639 research outputs found
Sterilization Assembly Development Laboratory - Routine cleaning and decontamination of the SADL facility
Procedures for preparing cleaning and germicidal solutions and cleaning equipment for spacecraft sterilizatio
A state-of-the-art review and feasibility analysis of high altitude wind power in Northern Ireland
AbstractIn many countries wind energy has become an indispensable part of the electricity generation mix. The opportunity for ground based wind turbine systems are becoming more and more constrained due to limitations on turbine hub heights, blade lengths and location restrictions linked to environmental and permitting issues including special areas of conservation and social acceptance due to the visual and noise impacts. In the last decade there have been numerous proposals to harness high altitude winds, such as tethered kites, airfoils and dirigible based rotors. These technologies are designed to operate above the neutral atmospheric boundary layer of 1300m, which are subject to more powerful and persistent winds thus generating much higher electricity capacities. This paper presents an in-depth review of the state-of-the-art of high altitude wind power, evaluates the technical and economic viability of deploying high altitude wind power as a resource in Northern Ireland and identifies the optimal locations through considering wind data and geographical constraints. The key findings show that the total viable area over Northern Ireland for high altitude wind harnessing devices is 5109.6km2, with an average wind power density of 1998W/m2 over a 20-year span, at a fixed altitude of 3000m. An initial budget for a 2MW pumping kite device indicated a total cost £1,751,402 thus proving to be economically viable with other conventional wind-harnessing devices
Search for supernova-produced 60Fe in a marine sediment
An 60Fe peak in a deep-sea FeMn crust has been interpreted as due to the
signature left by the ejecta of a supernova explosion close to the solar system
2.8 +/- 0.4 Myr ago [Knie et al., Phys. Rev. Lett. 93, 171103 (2004)]. To
confirm this interpretation with better time resolution and obtain a more
direct flux estimate, we measured 60Fe concentrations along a dated marine
sediment. We find no 60Fe peak at the expected level from 1.7 to 3.2 Myr ago.
However, applying the same chemistry used for the sediment, we confirm the 60Fe
signal in the FeMn crust. The cause of the discrepancy is discussed.Comment: 15 pages, 5 figures, submitted to PR
Extinction of the N=20 neutron-shell closure for 32Mg examined by direct mass measurements
The 'island of inversion' around Mg is one of the most important
paradigm for studying the disappearance of the stabilizing 'magic' of a shell
closure. We present the first Penning-trap mass measurements of the exotic
nuclides Na and Mg, which allow a precise determination of
the empirical shell gap for Mg. The new value of 1.10(3) MeV is the
lowest observed shell gap for any nuclide with a canonical magic number.Comment: 6 pages, 4 figures, submitted to Physical Review
TOF-Brho Mass Measurements of Very Exotic Nuclides for Astrophysical Calculations at the NSCL
Atomic masses play a crucial role in many nuclear astrophysics calculations.
The lack of experimental values for relevant exotic nuclides triggered a rapid
development of new mass measurement devices around the world. The
Time-of-Flight (TOF) mass measurements offer a complementary technique to the
most precise one, Penning trap measurements, the latter being limited by the
rate and half-lives of the ions of interest. The NSCL facility provides a
well-suited infrastructure for TOF mass measurements of very exotic nuclei. At
this facility, we have recently implemented a TOF-Brho technique and performed
mass measurements of neutron-rich nuclides in the Fe region, important for
r-process calculations and for calculations of processes occurring in the crust
of accreting neutron stars.Comment: 8 pages, 4 figures, submitted to Journal of Physics G, proceedings of
Nuclear Physics in Astrophysics II
Evidence for a breakdown of the Isobaric Multiplet Mass Equation: A study of the A=35, T=3/2 isospin quartet
Mass measurements on radionuclides along the potassium isotope chain have
been performed with the ISOLTRAP Penning trap mass spectrometer. For 35K
T1/2=178ms) to 46K (T1/2=105s) relative mass uncertainties of 2x10-8 and better
have been achieved. The accurate mass determination of 35K (dm=0.54keV) has
been exploited to test the Isobaric Multiplet Mass Equation (IMME) for the
A=35, T=3/2 isospinquartet. The experimental results indicate a deviation from
the generally adopted quadratic form.Comment: 8 pages, 4 figure
A linear radiofrequency ion trap for accumulation, bunching, and emittance improvement of radioactive ion beams
An ion beam cooler and buncher has been developed for the manipulation of
radioactive ion beams. The gas-filled linear radiofrequency ion trap system is
installed at the Penning trap mass spectrometer ISOLTRAP at ISOLDE/CERN. Its
purpose is to accumulate the 60-keV continuous ISOLDE ion beam with high
efficiency and to convert it into low-energy low-emittance ion pulses. The
efficiency was found to exceed 10% in agreement with simulations. A more than
10-fold reduction of the ISOLDE beam emittance can be achieved. The system has
been used successfully for first on-line experiments. Its principle, setup and
performance will be discussed
Elucidation of the anomalous A = 9 isospin quartet behaviour
Recent high-precision mass measurements of Li and Be, performed
with the TITAN Penning trap at the TRIUMF ISAC facility, are analyzed in light
of state-of-the-art shell model calculations. We find an explanation for the
anomalous Isobaric Mass Multiplet Equation (IMME) behaviour for the two = 9
quartets. The presence of a cubic = 6.3(17) keV term for the =
3/2 quartet and the vanishing cubic term for the excited =
1/2 multiplet depend upon the presence of a nearby = 1/2 state in
B and Be that induces isospin mixing. This is contrary to previous
hypotheses involving purely Coulomb and charge-dependent effects. = 1/2
states have been observed near the calculated energy, above the = 3/2
state. However an experimental confirmation of their is needed.Comment: 5 pages, 2 figure
Updated optical design and trade-off study for MOONS, the Multi-Object Optical and Near Infrared spectrometer for the VLT
This paper presents the latest optical design for the MOONS triple-arm
spectrographs. MOONS will be a Multi-Object Optical and Near-infrared
Spectrograph and will be installed on one of the European Southern Observatory
(ESO) Very Large Telescopes (VLT). Included in this paper is a trade-off
analysis of different types of collimators, cameras, dichroics and filters.Comment: 10 pages, 8 figures, 5 tables. Presented at SPIE Astronomical
Telescope + Instrumentation 2014 (Ground-based and Airbone Instrumentation
for Astronomy 5, 9147-84). To be published in Proceeding of SPIE Volume 914
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