Perspectives of Nuclear Physics in Europe - European Science ...

4.2 Phases of Strongly Interacting Matter
4.2.6 R&D, Computing,
Networking
New generation of detectors, front-end electronics,
DAQ – Forefront experiments in nuclear physics require,
in general, innovative instrumentation. Therefore, better
performing accelerators, detectors, data acquisition
and the associated highly sophisticated electronics are
in continuous demand. At moderate energies, pulse
shape analysis of stopped charged particles in silicon
permits to identify all atomic and partially even their mass
numbers. Meanwhile, modern implementations of the
standard ⊗E/E approach have reached unprecedented
mass identification up to Z=50. This has been achieved
via fast, high-resolution digitisation in conjunction with
sophisticated digital signal processing. Moreover, close
relationships with silicon manufacturers are necessary
in order to obtain silicon wafers free of ‘channeling’. This
is achieved with the highest possible doping uniformity
(1%).
Next generation particle detectors have to be operated
at extremely high counting rates and track densities. At
the same time, these detectors have to provide excellent
time and position resolution, as well as a low material
budget to reduce multiple scattering and background.
Evolving detector technologies with a rich R&D programme
include: advanced diamond detectors, frontier
photon detectors based on nanotechnology, inorganic
scintillation fibres, or on silicon photo multipliers, largearea
low-mass gas counters, fast compact Cherenkov
counters for particle identification, ultra-light and largearea
tracking systems based on GEM or Micromegas
technology, ultra-light tracking and high-resolution vertex
detection systems based on silicon sensors. The
future CBM experiment at FAIR will be confronted with
the selection of rare probes in high multiplicity environment
at collision rates of up to 10 7 events/sec. Therefore
fast, large granularity and radiation hard detectors for
electron as well as hadron identification, high resolution
secondary vertex determination and a high speed
event-selection and data acquisition system have to
be developed. The ongoing R&D activities along these
lines have to be continued in order to exploit the high
intensity beams envisaged at the future FAIR facility by
the CBM experiment.
At the same time, the ALICE upgrade programme will
enhance the present discovery potential and make use
of the high luminosity of LHC. Recent developments
in integrated circuit technology and advances in computing
and networking power significantly improved
the performance of all experiments in nuclear physics.
Field-programmable gate arrays, including more than
one million logic gates, are used in fast trigger-, pattern
recognition-, real-time tracking and position-determination
circuits and event builders. Upgrades of present
experimental devices and design of future ones will take
advantage of these developments and advances in fast
digitisers. Optical fibres and transceiver performance
with transfer rates of 5–10 Gbits/s/link is now available
off-the-shelf. Therefore, event building and recording
rates of up to 1 Gbytes/s is within reach.
The storage and analysis of the resulting dataset that
are of the order of hundreds of Petabytes (1 Petabyte
= 1 million Gigabyte) pose challenges that must be
addressed by new developments in distributed computing
and GRID technology.
Computing requirements – The complexity of the
experimental devices and physics programmes of
high-energy nuclear physics has already reached the
level typical for particle physics experiments. The new
generation nuclear physics experiments will exceed HEP
experiments in terms of computing requirements, both
CPU power and data volume. The recommendation made
in the previous LRP for developing GRID computing
infrastructures has turned into an essential need.
The GRID has demonstrated its potential to distribute
computing resources in a coherent fashion, and the
ALICE Grid implementation is one of the most efficient
such structure within the Worldwide LHC Computing
Grid. In view of this, a joint venture between the nuclear
and particle physics communities will be beneficial to
both programmes. The LHC experiments offer a very
good starting point in this direction.
At present, lattice calculations are the only means
to extract exact non-perturbative predictions of QCD
from first principles, playing an important role in the
interpretation of the existing experimental results and
in the prediction of observables to be measured by
future experiments. Accomplishments over the last five
years have established the methodology and laid the
groundwork for lattice QCD calculations. Dedicated
hardware and software infrastructure is necessary for
world-class lattice QCD research. As the demands of
full QCD computations grow with a large inverse power
of the quark mass, initial calculations were restricted to
relatively heavy quarks. To reach the required accuracy
requested by the experiments, simulations for physical
quark masses and close to the continuum limit are
mandatory. To reach this goal, petaflop/scale computing
facilities, a unified programming environment, and
a pooling of resources are required.
It has proven more cost effective to build dedicated
computers rather than to make use of general purpose
machines. QPACE (QCD parallel computer using cell
100 | Perspectives of Nuclear Physics in Europe – NuPECC Long Range Plan 2010