Tag Archives: Atlas

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.

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 ››

ATLAS collision animations

At the Oskar Klein Center there are researchers working hard to figure out the content of the universe and the fundamental laws of physics. Erik Johansson, Professor emeritus at Stockholm University and Director emeritus of the Stockholm House of Science, has created some animations aimed at describing ATLAS collisions happening in Large Hadron Collider at CERN. When two high energy protons collide, it is the constituents of the protons – the quarks and gluons – that interact. The dynamics of quark and gluon interactions are described in five animations, focusing on … Continue Reading ››

Fresh Summer Harvest of ATLAS Results: Top quarks, Sleptons and Gauginos

Since monday the last of a string of summer High Energy Physics (HEP) conferences is unwinding in Beijing, SUSY-12 and before that in Melbourne ICHEP-2012. Some results with leading contributions from the Stockholm HEP group figure high in the topics of discussion. Finally ATLAS physicists can breathe a  little bit, with most results out for now. The Higgs boson discovery got a lot of attention, and this is great because it is not every day that there is a discovery of that magnitude, but there is an other important reason: simply said, the existence of the Higgs boson is at the basis of much of the research being carried out at Stockholm University and in ATLAS.

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.

And the ATLAS Thesis Award 2011 goes to Christian Ohm!

Only five of the about 100 PhD students who graduated in 2011 received the ATLAS Thesis Award 2011, and we are very proud to know that Christian Ohm, PhD student at the Oskar Klein Centre is one of them. The other winners are Michael Hance, David Lopez Mateos, David Miller and Verena Martinez Outschoorn.
“It is very exciting!” tells me a radiant Christian when he joins me in my office “if you think that the other four are all Americans, and I am the only European! And they come from places like Harvard, Caltech and Berkeley!”
The five winners were selected by the CB Chair Advisory Committee, which acted as the Thesis Awards Committee, from a selection of 21 nominations received.

An ATLAS art installation at AlbaNova

Since early Autumn the ATLAS Art Installation is on the first floor of Stockholm House of Science at AlbaNova.
“In ATLAS we have made rather artistic animations of particle physics. In addition an artist has made the mural painting at CERN on one of the ATLAS buildings. The ATLAS events have also been rather artistic and made it to the many magazines and newspapers. I think that is why the installation is called the ATLAS Art Installation. I prefer to call it the People of ATLAS, as it is very much about the ATLAS people.” says Erik Johansson, professor at the Oskar Klein Centre.

One big step closer to finding or excluding the Higgs boson.

Today the ATLAS and CMS experiments at CERN’s Large Hadron Collider (LHC) have presented the results of the analysis of all their most recent data. One tricky thing about the Higgs boson is that we do not know what is its mass, and so one needs to look for it in all its possible decay channels. ATLAS and CMS show that there is no Higgs boson with a mass above about 130 GeV and below 115 GeV (it could still be heavier than about 500 GeV but this is not favored by the theory).