Author Archives: Renilde Vanden Broeck

New ALICE experiment results show novel phenomena in proton collisions

Experiments and Tracks

As the number of particles produced in proton collisions (the blue lines) increase, the more of these so-called strange hadrons are seen (as shown by the red squares in the graph). (Image: CERN)Geneva 24 April 2017. In a paper published today in Nature Physics, the ALICE collaboration reports that proton collisions sometimes present similar patterns to those observed in the collisions of heavy nuclei. This behaviour was spotted through observation of so-called strange hadrons in certain proton collisions in which a large number of particles are created. Strange hadrons are well-known particles with names such as Kaon, Lambda, Xi and Omega, all containing at least one so-called strange quark. The observed ‘enhanced production of strange particles’ is a familiar feature of quark-gluon plasma, a very hot and dense state of matter that existed just a few millionths of a second after the Big Bang, and is commonly created in collisions of heavy nuclei. But it is the first time ever that such a phenomenon is unambiguously observed in the rare proton collisions in which many particles are created. This result is likely to challenge existing theoretical models that do not predict an increase of strange particles in these events.

“We are very excited about this discovery,” said Federico Antinori, Spokesperson of the ALICE collaboration. “We are again learning a lot about this primordial state of matter. Being able to isolate the quark-gluon-plasma-like phenomena in a smaller and simpler system, such as the collision between two protons, opens up an entirely new dimension for the study of the properties of the fundamental state that our universe emerged from.”

The study of the quark-gluon plasma provides a way to investigate the properties of strong interaction, one of the four known fundamental forces, while enhanced strangeness production is a manifestation of this state of matter. The quark-gluon plasma is produced at sufficiently high temperature and energy density, when ordinary matter undergoes a transition to a phase in which quarks and gluons become ‘free’ and are thus no longer confined within hadrons. These conditions can be obtained at the Large Hadron Collider by colliding heavy nuclei at high energy. Strange quarks are heavier than the quarks composing normal matter, and typically harder to produce. But this changes in presence of the high energy density of the quark-gluon plasma, which rebalances the creation of strange quarks relative to non-strange ones. This phenomenon may now have been observed within proton collisions as well.

In particular, the new results show that the production rate of these strange hadrons increases with the ‘multiplicity’ – the number of particles produced in a given collision – faster than that of other particles generated in the same collision. While the structure of the proton does not include strange quarks, data also show that the higher the number of strange quarks contained in the induced hadron, the stronger is the increase of its production rate. No dependence on the collision energy or the mass of the generated particles is observed, demonstrating that the observed phenomenon is related to the strange quark content of the particles produced. Strangeness production is in practice determined by counting the number of strange particles produced in a given collision, and calculating the ratio of strange to non-strange particles.

Enhanced strangeness production had been suggested as a possible consequence of quark-gluon plasma formation since the early eighties, and discovered in collisions of nuclei in the nineties by experiments at CERN1‘s Super Proton Synchrotron. Another possible consequence of the quark gluon plasma formation is a spatial correlation of the final state particles, causing a distinct preferential alignment with the shape of a ridge. Following its detection in heavy-nuclei collisions, the ridge has also been seen in high-multiplicity proton collisions at the Large Hadron Collider, giving the first indication that proton collisions could present heavy-nuclei-like properties. Studying these processes more precisely will be key to better understand the microscopic mechanisms of the quark-gluon plasma and the collective behaviour of particles in small systems.

The ALICE experiment has been designed to study collisions of heavy nuclei. It also studies proton-proton collisions, which primarily provide reference data for the heavy-nuclei collisions. The reported measurements have been performed with 7 TeV proton collision data from LHC run 1.

Footnote(s)

1. CERN, the European Organization for Nuclear Research, is one of the world’s leading laboratories for particle physics. The Organization is located on the French-Swiss border, with its headquarters in Geneva. Its Member States are: Austria, Belgium, Bulgaria, Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Spain, Sweden, Switzerland and United Kingdom. Cyprus and Serbia are Associate Member States in the pre-stage to Membership. India, Pakistan, Turkey and Ukraine are Associate Member States. The European Union, Japan, JINR, the Russian Federation, UNESCO and the United States of America currently have Observer status.

Arts@CERN announces three new open calls and the arrival of new artists in residence

Geneva, 12 October 2015. CERN1 has today announced three new open calls giving a chance to artists to immerse themselves in the research of particle physics and its community. Two new international partners have joined the Accelerate @ CERN programme: the Abu Dhabi Music & Arts Foundation (ADMAF) from UAE2 and Rupert, the centre for Art and Education from Vilnius, Lithuania3. The Collide @ CERN Geneva award is also now calling for entries, continuing the fruitful collaboration with The Republic and Canton of Geneva and the City of Geneva4. Last but not least, the Collide @ CERN Ars Electronica winning artists start their residency at CERN this week.

“Science and the arts are essential parts of a vibrant, healthy culture, and the Arts @ CERN programme is bringing them closer together,” said CERN DG Rolf Heuer. “With CERN’s diverse research programme, including the LHC’s second run getting underway, there’s no better place in the world to do that than here.”

With the support of The Abu Dhabi Music & Arts Foundation (ADMAF), Arts @ CERN gives the chance for an Emirati visual artist to come to CERN for a fully funded immersion in high-energy physics in the Accelerate @ CERN programme. Thanks to the support by Rupert, Centre for Art and Education in Vilnius, the same door opens to Lithuanian artists who wish to deepen their knowledge in science and use it as a source of inspiration for their work. Each of the two open calls begins today for artists to win a one-month research stay at CERN. Applications can be submitted up to 11 January 2016.

Funded by The Republic and Canton of Geneva and The City of Geneva, Collide @ CERN Geneva has operated successfully since 2012. Arts @ CERN announces the fourth open call for artists from Geneva, this time celebrating the city’s strength in digital writing. Today, the competition opens to writers who were born, live or work in the Geneva region, and would like to win a three-month residency where scientific and artistic creativity collide.  The winner will also receive a stipend of 15,000CHF. The deadline for applications is 11 January 2016.

“Arts and science have always been interlinked as major cultural forces, and this is the fundamental reason for CERN to continue to proactively pursue this relationship,” said Mónica Bello, Head of Arts @ CERN. “The arts programme here continues to flourish.”

Semiconductor, the artist duo formed by Ruth Jarman and Joe Gerdhardt, are the winners of the Collide @ CERN Ars Electronica award5. Out of 161 projects from 53 countries, the jury6 awarded Semiconductor for their broad sense of speculation, complexity and wonder, using strategies of analysis and translation of the phenomena into tangible and beautiful forms. Their two-month Collide @ CERN residency starts on 12 October 2015.

Online submissions for artists CERN.ch/arts

Further information:

Arts@CERN website
Accelerate@CERN website
Collide@CERN Facebook site
Twitter ArtsAtCern

Media contact:

Arts @ CERN
Monica Bello, Head of Arts @ CERN
monica.bello@cern.ch
+41 22 766 36 63

The Abu Dhabi Music & Arts Foundation (ADMAF)
Michel El Gemayel
Senior Manager – Marketing & Communications
P.O. Box 47488, Abu Dhabi, United Arab Emirates
E. michel.g@admaf.org
T. +971 2 3336425; F. +971 2 6411055; M. +971 529755000

Rupert, Centre for Art and Education in Vilnius
info@rupert.lt
Vaidilutės g. 79, Vilnius 10100
Lithuania

DIP 
République et canton de Genève 

Cléa Redalié ,
 Conseillère culturelle 
Livre et lieux culturels 

Service cantonal de la culture
+41 (0)22 546 66 83 
clea.redalie@etat.ge.ch

Ville de Genève
Dominique Berlie
Conseiller culturel
Livre et édition, musiques actuelles
. Service culturel
.
dominique.berlie@ville-ge.ch
+41(0)22 418 65 23

Ars Electronica, Veronika Liebl
Veronika.Liebl@aec.at
+43-732-7272-74

Footnote(s)

1. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. Pakistan and Turkey are Associate Members. India, Japan, the Russian Federation, the United States of America, the European Union, JINR and UNESCO have observer status.

2. Accelerate @ CERN UAE is funded by The Abu Dhabi Music & Arts Foundation (ADMAF).

3. Accelerate @ CERN Lithuania is funded by Rupert, Centre for Art and Education in Vilnius, Lithuania.

4. Collide @ CERN Geneva is funded by The Republic and Canton of Geneva and The City of Geneva

6. Members of the Jury for Collide @ CERN Ars Electronica were: Mónica Bello (ES), Michael Doser (AT), Horst Hörtner (AT), Gerfried Stocker (AT) and Mike Stubbs (UK).

Arts@CERN announces three new open calls and the arrival of new artists in residence

Geneva, 12 October 2015. CERN1 has today announced three new open calls giving a chance to artists to immerse themselves in the research of particle physics and its community. Two new international partners have joined the Accelerate @ CERN programme: the Abu Dhabi Music & Arts Foundation (ADMAF) from UAE2 and Rupert, the centre for Art and Education from Vilnius, Lithuania3. The Collide @ CERN Geneva award is also now calling for entries, continuing the fruitful collaboration with The Republic and Canton of Geneva and the City of Geneva4. Last but not least, the Collide @ CERN Ars Electronica winning artists start their residency at CERN this week.

“Science and the arts are essential parts of a vibrant, healthy culture, and the Arts @ CERN programme is bringing them closer together,” said CERN DG Rolf Heuer. “With CERN’s diverse research programme, including the LHC’s second run getting underway, there’s no better place in the world to do that than here.”

With the support of The Abu Dhabi Music & Arts Foundation (ADMAF), Arts @ CERN gives the chance for an Emirati visual artist to come to CERN for a fully funded immersion in high-energy physics in the Accelerate @ CERN programme. Thanks to the support by Rupert, Centre for Art and Education in Vilnius, the same door opens to Lithuanian artists who wish to deepen their knowledge in science and use it as a source of inspiration for their work. Each of the two open calls begins today for artists to win a one-month research stay at CERN. Applications can be submitted up to 11 January 2016.

Funded by The Republic and Canton of Geneva and The City of Geneva, Collide @ CERN Geneva has operated successfully since 2012. Arts @ CERN announces the fourth open call for artists from Geneva, this time celebrating the city’s strength in digital writing. Today, the competition opens to writers who were born, live or work in the Geneva region, and would like to win a three-month residency where scientific and artistic creativity collide.  The winner will also receive a stipend of 15,000CHF. The deadline for applications is 11 January 2016.

“Arts and science have always been interlinked as major cultural forces, and this is the fundamental reason for CERN to continue to proactively pursue this relationship,” said Mónica Bello, Head of Arts @ CERN. “The arts programme here continues to flourish.”

Semiconductor, the artist duo formed by Ruth Jarman and Joe Gerdhardt, are the winners of the Collide @ CERN Ars Electronica award5. Out of 161 projects from 53 countries, the jury6 awarded Semiconductor for their broad sense of speculation, complexity and wonder, using strategies of analysis and translation of the phenomena into tangible and beautiful forms. Their two-month Collide @ CERN residency starts on 12 October 2015.

Online submissions for artists CERN.ch/arts

Further information:

Arts@CERN website
Accelerate@CERN website
Collide@CERN Facebook site
Twitter ArtsAtCern

Media contact:

Arts @ CERN
Monica Bello, Head of Arts @ CERN
monica.bello@cern.ch
+41 22 766 36 63

The Abu Dhabi Music & Arts Foundation (ADMAF)
Michel El Gemayel
Senior Manager – Marketing & Communications
P.O. Box 47488, Abu Dhabi, United Arab Emirates
E. michel.g@admaf.org
T. +971 2 3336425; F. +971 2 6411055; M. +971 529755000

Rupert, Centre for Art and Education in Vilnius
info@rupert.lt
Vaidilutės g. 79, Vilnius 10100
Lithuania

DIP 
République et canton de Genève 

Cléa Redalié ,
 Conseillère culturelle 
Livre et lieux culturels 

Service cantonal de la culture
+41 (0)22 546 66 83 
clea.redalie@etat.ge.ch

Ville de Genève
Dominique Berlie
Conseiller culturel
Livre et édition, musiques actuelles
. Service culturel
.
dominique.berlie@ville-ge.ch
+41(0)22 418 65 23

Ars Electronica, Veronika Liebl
Veronika.Liebl@aec.at
+43-732-7272-74

Footnote(s)

1. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its member states are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Israel, Italy, the Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. Romania is a Candidate for Accession. Serbia is an Associate Member in the pre-stage to Membership. Pakistan and Turkey are Associate Members. India, Japan, the Russian Federation, the United States of America, the European Union, JINR and UNESCO have observer status.

2. Accelerate @ CERN UAE is funded by The Abu Dhabi Music & Arts Foundation (ADMAF).

3. Accelerate @ CERN Lithuania is funded by Rupert, Centre for Art and Education in Vilnius, Lithuania.

4. Collide @ CERN Geneva is funded by The Republic and Canton of Geneva and The City of Geneva

6. Members of the Jury for Collide @ CERN Ars Electronica were: Mónica Bello (ES), Michael Doser (AT), Horst Hörtner (AT), Gerfried Stocker (AT) and Mike Stubbs (UK).