Open Days – The final countdown

In only a few days CERN will open its doors to everyone! Thousands of volunteers are working very hard so that your visit will be both mind-boggling and fun. Where is the coldest place in the Universe? How can you move 30 tonne magnets with sub-millimetre precision? Why do you need huge detectors to look at the infinitely small? There’s only one way to find the answers: Come to CERN!

The organising committee has stretched every sinew to make these two days exceptional.

The visits and activities on Saturday 5 April (9:00 a.m. to 4:00 p.m.) will be reserved for CERN employees and their families, while all the sites around the ring will be open to the general public from 9 a.m. to 7 p.m. on Sunday, 6 April.

Unwrapping the LHC and its experiments

The 2008 Open Days will be the first and probably the last time you will have the opportunity to explore each of the four main experiment caverns as well as the LHC tunnel, which will be accessible from seven different locations around the ring. Tours, exhibits, posters, shows and activities have been organised at different points around the site especially for visitors. It’s going to be a once-in-a-lifetime experience – so don’t miss out!

Dipole magnet from the LHC on board Fred’s lorry.

As well as the underground tours to the tunnel and experiment caverns there will be a host of interactive activities and events on the surface aimed to intrigue, amaze and entertain you. Physicists and guides working specifically on ATLAS, CMS, ALICE, LHCb, Totem, CAST and the LHC will be on call to answer all your questions. From the history of our Universe to the secrets of matter and antimatter there are a lot of mind-blowing ideas to get enthusiastic about!

For example, at Echenevex (Point 4), the focus will be on the immense accelerating power of the LHC. In the Salle Communale La Chenaille an accelerating cavity will be on display, giving you the chance to learn about how particles are made to travel at just under the speed of light.

At Cessy, the home of CMS, there will be demonstrations of ‘superfluidity’, a strange property of ultra-cold helium that is used to cool the LHC magnets close to absolute zero. If that isn’t enough there will also be the opportunity to talk to CERN surveyors about how they aligned the LHC detectors and experiments in the 27km tunnel.

On Sunday 6 April, Fred, who presents the French television programme "C’est pas sorcier", will be on board a CERN lorry carrying a 35 tonne 15 m long dipole magnet, making eight stops in the salle communales around the LHC ring to meet people from the local areas. Twelve children of CERN staff members will accompany him and the special programme will be screened in the salle communales at each stop.

For more information on other activities and shows taking place around the LHC ring take a look at the boxes on these pages.

In and around Meyrin and Prévessin

Ever wondered what is happening in all the buildings and labs around the site where you go to work everyday? On the Open Days you can discover the LHC workshops by following the magnets’ route to the pit where they are lowered down into the tunnel, and find out more about supraconductivity and cryogenics for CERN’s largest accelerator.

The demonstrations, visits and shows put on by the LHC workshops around the sites will be complemented by exhibitions and talks in the Main Building, highlighting different aspects of this great scientific and technological adventure. As special guests CERN has invited two Nobel laureates, Georg Bednorz and Antony Leggett, without whose prize-winning discoveries of superconductivity and superfluidity, respectively, the LHC could not have been built.

However, the LHC is the last and largest ring in a whole chain of accelerators, which are controlled and supervised in the CERN Control Centre. On the Open Days, visitors will also have the chance to visit the other rings: the SPS, CERN’s second-largest accelerator, the PS, CERN’s oldest accelerator, the Linacs, which are the first in the chain, and LEIR, which will supply lead ions to the LHC. There will even be an opportunity to look into the future by visiting CLIC and the new technologies being tested there.

Improvisation actors are planning to perform in the crowds at the Open Days (photo: Eric Velardo).

The fun of physics will be shown in many places around the sites, not least in the "Globeshow", which will also be broadcast live on large screens at all queuing points. The show will include the "Hadron Café", where invited experts will discuss topics such as black holes, and "Show Physics", which normally brings the excitement of physics to school classrooms all over Europe.

For more details about the entire programme see:


The countdown is T-5 days and the organisers of the Open Days would like to say a big thank you in advance to all the volunteers who have committed substantial effort and time to make these days happen. To the people on the sites both above and below ground, the guides, the animators and speakers, the technicians and various groups providing material, the hostesses, paramedics, fire fighters, the security teams and everyone else involved in the organisation of the Open Days: THANK YOU!

Improvisation Actors

Members of the Geneva Improvisation Federation (FIG) will be joining visitors on the public Open Day. How will you know where to find them? How will you know who they are? How will you know what they’ll do? You won’t, that’s the beauty of improvisation! But rest assured, you will be entertained. For more details about FIG visit their website:

Human beam dump game

Imagine you are a high energy proton travelling at almost the speed of light around the LHC ring. Suddenly you are rerouted, and in an instant smack headfirst into a mighty block of graphite. You’ve just arrived at Point 6: the beam dump. To experience a similar sensation, come to Point 6 for the Open Day. Thanks to Air Games France, the ground- level entertainments will include an inflatable "attrape mouche" (weather permitting). Dress up in a velcro costume, run towards the inflatable wall and "splat": be stopped in your tracks! (Participants must be 1.40m or taller).

A superconducting key ring: a real piece of the LHC!

As a souvenir of these two special Open Days, 20,000 emblematic superconducting key rings will be on sale in the various sales points on 5 and 6 April. 800m of superconducting cable was used to make them! These attractive key rings will feature the superconducting cable with its thousands of filaments inside their copper coating.

CERNois Open Day – 5 April

Please note that everyone with a valid CERN card can bring up to a maximum of 4 visitors onto the site. Most of the activities planned for the public Open Day on 6 April will also take place on 5 April. For further details, please refer to the website:

A superconducting key ring will be sold at the Open Day. Don't go home without one!

Parking 5 and 6 April

CERN CARS: Please clear all car parks and park CERN cars in the car parks which will be closed to the public, i.e.: around the ISR ring and the "Centre Anneau" zone, near to the PS Complex (Buildings 588, 587, 573, 574 and 575) and the "zone de brulage" in Prévessin (Buildings 917 and neighbouring buildings). Please lock all cars.

SHUTTLE SERVICE ON OPEN DAYS: There will be no shuttle service on 5 April.

Please consult the website for the Park and Ride system on 6 April:


Due to safety and security concerns, all CERN staff are advised to make sure that the windows and doors to their offices are locked for the whole weekend. Buildings not involved in any of the activities on the weekend of 5 and 6 April should also be closed to external people.

Safety Rules

The following general safety rules apply in all experimental areas:

  • High-heeled shoes or open-toed shoes, flip-flops or sandals are not permitted.
  • Visits in underground areas are forbidden to:
    • pregnant women (after the sixth month of pregnancy)
    • people suffering from claustrophobia or vertigo
    • children less than 10 years old
    • children between 10 and 16 years old: maximum of 4 children for each accompanying adult.

NOTE: Please note that the number of visitors to the underground tunnel and caverns is limited by the capacity of the lifts. Depending on the site, that means a maximum of 200 to 300 people per hour.