Analysis of kaon spectra at SIS energies - what remains from the KN potential

We study the reaction Au+Au at 1.48 AGeV and analyze the influence of the KN optical potential on cm spectra and azimuthal distributions at mid-rapidity. We find a significant change of the yields but only slight changes in the shapes of the distributions when turning off the optical potential. However, the spectra show contributions from different reaction times, where early kaons contribute stronger to higher momenta and late kaons to lower momenta. Azimuthal distributions of the kaons at mid-rapidity show a strong centrality dependence. Their shape is influenced by the KN optical potential as well as by re-scattering.Comment: SQM 2003 proceedings, 4 figures, 6 page

On the exact conservation laws in thermal models and the analysis of AGS and SIS experimental results

The production of hadrons in relativistic heavy ion collisions is studied using a statistical ensemble with thermal and chemical equilibrium. Special attention is given to exact conservation laws, i.e. certain charges are treated canonically instead of using the usual grand canonical approach. For small systems, the exact conservation of baryon number, strangeness and electric charge is to be taken into account. We have derived compact, analytical expressions for particle abundances in such ensemble. As an application, the change in $K/\pi$ ratios in AGS experiments with different interaction system sizes is well reproduced. The canonical treatment of three charges becomes impractical very quickly with increasing system size. Thus, we draw our attention to exact conservation of strangeness, and treat baryon number and electric charge grand canonically. We present expressions for particle abundances in such ensemble as well, and apply them to reproduce the large variety of particle ratios in GSI SIS 2 A GeV Ni-Ni experiments. At the energies considered here, the exact strangeness conservation fully accounts for strange particle suppression, and no extra chemical factor is needed.Comment: Talk given at Strangeness in Quark Matter '98, Padova, Italy (1998). Submitted to J.Phys. G. 5 pages, 2 figure

Film-Norge : et sosiologisk blikk på det norske filmfeltet

I denne oppgaven gjør jeg et forsøk på å forstå det norske filmfeltet med utgangspunkt i Solhjell og Øiens (2012) modell for det norske kunstfeltet. Jeg forsøker også å vise hva en slik sosiologisk modell for det norske filmfeltet kan bidra til å vise. Bakgrunnen er en opplevelse av et felt som er vanskelig å forstå seg på for andre enn feltets mest erfarne agenter, samt en observert mangel på en sosiologisk modell for forståelse av det norske filmfeltet. Oppgavens hovedfokus er relatert til norske spillefilmer i dagens produksjonslandskap og regissører, produsenter/ produksjonsselskaper og Norsk Filminstitutts ulike roller og posisjoner i dette feltet. Jeg har benyttet meg av kvalitative intervjuer med strategisk utvalgte informanter som hovedmetode. I tillegg har jeg brukt den offentlige diskusjonen i filmfeltet (hovedsakelig fra bransjetidsskriftet Rushprints nettsider) til å supplere. Resultatet er en forståelse av det norske filmfeltet som et sosialt felt som kan deles inn i tre delfelt: Det eksklusive, det kommersielle og det inklusive delfelt. Hvert delfelt har særegne verdisett og måter å rangere agenter på. Det eksklusive delfeltet representerer kunstneriske verdier, og her kjemper agentene om symbolsk kapital i form av kunstnerisk anerkjennelse. Det kommersielle delfeltet representerer økonomiske verdier, og her kjempes det om økonomisk kapital. Det inklusive delfeltet representerer politisk instrumentelle verdier og forvalter politisk kapital. Agenter i filmfeltet hører til det delfeltet hvis spilleregler de følger mest, men beveger seg i ulike posisjoner (også mellom delfeltene) i løpet av sin karriere. En slik modell kan bidra til en reflektert forståelse for hvordan feltet er strukturert, og hvordan de ulike verdisettene gjør seg gjeldende i ulik grad for agenter i feltet

Kaon production at subthreshold and threshold energies

We summarize what we have learnt about the kaon production in nucleus-nucleus collisions in the last decade. We will address three questions: a) Is the $K^+$ production sensitive to the nuclear equation of state? b) How can it happen that at the same excess energy the same number of $K^+$ and $K^-$ are produced in heavy ion collisions although the elementary cross section in pp collisions differs by orders of magnitudes? and c) Why kaons don't flow?Comment: 5 pages, 4 figures, contribution to Strange Quark Matter 200

Kaon and Antikaon Production in Heavy Ion Collisions at 1.5 AGeV

At the Kaon Spectrometer KaoS at SIS, GSI the production of kaons and antikaons in heavy ion reactions at a beam energy of 1.5 AGeV has been measured for the collision systems Ni+Ni and Au+Au. The K-/K+ ratio is found to be constant for both systems and as a function of impact parameter but the slopes of K+ and K- spectra differ for all impact parameters. Furthermore the respective polar angle distributions will be presented as a function of centrality.Comment: 4 pages, 4 figures, SQM2001 in Frankfurt, Sept.2001, submitted to Journal of Physics

Strangeness at SIS energies

In this contribution we discuss the physics of strange hadrons in low energy ($\simeq 1-2 \rm AGeV$) heavy ion collision. In this energy range the relevant strange particle are the kaons and anti-kaons. The most interesting aspect concerning these particles are so called in-medium modifications. We will attempt to review the current status of understanding of these in medium modifications. In addition we will briefly discuss other issues related with kaon production, such as the nuclear equation of state and chemical equilibrium.Comment: Proceedings Strange Quark Matter 2003, Atlantic Beach, NC, USA, March 200