| 1. |
- Rodriguez, D., et al.
(författare)
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MATS and LaSpec : High-precision experiments using ion traps and lasers at FAIR
- 2010
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Ingår i: The European physical journal. Special topics. - : Springer Science and Business Media LLC. - 1951-6355 .- 1951-6401. ; 183, s. 1-123
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Forskningsöversikt (refereegranskat)abstract
- Nuclear ground state properties including mass, charge radii, spins and moments can be determined by applying atomic physics techniques such as Penning-trap based mass spectrometry and laser spectroscopy. The MATS and LaSpec setups at the low-energy beamline at FAIR will allow us to extend the knowledge of these properties further into the region far from stability. The mass and its inherent connection with the nuclear binding energy is a fundamental property of a nuclide, a unique ""fingerprint"". Thus, precise mass values are important for a variety of applications, ranging from nuclear-structure studies like the investigation of shell closures and the onset of deformation, tests of nuclear mass models and mass formulas, to tests of the weak interaction and of the Standard Model. The required relative accuracy ranges from 10(-5) to below 10(-8) for radionuclides, which most often have half-lives well below 1 s. Substantial progress in Penning trap mass spectrometry has made this method a prime choice for precision measurements on rare isotopes. The technique has the potential to provide high accuracy and sensitivity even for very short-lived nuclides. Furthermore, ion traps can be used for precision decay studies and offer advantages over existing methods. With MATS (Precision Measurements of very short-lived nuclei using an Advanced Trapping System for highly-charged ions) at FAIR we aim to apply several techniques to very short-lived radionuclides: High-accuracy mass measurements, in-trap conversion electron and alpha spectroscopy, and trap-assisted spectroscopy. The experimental setup of MATS is a unique combination of an electron beam ion trap for charge breeding, ion traps for beam preparation, and a high-precision Penning trap system for mass measurements and decay studies. For the mass measurements, MATS offers both a high accuracy and a high sensitivity. A relative mass uncertainty of 10(-9) can be reached by employing highly-charged ions and a non-destructive Fourier-Transform Ion-Cyclotron-Resonance (FT-ICR) detection technique on single stored ions. This accuracy limit is important for fundamental interaction tests, but also allows for the study of the fine structure of the nuclear mass surface with unprecedented accuracy, whenever required. The use of the FT-ICR technique provides true single ion sensitivity. This is essential to access isotopes that are produced with minimum rates which are very often the most interesting ones. Instead of pushing for highest accuracy, the high charge state of the ions can also be used to reduce the storage time of the ions, hence making measurements on even shorter-lived isotopes possible. Decay studies in ion traps will become possible with MATS. Novel spectroscopic tools for in-trap high-resolution conversion-electron and charged-particle spectroscopy from carrier-free sources will be developed, aiming e. g. at the measurements of quadrupole moments and E0 strengths. With the possibility of both high-accuracy mass measurements of the shortest-lived isotopes and decay studies, the high sensitivity and accuracy potential of MATS is ideally suited for the study of very exotic nuclides that will only be produced at the FAIR facility. Laser spectroscopy of radioactive isotopes and isomers is an efficient and model-independent approach for the determination of nuclear ground and isomeric state properties. Hyperfine structures and isotope shifts in electronic transitions exhibit readily accessible information on the nuclear spin, magnetic dipole and electric quadrupole moments as well as root-mean-square charge radii. The dependencies of the hyperfine splitting and isotope shift on the nuclear moments and mean square nuclear charge radii are well known and the theoretical framework for the extraction of nuclear parameters is well established. These extracted parameters provide fundamental information on the structure of nuclei at the limits of stability. Vital information on both bulk and valence nuclear properties are derived and an exceptional sensitivity to changes in nuclear deformation is achieved. Laser spectroscopy provides the only mechanism for such studies in exotic systems and uniquely facilitates these studies in a model-independent manner. The accuracy of laser-spectroscopic-determined nuclear properties is very high. Requirements concerning production rates are moderate; collinear spectroscopy has been performed with production rates as few as 100 ions per second and laser-desorption resonance ionization mass spectroscopy (combined with beta-delayed neutron detection) has been achieved with rates of only a few atoms per second. This Technical Design Report describes a new Penning trap mass spectrometry setup as well as a number of complementary experimental devices for laser spectroscopy, which will provide a complete system with respect to the physics and isotopes that can be studied. Since MATS and LaSpec require high-quality low-energy beams, the two collaborations have a common beamline to stop the radioactive beam of in-flight produced isotopes and prepare them in a suitable way for transfer to the MATS and LaSpec setups, respectively.
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| 2. |
- Bracale, A., et al.
(författare)
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A new joint sliding-window ESPRIT and DFT scheme for waveform distortion assessment in power systems
- 2012
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Ingår i: Electric Power Systems Research. - : Elsevier BV. - 0378-7796 .- 1873-2046. ; 88, s. 112-120
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a novel scheme that jointly employs a sliding-window ESPRIT and DFT for estimating harmonic and interharmonic components in power system disturbance data. In the proposed scheme, separate stages are utilized to estimate the voltage fundamental component, harmonics and interharmonics. This includes the estimation of the fundamental component from lowpass filtered data using a sliding-window ESPRIT, of harmonics from a sliding-window DFT with a synchronized window, and of interharmonics from the residuals by applying the sliding-window ESPRIT. Main advantages of the approach include high resolution and accuracy in parameter estimation and significantly reduced computational cost. Experiments and comparisons are made on both synthetic and measurement data. Results have shown the effectiveness and efficiency of the proposed scheme.
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| 3. |
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| 4. |
- Bollen, Math, et al.
(författare)
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Continuity of supply and voltage quality in the electricity network of the future
- 2012
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Ingår i: 15th International Conference on Harmonics and Quality of Power (ICHQP). - : IEEE Communications Society. - 9781467319447 ; , s. 375-377
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Konferensbidrag (refereegranskat)abstract
- This paper introduces three examples of new thinking for addressing the challenges that the power system has to cope with. Such new thinking in combination with new technology will be an important element in the transition to the future electricity network (the —). With overload protection it is important to not remove the overloaded component but the cause of the overload so as to protect the other network users against an interruption. The limits set to the hosting capacity by potential overvoltages can be removed either by new technology (curtailment of production) or by allowing occasional overvoltages. Allowing higher levels of non-characteristic harmonics is a possible alternative for strict emission limits on new installations. In all cases it is essential that the interests of the network user are considered.
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| 5. |
- Bollen, Math, et al.
(författare)
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Voltage dip immunity aspects of power-electronics equipment : Recommendations from CIGRE/CIRED/UIE JWG C4.110
- 2011
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Ingår i: 2010 14th International Power Electronics and Motion Control Conference (EPE/PEMC 2010). - Piscataway, NJ : IEEE Communications Society. ; , s. 803-810
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Konferensbidrag (refereegranskat)abstract
- This paper presents some of the results from an international working group on voltage-dip immunity. The working group has made a number of recommendations to reduce the adverse impact of voltage dips. Specific recommendations to researchers and manufacturers of powerelectronic equipment are: considering all voltage dip characteristics early in the design of equipment; characterize performance of equipment by means of voltage-dip immunity curves; and made equipment with different immunity available
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| 6. |
- Bollen, Math, et al.
(författare)
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Voltage dip immunity aspects of power electronics equipment : Recommendations from CIGRE/CIRED/UIE JWG C4.110
- 2011
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Ingår i: Proceeding of the International Conference on Electrical Power Quality and Utilisation, EPQU. - : IEEE Communications Society. - 9781467303798 ; , s. 803-810
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Konferensbidrag (refereegranskat)abstract
- This paper presents some of the results from an international working group on voltage-dip immunity. The working group has made a number of recommendations to reduce the adverse impact of voltage dips. Specific recommendations to researchers and manufacturers of power-electronic equipment are: considering all voltage dip characteristics early in the design of equipment; characterize performance of equipment by means of voltage-dip immunity curves; and made equipment with different immunity available.
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| 7. |
- Bollen, Math, et al.
(författare)
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Voltage dip immunity of equipment and installations - Messages to stakeholders
- 2012
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Ingår i: 2012 IEEE 15th International Conferenceon Harmonics and Quality of Power. - : IEEE Communications Society. - 9781467319447 - 9781467319430 ; , s. 915-919
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Konferensbidrag (refereegranskat)abstract
- This paper presents the messages to the stakeholders on voltage-dip immunity as extracted by UIE WG2 from CIGRE TB412 [1]. The paper summarizes the main recommendations from this technical brochure in the form of messages towards regulators, standard-setting-organizations, network operators, industrial customers, equipment manufacturers, and power quality monitor manufacturers, researchers.
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| 8. |
- Bollen, Math, et al.
(författare)
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Voltage dip immunity of equipment and installations messages to stakeholders
- 2012
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Ingår i: The Renewable Energies and Power Quality Journal. - : AEDERMACP (European Association for the Development of Renewable Energies and Power Quality). - 2172-038X. ; 1:10, s. 452-456
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the messages to the stakeholders on voltage-dip immunity as extracted by UIE WG2 from CIGRE TB412 [1]. The paper summarizes the main recommendations from this technical brochure in the form of messages towards regulators, standard-setting-organizations, network operators, industrial customers, equipment manufacturers, and power quality monitor manufacturers, researchers.
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| 9. |
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| 10. |
- Chang, G.W., et al.
(författare)
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Monitoring issues and analysis techniques : smart grid aspect of power quality
- 2012
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Ingår i: 15th International Conference on Harmonics and Quality of Power (ICHQP). - : IEEE Communications Society. - 9781467319447 ; , s. 673-677
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Konferensbidrag (refereegranskat)abstract
- In recent years, many countries have started to integrate the power system with more advanced information and communication technologies. With transforming the electrical data to useful information, the stability and reliability of power system operation can be secured. By observing this world-wide trend, it is believed that the development of smart grid would be the vital strategy for energy saving, integration of renewable energy resources, and improvement of power quality. Meanwhile, the related measuring and control equipments are necessary to redesign based on information and communication technologies (ICT), which are key factors to the success of the smart grid implementation. This paper gives an overview of some important issues and techniques for the enhancement of power quality monitoring and analysis when deploying the smart grid.
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