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).

ATLAS is ready for Run 2 of the Large Hadron Collider (LHC) where proton beams will be collided together at a higher centre of mass collision energy of 13 TeV, and reach higher luminosities than ever before.

As ATLAS gears up to record data from proton collisions delivered by the Large Hadron Collider (LHC) at an unprecedented energy level, here are glimpses from the last two years of preparations.

The first long shutdown of the Large Hadron Collider has now ended, after two years of intense but careful activity refurbishing and improving many aspects of ATLAS, mirroring the work to prepare the LHC for collisions at the new energy of 13 TeV.

A few weeks ago, I found myself in one of the most beautiful places on earth: wedged between a metallic cable tray and a row of dusty cooling pipes at the bottom of Sector 13 of the ATLAS Detector at CERN. My wrists were scratched from hard plastic cable ties, I had an industrial vacuum strapped to my back, and my only light came from a battery powered LED fastened to the front of my helmet. It was beautiful.

After completing more than 250 work packages concerning the whole detector and experimental site, the ATLAS and CERN teams involved with Long Shutdown 1 (LS1) operations are now wrapping things up before starting the commissioning phase in preparation for the Large Hadron Collider's restart. The giant detector is now more efficient, safer and even greener than ever thanks to the huge amount of work carried out over the past two years.

For five days last week, 110 ATLAS collaborators worked in 10 different shifts to help clean and inspect the detector and the cavern that houses it before the toroid magnets are turned on.

An obligatory eye scan is required for all ATLAS underground personnel entering the experimental cavern. The iris recognition is performed by the IrisID iCAM7000. Its only point in life is to keep track of who enters and leaves the Zone. It sounds like a simple task for such an advanced technology, but -- like most things in the world of research -- it's never without some hiccups.

Bringing the nine-storey high, many-layered ATLAS detector back to life and preparing it for the Large Hadron Collider's next run is a complex task. Each sub-detector is setup and thoroughly tested before they are joined and the detector as a whole can begin recording data again.

Closest to the beam pipe where particle collisions will occur in the very heart of ATLAS, a new sub-detector – the Insertable B-Layer – was put in place on 7 May. The IBL team had been developing and practicing the insertion procedure and tooling for two years because of the operation’s delicate nature.

We physicists refer to the vast underground cavern that houses the ATLAS experiment as ‘the pit’. That may be a strange term to use for a marvel of civil, mechanical and electrical engineering, but nonetheless there are parallels to what you might imagine a ‘pit’ to be. Working inside the ATLAS detector in the pit can be dark, sometimes hot and not suited to those with claustrophobia. It often involves climbing several sets of makeshift steps and gantries and crawling flat on your stomach through narrow gaps to get to the part of the detector where you need to be. You will be wearing a safety helmet with mounted lamp, steel toe-cap shoes, one or more dosimeters to monitor radiation exposure and even a harness, if working at heights. Not to mention tools, laptop and any equipment you need to do your job. You tend to recognize the experimental physicists, engineers and technicians who have just come up from the pit – they stand blinking in the sunlight with a tired and rather sweaty appearance.

In the first run of the Large Hadron Collider, almost a billion proton-proton collisions took place every second in the centre of the ATLAS detector. That amounts to enough data to fill 100,000 CDs each second. If you stacked the CDs on top of each other, in a year it would reach the moon four times. Only a small fraction of the observed proton–proton collisions have interesting characteristics that might lead to discoveries. How does ATLAS deal with this mountain of data?

Hold out your hand and in one minute hundreds of muons will have passed through your palm. Muons are one of the high-energy cosmic ray particles that can pass through most solid structures – even the ATLAS detector’s calorimeter, which is designed to absorb particles and measure their energy. A specific system is required to measure muons. Until now, the ATLAS muon system was almost completed, but not quite. The last of the 62 chambers in the Extended Endcap (EE) region was installed just before summer this year.

More than 70,000 people visited CERN Open Days over the weekend, with 20,000 going underground to see the LHC tunnel and the detectors. Of these, an estimated 5,000 people visited the ATLAS exhibits aboveground, and another 2,500 had the opportunity to see the ATLAS detector.

Only a few more days to go before CERN opens its doors and our universe becomes yours on 28 and 29 September. With 35 surface sites and seven underground visits available, there will be plenty of activities for visitors of all ages.