Visiting Geneva

Finally the weekends and a chance to do something in Geneva.  Although I did not manage to get a free bike from CERN, there were free four hour bike rentals waiting for me in Geneva. Genèveroule is a voluntary organization with at five spots in the city where you can rent a bike for zero swiss franc.  All you need is some identification papers and an address of your hotel.  Here are some of the pictures I took.

Some random street photo soon after I got off the tram from CERN to Coutance.

Tram terminal.  Nice and clean tram.

View from the Tourist Information building.  You can see the Jet d'Eau.

View from another angle.

Old model boats that carry tourist across Lake Geneva.

I was cycling along the lake.  Nice weather coupled with a nice view of the surrounding lakes makes it an unforgettable journey.

Weekend market?  Looks like any other market in Europe.

A nice little crepe restaurant beside Cathedral St. Pierre.

Cathedral St. Pierre

A portion of the poster about the reformation.

This photo didn't turn out as it was supposed to.  You are supposed to be able to see the 'seven' colours of the rainbow  due to the water droplets from the fountain.

The United Nations office in Geneva.  Closed during weekends.  Did not stop tourists from taking photos.  Heh..

Ariana, a museum of glass and ceramics.

The red cross museum.  Closed until 2013. Sad.

Fondue pots!  So many different designs of it.

A side view of Cathedral St. Pierre.

Faster-than-light neutrinos?

Just about two hours ago in CERN, there was a groundbreaking claim about an experiment detecting neutrinos that travel faster than light.  The OPERA experiment in Gran Sasso, Italy collected data and analysed the speed of these tiny particles that only interact gravitationally and weakly since neutrinos are neutral leptons.  They have shown in their experiment that the speed of the neutrinos were faster than light by a factor of

(2.48 ± 0.28 (statistical errors) ± 0.30 (systematic errors) ) ×10^-5

or 6.0 σ.  It is big news all over the world with major news networks(for example, BBC) reporting them on webpages and TV channels.

The auditorium room filling up half and hour before the seminar starts.
I am really lucky to get a seat at the back  row!

The speaker, Dario Autiero (Institut de Physique Nucleaire de Lyon)

So what are neutrinos?  Originally, they are postulated to exist by Wolfgang Pauli to explain missing transverse energy of beta decay.  A simple representative decay process would be neutron decay.

But then when they measured the energy of the beta particle, or the fast electron, they found that the reaction did not obey the Law of Conservation of Energy.  So W. Pauli thought that maybe there is some kind of small undetected particle that carried that energy away.  Now we know to reasonable doubt that this is true so we rewrite this decay process as

Now that we got rid of the basic question of what neutrinos really are, you may ask, what was OPERA's experiment about?  Well, OPERA was trying to catch neutrinos that change flavours.  Flavours?  We now know that there are three flavours.  The electron neutrino, muon neutrino and the tau neutrino and by changing flavours (or the technical term is neutrino oscillation) the electron neutrino changes in the muon or tau neutrino.  The OPERA experiment is an appearance experiment; to detect the appearance of tau neutrinos from the oscillation of muon neutrinos sent from CERN.

They are still looking for tau neutrinos right now.  At the same time, they need some kind of accurate measurements of distance and time since the travel time from CERN to Gran Sasso, Italy (730km) took the muon neutrinos only 3ms.  They used GPS synchronizations for timing and help from land surveying to figure out the distance accurate to the centimeter level.  According to them, after months of checking and rechecking their results they decided that their experimental results and analysis work were correct and decided to show it to the world.  In particle physics, it is enough to claim discovery with a 5.0 σ significance (signal over background events).

The CERN Neutrinos to Gran Sasso (CNGS) beam line.  It produces muon neutrinos from a proton beam source accelerated  by the proton synchrotron in CERN.  The protons hit a target producing pions and kaons that decay into muons and neutrinos.  The neutrinos then pass through 730km of earth and rock to reach the OPERA experiment in Italy.    They could do that because they very rarely interact with matter.

What is particle physics?

Today, I boarded a flight to Geneva from Copenhagen, and arrived at CERN roughly about noon time.  The weather was the total opposite of the Lund's where it has been cloudy, rainy and windy the past few weeks if not most of summer.  The sun was terrific and warm which reminded me so much about the trip I had in Italy.

CERN is located in the part of Geneva called Meyrin, which is really at the border with France.  For the uninitiated, CERN is a major research center for major discoveries in the field of particle physics.  In the past, it has contributed to the discovery of

• 1973: The discovery of neutral currents in the Gargamelle bubble chamber.
• 1983: The discovery of W and Z bosons in the UA1 and UA2 experiments.
• 1989: The determination of the number of light neutrino families at the Large Electron–Positron Collider (LEP) operating on the Z boson peak.
• 1995: The first creation of antihydrogen atoms in the PS210 experiment.
• 1999: The discovery of direct CP-violation in the NA48 experiment.
• 2010: The isolation of 38 atoms of anti-hydrogen.
• 2011: Maintaining anti-hydrogen for over 15 minutes.

source: wikipedia

These experiments have increased our knowledge of what forms matter and how they interact with each other.  Current experiments that have been followed by the media are ATLAS, CMS, ALICE amongst others.  They are discovery machines that find new physics, which sometimes mean new particles or new properties of matter.  The Higgs boson is one of the most talked about but however till now, it has not been discovered yet.  Other hypothetical particles waiting to be discovered are like the sparticles; neutralinos, charginos and squarks.

The CERN research complex looks like an industrial area with a smattering of workshops and warehouses.  Ocassionally you find some art pieces, which are actually decommissioned detector pieces like the Gargamelle bubble chamber.  There are also two beam pipes used as banner placeholders and you will see in the pictures.  In 2000, the Swiss built and object for the World Expo in Hannover.  This object has then been transplanted to the CERN site and is called the Globe of Science and Innovation, and it one of the donated art pieces which is slowly becoming a landmark icon (according to the CERN site, but if you visit, it definitely catches your eye orders of magnitude higher than the boring 70's type architecture of the CERN buildings).

The CERN signboard outside Entrance B

Where all the accelerator actions happens.

... so the beam from SPS goes to LEP then LHC ...

All is calm in the control room.  No beams running yet.

Sample beam pipe or rather drift tubes.

The cafeteria that is chaotic at lunch time.  Reminds me much about the canteens in NUS.

This picture and the previous one was once a piston activated bubble chamber.

The interior of the bubble chamber, which is a particle detector.

The Gargamelle detector.  The one that discovered the neutral current.

A Van deGraff generator.  The first step in accelerating charged particles in the old days.

The Globe of Science and Innovation on the opposite side of the road from CERN.

Can you see Mont Blanc.

The ATLAS control room building.  You can tell from the mural of the cross section of the detector on the wall.