data preparation

Ensuring high-quality data at ATLAS

During Run 2, ATLAS achieved an exceptionally high data-quality efficiency for a hadron collider, with over 95% of the 13 TeV proton-proton collision data certified for physics analysis. In a new paper released today, the ATLAS data quality team summarises how this excellent result was achieved.

13th November 2019

The trouble with terabytes

2016 has been a record-breaking year. The LHC surpassed its design luminosity and produced stable beams a staggering 60% of the time – up from 40% in previous years, and even surpassing the hoped for 50% threshold. While all of the ATLAS experiment rejoiced – eager to analyse the vast outpouring of data from the experiment – its computing experts had their work cut out for them.

14th December 2016

Behind very great results lies great computing

At the ATLAS experiment, masterful computing infrastructure is transforming raw data from the detector into particles for analysis, with a set direction, energy and type.

13th November 2015

ATLAS awards Long Shutdown 1 achievements

The ATLAS Outstanding Achievement Awards 2015 were presented on 18 June to 26 physicists and engineers, in 11 groups, for their excellent work carried out during Long Shutdown 1 (LS1).

25th June 2015

ATLAS records first test collisions at 13 TeV

On 20 May at around 22:24, ATLAS recorded the first 13 TeV test collisions delivered by the Large Hadron Collider. The proton collisions set a new high energy record, marking the beginning of ATLAS' journey into unexplored physics frontiers as we prepare for production data-taking, scheduled to start in early June.

22nd May 2015

First collisions at injection energy

On the morning of 5 May 2015, ATLAS recorded the first scheduled proton beam collisions since the Large Hadron Collider and its experiments started up after two years of maintenance and repairs.

8th May 2015

From 0-60 in 10 million seconds! – Part 2

This is continuing from the previous post, where I discussed how we convert data collected by ATLAS into usable objects. Here I explain the steps to get a Physics result. I can now use our data sample to prove/disprove the predictions of Supersymmetry (SUSY), string theory or what have you. What steps do I follow?

19th February 2012

From 0-60 in 10 million seconds! – Part 1

OK, so I’ll try to give a flavour of how the data that we collect gets turned into a published result. As the title indicates, it takes a while! The post got very long, so I have split it in two parts. The first will talk about reconstructing data, and the second will explain the analysis stage.

17th February 2012

ATLAS reaches milestone: 5 inverse femtobarns of data!

In an amazing year that has exceeded our expectations, the Large Hadron Collider has delivered, and ATLAS has recorded, over 5 inverse femtobarns (fb-1) of collisions. These units correspond to having 3.4 x 1014 or 340 000 000 000 000 total collisions. Most analyses presented at the last major conference (the Lepton Photon Symposium in August in Mumbai) made use of about 1 fb-1, so this is a big jump.

28th October 2011

ATLAS starting to get on Top of things

ATLAS is about to check one more particle off of its Standard Model (SM) checklist. Namely the top quark. This famous quark is perhaps one of the most complex of the SM particles.

26th July 2010

One in a few million

ATLAS has been designed to detect rare events in high energy proton-proton collisions. ATLAS ultimate goal is to measure events as rare as one in several thousand billions, but we are modest (for the time being) waiting for the luminosity to rise.

24th April 2010

Its All About The Lumi!

Now that the LHC has established colliding stable beams at a center of mass energy of 7 TeV, the next step to maximize its physics reach is to provide the most luminosity possible. As Leo posted, we need to increase the number of proton - proton collisions to make sure we have a chance of seeing the physics that we are looking for. The reason for that is because different p.hysics processes have different probabilities. These probabilities are referred to as cross-sections (in a vague reference to the particle's size). If one multiplies a cross section by a luminosity than what you get is a number of events.

6th April 2010

Let The Physics Begin!

After decades of planning. After years of delays and immeasureable amounts of patience and hard work. The physics operations of the LHC has begun!

30th March 2010

First collisions in ATLAS

A few days ago, loud cheers and happy faces filled the ATLAS Control Room while the whole detector lit up: protons are back at the experiment's door, and everybody forgot in a second the long year of waiting for the Large Hadron Collider (LHC) to resume operation.

23rd November 2009

LHC beams and events back in ATLAS

Loud cheers and happy faces fill the ATLAS Control Room while the whole detector lights up: protons are back today at the experiment's door, and everybody forgets in a second the long year of waiting for the Large Hadron Collider (LHC) to resume operation.

21st November 2009

ATLAS preparing for collisions in mid-2009

The full ATLAS Experiment has been operational and taking cosmic ray data since September 2008, and high-energy collisions are scheduled for late summer 2009. Data from cosmic rays that hit the ATLAS detector are valuable to calibrate and synchronize the many detector elements. Even more exciting were the so-called “splash events” that occurred as the LHC was being tuned up starting 10 September 2008.

15th December 2008

Dress Rehearsal for ATLAS debut

Dave Charlton and his team have a mammoth job on their hands; Charlton has been tasked with coordinating the Full Dress Rehearsal (FDR) of the computing and data analysis processes of the ATLAS experiment, a run–through which he describes as "essential, almost as much as ensuring the detector itself actually works".

15th December 2007

Triggering and measuring bent cosmic muon tracks with the muon spectrometer barrel for the first time

Data have recently been collected with the toroidal magnetic field will provide for the first time the measurement of the cosmic ray muons' momenta in the ATLAS experiment and allow studies on trigger optimization, chamber calibration, chamber alignment and magnetic field maps. More than one million events were acquired. They are now being analyzed by enthusiastic members of the collaboration.

22nd December 2006

First combined SCT/TRT end-cap cosmic rays seen in building SR1

Following the successful combined SCT/TRT barrel test in the Spring 2006, a similar combined SCT/TRT endcap test is currently being performed in the SR1 building on the ATLAS experimental site at CERN. One quadrant of the SCT and two sectors of the TRT have been cabled up and are used in this test. The data taking and combined testing is expected to last until December 11th.

9th December 2006

First physics pulses in the barrel electromagnetic calorimeter with cosmic rays

The electromagnetic barrel calorimeter was installed in its final position in October 2005. Since then, the calorimeter is being equipped with front-end electronics. Starting in April 2006, electronics calibration runs are taken a few times per week to debug the electronics and to study the performance in the pit (stability, noise). Today, 10 out of the 32 Front End crates are being read out, amounting to about 35000 channels.

20th November 2006

ATLAS copies its first PetaByte out of CERN

On 6th August ATLAS reached a major milestone for its Distributed Data Management project - copying its first PetaByte (1015 Bytes) of data out from CERN to computing centers around the world. This achievement is part of the so-called 'Tier-0 exercise' running since 19th June, where simulated fake data is used to exercise the expected data flow within the CERN computing centre and out over the Grid to the Tier-1 computing centers as would happen during the real data taking.

1st November 2006