13th June 2017 – Discovered almost 100 years ago by Ernest Rutherford, the proton was one of the first particles to be studied in depth. Yet there’s still much about it that remains a mystery. Where does its mass and spin come from? What is it made of? To answer these questions, ATLAS physicists are using “jets” of particles emitted by the LHC as a magnifying glass to examine the inner structure of the proton.
7th June 2017 – More than 400 physicists from around the world visiting Shanghai to hear the latest LHC results, at the fifth annual Large Hadron Collider Physics (LHCP17) conference. It was a wonderful opportunity for Chinese particle physicists and students, who do not often have the chance to travel abroad! Even for me, although I have been working on the LHC for almost 10 years, this was still my first time attending such a high-level conference to hear the first-rate physics results from all four experiments at the Large Hadron Collider.
23rd May 2017 – Geneva, 23 May 2017. A new season of record-breaking kicked off today, as the ATLAS experiment began recording first data for physics of 2017. This will be the LHC’s third year colliding beams at an energy of 13 tera electron volts (TeV), allowing the ATLAS Experiment to continue to push the limits of physics.
23rd May 2017 – The fifth annual Large Hadron Collider Physics (LHCP2017) conference was held this week at Shanghai Jiao Tong University in a leafy suburb in the former French concession in Shanghai, China. This year there were more participants than ever before: 470 people from universities across the globe. ATLAS presented an interesting set of new results exploiting the high statistics of the combined 2015 and 2016 dataset.
19th May 2017 – The start of the 2017 run marks the conclusion of a maintenance period known as the Extended Year-End-Technical-Stop (EYETS). This upkeep is vital for the health and well-being of the detector, ensuring that ATLAS can thrive for the months of high-intensity operation that follow.
18th May 2017 – Supersymmetry is an extension to the Standard Model that may explain the origin of dark matter and pave the way to a grand unified theory of nature. For each particle of the Standard Model, supersymmetry introduces an exotic new “super-partner,” which may be produced in proton-proton collisions. Searching for these particles is currently one of the top priorities of the LHC physics program. A discovery would transform our understanding of the building blocks of matter and the fundamental forces, leading to a paradigm shift in physics similar to when Einstein’s relativity superseded classical Newtonian physics in the early 20th century.
17th May 2017 – Supersymmetry (SUSY) is one of the most attractive theories extending the Standard Model of particle physics. SUSY would provide a solution to several of the Standard Model’s unanswered questions, by more than doubling the number of elementary particles, giving each fermion a bosonic partner and vice versa. In many SUSY models the lightest supersymmetric particle (LSP) constitutes dark matter.
15th May 2017 – With the huge amount of proton–proton collisions delivered by the LHC in 2015 and 2016 at the increased collision energy of 13 TeV, ATLAS has entered a new era of Higgs boson property measurements. The new data allowed ATLAS to perform measurements of inclusive and differential cross sections using the “golden” H->ZZ*->4l decay.
9th May 2017 – Ever since the LHC collided its first protons in 2009, the ATLAS Collaboration has been persistently studying their interactions with increasing precision. To this day, it has always observed them to be as expected by the Standard Model. Though it remains unrefuted, physicists are convinced that a better theory must exist to explain certain fundamental questions: What is the nature of the dark matter? Why is the gravitational force so weak compared to the other forces?
2nd May 2017 – Up to now, ATLAS has measured the energies and positions of jets using the finely segmented calorimeter system, in which both electrically charged and neutral particles interact. However, the inner detector tracking system provides more precise measurements of charged particle energies and positions. A recent ATLAS paper describes a particle flow algorithm that extrapolates the charged tracks seen by the inner detector to the calorimeter regions.