Proposal to Search for Heavy Neutral Leptons at the SPS

A new fixed-target experiment at the CERN SPS accelerator is proposed that will use decays of charm mesons to search for Heavy Neutral Leptons (HNLs), which are right-handed partners of the Standard Model neutrinos. The existence of such particles is strongly motivated by theory, as they can simultaneously explain the baryon asymmetry of the Universe, account for the pattern of neutrino masses and oscillations and provide a Dark Matter candidate. Cosmological constraints on the properties of HNLs now indicate that the majority of the interesting parameter space for such particles was beyond the reach of the previous searches at the PS191, BEBC, CHARM, CCFR and NuTeV experiments. For HNLs with mass below 2 GeV, the proposed experiment will improve on the sensitivity of previous searches by four orders of magnitude and will cover a major fraction of the parameter space favoured by theoretical models. The experiment requires a 400 GeV proton beam from the SPS with a total of 2x10^20 protons on target, achievable within five years of data taking. The proposed detector will reconstruct exclusive HNL decays and measure the HNL mass. The apparatus is based on existing technologies and consists of a target, a hadron absorber, a muon shield, a decay volume and two magnetic spectrometers, each of which has a 0.5 Tm magnet, a calorimeter and a muon detector. The detector has a total length of about 100 m with a 5 m diameter. The complete experimental set-up could be accommodated in CERN's North Area. The discovery of a HNL would have a great impact on our understanding of nature and open a new area for future research

Fatigue testing of a proximal femoral hip component

Published versio

Deltagardriven forskning – Växtodlingsgruppen, resultat och utvärdering av arbetet under 1998 till 2001

Då arbetet i växtodlingsgruppen påbörjades var förväntningarna på deltagardriven forskning att den sammanlagda erfarenheten hos lantbrukare, forskare och rådgivare skulle bidra till utförandet av relevanta gårdsförsök. Lantbrukarna önskade dessutom sträva efter att öka och vidarebefordra den kunskap som fanns i gruppen, samt att få etablerade forskare att undersöka områden som praktikerna upplever som viktiga och svåra. Redan i initialskedet slog växtodlingsgruppen fast att arbeta för att gemensamt identifiera problem och använda relevanta forskningsmetoder på gårdsnivå. Syftet var att genom olika odlingsåtgärder kunna förbättra förutsättningarna för ekologisk växtodling. Ett mål var att finna effektiva metoder för optimal växtnäringstillförsel i ekologisk produktion på lerjordar i Mälardalen. För närvarande saknas bra underlag för hur kväveleveransen varierar under säsongen framförallt till stråsäd. Detta påverkar i sin tur både skördeutfall, proteinhalt, miljöbelastning och ekonomi. Ett annat mål var att kunna reglera ogräsförekomsten, främst kvickrot och tistel, på ett effektivt sätt i växtföljden. Motivationen för lantbrukarna har under projektets gång varit att främja det ekologiska lantbruket som helhet. Detta har möjliggjorts genom erfarenhetsutbyte på gruppträffar kombinerat med gårdsbesök där lantbrukarnas intressen och frågeställningar har varit drivande. Växtodlingsgruppen har på så vis initialt bidragit till ett lokalt utvecklingsarbete och en uppbyggnad av ökat kunnande inom ekologiskt växtodling

Neutrino tomography - Learning about the Earth's interior using the propagation of neutrinos

Because the propagation of neutrinos is affected by the presence of Earth matter, it opens new possibilities to probe the Earth's interior. Different approaches range from techniques based upon the interaction of high energy (above TeV) neutrinos with Earth matter, to methods using the MSW effect on the neutrino oscillations of low energy (MeV to GeV) neutrinos. In principle, neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.) can be used. In this talk, we summarize and compare different approaches with an emphasis on more recent developments. In addition, we point out other geophysical aspects relevant for neutrino oscillations.Comment: 22 pages, 9 figures. Proceedings of ``Neutrino sciences 2005: Neutrino geophysics'', December 14-16, 2005, Honolulu, USA. Minor changes, some references added. Final version to appear in Earth, Moon, and Planet

Shotgun Phage Display - Selection for Bacterial Receptins or other Exported Proteins

Shotgun phage display cloning involves construction of libraries from randomly fragmented bacterial chromosomal DNA, cloned genes, or eukaryotic cDNAs, into a phagemid vector. The library obtained consists of phages expressing polypeptides corresponding to all genes encoded by the organism, or overlapping peptides derived from the cloned gene. From such a library, polypeptides with affinity for another molecule can be isolated by affinity selection, panning. The technique can be used to identify bacterial receptins and identification of their minimal binding domain, and but also to identify epitopes recognised by antibodies. In addition, after modification of the phagemid vector, the technique has also been used to identify bacterial extracytoplasmic proteins

An Insight into Life at Geometric Zagora Provided by the Animal Bones

This thesis is a study of the animal bone distribution at the Geometric period settlement of Zagora (ca. 850-700 BC), on the island of Andros. The animal bones were excavated during the 1967-74 University of Sydney excavations and analysed in 1977 by a specialist who compiled a report of her findings. The report is currently in preparation for publication and is the primary source for this thesis. The data it provided was limited but enough could be extracted to identify patterns that permitted a tentative reconstruction of social life and the economy at Zagora. There is a paucity of excavated settlements from the Greek EIA and few of these have published faunal material, an essential element in reconstructing past lifeways. Those preserved settlements from which animal bones have been published are not extensive with good domestic contexts but usually sites of minimal extent. Hence, it has not been possible to conduct an analysis of the spatial distribution of animal bones from such a settlement. Zagora, being an extensive settlement containing mainly domestic structures, is therefore unique and the animal bone report provided the opportunity for such a study to be undertaken. A number of analyses were performed using both statistical and non-statistical methods. Through these it was discovered that there is a relationship between the animal size and the size of the architectural unit within which it was found. Similarly, there appeared to be a relationship between larger architecture and the presence of fish, postulated as being a pelagic species. The patterns observed were interpreted as evidence of ‘special’ meals with a larger than usual number of diners in attendance and hence the need for a larger space to host them. Using the animal bones’ distribution and architectural evidence it is proposed that feasting was an important event at Zagora, conducted at the household level to possibly reinforce bonds of kinship and friendship. The evidence also suggests that the H area could have been inhabited by people of better means than elsewhere in the settlement, particularly by the hypaethral sanctuary. Ideally the animal bones would have been studied in conjunction with associated artefacts, but this was not possible and so this would be something desirable to be performed in the near future. With 21st century excavation techniques, the future Zagora excavations should provide greater granularity in the faunal information obtained from the settlement to allow better precision in subsequent analyses

The role of matter density uncertainties in the analysis of future neutrino factory experiments

Matter density uncertainties can affect the measurements of the neutrino oscillation parameters at future neutrino factory experiments, such as the measurements of the mixing parameters $\theta_{13}$ and \deltacp. We compare different matter density uncertainty models and discuss the possibility to include the matter density uncertainties in a complete statistical analysis. Furthermore, we systematically study in which measurements and where in the parameter space matter density uncertainties are most relevant. We illustrate this discussion with examples that show the effects as functions of different magnitudes of the matter density uncertainties. We find that matter density uncertainties are especially relevant for large \stheta \gtrsim 10^{-3}. Within the KamLAND-allowed range, they are most relevant for the precision measurements of \stheta and \deltacp, but less relevant for ``binary'' measurements, such as for the sign of \ldm, the sensitivity to \stheta, or the sensitivity to maximal CP violation. In addition, we demonstrate that knowing the matter density along a specific baseline better than to about 1% precision means that all measurements will become almost independent of the matter density uncertainties.Comment: 21 pages, 7 figures, LaTeX. Final version to be published in Phys. Rev.

Influence of Radiation on the Properties and the Stability of Hybrid Perovskites

Organic inorganic perovskites are well suited for optoelectronic applications. In particular, perovskite single and perovskite tandem solar cells with silicon are close to their market entry. Despite their swift rise in efficiency to more than 21 , solar cell lifetimes are way below the needed 25 years. In fact, comparison of the time when the device performance has degraded to 80 of its initial value T80 lifetime of numerous solar cells throughout literature reveals a strongly reduced stability under illumination. The various detrimental effects are discussed. Most notably, moisture and heat related degradation can be mitigated easily by now. Recently however, several photo induced degradation mechanisms have been observed. Under illumination alloyed perovskites tend to phase segregate, while further, oxygen catalyzes deprotonation of the organic cations. Additionally, during illumination photo generated charge can be trapped in the N H antibonding orbitals causing the dissociation of the organic cation. On the other hand, organic inorganic perovskites exhibit a high radiation hardness that is superior to crystalline silicon. This progress report thoroughly reviews proposed degradation mechanisms reported in literature and discusses the microscopic mechanisms and their implications for solar cell

Properties of Contact and Bulk Impedances in Hybrid Lead Halide Perovskite Solar Cells Including Inductive Loop Elements

Impedance spectroscopy offers access to all the different electronic and ionic processes taking place simultaneously in an operating solar cell. To date, its use on perovskite solar cells has been challenging because of the richness of the physical processes occurring within similar time domains. The aim of this work is to understand the general impedance response and propose a general equivalent circuit model that accounts for the different processes and gives access to quantitative analysis. When the electron-selective contacts and the thickness of the perovskite film are systematically modified, it is possible to distinguish between the characteristic impedance signals of the perovskite layer and those arising from the contacts. The study is carried out using mixed organic lead halogen perovskite (FA(0.85)MA(0.15)Pb(I0.85Br0.15)(3)) solar cells with three different electron-selective contacts: SnO2, TiO2, and Nb2O5. The contacts have been deposited by atomic layer deposition (ALD), which provides pinhole-free films and excellent thickness control in the absence of a mesoporous layer to simplify the impedance analysis. It was found that the interfacial impedance has a rich structure that reveals different capacitive processes, serial steps for electron extraction, and a prominent inductive loop related to negative capacitance at intermediate frequencies. Overall, the present report provides insights into the impedance response of perovskite solar cells which enable an understanding of the different electronic and ionic processes taking place during device operation.The work at INAM-UJI was supported by Generalitat Valenciana project PROMETEO/2014/020 and MINECO of Spain under Project MAT2013-47192-C3-1-R. A.G. thanks the Spanish Ministerio de Economía y Competitividad for a Ramón y Cajal Fellowship (RYC-2014-16809). T.J.J. gratefully acknowledges the GRAPHENE project supported by the European Commission Seventh Framework Program under Contract 604391