| 1. |
- Akkoyun, S., et al.
(author)
-
AGATA - Advanced GAmma Tracking Array
- 2012
-
In: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002 .- 0167-5087 .- 1872-9576. ; 668, s. 26-58
-
Journal article (peer-reviewed)abstract
- The Advanced GAmma Tracking Array (AGATA) is a European project to develop and operate the next generation γ-ray spectrometer. AGATA is based on the technique of γ-ray energy tracking in electrically segmented high-purity germanium crystals. This technique requires the accurate determination of the energy, time and position of every interaction as a γ ray deposits its energy within the detector volume. Reconstruction of the full interaction path results in a detector with very high efficiency and excellent spectral response. The realisation of γ-ray tracking and AGATA is a result of many technical advances. These include the development of encapsulated highly segmented germanium detectors assembled in a triple cluster detector cryostat, an electronics system with fast digital sampling and a data acquisition system to process the data at a high rate. The full characterisation of the crystals was measured and compared with detector- response simulations. This enabled pulse-shape analysis algorithms, to extract energy, time and position, to be employed. In addition, tracking algorithms for event reconstruction were developed. The first phase of AGATA is now complete and operational in its first physics campaign. In the future AGATA will be moved between laboratories in Europe and operated in a series of campaigns to take advantage of the different beams and facilities available to maximise its science output. The paper reviews all the achievements made in the AGATA project including all the necessary infrastructure to operate and support the spectrometer. © 2011 Elsevier B.V. All rights reserved.
|
|
| 2. |
- Valiente-Dobon, J. J., et al.
(author)
-
Conceptual design of the AGATA 2 pi array at LNL
- 2023
-
In: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 1049
-
Journal article (peer-reviewed)abstract
- The Advanced GAmma Tracking Array (AGATA) has been installed at Laboratori Nazionali di Legnaro (LNL), Italy. In this installation, AGATA will consist, at the beginning, of 13 AGATA triple clusters (ATCs) with an angular coverage of 1n,and progressively the number of ATCs will increase up to a 2 pi angular coverage. This setup will exploit both stable and radioactive ion beams delivered by the Tandem-PIAVE-ALPI accelerator complex and the SPES facility. The new implementation of AGATA at LNL will be used in two different configurations, firstly one coupled to the PRISMA large-acceptance magnetic spectrometer and lately a second one at Zero Degrees, along the beam line. These two configurations will allow us to cover a broad physics program, using different reaction mechanisms, such as Coulomb excitation, fusion-evaporation, transfer and fission at energies close to the Coulomb barrier. These setups have been designed to be coupled with a large variety of complementary detectors such as charged particle detectors, neutron detectors, heavy-ion detectors, high-energy gamma-ray arrays, cryogenic and gasjet targets and the plunger device for lifetime measurements. We present in this paper the conceptual design, characteristics and performance figures of this implementation of AGATA at LNL.
|
|
| 3. |
|
|
| 4. |
- Dallmer-Zerbe, K., et al.
(author)
-
Droop controlled operation of heat pumps on clustered distribution grids with high PV penetration
- 2016
-
In: 2016 IEEE International Energy Conference, ENERGYCON 2016. - : IEEE conference proceedings. - 9781467384636
-
Conference paper (peer-reviewed)abstract
- In this work the impact of a high penetration of air to water heat pumps and PV plants on the distribution grid in residential areas is investigated. Results show that increasing PV penetration increases the hours of critical states in the distribution grid. Air to water heat pumps reduce those effects slightly when they are added to the grid. With an increasing penetration of heat pumps new problems, such as load peaks in the mornings, arise. By integrating voltage dependent droop control into the heat pumps, the negative effects on the distribution grid can be reduced. This reduction comes with a loss of HP efficiency and shows strong seasonal variability. For this study a set of representative grid layouts is used. Electric and thermal load profiles for each house are generated using the synPRO stochastic bottom-up model. The thermal load is covered by variable speed electric heat pumps combined with thermal storage. Resulting electric loads are used as input for a probabilistic load flow model.
|
|
| 5. |
- Dwibedi, Chinmay Kumar, et al.
(author)
-
Long-range dispersal moved Francisella tularensis into Western Europe from the East
- 2016
-
In: Microbial Genomics. - : Microbiology Society. - 2057-5858. ; 2:12
-
Journal article (peer-reviewed)abstract
- For many infections transmitting to humans from reservoirs in nature, disease dispersal patterns over space and time are largely unknown. Here, a reversed genomics approach helped us understand disease dispersal and yielded insight into evolution and biological properties of Francisella tularensis, the bacterium causing tularemia. We whole-genome sequenced 67 strains and characterized by single-nucleotide polymorphism assays 138 strains, collected from individuals infected 1947-2012 across Western Europe. We used the data for phylogenetic, population genetic and geographical network analyses. All strains (n= 205) belonged to a monophyletic population of recent ancestry not found outside Western Europe. Most strains (n= 195) throughout the study area were assigned to a star-like phylogenetic pattern indicating that colonization of Western Europe occurred via clonal expansion. In the East of the study area, strains were more diverse, consistent with a founder population spreading from east to west. The relationship of genetic and geographic distance within the F. tularensis population was complex and indicated multiple long-distance dispersal events. Mutation rate estimates based on year of isolation indicated null rates; in outbreak hotspots only, there was a rate of 0.4 mutations/genome/year. Patterns of nucleotide substitution showed marked AT mutational bias suggestive of genetic drift. These results demonstrate that tularemia has moved from east to west in Europe and that F. tularensis has a biology characterized by long-range geographical dispersal events and mostly slow, but variable, replication rates. The results indicate that mutation-driven evolution, a resting survival phase, genetic drift and long-distance geographical dispersal events have interacted to generate genetic diversity within this species.
|
|
| 6. |
- Fischer, David, et al.
(author)
-
Comparison of control approaches for variable speed air source heat pumps considering time variable electricity prices and PV
- 2017
-
In: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 204, s. 93-105
-
Journal article (peer-reviewed)abstract
- The influence of different control strategies and boundary conditions on heat pump system performance are investigated in this study and the trade-off between complexity and performance of different controllers is addressed. For this purpose five different control approaches for a variable speed air source heat pump in a multi family house are compared for three different use-cases. The used controls differ in complexity and the use of external input data like price and weather forecasts. The use-cases are: Constant electricity prices, time variable electricity prices and PV self-consumption. Four different rule-based controllers are compared to a convex MPC approach, presented in this work. Results show that the MPC approach reduces annual operating cost by 6–11% for constant electricity prices and 6–16% in the case of variable electricity prices. Rule-based approaches lead to cost reductions of 2–4%. MPC could increases PV self-consumption from 56% to 58% up to 64–71%. The rule base approaches are found computationally less demanding and easier to design. However fine-tuning has been considerable work and with changing boundary conditions rules had to be readjusted. It showed that increasing thermal storage without MPC is not beneficial and optimised controls are a prerequisite to benefit from increased storage sizes.
|
|
| 7. |
- Parfeniukas, Karolis, et al.
(author)
-
Improved tungsten nanofabrication for hard X-ray zone plates
- 2016
-
In: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 152, s. 6-9
-
Journal article (peer-reviewed)abstract
- We present an improved nanofabrication method of high aspect ratio tungsten structures for use in high efficiency nanofocusing hard X-ray zone plates. A ZEP 7000 electron beam resist layer used for patterning is cured by a second, much larger electron dose after development. The curing step improves pattern transfer fidelity into a chromium hard mask by reactive ion etching using Cl2/O2 chemistry. The pattern can then be transferred into an underlying tungsten layer by another reactive ion etching step using SF6/O2. A 630 nm-thick tungsten zone plate with smallest line width of 30 nm was fabricated using this method and characterized. At 8.2 keV photon energy the device showed an efficiency of 2.2% with a focal spot size at the diffraction limit, measured at Diamond Light Source I-13-1 beamline.
|
|
| 8. |
- Seiboth, Frank, et al.
(author)
-
Aberration Correction for Hard X-ray Focusing at the Nanoscale
- 2017
-
In: Advances in X-Ray/EUV Optics and Components XII. - : SPIE - International Society for Optical Engineering. - 9781510612303 - 9781510612297
-
Conference paper (peer-reviewed)abstract
- We developed a corrective phase plate that enables the correction of residual aberration in reflective, diffractive, and refractive X-ray optics. The principle is demonstrated on a stack of beryllium compound refractive lenses with a numerical aperture of 0.49 x 10(-3) at three different synchrotron radiation and x-ray free-electron laser facilities. By introducing this phase plate into the beam path, we were able to correct the spherical aberration of the optical system and improve the Strehl ratio of the optics from 0.29(7) to 0.87(5), creating a diffraction-limited, large aperture, nanofocusing optics that is radiation resistant and very compact.
|
|
| 9. |
- Seiboth, Frank, et al.
(author)
-
Perfect X-ray focusing via fitting corrective glasses to aberrated optics
- 2017
-
In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 8
-
Journal article (peer-reviewed)abstract
- Due to their short wavelength, X-rays can in principle be focused down to a few nanometres and below. At the same time, it is this short wavelength that puts stringent requirements on X-ray optics and their metrology. Both are limited by today’s technology. In this work, we present accurate at wavelength measurements of residual aberrations of a refractive X-ray lens using ptychography to manufacture a corrective phase plate. Together with the fitted phase plate the optics shows diffraction-limited performance, generating a nearly Gaussian beam profile with a Strehl ratio above 0.8. This scheme can be applied to any other focusing optics, thus solving the X-ray optical problem at synchrotron radiation sources and X-ray free-electron lasers.
|
|
