotopes: Microlaboratories for Fundamental Physics (TRIP). The
main focus of TRIP is the search for new interactions by precision measurements of
correlations in nuclear -decay and of parity and time-reversal violation effects in the
electric dipole moment (EDM) of radium.
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Astroparticle physics
A new interdisciplinary research domain is emerging at the interface of physics and
astronomy. This field of research, which is known as astroparticle physics, is addressing a
number of issues that may revolutionise our scientific view of the Universe. These issues
include questions on the nature of dark matter and dark energy, the origin of ultra-high
energy cosmic rays, the large-scale structure of the Universe, and the existence and
exploration of gravitational waves. The FOM approved ANTARES programme addresses
some of these issues.
Since 2004 a new astroparticle physics research community is emerging in the
Netherlands, in which four research institutes (ASTRON, KVI, NIKHEF and SRON) and six
university groups (in Amsterdam, Groningen, Leiden, Nijmegen and Utrecht) participate.
In 2005, this community has prepared a long-range plan proposing to focus research in
this new field on the study of the origin of ultra-high energy cosmic rays in a multimessenger approach [2]. In practice this means that neutrinos, radio signals and
gravitational waves are used to study the unknown origin of cosmic rays. This programme
has the potential to make several ground-breaking discoveries that include the observation
of dark matter relics, the identification of cosmic ray point sources and the detection of
gravitational waves.
Deep-sea neutrino detection
Neutrinos abound in the Universe. In addition to the expected background of low-energy
cosmic neutrinos, intermediate and high-energy neutrinos are produced abundantly in
stars and in large numbers in supernovae. It is likely that neutrinos are produced in highenergy jets associated with active galactic nuclei, and they may result from the
annihilation of weakly interacting particles thought to be present in the dark matter in the
Universe. Such neutrinos can provide new information about the Universe.
The quest for high-energy neutrinos and their origin has started a worldwide effort to
develop neutrino telescopes, such as the ANTARES project in the Mediterranean Sea. The
ANTARES detector combines a large detection volume with good directional resolution. By
interacting with matter in the Earth neutrinos can turn into muons. The neutrino track is
reconstructed from the Cherenkov light emitted by this muon, while passing through sea
water. The Cherenkov light is observed with a large number of very sensitive
photomultipliers attached to cables anchored to the sea bottom.
Following the successful deployment of several prototype detector lines, the ANTARES
collaboration started to collect data in March 2006 with its first fully equipped detector
line. At present five detector lines are installed and by the end of 2007 the remaining
seven detector lines will be deployed thus completing the first deep-sea neutrino
observatory in the Mediterranean Sea. NIKHEF has developed the readout system and onshore data-acquisition system for ANTARES using the novel All-Data-To-Shore concept.
This idea has increased the science potential of the neutrino detector significantly, as use
can be made of a very flexible software trigger system.
Because of the success of the All-Data-To-Shore concept, NIKHEF has been asked to lead
the information technology work package of the KM3NeT project, a European funded
design study for a kilometre sized neutrino telescope that will surpass the sensitive volume
of ANTARES by a factor of 20. It is important to maintain the present strong position of
the Netherlands in the field of deep-sea neutrino detection in the future in view of the
discovery potential of KM3NeT and because KM3NeT is part of the ESFRI authorised
prestigious European roadmap for research infrastructures [3].
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Radio detection of cosmic rays
The information that is presently available on high-energy cosmic rays is largely limited to
observation of electrons and muons in extensive air showers reaching the surface of the
Earth. Given the unknown origin of cosmic rays and the poorly understood acceleration
mechanisms leading to ultra-high energy cosmic rays, additional measurements need to
be carried out. Reliable measurements of ultra-high energy cosmic rays are required and
the nature of the particle showers must be studied.
The Netherlands is in a unique position to contribute to both questions. The LOFAR radio
synthesis telescope under construction in Drenthe offers the opportunity to carry out radio
observations of extensive showers in the Earth’s atmosphere or in the rim of the Moon.
Once the LOFAR telescope comes on line, it will be possible to study radio signals of
cosmic rays with energies up to 1018 eV in the Earth’s atmosphere and far beyond 1021 eV
if they hit the surface of the Moon.
The Netherlands can also contribute to the study of the highest energy cosmic rays,
through the Netherlands' Ultra-high energy Cosmic ray Collaboration (NUCC). In 2005
NUCC has joined the Pierre Auger collaboration, which is building an observatory in
Argentina to measure cosmic rays. An important issue is the existence of cosmic rays with
energies in excess of 51019 eV. If such cosmic rays are observed, there must either be a
very nearby (at cosmic scales) source, or our basic understanding of the relevant physics
is wrong. Moreover, the observation of high-energy cosmic rays could lead to the
discovery of cosmic-ray point sources in the Universe.
The Pierre Auger Observatory is located on a vast plain known as the Pampa Amarilla in
western Argentina. It is a hybrid detector, employing two independent methods to detect
and study high-energy cosmic rays. One technique detects high-energy particles through
their emission of Cherenkov light in water. The other technique tracks the development of
air showers by observing ultraviolet light emitted high in the Earth's atmosphere. As the
latter technique is only available for about 10% of the time, it is attractive to extend the
detector with radio stations e.g. of the LOFAR type. This creates a unique possibility for
Dutch astroparticle physics to contribute to the world’s most advanced cosmic ray facility.
KVI coordinates this international R&D programme.
Gravitational-wave detection
Gravitation plays a central role in the evolution of the Universe. It is well described by
general relativity, but it is unclear how general relativity acts at the quantum level (which
has an immediate impact on models of the early Universe). One of the predictions of
general relativity -- so far confirmed only indirectly -- is the existence of gravitational
waves. Hence, the question emerges whether we can actually observe gravitational waves,
and, if so, whether their observation can be exploited to address open questions in
astroparticle physics.
In line with the strategic plan for astroparticle physics in the Netherlands, NIKHEF has
taken the initiative to form a research group in the area of gravitational-wave detection.
This group has been invited to participate in the VIRGO collaboration, and is preparing
participation -- together with the Dutch institute for space research SRON -- in the LISA
gravitational-wave mission.
The VIRGO detector is essentially a Michelson laser interferometer with two orthogonal 3
km long arms. Multiple reflections between mirrors located at the extremities of each arm
extend the effective optical length up to 120 km. The interferometer is located near Pisa in
Italy. The frequency range of VIRGO extends from 10 to 6,000 Hz. This range in
combination with the very high sensitivity should allow detection of gravitational radiation
produced by supernovae and the coalescence of binary star systems in the Milky Way and
nearby galaxies. LISA is a laser interferometer in space with an extremely long arm length
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of 5,000,000 km. The frequency domain of LISA extends to as low as 104 Hz, and hence
allows to observe the coalescence of massive black holes and mergers of white dwarf
stars. VIRGO is in the commissioning phase, first results are expected in the coming five
years. The LISA space mission is foreseen for the end of the next decade.
Technical developments
Progress in experimental subatomic physics has always been intertwined with
technological advances in areas as diverse as: accelerators, detectors and computers.
Hence, it is essential for the subatomic-physics research community to be directly involved
herein and, where possible, to lead important technical developments. This is why a strong
technical infrastructure at institutes like NIKHEF and KVI is of crucial importance if the
Dutch subatomic-physics community wants to maintain its strong presence and record in
this field.
Accelerator R&D
Accelerator-based subatomic-physics dates back to the first table-top linacs and cyclotrons
in the 1930’s. This year, the LHC at CERN will start as a joint project of the worldwide
particle physics community. The potential of accelerators for other domains of science, for
technology and for industry has always been realised and exploited. Appealing examples in
the long list of today’s use of accelerators outside subatomic-physics are radiotherapy
(from the first neutron therapy in the 1930’s to the 12C therapy now being developed),
synchrotron radiation sources and free electron lasers.
With the 27 km circumference of LHC (and LEP) the practical size limit for building
(circular) accelerators has been reached. New acceleration schemes are needed to reach
even higher energies. For the medium term the CLIC-concept, under development at
CERN, will allow the accelerating gradients to be increased at least tenfold, thus leading to
a still reasonably sized system for a future e+e linear collider. For the longer term, laserbased schemes offer the perspective of a further increase in gradients. Large-scale
computer simulations have recently resulted in an impressive progress in the
understanding of the so-far mainly phenomenology-driven investigations of this new
technology, in particular for electrons. However, a lot of research is still required before
practical applications of laser-based acceleration schemes can be envisaged.
For many current and planned accelerator-based research facilities the performance of the
ion sources is a limiting factor. Facilities that rely on high intensity, such as LHC, would
benefit from a better quantitative understanding of the first stages of the beam formation
process. Facilities accelerating secondary radioactive ion beams, such as SPIRAL-II,
require element selective ion sources that can easily be tuned for the different elements.
In the Netherlands expertise in accelerator technology exists at research institutes KVI and
Rijnhuizen and at universities in Eindhoven, Amsterdam (VU) and Twente. A joint effort on
the further development of laser-driven acceleration and new ion sources is desirable.
Detector R&D
Experiments to study subatomic-physics, i.e. phenomena at the sub-femtometer scale,
require high-resolution state-of-the-art detector technologies to measure the direction,
energy and identity of all particles produced in e.g. proton-proton collisions. Paradoxically,
the experiments themselves are often huge and can only be carried out by large-scale
international collaborations. Sensor materials range from noble gases and liquids to
extremely pure semi-conducting crystals. These sensors are combined with custom
designed Application Specific Integrated Circuits (ASICs). Many tens of thousands of mixed
(analogue and digital) circuits can presently be combined on a single front-end ASIC, and
radiation hardness can be obtained in standard industrial processes, by adding extra
design features in the layout (enclosed gates and guard-ring structures). Integration of
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semi-conducting sensors with these front-end ASICs using ultra-high density interconnects
leads to small modular and functional detection units, with a standard multi-Gigabit per
second serial readout protocol. Technologies for interconnecting and 3D stacking of
electronics are arising in subatomic-physics applications and are presently a hot topic in
the semi-conductor manufacturing industry.
NIKHEF and KVI collaborate in this field with many partners like MESA+ institute at
Twente University, PANanalytical (NL), Canberra (B), ESA and the specialised microelectronics institute IMEC (B). Of course, NIKHEF also maintains close ties with the CERN
micro electronics group. This work is partly subsidised by the RELAXD Senter Novem
project which has EUREKA status and EUDET FP6 European Community subsidy.
Grid computing
Experiments in subatomic-physics generate staggering amounts of data, which have to be
recorded, distributed, analyzed and archived. In the past this has led to the development
of the world-wide web (WWW), an ICT networking technology invented at CERN. The
socio-economic importance of this development can hardly be overestimated.
In data-taking mode, the LHC experiments will generate data streams orders of magnitude
larger than ever before. Ordering, moving, using and storing these data require new
networking and computing technologies. To this end the LHC community has chosen to
focus on the grid-computing paradigm. The choice was driven by technological, political
and socio-economic factors, and the community (with NIKHEF as one of the leaders) has
been working on making grid technology a reality since 2001.
Given NIKHEF's leadership position in grid computing in the LHC world, NIKHEF is a
natural partner for other scientific disciplines developing large-scale computing and ICT
technology, in particular in the Netherlands. NIKHEF is a leading participant in the Virtual
Laboratory for e-Science project. Together with NCF and NBIC, NIKHEF is responsible to
set up a Dutch grid-based e-Science infrastructure, BIG GRID. This project is funded by
NWO and includes a full so-called 'Tier-1' for LHC experiments, data archive centres for
the LOFAR radio synthesis telescope, for the Dutch bio-informatics community and
national hospitals, and a component dedicated to ‘in-silico’ design studies by a large Dutch
industry. BIG GRID also supports archives and computing related to anthropological
studies, linguistics, and climate modelling.
NIKHEF will vigorously continue this line of research, which has proved very profitable for
both the institute and for the general scientific community. Indeed, earlier efforts in this
area (www.nikhef.nl was the first Dutch website and the third website in the world) are
partially responsible for the Netherlands' position of world leadership in the networking
world.
Perspectives & new FOM programme directions
Recently, roadmaps or strategy papers, with major Dutch involvement, have been
published by the European nuclear, particle and astroparticle physics communities [4], [5]
and [6]. They sketch a wealth of exciting research opportunities some of which extend
well beyond 2020. The actual Dutch involvement will not be limited by a lack of highquality (European) project proposals, but by available funds. Even though their timescales
are beyond the FOM Strategic Plan 2004-2010, two planned international facilities must be
singled out upfront because they have the top priority in their respective strategy paper
and roadmap: the international linear e+e collider, ILC, (accelerator-based particle physics
community) and FAIR (nuclear physics community). Brief descriptions of the ILC and FAIR
projects are given in Appendix A and B, respectively.
The approved and presently running subatomic-physics FOM programmes (end dates in
8
parentheses) are:







ANTARES: A cosmic neutrino observatory (2007);
Theoretical subatomic physics (2007);
String theory and quantum gravity (2009);
Trapped radioactive isotopes: micro-laboratories for fundamental physics TRIP (2013);
ALICE (CERN): Quark-gluon plasma (2013);
Study of charge-parity violation with the LHCb experiment at CERN (2014);
Exploration of new phenomena at the highest energy frontier with D0 and ATLAS (2015).
The theoretical physics community is in urgent need of new FOM programme funding. This
deserves top priority, both because theoretical particle physics in the Netherlands has a
long tradition and an excellent reputation (e.g. 1999 Nobel prize for Veltman and ‘t Hooft)
and because a FOM theory programme has good value for money: the expensive
permanent staff is largely paid for by universities, while the FOM programme money pays
for PhD students, postdocs and travel. No technical support is required.
If the Netherlands wants to maintain an important role in the new and exciting field of
astroparticle physics, an approved FOM programme in this area is mandatory. The first
priority is to maintain a strong Dutch presence in the ANTARES/KM3NeT neutrino
observatory. The next priority is a participation in the Pierre Auger large area cosmic ray
observatory in particular in view of its synergy with the large Dutch LOFAR project. A
proposal for a ‘NWO-groot’ subsidy for KM3NeT investment funds will be submitted in
2007.
The FOM programmes for ALICE, ATLAS and LHCb allow to exploit (manpower and running
costs) LHC data taking until about 2015. The only, relatively minor, additional
(intermediate) investment for these programmes will be a possible upgrade of the
innermost detector layers of LHCb and/or ATLAS in view of radiation damage. Depending
on the physics harvest, the LHC might undergo a luminosity or energy upgrade in 2015. In
that case, a request for an extension of the FOM ATLAS programme will be submitted.
It is premature to speculate about a continuation of the TRIP programme beyond 2013.
However, in the area of small-scale low-energy precision measurements numerous
exciting opportunities are available: e.g. dedicated dark matter searches, neutrinoless decay searches and -mass measurements.
Subatomic-physics technology pervades our society: CRT-based TV, medical diagnosis
tools (X-ray, NMRI, CT, PET, SPECT), medical treatment procedures (X-ray, hadron
therapy, radioactive isotopes), synchrotron facilities, the concept of distributed sensor
networks, the worldwide web, etc. This and today’s Dutch political climate with its strong
emphasis on valorisation, will almost certainly lead to submission of proposals by the
subatomic-physics community to the FOM Industrial Partnership Programme.
References
1. Theoretical Particle Physics, Focusnotitie, December 2006.
http://www.fom.nl/live/overfom/netwerken/wetenschappelijke_netwerken/hth_netwerk.pag
2. Strategic Plan for Astroparticle Physics in the Netherlands, September 2005.
http://www.astroparticlephysics.nl/papers/APP-4.0.pdf
3. European roadmap for research infrastructures, 2006.
ftp://ftp.cordis.europa.eu/pub/esfri/docs/esfri-roadmap-report-26092006_en.pdf
4. Roadmap for Construction of Nucl. Phys. Research Infrastructures in Europe, 2005.
http://www.nupecc.org/pub/NuPECC_Roadmap.pdf
5. The European strategy for particle physics, July 2006.
http://council-strategygroup.web.cern.ch/council-strategygroup/Strategy_Brochure.pdf
6. Astroparticle Physics in Europe, A Roadmap, January 2007.
http://www.ifh.de/~csspier/Roadmap-Jan30.pdf
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Appendix A
The international linear e+e collider (ILC)
The LHC provides the tantalising possibility of finding new particles and phenomena; as
such it is the instrument of choice for exploring a new domain of physics. To chart in detail
the high energy domain, irrespective of the initial findings of LHC operation, another type
of accelerator is required. Indeed, the precise details of the Higgs sector or
supersymmetric particles can best be measured with an e+e collider, as the interactions of
point-like particles like the electron and positron are known very precisely; also, in these
leptonic collisions there is no uncertainty in the initial state, as opposed to the LHC case
where protons with a complex internal structure collide. Evidently, a linear e+e collider
should provide sufficiently high centre-of-mass energy, 500-1000 GeV, and luminosity,
1034/cm2s, to produce these new particles with a detectable rate.
A worldwide initiative has been launched for the development of a linear e+e collider, for
which the TESLA accelerator championed by DESY, serves as a starting point; the
proposed accelerator is known as the International Linear Collider (ILC). The experimental
conditions at the ILC allow for precision measurements of coupling constants, masses and
spins as well as decay modes of new particles, including the possibility to determine the
Higgs self coupling. In addition to the study of the physics of new particles and fields, the
ILC will also allow precision tests of the Standard Model with an accuracy an order of
magnitude better than achieved by the LEP experiments in the past. This large
improvement in precision is the combined result of the ILC’s high luminosity, the
possibility to polarise the electron and positron beam, and the option to vary the collision
energy. This operational flexibility will also allow very detailed studies of the Z-boson (at
91 GeV) and threshold production of W+W boson pairs (at 161 GeV) and t-quark pairs (at
350 GeV).
Laboratories in Europe (CERN, DESY), North America (SLAC, Cornell) and Japan (KEK)
have come up with more or less detailed proposals for the construction of an e+e collider
and an associated detector. An International Linear Collider Steering Committee (ILCSC)
co-ordinates the various regional activities in accelerator research and detector R&D. It
has already decided to select the superconducting accelerator technology as proposed in
the TESLA design. A decision about the location of the ILC is yet to be made. The
construction cost of the ILC is estimated to be about five billion euros.
The three main components of a detector for experiments at the ILC are: very accurate
vertex detectors with many read-out channels, a large Time Projection Chamber (TPC) as
tracker, and a calorimeter with high granularity for energy measurements and particle
identification. At NIKHEF new ideas and concepts for the development and construction of
such detectors emerge naturally from its half a century long experience in this field.
NIKHEF has hosted the 4th and concluding ECFA-DESY Workshop on Physics and Detectors
for a 90-800 GeV Linear e+e Collider in 2003. NIKHEF leads the tracking detector activity
of EUDET: Detector R&D towards the International Linear Collider, an EU supported FP6
programme. A NIKHEF scientist is chairman-elect of the recently formed LCTPC
Collaboration for R&D towards a TPC at the ILC and is a member of the WWSOC (World
Wide Study Organising Committee) that coordinates the physics and detector studies for
the ILC.
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Appendix B
Facility for anti-proton and ion research (FAIR)
Together with its users and the international science communities, GSI has developed the
concept for a future facility with intense and high-quality beams of ions and anti-protons.
The principal goal of the new facility is to provide the European/international science
community with a worldwide unique and technically innovative accelerator complex. This is
based on a 100/300 Tm double-ring synchrotron, the heart of the new facility, using the
existing and upgraded 18 Tm synchrotron as injector. Novel, rapidly cycling superconducting magnets are being developed. All ions from hydrogen up to the heaviest
element, uranium, can be accelerated with beam intensities increased by a factor of 100 1000, e.g. for uranium with intensities of 1012 ions per second or above, and with beam
energies increased by about a factor of 15 over the present GSI facility.
A key feature of the new facility will be the production of intense and high-quality
secondary beams such as of anti-protons and of short-lived nuclei. A system of associated
storage rings serves for beam accumulation, beam cooling, and phase space optimisation,
but also plays a crucial role in the advanced experimental programmes with in-ring
experiments. The system of intertwined accelerator and storage rings enables a highly
efficient, thus very cost-effective scheme of truly parallel operation of several different
research programmes.
The secondary beams of exotic unstable nuclei are produced in fragmentation reactions or
by fission of a 238U primary beam. In-flight separation of high-purity mono-isotopic
secondary beams is performed by means of a two-stage, super-conducting fragment
separator (Super-FRS). Its large phase-space acceptance ensures a very efficient
collection in particular of 238U fission fragments, resulting in overall gain factors of 1000 10000 over the secondary beam intensities presently available at GSI. Fission of uranium
is an indispensable source in producing the most neutron-rich medium-mass nuclei.
The fast-cycling 100 Tm synchrotron provides for intense 30 GeV proton beams, which
allow the production of an intense beam of anti-protons in a specially designed production
target. Anti-protons are collected, stored and cooled, accelerated to high energies and
then stored for in-ring, internal-target experiments in a high-energy (up to 15 GeV) antiproton storage ring (HESR). It is also planned to decelerate and trap anti-protons for antihydrogen and anti-matter research.
The scientific programme spreads over a wide range of research areas. It essentially
encompasses all aspects of hadronic matter, from fundamental interactions and
symmetries towards the enormous richness of phenomena in many-body to macroscopic
systems:
- Hadronic structure at the sub-nuclear level is studied with intense beams of stored
and cooled anti-protons of up to 15 GeV kinetic energies (PANDA Collaboration). The
spectroscopy of gluonic excitations and in particular observation of pure gluonic modes
and hybrids probe the theory Quantum Chromodynamics in the non-perturbative
regime. Confinement of quarks and the generation of hadron masses are key aspects
being addressed.
- Compressed hadronic matter, at about 5 to 10 times the normal nuclear density, is
produced in high-energy heavy-ion collisions. The transition to the quark gluon plasma
phase in an environment of high baryon density is the research objective.
- Nuclei far from stability are studied with secondary beams of short-lived exotic
nuclei, to investigate nuclear structure effects not occurring in stable nuclei (NuSTAR
Collaboration). Nuclear regions far from stability are of equal interest to
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nucleosynthesis and other stellar processes, and also allow to search for violations of
fundamental symmetries.
Macroscopic matter in a high-density plasma state, of interest for the fundamental
understanding of dense plasma physics and for astrophysics, can be produced using
heating through a combination of high-power (petawatt) laser (PHELIX) and ion
beams.
Quantum electrodynamics studies, extremely strong electromagnetic fields, and ionmatter interactions at very high energies are also part of the research programme at
the new facility.
An important consideration in the design of the facility was a high degree of truly parallel
operation of the different research programmes. With the proposed scheme of accelerator
and storage rings, maximum integrated beam time, or integrated luminosity, can be
provided for each of the different research programmes operated in parallel. In
conception, FAIR has very ambitious scientific and technical programmes and its broad
scientific scope allows forefront research in five different sub-disciplines of physics.
Because of these aspects and its great potential for new discoveries the FAIR project has
been given highest priority in the NuPECC Long-Range Plan 2004.
FAIR provides great opportunities for research to the subatomic, atomic and plasma
physics communities. Physicists from KVI are involved in the PANDA and NuSTAR
collaborations, as well as in the atomic physics programme at FAIR and are contributing to
accelerator research and development.
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