99 research outputs found
THE ESS LINAC DESIGN
Abstract The European Spallation Source (ESS) is a 5 MW, 2.5 MeV long pulse proton machine. It represents a big jump in power compare to the existing spallation facilities. The design phase is well under way, with the delivery of a Conceptual Design Report published in the beginning of 2012, and a Technical Design Report in December 2012. Why and how the 5 MW goal influences the parameter choices will be described
Experimental N V and Ne VIII low-temperature dielectronic recombination rate coefficients
The dielectronic recombination rate coefficients of N V and Ne VIII ions have
been measured at a heavy-ion storage ring. The investigated energy ranges
covered all dielectronic recombination resonances attached to 2s -> 2p (Delta
n=0) core excitations. The rate coefficients in a plasma are derived and
parameterized by using a convenient fit formula. The experimentally derived
rate coefficients are compared with theoretical data by Colgan et al. (2004,
A&A, 417, 1183) and Nahar & Pradhan (1997, ApJ, 111, 339) as well as with the
recommended rate coefficients by Mazzotta et al. (1998, A&A, 133, 403). The
data of Colgan et al. and Nahar & Pradhan reproduce the experiment very well
over the temperature ranges where N V and Ne VIII are expected to exist in
photoionized as well as in collisionally ionized plasmas. In contrast, the
recommendation of Mazzotta et al. agrees with the experimental rate coefficient
only in the temperature range of collisional ionization. At lower temperatures
it deviates from the measured rate coefficient by orders of magnitude. In
addition the influence of external electric fields with field strengths up to
1300 V/cm on the dielectronic recombination rate coefficient has been
investigated.Comment: 9 pages, 9 figures, to be published in Astronomy & Astrophysic
A Very Intense Neutrino Super Beam Experiment for Leptonic CP Violation Discovery based on the European Spallation Source Linac: A Snowmass 2013 White Paper
Very intense neutrino beams and large neutrino detectors will be needed in
order to enable the discovery of CP violation in the leptonic sector. We
propose to use the proton linac of the European Spallation Source currently
under construction in Lund, Sweden to deliver, in parallel with the spallation
neutron production, a very intense, cost effective and high performance
neutrino beam. The baseline program for the European Spallation Source linac is
that it will be fully operational at 5 MW average power by 2022, producing 2
GeV 2.86 ms long proton pulses at a rate of 14 Hz. Our proposal is to upgrade
the linac to 10 MW average power and 28 Hz, producing 14 pulses/s for neutron
production and 14 pulses/s for neutrino production. Furthermore, because of the
high current required in the pulsed neutrino horn, the length of the pulses
used for neutrino production needs to be compressed to a few s with the
aid of an accumulator ring. A long baseline experiment using this Super Beam
and a megaton underground Water Cherenkov detector located in existing mines
300-600 km from Lund will make it possible to discover leptonic CP violation at
5 significance level in up to 50% of the leptonic Dirac CP-violating
phase range. This experiment could also determine the neutrino mass hierarchy
at a significance level of more than 3 if this issue will not already
have been settled by other experiments by then. The mass hierarchy performance
could be increased by combining the neutrino beam results with those obtained
from atmospheric neutrinos detected by the same large volume detector. This
detector will also be used to measure the proton lifetime, detect cosmological
neutrinos and neutrinos from supernova explosions. Results on the sensitivity
to leptonic CP violation and the neutrino mass hierarchy are presented.Comment: 28 page
The ESSnuSB design study: overview and future prospects
ESSnuSB is a design study for an experiment to measure the CP violation in
the leptonic sector at the second neutrino oscillation maximum using a neutrino
beam driven by the uniquely powerful ESS linear accelerator. The reduced impact
of systematic errors on sensitivity at the second maximum allows for a very
precise measurement of the CP violating parameter. This review describes the
fundamental advantages of measurement at the 2nd maximum, the necessary
upgrades to the ESS linac in order to produce a neutrino beam, the near and far
detector complexes, the expected physics reach of the proposed ESSnuSB
experiment, concluding with the near future developments aimed at the project
realization.Comment: 19 pages, 11 figures; Corrected minor error in alphabetical ordering
of the authors: the author list is now fully alphabetical w.r.t. author
surnames as was intended. Corrected an incorrect affiliation for two authors
per their reques
Updated physics performance of the ESSnuSB experiment
In this paper, we present the physics performance of the ESSnuSB experiment in the standard three flavor scenario using the updated neutrino flux calculated specifically for the ESSnuSB configuration and updated migration matrices for the far detector. Taking conservative systematic uncertainties corresponding to a normalization error of for signal and for background, we find that there is CP violation discovery sensitivity for the baseline option of 540 km (360 km) at . The corresponding fraction of for which CP violation can be discovered at more than is . Regarding CP precision measurements, the error associated with is around and with is around for the baseline option of 540 km (360 km). For hierarchy sensitivity, one can have sensitivity for 540 km baseline except and sensitivity for 360 km baseline for all values of . The octant of can be determined at for the values of: ( and ) for baseline of 540 km (360 km). Regarding measurement precision of the atmospheric mixing parameters, the allowed values at are: () and eV eV ( eV eV) for the baseline of 540 km (360 km)
DESIGN AND BEAM DYNAMICS STUDY OF HYBRID ESS LINAC
Abstract The European Spallation Source, ESS, will use a superconducting linear accelerator delivering high current long pulses with an average beam power of 5 MW to the target station at 2.5 GeV. A new cryomodule architecture is proposed that can have a quasi-segmented interlacing which provides enough room for beam diagnostics, and can reduce the cryo heat load with respect to the segmented design by keeping the transition regions at sub-100 K region. This paper will present a review of the linac design, beam dynamics studies and a preliminary cryogenic analysis of the transition region
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