Speakers – Annual Meeting 2023 – Dansk fysisk selskab

Invited Talks

Dorthe Dahl-Jensen
Centre for Earth Observation Sciences, University of Manitoba, Canada and the Niels Bohr Institute, University of Copenhagen, Denmark

Title of talk: “Greenland Ice Cores Tell Tales on Past Sea Level Contributions”

Abstract: The Greenland Ice Sheet is reacting to climate change and is losing progressively more mass every year. One of our challenges in the future is to adapt to rising sea levels. Looking into the past provides knowledge on how the ice sheets react to changing climate, and this can be used to improve future predictions of sea level rise. The deep ice cores from Greenland contain information on past climate that goes back more than 130,000 years, telling tales about past abrupt climate and sea level changes.

The last interglacial, 130,000 to 115,000 years before present, is a key analogue for future climate. At this time, climate was 5^oC warmer over Greenland, and global sea level was 6-9 m higher than present. All the ice cores from Greenland show that the ice sheet survived, making only a modest contribution to global sea level rise of approximately 2 m at this time. Besides from contributions to sea-level rise from Greenland there must have been contributions from Antarctica.

Finally results from the present deep ice core drilling project, EGRIP, will be presented. The EGRIP ice cores are drilled in the Northeast Greenland Ice Stream (NEGIS) with the purpose of learning about ice stream flow. 50% of the present mass loss from the Greenland ice sheet is from discharge from the ice streams and it is a knowledge gab how the ice streams will adjust to the future warmer climate.

Marco van Leeuwen
Professor, National Institute for Subatomic Physics (Nikhef), Amsterdam and spokesperson for ALICE at CERN

Title of talk: “Understanding the Quark-Gluon Plasma with ALICE at the LHC”

Abstract: Collisions of lead nuclei at high energy in the Large Hadron Collider (LHC) at CERN provide a unique opportunity to study the ‘condensed matter physics’ of quarks and gluons, the fundamental particles of the strong interaction, which are normally bound in hadrons. In these collisions, temperatures of around 10¹² K are reached, and a plasma of quarks and gluons is formed, under conditions that are comparable to those of the universe briefly after the Big Bang. I will present highlights of the experimental study of the Quark-Gluon Plasma by ALICE at the LHC, showing how we use experimental results to determine the temperature and flow fields in the collisions, as well as the transport properties of the plasma. I will also briefly outline our plans for new studies of the Quark-Gluon Plasma with the recently installed detector upgrades in the ongoing Run 3 of the LHC, as well as our future plans.

Manuel Meyer
Associate Professor, Department of Physics, Chemistry and Pharmacy, University of Southern Denmark

Title of talk: “Light on the Other Side of the Wall: A New Era for the Search of Axions and Axion-like Particles”

Abstract: Astrophysical observations provide overwhelming evidence for the existence of dark matter, which should make up more than 80% of all matter in the Universe. Yet, even after almost a century, we still lack a an understanding of what this substance is made of. One possibility is that it is comprised of so-far undetected fundamental particles. One such candidate is the axion, or more generally axion-like particles, which would also explain the non-observation of an electric dipole of the neutron. Earlier this year, the Any Light Particle Search II (ALPS II) experiment started its first science run. ALPS II is a light-shining-thorugh-the-wall type experiment which will have unprecedented sensitivity for the production and sub-sequent detection of axions. In this talk, I will introduce the experiment. In particular, I will focus on future capabilities and recent characterization results of the superconducting single photon detector foreseen for a later science run. If time permits, I will also highlight how we can use astrophysical observations to search for axions.