Verification of the code DYN3D for calculations of neutron flux fluctuations

Insufficiently explained magnitudes and patterns of flux fluctuation observed mainly in KWU PWRs are recently investigated by various European institutions. Among the numerical tools used to investigate the\ua0neutron flux\ua0fluctuations is the time-domain reactor dynamics code\ua0DYN3D. As\ua0DYN3D\ua0and comparable codes have not been developed with the primary intention to simulate low-amplitude neutron flux fluctuations, their applicability in this field has to be verified.In order to contribute to the verification of\ua0DYN3D\ua0for the simulation of neutron flux fluctuations, two special cases of perturbations of the neutron flux (a localized absorber of variable/oscillatory strength and a travelling oscillatory perturbation) are considered with\ua0DYN3D\ua0on the one hand and with the frequency-domain neutron noise tool\ua0CORE SIM\ua0as well as analytical frequency-domain approaches, respectively, on the other hand. The obtained results are compared with respect to the distributions of the amplitude and the phase of the induced neutron flux fluctuations. The comparisons are repeated with varied amplitudes and frequencies of the perturbation.The results agree well both qualitatively and quantitatively for each of the conducted calculations. The remaining deviations between the\ua0DYN3D\ua0results and the reference results exhibit a dependence on the perturbation magnitude, which is attributed to the neglect of higher-order terms (linear theory) of the perturbed quantities in the calculation of the reference solutions

Dielectron production in proton-proton and proton-lead collisions at root s(NN)=5.02 TeV

The first measurements of dielectron production at midrapidity (vertical bar eta(e)vertical bar <0.8) in proton-proton and proton-lead collisions at root s(NN) = 5.02 TeV at the LHC are presented. The dielectron cross section is measured with the ALICE detector as a function of the invariant mass m(ee) and the pair transverse momentum p(T,ee) in the ranges m(ee) <3.5 GeV/c(2) and p(T,ee) <8 GeV/c, in both collision systems. In proton-proton collisions, the charm and beauty cross sections are determined at midrapidity from a fit to the data with two different event generators. This complements the existing dielectron measurements performed at root s = 7 and 13 TeV. The slope of the root s dependence of the three measurements is described by FONLL calculations. The dielectron cross section measured in proton-lead collisions is in agreement, within the current precision, with the expected dielectron production without any nuclear matter effects for e(+)e(-) pairs from open heavy-flavor hadron decays. For the first time at LHC energies, the dielectron production in proton-lead and proton-proton collisions are directly compared at the same root s(NN) via the dielectron nuclear modification factor R-pPb. The measurements are compared to model calculations including cold nuclear matter effects, or additional sources of dielectrons from thermal radiation.Peer reviewe

Alétheia and the Making of the World::Inner and Outer Dimensions of Memorials in Rwanda

After the experience of mass violence communities and individuals alike have to come to terms with these violent histories which reverberate into the present and future. On the societal and political level, mechanisms commonly referred to as transitional justice are being deployed to deal with the legacy of repressive regimes and violent conflicts. Memorialisation – understood as the practice of remembrance such as through commemorations, the writing of history text books and the establishment of memorials – has become part of this wider transitional justice tool-box, although it has garnered much less attention than legal and truth-telling mechanisms. Memorials as one form of memorialisation can be understood as symbolic reparation for the victims and survivors of mass violence since they acknowledge their suffering and grief and pay respect to the dead. Therefore, after mass violence memorials can be understood as physical loci of recognition and the imperative not to forget the atrocities of the past.Memorials to mass violence restore the violent past in the present moment and try to rewrite it by making the event intelligible to the onlooker. For the society which suffered the violence it is a steady reminder of its past and thus also forms a ‘point of connection’. In this sense, memorials move remembrance as a cultural practice beyond the boundaries of the individual, or as William Booth calls it, beyond the personal “thick memory” of one's mind. As a ‘point of connection’ memorials serve as a focal point for remembering the past, for the fight against the oblivion of injustice and inhumanity. At the same time, memorials constitute a medium to conserve the past (Speichermedium) and to ensure that personal memories are bonded to the cultural memory practices of the community. Thus, according to Maurice Halbwachs, memories must be tied to a physical presence in the world in order to recall the past and to contextualize it in the present. Memorials therefore serve to preserve that which might otherwise be at risk of being forgotten and eradicated from a community's memory

Place-bound Proximity at Rwanda’s Genocide Memorials::On Coming Home to the Dead and the Affective Force of their Remains

This chapter analyses the connectivities between violence, memory, place, and human substances after the 1994 genocide against the Tutsi in Rwanda. It argues that the memorials are a vehicle for what the author coins “place-bound proximity” that enables a material space of communication between caretakers and their dead loved ones, and provides the last resting place and a “home” for both the living and the dead. Following a “victim-approach”, this chapter draws on extensive fieldwork conducted in Rwanda since 2011