Tag Archives: dark matter

Hunting light dark matter with gamma rays

Physicists around the globe are working relentlessly to pin down the nature of dark matter. This enigmatic entity hides itself from our view as it does neither emit nor absorb any radiation. It only reveals itself through its gravitational interaction. With a new analysis of data from NASA’s gamma-ray large area telescope (LAT) on board the Fermi satellite, we have now come closer to test very light dark matter candidates. Many regard the astrophysical evidence for dark matter as evidence for yet undiscovered fundamental particles. Well-motivated theories suggest that these particles … Continue Reading ››

ATLAS Thesis Award goes to the Dark Side

Ruth Pöttgen is a postdoctoral researcher in the ATLAS group at Stockholm University. In 2015, she obtained her Ph.D. at the Johannes Gutenberg – University in Mainz, Germany, for her thesis on a “Search for Dark Matter in Events with a highly energetic jet and missing transverse momentum at a centre-of-mass energy of 8 TeV with the ATLAS Detector”. At the ATLAS collaboration meeting in February, Ruth was awarded one out of 4 ATLAS Thesis Awards for outstanding contributions to the ATLAS-Experiment in the context of a Ph.D. thesis; more than 100 theses were eligible.

The XENON1T inauguration

Dark matter is one of the basic ingredients of the Universe, and searches to detect it in laboratory-based experiments are being conducted since decades. However, until today dark matter has been observed via its gravitational interactions that govern the dynamics of the Cosmos at all length-scales. In 2014, with a grant of the Knut and Alice Wallenberg foundation, OKC has joined an international collaboration, called XENON, that builds and operates detectors to find the elusive dark matter particles in the laboratory.

Dark matter at the heart of the Galaxy

A new study is providing evidence for the presence of dark matter in the innermost part of the Milky Way, including in our own cosmic neighbourhood and the Earth’s location. The study demonstrates that large amounts of dark matter exist around us, and also between us and the Galactic centre. The result constitutes a fundamental step forward in the quest for the nature of dark matter.

Still no Dark Matter in the latest analysis of LHC data…

Last night the ATLAS Collaboration released its latest search for dark matter and other beyond the standard model theories [1] based on the full dataset from the LHC Run I (2010-2012). By looking for proton-proton collisions where jets of hadronic particles are produced only in one direction (Figure 1), violating conservation of momentum only in appearance, we use ATLAS to search for  weakly interacting massive particles (WIMPs), such as dark matter particles. Because they are weakly interacting, the WIMPs escape ATLAS undetected and lead to what looks like missing momentum. Continue Reading ››

Detecting dark matter in the lab with Xenon

In the beginning of November 2014, The Oskar Klein Centre officially joined the XENON dark matter project. The idea is to detect dark matter particles scattering of heavy nuclei.
Since one of the strongest limitation of dark matter detection is due to cosmic ray induced background, it is important to shield the detectors. For this reason XENON is situated in the Gran Sasso National Laboratory, on the side of a ten kilometer long freeway tunnel crossing the Gran Sasso mountain, about 120 km from Rome. Thus, there is about 1500 meters of rock protecting the laboratory from cosmic ray backgrounds.

Do we see dark matter emission from dwarf spheroidal galaxies?

From a dark matter (DM) hunter’s perspective, this year’s Fermi Symposium was highly anticipated. In the six years since the launch of the Large Area Telescope (LAT), we’ve seen our share of ups and downs. An active community, both in and outside the Fermi Collaboration (FC), works hard to fit dark matter to or explain away every deviation in excess of what we expect from the gamma-ray sky. This year’s gathering got the answer to the latest burning question: do we see dark matter emission from dwarf spheroidal galaxies (dSphs)? … Continue Reading ››

Interview with Katherine Freese

Katherine Freese is in Stockholm these days since she will be receiving a prestigious Honorary doctorate at Stockholm University on Friday, the 28th September. I met with her in one of the offices at the Oskar Klein Centre in front of cup of coffee to talk a bit with this energetic woman, and try to grab her secrets.

What was you reaction when you heard you will receive this title?
Oh I was very happy, I think it is really an honor to get this. First when Lars told me I was a candidate, and then when I got it, I couldn’t believe it. It is going to be great tomorrow. I am a bit nervous, you know, because of the jet leg I am going to be so tired!

ATLAS and CMS experiments observe new particle consistent with long-sought Higgs boson

Today the ATLAS and CMS experiments have reported the observation of a strong excess of proton-proton collision events compatible with the Higgs boson.

The observed excess is obtained by combining 5 channels in the case of CMS to reach a level of 4.9 sigma of statistical significance. ATLAS has presented so far the result from two channels and observes an excess of 5 sigma. The number of events and the type of decays observed are both compatible with the standard model Higgs boson with a mass of about 125 GeV, and given the statistical significance of both ATLAS and CMS observations this can no longer be a statistical fluctuation. So today we have the discovery of a new particle.

LHC Experiments ATLAS and CMS to update their Higgs boson hunt results

CERN has announced that the two experiments leading the search for the Higgs boson, ATLAS and CMS will update their results concerning the search for the Higgs boson tomorrow on July 4th.

Last December the ATLAS and CMS experiments reported they excluded a Higgs boson in the mass range above 130 GeV and up to 500 GeV and observed a modest excess of collisions compatible with a Higgs boson at about 125 GeV, but with a low statistical significance.