lnu.sePublications
Change search
Refine search result
45678910 301 - 350 of 860
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf
Rows per page
• 5
• 10
• 20
• 50
• 100
• 250
Sort
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
• Standard (Relevance)
• Author A-Ö
• Author Ö-A
• Title A-Ö
• Title Ö-A
• Publication type A-Ö
• Publication type Ö-A
• Issued (Oldest first)
• Created (Oldest first)
• Last updated (Oldest first)
• Disputation date (earliest first)
• Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
• 301.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics.
Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics. Department of Quantum Chemistry, Uppsala University, Box 518, Se-751 20 Uppsala, Sweden.
Universal Non-adiabatic Holonomic Gates in Quantum Dots and Single-Molecule MagnetsManuscript (preprint) (Other academic)

Geometric manipulation of a quantum system offers a method for fast, universal, and robust quantum information processing. Here, we propose a scheme for universal all-geometric quantum computation using non-adiabatic quantum holonomies. We propose three different realizations of the scheme based on an unconventional use of quantum dot and single-molecule magnet devices,which offer promising scalability and robust efficiency.

• 302.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Uppsala University ; National University of Singapore, Singapore.
Universal Non-adiabatic Holonomic Gates in Quantum Dots and Single-Molecule Magnets2014In: New Journal of Physics, ISSN 1367-2630, E-ISSN 1367-2630, Vol. 16, article id 013029Article in journal (Refereed)

Geometric manipulation of a quantum system offers a method for fast, universal, and robust quantum information processing. Here, we propose a scheme for universal all-geometric quantum computation using non-adiabatic quantum holonomies. We propose three different realizations of the scheme based on an unconventional use of quantum dot and single-molecule magnet devices,which offer promising scalability and robust efficiency.

• 303.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
Uppsala Univ.
Non-Abelian geometric phases in a system of coupled quantum bits2014In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 89, no 2, p. 022117-Article in journal (Refereed)

A common strategy to measure the Abelian geometric phase for a qubit is to let it evolve along an orange-slice-shaped path connecting two antipodal points on the Bloch sphere by two different semi-great-circles. Since the dynamical phases vanish for such paths, this allows for direct measurement of the geometric phase. Here, we generalize the "orange-slice" setting to the non-Abelian case. The proposed method to measure the non-Abelian geometric phase can be implemented in a cyclic chain of four qubits with controllable interactions.

• 304.
ASTRON, Oude Hoogeveensedijk 4, 7991 PD Dwingeloo, The Netherlands .
Dense gas in luminous infrared galaxies2008In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 477, no 3, p. 747-762Article in journal (Refereed)

Aims.Molecules that trace the high-density regions of the interstellar medium have been observed in (ultra-)luminous (far-)infrared galaxies, in order to initiate multiple-molecule multiple-transition studies to evaluate the physical and chemical environment of the nuclear medium and its response to the ongoing nuclear activity.

Methods.The HCN(1-0), HNC(1-0), ${\rm HCO}^+$(1-0), CN(1-0) and CN(2-1), CO(2-1), and CS(3-2) transitions were observed in sources covering three decades of infrared luminosity including sources with known OH megamaser activity. The data for the molecules that trace the high-density regions were augmented with data available in the literature.

Results.The integrated emissions of high-density tracer molecules show a strong relation to the far-infrared luminosity. Ratios of integrated line luminosities were used for a first-order diagnosis of the integrated molecular environment of the evolving nuclear starbursts. Diagnostic diagrams display significant differentiation among the sources that relate to the initial conditions and the radiative excitation environment. Initial differentiation was introduced between the FUV radiation field in photon-dominated-regions and the X-ray field in X-ray-dominated-regions. The galaxies displaying OH megamaser activity have line ratios typical of photon-dominated regions.

• 305.
Linnaeus University, Faculty of Technology, Department of computer science and media technology (CM), Department of Computer Science. ASTRON, Netherlands;Shanghai Astron Observ, Peoples Republic of China.
ASTRON, Netherlands;Kapteyn Astron Inst, Netherlands. Kapteyn Astron Inst, Netherlands.
Multimolecular studies of Galactic star-forming regions2014In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 445, no 4, p. 3331-3344Article in journal (Refereed)

Molecular emission-line observations of isolated Galactic star-forming regions are used to model the physical properties of the molecular interstellar medium in these systems. Observed line ratios are compared with the results predicted by models that incorporate gas-phase chemistry and the heating by stellar radiation and non-radiative feedback processes. The line ratios of characteristic tracer molecules may be interpreted using the contributions of two distinct components: a cold (40-50 K) and high-density (105-105.5 cm(-3)) photon-dominated region (PDR) with a nominal UV flux density and a warm (similar to 300 K) mechanical heating-dominated region (MHDR) with a slightly lower density (10(4.5)-10(5) cm(-3)). The relative contributions of these structural components are used to model the observed line ratios. Ionized species may be better modelled by adopting an increase of the cosmic ray flux towards the Galactic Centre and the sulphur abundance should depleted by a factor of 200-400 relative to solar values. The line ratios of the Galactic sample are found to be very similar to those of the integrated signature of prominent (ultra) luminous IR Galaxies. The PDRs and MHDRs in the isolated Galactic regions may be modelled with slightly higher mean densities than in extragalactic systems and a higher MHDR temperature resulting from non-radiative mechanical heating. Multimolecular studies are effective in determining the physical and chemical properties of star formation regions by using characteristic line ratios to diagnose their environment. The addition of more molecular species will reduce the existing modelling redundancy.

• 306. Bai, X.
University of Kalmar, Department of Technology. University of Kalmar, Department of Technology.
Status of the Neutrino Telescope AMANDA: Monopoles and WIMPS2001In: Dark Matter in Astro- and Particle Physics: Proceedings of the International Conference DARK 2000 Heidelberg, Germany, 10–14 July 2000 / [ed] H. V. Klapdor-Kleingrothaus, Springer, 2001, p. 699-706Conference paper (Refereed)

The neutrino telescope AMANDA has been set up at the geographical South Pole as first step to a neutrino telescope of the scale of one cubic kilometer, which is the canonical size for a detector sensitive to neutrinos from Active Galactic Nuclei (AGN), Gamma Ray Bursts (GRB) and Topological Defects (TD). The location and depth in which the detector is installed is given by the requirement to detect neutrinos by the Cherenkov light produced by their reaction products and to keep the background due to atmospheric muons as small as possible. However, a detector optimized for this purpose is also capable to detect the bright Cherenkov light from relativistic Monopoles and neutrino signals from regions with high gravitational potential, where WIMPS are accumulated and possibly annihilate. Both hypothetical particles might contribute to the amount of dark matter. Therefore here a report about the status of the experiment (autumn 2000) and about the status of the search for these particles with the AMANDA B10 sub-detector is given.

• 307. Bakari, D
Estimate of the energy of upgoing muons with multiple coulomb scattering2001In: Cosmic Radiations: from Astronomy to Particle Physics / [ed] Giacommelli, G; Spurio, M; Derkaoui, JE, Dordrecht: Springer, 2001, Vol. 42, p. 135-140Conference paper (Other academic)
• 308.
Polish Acad Sci, Poland. Polish Acad Sci, Poland. Polish Acad Sci, Poland. Polish Acad Sci, Poland. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Polish Acad Sci, Poland ; Lund University.
Off-Axis Electron Holography of Magnetic Nanostructures: Magnetic Behavior of Mn Rich Nanoprecipitates in (Mn,Ga) As System2017In: Acta Physica Polonica. A, ISSN 0587-4246, E-ISSN 1898-794X, Vol. 131, no 5, p. 1406-1408Article in journal (Refereed)

The Lorentz off-axis electron holography technique is applied to study the magnetic nature of Mn rich nanoprecipitates in (Mn,Ga) As system. The effectiveness of this technique is demonstrated in detection of the magnetic field even for small nanocrystals having an average size down to 20 nm.

• 309. Barbiellini, G.
Stanford Univ, USA.
Fermi Large Area Telescope Observations of Blazar 3C 279 Occultations by the Sun2014In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 784, no 2, article id 118Article in journal (Refereed)

Observations of occultations of bright. gamma-ray sources by the Sun may reveal predicted pair halos around blazars and/or new physics, such as, e.g., hypothetical light dark matter particles-axions. We use Fermi Gamma-Ray Space Telescope (Fermi) data to analyze four occultations of blazar 3C 279 by theSun on October 8 each year from 2008 to 2011. A combined analysis of the observations of these occultations allows a point-like source at the position of 3C279 to be detected with significance of approximate to 3 sigma, but does not reveal any significant excess over the flux expected from the quiescent Sun.The likelihood ratio test rules out complete transparency of the Sun to the blazar. gamma-ray emission at a 3s confidence level.

• 310. Barwick, S. W.
University of Kalmar, Department of Technology. University of Kalmar, Department of Technology.
Initial results from the AMANDA high-energy neutrino detector1998In: High-energy physics. Proceedings, 29th International Conference, ICHEP'98, Vancouver, Canada, July 23-29, 1998. Vol. 1, 2 / [ed] A. Astbury, D. Axen, J. Robinson, 1998, p. 1447-1452Conference paper (Refereed)
• 311. Basiev, T. T.
Linnaeus University, Faculty of Technology, Department of Mathematics.
Luminescent nanophotonics and advanced solid state lasers2013In: Journal of Luminescence, ISSN 0022-2313, E-ISSN 1872-7883, Vol. 133, p. 233-243Article in journal (Refereed)

In this review, authors present their latest findings in luminescence quenching kinetics theory and advanced solid state laser experiments. Luminescence quenching kinetics is a popular and exceptionally useful tool to analyze the nanosized luminophores and laser material nanostructure. Quenching kinetics may be multistage, some stages having a complex, not exponential, form. It is often the case for modern laser materials, which are nanostructurized, and for particular cases of energy transfer (such as cooperative down-conversion). We present compact and easy-to-use analytical expressions and computer simulation for various cases of nonexponential quenching kinetics: migration-accelerated quenching in bulk material; cooperative luminescence quenching in bulk material; and two extreme cases of energy transfer in nanoparticles - static and with superfast migration (both including cooperative case of luminescence quenching in ensembles of acceptors comprised of two-, three-, and more particles). We also review the most perspective laser experiments lately performed in our laboratory, including those on fluoride laser nanoceramics and materials for middle infra-red lasers. (c) 2011 Elsevier B.V. All rights reserved.

• 312.
Linnaeus University, Faculty of Technology, Department of Mathematics.
Theoretical method for states dynamics and entanglement optimization in bichromatically driven clusters of two and four resonantly interacting particles2013In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, E-ISSN 1520-8540, Vol. 30, no 7, p. 1804-1814Article in journal (Refereed)

Bichromatic laser pumping is an effective tool to control (e. g., to drive into an entangled state) solid-state quantum bits of different nature. For clusters of resonantly interacting ions under bichromatic laser pumping, we present a theoretical approach and approximate analytical solution for quantum states dynamics. The solution provides an optimal ratio of laser pulse intensities needed for creating the maximally entangled states and performing quantum gates. Numerical simulation corroborates the analytical results. (C) 2013 Optical Society of America

• 313.
Prokhorov Gen Phys Inst, Russia.
Linnaeus University, Faculty of Technology, Department of Mathematics.
On the Possibility to Combine the Order Effect with Sequential Reproducibility for Quantum Measurements2015In: Foundations of physics, ISSN 0015-9018, E-ISSN 1572-9516, Vol. 45, no 10, p. 1379-1393Article in journal (Refereed)

In this paper we study the problem of a possibility to use quantum observables to describe a possible combination of the order effect with sequential reproducibility for quantum measurements. By the order effect we mean a dependence of probability distributions (of measurement results) on the order of measurements. We consider two types of the sequential reproducibility: adjacent reproducibility () (the standard perfect repeatability) and separated reproducibility(). The first one is reproducibility with probability 1 of a result of measurement of some observable A measured twice, one A measurement after the other. The second one, , is reproducibility with probability 1 of a result of A measurement when another quantum observable B is measured between two A's. Heuristically, it is clear that the second type of reproducibility is complementary to the order effect. We show that, surprisingly, this may not be the case. The order effect can coexist with a separated reproducibility as well as adjacent reproducibility for both observables A and B. However, the additional constraint in the form of separated reproducibility of the type makes this coexistence impossible. The problem under consideration was motivated by attempts to apply the quantum formalism outside of physics, especially, in cognitive psychology and psychophysics. However, it is also important for foundations of quantum physics as a part of the problem about the structure of sequential quantum measurements.

• 314.
INFN Sez. di Milano, Italy.
Universita’ di Bologna, Italy. Universita’ di Bologna, Italy ; INAF/IASF Sez. di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy ; University Mohamed 1st, Morocco. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy ; ISS, Romania. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy. Universita’ di Bologna, Italy.
Search for exotic contributions to atmospheric neutrino oscillations2005In: 29th International Cosmic Ray Conference: August 3 - 10, 2005, Pune, India, Mumbai: Tata Institute of Fundamental Research , 2005, p. 171-174Conference paper (Other academic)

The energy spectrum of neutrino-induced upward-going muons in MACRO was analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of v(mu) -> v(tau) transitions. The data disfavor these possibilities even at a sub-dominant level; stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter vertical bar Delta v vertical bar < 6 x 10(-24) at sin 2 theta(v) = 0 and vertical bar Delta v vertical bar < 2.5 divided by 5 x 10(-26) at sin 2 theta(v) = +/- 1. The limits can be re-interpreted as bounds on the Equivalence Principle violation parameters.

• 315. Battistoni, G
Università di Bologna, Italy ; INFN, Italy.
Search for a Lorentz invariance violation contribution in atmospheric neutrino oscillations using MACRO data2005In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 615, no 1-2, p. 14-18Article in journal (Refereed)

The energy spectrum of neutrino-induced upward-going muons in MACRO has been analysed in terms of relativity principles violating effects, keeping standard mass-induced atmospheric neutrino oscillations as the dominant source of v(u) -> v(tau) transitions. The data disfavor these exotic possibilities even at a subdominant level, and stringent 90% C.L. limits are placed on the Lorentz invariance violation parameter vertical bar Delta v vertical bar < 6 x 10(-24) at sin2 theta(v) = 0 and vertical bar Delta(v)vertical bar < 2.5-5 x 10(-26) at sin 2 theta(v) = +/- 1. These limits can also be re-interpreted as upper bounds on the parameters describing violation of the equivalence principle. (c) 2005 Elsevier B.V. All rights reserved.

• 316. Bay, R. C.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
The AMANDA neutrino telescope and the indirect search for dark matter: AMANDA Colaboration1998In: Physics reports, ISSN 0370-1573, E-ISSN 1873-6270, Vol. 307, no 1-4, p. 243-252Article in journal (Refereed)

With an effective telescope area of order 104m2, a threshold of ~50GeV and a pointing accuracy of 2.5°, the AMANDA detector represents the first of a new generation of high energy neutrino telescopes, reaching a scale envisaged over 25 years ago. We describe its performance, focussing on the capability to detect halo dark matter particles via their annihilation into neutrinos.

• 317.
Dipartimento di Fisica dell’Universita’ di Bologna.
ANTARES: Software organisation, reconstruction, performance studies2006In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 567, no 2, p. 477-479Article in journal (Refereed)

The ANTARES Collaboration is building an underwater neutrino telescope in the Mediterranean sea. The first full 480m line was connected to the shore station in March 2006. The full Monte Carlo simulation chain and offline software structure of the experiment is presented. The offline software structure consists of two main parts: the first concerns the generation of the Monte Carlo events in the detector and the cligitisation and filtering of the signals, while the second concerns offline event reconstruction of both Monte Carlo events and real data. The expected performances of the detector obtained from this accurate simulation procedure are also presented and discussed. (c) 2006 Elsevier B.V. All rights reserved.

• 318.
University of Bologna .
MACRO results on atmospheric neutrino oscillations2003In: Neutrino Physics / [ed] Bellotti, E; Declais, Y; Strolin, P; Zanotti, L, Amsterdam: IOS Press, 2003, Vol. 152, p. 269-273Conference paper (Other academic)
• 319.
University of Bologna.
The ANTARES neutrino telescope2003In: Neutrino Physics / [ed] Bellotti, E; Declais, Y; Strolin, P; Zanotti, L, Amsterdam: IOS Press, 2003, Vol. 152, p. 275-279Conference paper (Other academic)
• 320.
University of Paris Diderot .
Discovery of VHE gamma-ray emission from the very distant BL Lac KUV00311-1938 by HESS2012In: HIGH ENERGY GAMMA-RAY ASTRONOMY, American Institute of Physics (AIP), 2012, p. 490-493Conference paper (Refereed)

The observed spectra of very-high-energy (VHE) blazars may be deformed by gamma-gamma absorption onto the Extra-galactic Background Light (EBL) or, more speculatively, by photon-axion oscillations. As the resulting imprint on observed spectral characteristics may be redshift-dependent, it is important to enrich the catalogue of VHE high-redshift blazars. HESS-II [1], with its low-energy threshold and enhanced E > 100 GeV sensitivity, will be a major instrument in this field of study. While awaiting this new phase of the experiment, H. E. S. S. observed the very distant BL Lac KUV00311 - 1938 in a multi-year campaign, leading to the discovery of its VHE gamma-ray emission with a significance of 5.1 standard deviations. The detection of this source has been possible thanks to an enhanced low-energy sensitivity of recent-developed analysis techniques for IACTs (Paris-MVA) and a full refurbishment which markedly lowered the overall analysis threshold. The evaluation of the redshift of this source is difficult, due to the weakness of the absorption lines in the optical spectrum. A first attempt to evaluate this redshift was performed by [2], and [3], where a value of 0.61 was quoted with a question mark. More recently, [4] used the data from the X-Shooter spectrograph operating on the VLT to estimate a solid lower limit on the redshift of the source of z > 0.506, confirming that KUV00311 - 1938 is the farthest BL Lac ever detected at VHE.

• 321.
Università di Bologna, Italy ; INFN, Italy.
Time correlations of high energy muons in an underground detector2005In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 23, no 3, p. 341-348Article in journal (Refereed)

We present the result of a search for correlations in the arrival times of high energy muons collected from 1995 till 2000 with the streamer tube system of the complete MACRO detector at the underground Gran Sasso Lab. Large samples of single muons (8.6 million), double muons (0.46 million) and multiple muons with multiplicities from 3 to 6 (0.08 million) were selected. These samples were used to search for time correlations of cosmic ray particles coming from the whole upper hemisphere or from selected space cones. The results of our analyses confirm with high statistics a random arrival time distribution of high energy cosmic rays. (c) 2005 Elsevier B.V. All rights reserved.

• 322.
University of Bologna, Italy ; INFN Bologna, Italy.
University of Bologna, Italy ; INAF/IASF Sez. di Bologna, Italy. University of Bologna, Italy. University of Bologna, Italy ; University Mohamed 1st, Morocco. University Mohamed 1st, Morocco. University of Bologna, Italy. University of Bologna, Italy. University Mohamed 1st, Morocco. University of Bologna, Italy. University of Bologna, Italy. University of Bologna, Italy ; PRD, PINSTECH, Pakistan. University Mohamed 1st, Morocco. University of Bologna, Italy. University of Bologna, Italy ; ISS, Romania. University of Bologna, Italy. University of Bologna, Italy. University of Bologna, Italy. University of Bologna, Italy.
Time variations in the deep underground muon flux measured by MACRO2005In: 29th International Cosmic Ray Conference: August 3 - 10, 2005, Pune, India, Mumbai: Tata Institute of Fundamental Research , 2005, p. 157-160Conference paper (Other academic)

More than 30 million high-energy muons collected with the MACRO detector at the underground Gran Sasso Laboratory have been used to search for flux variations of different nature. Two kinds of studies were carried out: search for periodical variations and for the occurrence of clusters of events. Different analysis methods, including Lomb-Scargle spectral analysis and scan statistics have been applied to the data.

• 323.
University of Bologna.
Status report of the ANTARES experiment2006In: Taup 2005: Proceedings of the Ninth International Conference on Topics in Astroparticle and Underground Physics, 2006, p. 444-446Conference paper (Refereed)

The ANTARES Collaboration is building an underwater neutrino telescope in the Mediterranean sea. The telescope is designed to search for high energy (E > I TeV) galactic and extra-galactic neutrino sources, but could also be sensitive to neutrinos originating from the decay of neutralino and exotic particles. The detector is a 3-dimensional array of photomultipliers located at a depth of 2500 m, 40 km from the La Seyne sur Mer shore (near Toulon, France). During the year 2005 a full scale test line and an instrumented line have been successfully operated. In the winter '05-'06 the first full 480 m line will be deployed and connected to the shore station.

• 324.
Paris Diderot University, France ; École Polytechnique, France.
Paris Diderot University, France. Paris Diderot University, France. Paris Diderot University, France. Paris Diderot University, France.
A new analysis strategy for detection of faint gamma-ray sources with Imaging Atmospheric Cherenkov Telescopes2011In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 34, no 12, p. 858-870Article in journal (Refereed)

A new background rejection strategy for gamma-ray astrophysics with stereoscopic Imaging Atmospheric Cherenkov Telescopes (IACT), based on Monte Carlo (MC) simulations and real background data from the H.E.S.S. [High Energy Stereoscopic System, see [1].] experiment, is described. The analysis is based on a multivariate combination of both previously-known and newly-derived discriminant variables using the physical shower properties, as well as its multiple images, for a total of eight variables. Two of these new variables are defined thanks to a new energy evaluation procedure, which is also presented here. The method allows an enhanced sensitivity with the current generation of ground-based Cherenkov telescopes to be achieved, and at the same time its main features of rapidity and flexibility allow an easy generalization to any type of IACT. The robustness against Night Sky Background (NSB) variations of this approach is tested with MC simulated events. The overall consistency of the analysis chain has been checked by comparison of the real gamma-ray signal obtained from H.E.S.S. observations with MC simulations and through reconstruction of known source spectra. Finally, the performance has been evaluated by application to faint H.E.S.S. sources. The gain in sensitivity as compared to the best standard Hillas analysis ranges approximately from 1.2 to 1.8 depending on the source characteristics, which corresponds to an economy in observation time of a factor 1.4 to 3.2. (C) 2011 Elsevier B.V. All rights reserved.

• 325.
University of Paris Diderot.
Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
HESS-II reconstruction strategy and performance in the low-energy (20-150 GeV) domain2009In: HIGH ENERGY GAMMA-RAY ASTRONOMY / [ed] Aharonian, FA; Hofmann, W; Rieger, FM, American Institute of Physics (AIP), 2009, p. 738-741Conference paper (Refereed)

In mid-2009 a notable upgrade of the H.E.S.S. telescope system will take place: a new telescope with a 600 m(2) mirror area and very-high-resolution camera (0.07 degrees) will be positioned at the centre of the present configuration, with the aim of lowering the threshold and enhance its sensitivity in the 100 GeV to several TeV energy range. HESS-II will permit the investigation of the lower energy gamma-ray spectra in various cosmic accelerators, giving information on the origin of the gamma-rays observed, and will detect AGNs with a redshift greater than 0.2 (being less affected by absorption by Extragalactic Background Light - EBL - in this energy range) and will search for new classes of very high energy gamma-ray emitters (pulsars, microquasars, GRB, and dark matter candidates).

• 326.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Stockholms universitet. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Université Paris Diderot, France. LIGO, California Institute of Technology, USA. LIGO, California Institute of Technology, USA. Louisiana State University, USA. Università di Salerno, Italy;INFN, Italy. University of Florida, USA;OzGrav, Australia. LIGO Livingston Observatory, USA.
Multi-messenger Observations of a Binary Neutron Star Merger2017In: Astrophysical Journal Letters, ISSN 2041-8205, E-ISSN 2041-8213, Vol. 48, no 2, article id L12Article in journal (Refereed)

On 2017 August 17 a binary neutron star coalescence candidate (later designated GW170817) with merger time 12:41:04 UTC was observed through gravitational waves by the Advanced LIGO and Advanced Virgo detectors. The Fermi Gamma-ray Burst Monitor independently detected a gamma-ray burst (GRB 170817A) with a time delay of similar to 1.7 s with respect to the merger time. From the gravitational-wave signal, the source was initially localized to a sky region of 31 deg(2) at a luminosity distance of 40(-8)(+8) Mpc and with component masses consistent with neutron stars. The component masses were later measured to be in the range 0.86 to 2.26 M-circle dot. An extensive observing campaign was launched across the electromagnetic spectrum leading to the discovery of a bright optical transient (SSS17a, now with the IAU identification of AT 2017gfo) in NGC 4993 (at similar to 40 Mpc) less than 11 hours after the merger by the One-Meter, Two Hemisphere (1M2H) team using the 1 m Swope Telescope. The optical transient was independently detected by multiple teams within an hour. Subsequent observations targeted the object and its environment. Early ultraviolet observations revealed a blue transient that faded within 48 hours. Optical and infrared observations showed a redward evolution over similar to 10 days. Following early non-detections, X-ray and radio emission were discovered at the transient's position similar to 9 and similar to 16 days, respectively, after the merger. Both the X-ray and radio emission likely arise from a physical process that is distinct from the one that generates the UV/optical/near-infrared emission. No ultra-high-energy gamma-rays and no neutrino candidates consistent with the source were found in follow-up searches. These observations support the hypothesis that GW170817 was produced by the merger of two neutron stars in NGC4993 followed by a short gamma-ray burst (GRB 170817A) and a kilonova/macronova powered by the radioactive decay of r-process nuclei synthesized in the ejecta.

• 327.
University of Paris Diderot .
Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
Advanced analysis and event reconstruction for the CTA Observatory2012In: HIGH ENERGY GAMMA-RAY ASTRONOMY, American Institute of Physics (AIP), 2012, p. 769-772Conference paper (Refereed)

The planned Cherenkov Telescope Array (CTA) is a future observatory for very-high-energy (VHE) gamma-ray astronomy composed of one site per hemisphere [1]. It aims at 10 times better sensitivity, a better angular resolution and wider energy coverage than current installations such as H.E.S.S., MAGIC and VERITAS. In order to achieve this level of performance, both the design of the telescopes and the analysis algorithms are being studied and optimized within the CTA Monte-Carlo working group. Here, we present ongoing work on the data analysis for both the event reconstruction (energy, direction) and gamma/hadron separation, carried out within the HAP (H.E.S.S. Analysis Package) software framework of the H.E.S.S. collaboration, for this initial study. The event reconstruction uses both Hillas-parameter-based algorithms and an improved version of the 3D-Model algorithm [2]. For the gamma/hadron discrimination, original and robust discriminant variables are used and treated with Boosted Decision Trees (BDTs) in the TMVA [3] (Toolkit for Multivariate Data Analysis) framework. With this advanced analysis, known as Paris-MVA [4], the sensitivity is improved by a factor of similar to 2 in the core range of CTA relative to the standard analyses. Here we present the algorithms used for the reconstruction and discrimination, together with the resulting performance characteristics, with good confidence, since the method has been successfully applied for H.E.S.S.

• 328. Becherini, Yvonne
A parameterisation of single and multiple muons in the deep water or ice2006In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 25, no 1, p. 1-13Article in journal (Refereed)

Atmospheric muons play an important role in underwater/ice neutrino detectors. In this paper, a parameterisation of the flux of single and multiple muon events, their lateral distribution and of their energy spectrum is presented. The kinematics parameters were modelled starting from a full Monte Carlo simulation of the interaction of primary cosmic rays with atmospheric nuclei; secondary muons reaching the sea level were propagated in the deep water. The parametric formulas are valid for a vertical depth of 1.5-5 km.w.e. and lip to 85 degrees for the zenith angle, and can be used as input for a fast simulation of atmospheric muons in underwater/ice detectors. (c) 2005 Elsevier B.V. All rights reserved.

• 329.
Ecole Polytechnique.
Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France.
Performance of HESS-II in multi-telescope mode with a multi-variate analysis2012In: High energy gamma-ray astronomy, American Institute of Physics (AIP), 2012, p. 741-744Conference paper (Refereed)

The second phase of H. E. S. S. is being commissioned and will start physics data-taking in Autumn 2012. The 4-telescope configuration is now enriched with a new very-large Cherenkov telescope (VLCT) at the centre of the array. The similar to 600m(2) mirror area and high-resolution camera of the VLCT will permit to lower the energy threshold to about 30GeV in the single-telescope mode, opening a new observational window to a large number of new high-energy phenomena. Adding the VLCT also enhances the detection sensitivity in the multi-telescope mode. The performance in this latter data-taking mode of HESS-II with the advanced analysis procedure called Paris-MVA has been studied in order to understand the achievable low-energy sensitivity and preliminary results are shown here. The Monte Carlo (MC) simulations, the gamma-ray reconstruction procedures and the analysis strategy used to obtain the resulting improvement in sensitivity by adding the VLCT - of about a factor of similar to 2 at low energy - will be discussed.

• 330.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Paris Diderot University, France. Aix-Marseille University, France.
Very-High-Energy gamma-ray astronomy with the ALTO observatory2018In: 35th International Cosmic Ray Conference;ICRC2017, Busan, Korea, July 10-20, 2017, Trieste: Sissa Medialab , 2018, article id 782Conference paper (Refereed)

ALTO is a concept/project in the exploratory phase since 2013 aiming to build a wide-field Very-High-Energy gamma-ray observatory at very high altitude in the Southern hemisphere. The operation of such an observatory will complement the Northern hemisphere observations performed by HAWC and will make possible the exploration of the central region of our Galaxy and the hunt for PeVatrons, and to search for extended Galactic objects such as the Vela Supernova Remnant and the Fermi bubbles.

The ALTO project is aiming for a substantial improvement of the Water Cherenkov Detection Technique by increasing the altitude of the observatory in order to lower the energy threshold, by using a layer of scintillator below the water tank to optimize the signal over background discrimination, by minimizing the size of the tanks and having a more compact array to sample the air-shower footprints with better precision, and by using precise electronics which will provide time-stamped waveforms to improve the angular and energy resolution. ALTO is designed to have as low an energy threshold as possible so as to act as a fast trigger alert to other observatories -- primarily to the Southern part of CTA -- for transient Galactic and extra-galactic phenomena.

The wide field-of-view resulting from the detection technique allows the survey of a large portion of the sky continuously, thus giving the possibility to access emission from Gamma-Ray Bursts, Active Galactic Nuclei and X-ray binary flares, and extended emissions of both Galactic (Vela SNR, Fermi bubbles) and extra-galactic (AGN radio lobes) origin. The ALTO observatory will be composed of about a thousand detection units, each of which consists of a Water Cherenkov Detector positioned above a liquid Scintillation Detector, distributed within an area of about 200 m in diameter. The project is in the design study phase which is soon to be followed by a prototyping phase. The ALTO concept, design study and expected sensitivity together with the prototype status and plans for final deployment in the Southern hemisphere will be the subjects of this presentation.

• 331.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
"Det är ljudmolkyler som flyger": Elevers föreställningar om fenomenet ljud 2019Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis

Studien är en kvalitativ studie som syftar till att kartlägga elevers föreställningar om ljudets spridning, utifrån vetenskapliga föreställningar och vardagsföreställning. Studien kartlägger även elevernas föreställningar om vad som påverkar ljudets hastighet. Den insamlade empirin bygger på elevintervjuer. Intervjuerna genomfördes med totalt 16 elever från årskurs 4 och 6, detta för att kunna jämföra elevernas föreställningar mellan årskurserna.

Studien visar att elever anser att ljud är ett abstrakt ämne som de har svårt att förklara. Resultatet visar att elever i årskurs 4 och 6 har flertalet vardagsföreställningar om ljud. Vardagsföreställningarna i studien kan tolkas utifrån att eleverna använder sina erfarenheter och försöker skapa individuella förklaringar på abstrakta fenomen. En av de vanligaste vardagsföreställningarna som går att identifiera i denna studie är att ljud ses som en egen enhet. I intervjuerna visade det sig även att eleverna har föreställningar om ljudets hastighet som inte kan ses grundas på vetenskapliga föreställningar. Inga stora skillnader kunde identifieras mellan föreställningarna hos eleverna i årskurs 4 och 6, förutom användningen av fysikaliska begrepp.

"Det är ljudmolkyler som flyger"
• 332. Benza, V G
University of Kalmar, School of Pure and Applied Natural Sciences.
Landau-Zener quantum tunneling in disordered nanomagnets2004In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 70, no 18, p. 1844261-9-184426-9Article in journal (Refereed)
• 333. Bergenius, S.
University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences. University of Kalmar, School of Pure and Applied Natural Sciences.
Proton irradiation response of CsI(Tl) crystals for the GLAST calorimeter2003In: 2003 IEEE Nuclear Science Symposium Conference Record: vol. 2, IEEE Press, 2003, p. 1096-1099Conference paper (Refereed)

The electromagnetic calorimeter of the Gamma-Ray Large Area Space Telescope (GLAST) consists of 16 towers of CsI(Tl) crystals. Each tower contains 8 layers of crystals (each 326.0x26.7x19.9 mm3) arranged in a hodoscopic fashion. The crystals are read out at both ends with photodiodes. Crystals produced by Amcrys-H (Ukraine) are used. A full size crystal was irradiated with a 180 MeV proton beam and the radiation induced attenuation was measured. The induced radioactivity of the crystal was also studied. In this paper we will discuss the damage due to proton irradiation and compare this with the expected in-orbit background flux.

• 334.
The Royal Institute of Technology.
University of Kalmar, Department of Technology. The Royal Institute of Technology. Naval Research Laboratory, Washington DC. University of Kalmar, Department of Technology. The Royal Institute of Technology. University of Kalmar, Department of Technology. The Royal Institute of Technology.
Radiation hardness tests of CSI(Tl) crystals for the GLAST electromagnetic calorimeter2003In: Proceedings of 28th International Cosmic Ray Conference, 2003, p. 2787-2790Conference paper (Refereed)

The electromagnetic calorimeter of the Gamma ray Large Area Space Telescope(GLAST) consists of 16 towers of CsI(Tl) crystals. Each tower contains 8layers of crystals (each 326.0×26.7×19.9 mm3) arranged in a hodoscopic fashion.The crystals are read out at both ends with PIN photodiodes. Crystals producedby Amcrys-H (Ukraine) are used. As a part of the quality control procedureduring crystal production, samples from the uncut boules are systematically irradiatedwith gamma rays from a 60Co source. Studies have also been carried outto verify the correspondence between the post-irradiation properties of the boulesamples and the full size crystals which are subsequently cut from the boule. Thefull size crystals have also been irradiated with a 180 MeV proton beam and theradiation induced attenuation measured.

• 335. Bergstrom, L.
Uppsala University.
The AMANDA experiment: Status and prospects for indirect dark matter detection1996In: The identification of dark matter. Proceedings, 1st International Workshop, Sheffield, UK, September 8-12, 1996 / [ed] Spooner, N. J. C., 1996, p. 521-528Conference paper (Refereed)

At the AMANDA South Pole site, four new holes were drilled to depths 2050m to 2180 m and instrumented with 86 photomultipliers (PMTs) at depths1520-2000 m. Of these PMTs 79 are working, with 4-ns timing resolutionand noise rates 300 to 600 Hz. Various diagnostic devices were deployedand are working. An observed factor 60 increase in scattering length anda sharpening of the distribution of arrival times of laser pulses relative tomeasurements at 800-1000 m showed that bubbles are absent below 1500 m.Absorption lengths are 100 to 150 m at wavelengths in the blue and UV to337 nm. Muon coincidences are seen between the SPASE air shower arrayand the AMANDA PMTs at 800-1000 m and 1500-1900 m. The muon trackrate is 30 Hz for 8-fold triggers and 10 Hz for 10-fold triggers. The presentarray is the nucleus for a future expanded array. The potential of AMANDAfor SUSY dark matter search through the detection of high-energy neutrinosfrom the centre of the Sun or Earth is discussed.

• 336.
Chalmers University of Technology.
Chalmers University of Technology. Universität Konstanz, Germany. Chalmers University of Technology.
Basic theory of electron transport through molecular contacts2015In: Handbook of Single Molecule Electronics / [ed] K. Moth-Poulsen, Pan Stanford Publishing, 2015, p. 31-78Chapter in book (Refereed)
• 337. Bernloehr, K.
Ecole Polytechnique.
Monte Carlo design studies for the Cherenkov Telescope Array2013In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 43, p. 171-188Article in journal (Refereed)

The Cherenkov Telescopes Array (CTA) is planned as the future instrument for very-high-energy (VHE) gamma-ray astronomy with a wide energy range of four orders of magnitude and an improvement in sensitivity compared to current instruments of about an order of magnitude. Monte Carlo simulations are a crucial tool in the design of CTA. The ultimate goal of these simulations is to find the most cost-effective solution for given physics goals and thus sensitivity goals or to find, for a given cost, the solution best suited for different types of targets with CTA. Apart from uncertain component cost estimates, the main problem in this procedure is the dependence on a huge number of configuration parameters, both in specifications of individual telescope types and in the array layout. This is addressed by simulation of a huge array intended as a superset of many different realistic array layouts, and also by simulation of array subsets for different telescope parameters. Different analysis methods - in use with current installations and extended (or developed specifically) for CTA - are applied to the simulated data sets for deriving the expected sensitivity of CTA. In this paper we describe the current status of this iterative approach to optimize the CTA design and layout. (C) 2012 Elsevier B.V. All rights reserved.

• 338. Biteau, J.
Ecole Polytech.
The detection at high and very high energies of the blazar 1ES 1312-4232012In: HIGH ENERGY GAMMA-RAY ASTRONOMY, American Institute of Physics (AIP), 2012, p. 506-509Conference paper (Refereed)

The deep observation campaign led on Centaurus A with the High Energy Stereoscopic System (H. E. S. S.) has revealed a significant very high energy (VHE, E >= 100 GeV) excess coincident with the blazar 1ES 1312-423, 2 degrees away from the radio galaxy. The source is also detected at high energy (HE, 20 MeV - 300 GeV) with the Fermi Large Area Telescope (Fermi-LAT) after 3.5 years of all-sky monitoring. The high and very high energy spectra, together with Swift-XRT and ATOM observations are used to draw the first broad band spectral energy distribution (SED) of 1ES 1312-423. The non-thermal emission of this faint HBL is reproduced with a synchrotron self-Compton (SSC) model combined with a black-body spectrum for the host galaxy.

• 339. Boij, Susann
Växjö University, Faculty of Mathematics/Science/Technology, School of Mathematics and Systems Engineering. matematik.
Scattering properties of an orifice in a flow duct: simulations with a vortex sheet model.2008In: 14th AIAA/CEAS Aeroacoustics Conference, Vancouver 5-7 May 2008, American Institute of Aeronautics and Astronautics (AIAA), Reston, VA , USA , 2008Conference paper (Other academic)

The acoustic properties of an in-duct orifice are modeled with a vortex sheet model. Building block elements are used to construct a single slit in a two dimensional model of a flow duct. The foundation of this analytical model is the scattering properties of a trailing and leading edge, semi infinite splitter plate in an infinite duct. From the achieved model of the single slit, mode complex element can be constructed, such as periodically spaced orifices.

• 340.
Pierre-and-Marie-Curie University, France ; Paris Diderot University, France.
Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Pierre-and-Marie-Curie University, France ; Paris Diderot University, France. Paris Diderot University, France. Paris Diderot University, France. Univ Paris Diderot, APC, AstroParticule & Cosmology, CNRS,IN2P3,CEA,Irfu, Observ Paris,Sorbonne Paris C, 10 Rue Alice Domon & Leonie Duquet, F-75205 Paris 13, France. CEA Saclay, France. CEA Saclay, France. CEA Saclay, France. CEA Saclay, France. CEA Saclay, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. University of Savoy, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Ecole Polytechnique, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France. Montpellier 2 University, France.
The camera of the fifth H.E.S.S. telescope: Part I: System description2014In: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, ISSN 0168-9002, E-ISSN 1872-9576, Vol. 761, p. 46-57Article in journal (Refereed)

In July 2012, as the four ground based gamma-ray telescopes of the H.E.S.S. (High Energy Stereoscopic System) array reached their tenth year of operation in Khomas Highlands, Namibia, a fifth telescope Look its first data as part of the system. This new Cherenkov detector, comprising a 614.5 m(2) reflector with a highly pixelized camera in its focal plane, improves the sensitivity of the current array by a factor two and extends ifs energy domain down to a few Lens of GeV. The present part l of the paper gives a detailed description of the fifth H.E.S.S. telescope's camera, presenting the details of both the hardware and the software, emphasizing the main improvements as compared to previous H.E.S.S. camera technology.

• 341.
University of Bergen, Norway. Durham University, UK. Max Planck Institute, Germany. Max Planck Institute, Germany. Radboud University Nijmegen, Netherlands. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Stockholm University.
Central acceptance testing for camera technologies for the cherenkov telescope array2015In: Proceedings of Science, 2015Conference paper (Refereed)

The Cherenkov Telescope Array (CTA) is an international initiative to build the next generation ground based very-high energy gamma-ray observatory. It will consist of telescopes of three different sizes, employing several different technologies for the cameras that detect the Cherenkov light from the observed air showers. In order to ensure the compliance of each camera technology with CTA requirements, CTA will perform central acceptance testing of each camera technology. To assist with this, the Camera Test Facilities (CTF) work package is developing a detailed test program covering the most important performance, stability, and durability requirements, including setting up the necessary equipment. Performance testing will include a wide range of tests like signal amplitude, time resolution, dead-time determination, trigger efficiency, performance testing under temperature and humidity variations and several others. These tests can be performed on fully-integrated cameras using a portable setup at the camera construction sites. In addition, two different setups for performance tests on camera sub-units are being built, which can provide early feedback for camera development. Stability and durability tests will include the long-term functionality of movable parts, water tightness of the camera housing, temperature and humidity cycling, resistance to vibrations during transport or due to possible earthquakes, UV-resistance of materials and several others. Some durability tests will need to be contracted out because they will need dedicated equipment not currently available within CTA. The planned test procedures and the current status of the test facilities will be presented.

• 342.
Study of the LOFAR radio self-trigger and single-station acquisition mode2018In: 35th International Cosmic Ray Conference, ICRC 2017, 10-20 July 2017, Sissa Medialab Srl , 2018, article id 402Conference paper (Refereed)

• 343. Bondar, A.
Department of Radiation Sciences, Uppsala University.
The pp → ppπ0 reaction near the kinematical threshold1995In: Physics Letters B, ISSN 0370-2693, E-ISSN 1873-2445, Vol. 356, no 1, p. 8-12Article in journal (Refereed)

The reaction pp → ppπ0 has been measured using electron-cooled protons incident on an internal gas-jet target at seven different incident beam energies, from 280.7 MeV (1 MeV above the reaction threshold) up to 310.2 MeV. The pions were measured by their decay photons. In the overlapping energy region, the measured total cross sections agree with those measured in a recent Indiana experiment. The angular distributions are consistent with a 3P0 → 1S0S0 transition in the full energy range studied. The kinematical distributions are well described when taking into account the final state and the Coulomb interactions.

• 344.
Jena Universty, Germany .
Lund University. Lund University. Lund University. Lund University. Lund University. Lund University. Linnaeus University, Faculty of Science and Engineering, School of Computer Science, Physics and Mathematics. Halmstad University. Lund University. Jena University, Germany.
A New Route toward Semiconductor Nanospintronics: Highly Mn-Doped GaAs Nanowires Realized by Ion-Implantation under Dynamic Annealing Conditions2011In: Nano letters (Print), ISSN 1530-6984, E-ISSN 1530-6992, Vol. 11, no 9, p. 3935-3940Article in journal (Refereed)

We report on highly Mn-doped GaAs nanowires (NWs) of high crystalline quality fabricated by ion beam implantation, a technique that allows doping concentrations beyond the equilibrium solubility limit. We studied two approaches for the preparation of Mn-doped GaAs NWs: First, ion implantation at room temperature with subsequent annealing resulted in polycrystalline NWs and phase segregation of MnAs and GaAs. The second approach was ion implantation at elevated temperatures. In this case, the single-crystallinity of the GaAs NWs was maintained, and crystalline, highly Mn-doped GaAs NWs were obtained. The electrical resistance of such NWs dropped with increasing temperature (activation energy about 70 meV). Corresponding magnetoresistance measurements showed a decrease at low temperatures, indicating paramagnetism. Our findings suggest possibilities for future applications where dense arrays of GaMnAs nanowires may be used as a new kind of magnetic material system.

• 345.
Bhabha Atom Res Ctr, India.
Bhabha Atom Res Ctr, India. Bhabha Atom Res Ctr, India. Bhabha Atom Res Ctr, India. Bhabha Atom Res Ctr, India. Bhabha Atom Res Ctr, India. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering.
Simulation studies of MACE-I: Trigger rates and energy thresholds2016In: Astroparticle physics, ISSN 0927-6505, E-ISSN 1873-2852, Vol. 84, p. 97-106Article in journal (Refereed)

The MACE (Major Atmospheric Cherenkov Experiment) is an upcoming Very High Energy (VHE) gamma-ray telescope, based on imaging atmospheric Cherenkov technique, being installed at Hanle, a high altitude astronomical site in Ladakh, India. Here we present Monte Carlo simulation studies of trigger rates and threshold energies of MACE in the zenith angle range of 0 degrees-60 degrees for on-axis gamma-ray coming from point source and various cosmic ray species. We have simulated the telescope's response to gamma-rays, proton, electron and alpha initiated atmospheric Extensive Air Showers (EAS) in the broad energy range of 5 GeV to 20 TeV. For gamma-rays we consider power law and log parabolic spectra while other particles are simulated with their respective cosmic ray spectrum. Trigger rates and threshold energies are estimated for the trigger configuration of 4 Close Cluster Nearest Neighbour(CCNN) pixels as implemented in MACE hardware, in combination with single channel discriminator threshold ranging from 6-10 photo electrons (pe). We find that MACE can achieve the gamma-ray trigger energy threshold of similar to 17 GeV (4 CCNN, 9 pe) at 0 degrees zenith angle for power law spectrum. The total trigger rate at 0 degrees zenith is expected to be similar to 650 Hz, with protons contributing similar to 80% to it. For the zenith range of 0 degrees-40 degrees we find that the telescope can achieve gamma-gray trigger threshold energies of similar to 22 GeV at 20 degrees zenith angle and similar to 40 GeV at 40 degrees zenith angle. Integral rates are also almost constant for this zenith angle range. At zenith angle of 60 degrees, trigger energy threshold increases to similar to 173 GeV and total integral rate falls down to similar to 305 Hz. (C) 2016 Elsevier B.V. All rights reserved.

• 346.
Photonics and Semiconductor Nanophysics, Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, NL-5600 MB Eindhoven, The Netherlands.
Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. London Center for NanoTechnology, 17-19 Gordon Street, WC1H 0AH, London, U.K.. 5Department of Physics, University of New Hampshire, Durham, New Hampshire 03824-3520, USA. London Center for NanoTechnology, 17-19 Gordon Street, WC1H 0AH, London, U.K.. London Center for NanoTechnology, 17-19 Gordon Street, WC1H 0AH, London, U.K.. Department of Physics and Astronomy, University of Iowa, Iowa City, Iowa 52242-1479,U.S.A.. Photonics and Semiconductor Nanophysics, Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, NL-5600 MB Eindhoven, The Netherlands. Department of Chemistry, UCL, London, WC1H 0AJ, United Kingdom. Linnaeus University, Faculty of Technology, Department of Physics and Electrical Engineering. Photonics and Semiconductor Nanophysics, Department of Applied Physics, Eindhoven University of Technology, P. O. Box 513, NL-5600 MB Eindhoven, The Netherlands.
Magnetic anisotropy of single Mn acceptors in GaAs in an external magnetic field2013In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 88, p. Article ID: 205203-Article in journal (Refereed)

We investigate the effect of an external magnetic field on the physical properties of the acceptor hole statesassociated with single Mn acceptors placed near the (110) surface of GaAs. Cross-sectional scanning tunnelingmicroscopy images of the acceptor local density of states (LDOS) show that the strongly anisotropic hole wavefunction is not significantly affected by a magnetic field up to 6 T. These experimental results are supported bytheoretical calculations based on a tight-binding model of Mn acceptors in GaAs. For Mn acceptors on the (110)surface and the subsurfaces immediately underneath, we find that an applied magnetic field modifies significantlythe magnetic anisotropy landscape. However, the acceptor hole wave function is strongly localized around theMn and the LDOS is quite independent of the direction of the Mn magnetic moment. On the other hand, for Mnacceptors placed on deeper layers below the surface, the acceptor hole wave function is more delocalized andthe corresponding LDOS is much more sensitive on the direction of the Mn magnetic moment. However, themagnetic anisotropy energy for these magnetic impurities is large (up to 15 meV), and a magnetic field of 10 Tcan hardly change the landscape and rotate the direction of the Mn magnetic moment away from its easy axis.We predict that substantially larger magnetic fields are required to observe a significant field dependence of thetunneling current for impurities located several layers below the GaAs surface.

• 347.
Tech Univ Denmark.
DIPC, San Sebastian 20018, Spain. University of Kalmar, School of Pure and Applied Natural Sciences.
DFT-NEGF approach to current-induced forces, vibrational signals, and heating in nanoconductors2009In: Current-Driven Phenomena in Nanoelectronics / [ed] T. Seideman, Pan Stanford Publishing, 2009, p. 90-122Chapter in book (Other academic)
• 348.
Vrije Universiteit Brussel, Belgium.
Cosmic ray mass composition with LOFAR2018In: 35th International Cosmic Ray Conference — ICRC2017. 10–20 July, 2017. Bexco, Busan, Korea, Sissa Medialab Srl , 2018, article id 499Conference paper (Refereed)

• 349.
Method for high precision reconstruction of air shower Xmax using two-dimensional radio intensity profiles2014In: Physical Review D, ISSN 1550-7998, E-ISSN 1550-2368, Vol. 90, no 8, p. 1-12, article id 082003Article in journal (Refereed)

The mass composition of cosmic rays contains important clues about their origin. Accurate measurements are needed to resolve longstanding issues such as the transition from Galactic to extra-Galactic origin and the nature of the cutoff observed at the highest energies. Composition can be studied by measuring the atmospheric depth of the shower maximum Xmax of air showers generated by high-energy cosmic rays hitting the Earth’s atmosphere. We present a new method to reconstruct Xmax based on radio measurements. The radio emission mechanism of air showers is a complex process that creates an asymmetric intensity pattern on the ground. The shape of this pattern strongly depends on the longitudinal development of the shower. We reconstruct Xmax by fitting two-dimensional intensity profiles, simulated with CoREAS, to data from the Low Frequency Array (LOFAR) radio telescope. In the dense LOFAR core, air showers are detected by hundreds of antennas simultaneously. The simulations fit the data very well, indicating that the radiation mechanism is now well understood. The typical uncertainty on the reconstruction of Xmax for LOFAR showers is 17  g/cm2.

• 350.
Vrije Universiteit Brussel, Belgium ; Radboud University Nijmegen, The Netherlands.
Radboud University Nijmegen, The Netherlands. Radboud University Nijmegen, The Netherlands ; ASTRON, The Netherlands ; Science Park Amsterdam, The Netherlands ; Max-Planck-Institut für Radioastronomie, Germany. Radboud University Nijmegen, The Netherlands ; Science Park Amsterdam, The Netherlands. Karlsruhe Institute of Technology (KIT), Germany. University of California Irvine, USA. Radboud University Nijmegen, The Netherlands. Radboud University Nijmegen, The Netherlands. Radboud University Nijmegen, The Netherlands. University of Groningen, The Netherlands ; Vrije Universiteit Brussel, Belgium. Radboud University Nijmegen, The Netherlands.
A large light-mass component of cosmic rays at 1017–1017.5 electronvolts from radio observations2016In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 531, no 7592, p. 70-73Article in journal (Refereed)

Cosmic rays are the highest-energy particles found in nature. Measurements of the mass composition of cosmic rays with energies of 1017–1018 electronvolts are essential to understanding whether they have galactic or extragalactic sources. It has also been proposed that the astrophysical neutrino signal1 comes from accelerators capable of producing cosmic rays of these energies2. Cosmic rays initiate air showers—cascades of secondary particles in the atmosphere—and their masses can be inferred from measurements of the atmospheric depth of the shower maximum3 (Xmax; the depth of the air shower when it contains the most particles) or of the composition of shower particles reaching the ground4. Current measurements5 have either high uncertainty, or a low duty cycle and a high energy threshold. Radio detection of cosmic rays6, 7, 8 is a rapidly developing technique9 for determining Xmax (refs 10, 11) with a duty cycle of, in principle, nearly 100 per cent. The radiation is generated by the separation of relativistic electrons and positrons in the geomagnetic field and a negative charge excess in the shower front6, 12. Here we report radio measurements of Xmax with a mean uncertainty of 16 grams per square centimetre for air showers initiated by cosmic rays with energies of 1017–1017.5 electronvolts. This high resolution in Xmax enables us to determine the mass spectrum of the cosmic rays: we find a mixed composition, with a light-mass fraction (protons and helium nuclei) of about 80 per cent. Unless, contrary to current expectations, the extragalactic component of cosmic rays contributes substantially to the total flux below 1017.5 electronvolts, our measurements indicate the existence of an additional galactic component, to account for the light composition that we measured in the 1017–1017.5 electronvolt range.

45678910 301 - 350 of 860
Cite
Citation style
• apa
• ieee
• modern-language-association-8th-edition
• vancouver
• Other style
More styles
Language
• de-DE
• en-GB
• en-US
• fi-FI
• nn-NO
• nn-NB
• sv-SE
• Other locale
More languages
Output format
• html
• text
• asciidoc
• rtf