Author Archives: Sophie Tesauri

CERN experiment reports sixfold improved measurement of the magnetic moment of the antiproton

BASE

Stefan Ulmer, Spokesperson BASE Collaboration, in Base Experiment (Image: CERN)Geneva, 18 January 2017. In a paper published today in the journal Nature Communications, the BASE collaboration at CERN1 reports the most precise measurement ever made of the magnetic moment of the antiproton, allowing a fundamental comparison between matter and antimatter. The BASE measurement shows that the magnetic moments of the proton and antiproton are identical, apart from their opposite signs, within the experimental uncertainty of 0.8 parts per million. The result improves the precision of the previous best measurement by the ATRAP collaboration in 2013, also at CERN, by a factor of 6.

At the scale of elementary particles, an almost perfect symmetry between matter and antimatter exists. On cosmological scales, however, the amount of matter outweighs that of antimatter. Understanding this profound contradiction demands that physicists compare the fundamental properties of particles and their antiparticles with high precision.

BASE uses antiprotons from CERN’s unique antimatter factory, the Antiproton Decelerator (AD), and is designed specifically to perform precision measurements of the antimatter counterparts of normal matter particles. The magnetic moment, which determines how a particle behaves when immersed in a magnetic field, is one of the most studied intrinsic characteristics of a particle. Although different particles have different magnetic behaviour, the magnetic moments of protons and antiprotons are supposed to differ only in their sign as a consequence of so-called charge-parity-time symmetry. Any difference in their magnitudes would challenge the Standard Model of particle physics and would offer a glimpse of new physics.

To perform the experiments, the BASE collaboration cools down antiprotons to the extremely low temperature of about 1 degree above absolute zero, and traps them using sophisticated electromagnetic containers so that they do not come into contact with matter and annihilate (thanks to such devices, BASE has recently managed to store a bunch of antiprotons for more than one year). From here, antiprotons are fed one-by-one to further traps where their behaviour under magnetic fields allows researchers to determine their intrinsic magnetic moment. Similar techniques have already been successfully applied in the past to electrons and their antimatter partners, positrons, but antiprotons present a much bigger challenge because their magnetic moments are considerably weaker. The new BASE measurement required a specially designed magnetic “bottle” that is more than 1000 times stronger than that used in electron/positron experiments.

“This measurement is so far the culmination point of 10 years of hard work by the BASE team,” said Stefan Ulmer, spokesperson of the BASE collaboration. “Together with other AD experiments, we are really making rapid progress in our understanding of antimatter.”

BASE now plans to measure the antiproton magnetic moment using a new trapping technique that should enable a precision at the level of a few parts per billion – i.e. a factor of 200 to 800 improvement. “The implementation of this method is much more challenging than the method which was used here and will require several additional iteration steps,” says first author Hiroki Nagahama.

Further information:

Link to the paper in Nature Communications: http://dx.doi.org/10.1038/ncomms14084

Pictures of the BASE experiment: https://cds.cern.ch/record/2242307

Footnote(s)

1. CERN, the European Organization for Nuclear Research, is the world’s leading laboratory for particle physics. Its headquarters are 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.

CERN announces winners of its 2016 beamline for schools competition

Geneva, 13 June 2016. CERN1 today announced the winners of its 2016 Beamline for Schools competition. Two teams of high-school students, “Pyramid hunters” from Poland and “Relatively Special” from the United Kingdom, have been selected to travel to CERN in September to carry out their own experiments using a CERN accelerator beam. The winners were selected from a total of 151 teams from 37 countries around the world, adding up to more than 1250 high-school students.

The Beamline for Schools competition enables high-school students to run an experiment on a fully equipped CERN beamline, in the same way that researchers do at the Large Hadron Collider and other CERN facilities. Students had until 31 March to submit a written proposal and video explaining why they wanted to come to CERN, what they hoped to take away from the experience and initial thoughts of how they would use the particle beam for their experiment. CERN scientists and experts evaluated the proposals based on creativity, motivation, feasibility and scientific method. A final selection was put forward to the CERN scientific committee responsible for assigning beam time to experiments, who chose two winning teams to carry out their experiments together at CERN.

I am impressed with the level of interest within high schools all over Europe and beyond, as well as with the quality of the proposals. This competition is very effective in triggering motivation for fundamental physics of young brilliant students at a moment that is crucial for their future career choices”, said Claude Vallee, chairperson of the CERN SPSC committee that chose the winning teams.

“Pyramid hunters” are seven students from Liceum Ogólnokształcące im. Marsz. St. Małachowskiego, the oldest school in Poland. Their project involves measuring the muon absorption of limestone to help understand data from a muon tomography of the Chephren pyramid from many years ago.

“I can't imagine better way of learning physics than doing research in the largest particle physics laboratory in the world. I still can't believe it,” says student Kamil Szymczak. Classmate Kamil Krakowski adds: “It is fascinating how physics connects with archaeology. I am so glad that research taken in CERN can help to solve the mystery of pyramids. It is a wonderful adventure.”

“Relatively Special” is a team from Colchester Royal Grammar School and comprises 17 students, nine of which will travel to CERN. Their project aims to test the validity of the Lorentz factor by measuring the effect of time dilation due to Special Relativity on the decay rate of pions.

“My mum asked me “What is your team doing in the competition?” and I replied “Oh, just proving Einstein’s Special Theory of Relativity,” laughs student Achintya Singh.

The first Beamline for Schools competition was launched to coincide with CERN’s 60th anniversary two years ago. To date, winners from the Netherlands, Greece, Italy and South Africa have performed their experiments at CERN. This year, short-listed teams2 each receive a Cosmic-Pi detector for their school that will allow them to detect cosmic-ray particles coming from outer space.

Beamline for Schools is an education and outreach project supported by the CERN & Society Foundation, funded by individuals, foundations and companies.

“We are very happy to be able to offer this experience to high-school students, thanks to support received via donations to the CERN & Society Foundation,” said Markus Joos, Beamline for School project leader.

The project was funded in 2016 in part by the Alcoa Foundation; additional contributions were received by the Motorola Solutions Foundation, the Fund Ernest Solvay managed by the King Baudouin Foundation, and National Instruments. CERN would like to thank all the supporters for their generous contributions that made the 2016 competition possible.

 

Further information:

Team “Pyramid hunters”: Extract from their proposal “The pyramids are still the most mysterious pieces of architecture and it seems that they still hide numerousness mysteries … The fact that the Egyptians set up 2.5 million stone blocks without any purpose seems to be unimaginable. So we would like to try to examine the internal structure of the pyramid using muon tomography.” Watch their video (link is external) (link is external)

Team “Relatively Special”: Extract from their proposal “We would like to promote physics in our school to raise interest amongst our fellow students by sharing our adventure about what it is like to go into research. We believe this sort of motivation is vital for the successive generations of young scientists in order to help them learn the tools to make the next scientific breakthroughs and propel the human race to places previously out of reach.” Watch their video (link is external) (link is external)

Footnote(s)

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

2. Of the 151 proposals submitted, 29 were given the status of highly commended and receive certificates, t-shirts and a Cosmic Pi detector for their school. These were, listed alphabetically by country: The Rocket Bros from Bangladesh; Pharaonic Fermions from Egypt; Doesn’t Matter from France; 7th High School of N. Smyrni, Odysseus Comrades and Zanneio Stardust from Greece; Athomos Team, LAST MINUTE, I Taurinesi, Peano, TCO-4ASA and Volta Ψ-Team from Italy; Energetic Crew from Jordan; GGHiggs from the Netherlands; Beamcats from the Philippines; Quantum nerds and 30(ns) to Bang from Portugal; The Seklers from Romania; #reflector from Singapore; Elaios team from Spain; TEAM Nations from Switzerland; Lorosae Team from Timor-Leste; PowerCERN Girls and SLOW MUotiON from Turkey and The Particle Exhilarators, Fission Chips, The Feynwomen, JA JA GO and the Cambridge Perse Team from the United Kingdom.

CERN experiment points to a cloudier pre-industrial climate

Geneva, 26 May 2016. In two papers1,2 published today in the journal Nature, new results from the CLOUD3 experiment at CERN4 imply the baseline pristine pre-industrial climate may have been cloudier than presently thought. CLOUD shows that organic vapours emitted by trees produce abundant aerosol particles in the atmosphere in the absence of sulphuric acid. Previously it was thought that sulphuric acid – which largely arises from fossil fuels – was essential to initiate aerosol particle formation. CLOUD finds that these so-called biogenic vapours are also key to the growth of the newly-formed particles up to sizes where they can seed clouds.

“These results are the most important so far by the CLOUD experiment at CERN,” said CLOUD spokesperson, Jasper Kirkby. “When the nucleation and growth of pure biogenic aerosol particles is included in climate models, it should sharpen our understanding of the impact of human activities on clouds and climate.”

The Intergovernmental Panel on Climate Change (IPCC) considers that the increase in aerosols and clouds since pre-industrial times represents one of the largest sources of uncertainty in climate change5. CLOUD is designed to understand how new aerosol particles form and grow in the atmosphere, and their effect on clouds and climate.

CLOUD also finds that ions from galactic cosmic rays strongly enhance the production rate of pure biogenic particles – by a factor 10-100 compared with particles without ions. This suggests that cosmic rays may have played a more important role in aerosol and cloud formation in pre-industrial times than in today’s polluted atmosphere.

A paper published simultaneously in Science (Bianchi, F., et al. Science, doi 10.1126/ science.aad5456, 2016) describes an observation of pure organic nucleation at the Jungfraujoch observatory by the same mechanism reported by CLOUD. The measurements did not involve CLOUD directly but most of the authors are also members of the CLOUD collaboration.

“The observation of pure organic nucleation at the Jungfraujoch is very satisfying,” said Kirkby. “It confirms that the same process discovered by CLOUD in the laboratory also takes place in the atmosphere.”

 

Videos:

- CLOUD experiment – How it works

- CERN experiment points to a cloudier pre-industrial climate

- Footage and animations about CLOUD experiment

Photos:

Available here.

Footnote(s)

1. Kirkby, J., et al. Ion-induced nucleation of pure biogenic particles. Nature, doi 10.1038/nature 17953 (2016).

2. Tröstl, J., et al. The role of low-volatility organic compounds in initial particle growth in the atmosphere. Nature, doi 10.1038/nature18271 (2016).

3. The CLOUD experiment consists of a large instrumented chamber in which the atmosphere can be precisely simulated, and the formation and growth of aerosol particles and the clouds they seed can be studied under precisely controled atmospheric conditions. Unwanted contaminants can be suppressed well below the part-per-trillion level. The CLOUD experiment uses a beam from CERN’s Proton Synchrotron to simulate cosmic rays – particles bombarding the atmosphere from space.

The experimental collaboration comprises 21 institutes: Aerodyne Research, California Institute of Technology, Carnegie Mellon University, CERN, Finnish Meteorological Institute, Goethe University Frankfurt, Helsinki Institute of Physics, Karlsruhe Institute of Technology, Lebedev Physical Institute, Leibniz Institute for Tropospheric Research, Paul Scherrer Institute, Stockholm University, Tofwerk, University of Beira Interior, University of Eastern Finland, University of Helsinki, University of Innsbruck, University of Leeds, University of Lisbon, University of Manchester, and University of Vienna.

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

5. Boucher, O. et al. in Climate Change 2013: The Physical Science Basis. Working Group I Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change (eds. Stocker, T.F. et al.) 571–658 (Cambridge Univ. Press, 2013).

CERN Director-General Rolf Heuer passes the baton to Fabiola Gianotti

Geneva, 18 December 2015. The 178th session of the CERN Council today saw the handover ceremony from Rolf Heuer, CERN1’s Director-General for the past seven years, to Fabiola Gianotti, who will take up her functions at the head of the Organization on 1 January 2016. On the same day, Sijbrand de Jong will become the new CERN Council President, taking over from Agnieszka Zalewska at the end of her three-year term.

“I wish CERN a future rich in discoveries and innovations, and I wish the next President of Council, Sijbrand de Jong, every success in his new challenging position,” said President of the CERN Council Agnieszka Zalewska.

“I would like to thank the CERN Council delegates for entrusting me with this responsibility,” said incoming President of Council Sijbrand de Jong. “I wish to CERN a luminous and energetic year 2016.”

Council delegates paid tribute to, and warmly thanked Rolf Heuer for his leadership and the work accomplished during his term of office. During his mandate the LHC was successfully commissioned, providing the global scientific community with a unique tool for studying the fundamental laws of nature.

“These have been seven fantastic years for science and international collaboration. I have enjoyed every single day of it, and I’m confident that CERN will continue to shine in the future,” said Director-General Rolf Heuer.

The scientific highlight of the past seven years was the announcement in 2012 of the discovery of a new particle proving the existence of the Brout-Englert-Higgs mechanism. Many other significant scientific results also contributed to enlarging the sum of human knowledge before a two-year shutdown, which enabled the LHC to reach an unprecedented energy this year as Run 2 got underway. In the light of these achievements, the CERN Council congratulated the management team and all the personnel on the scientific and technical excellence demonstrated by the Organization, and presented its best wishes to incoming Director-General, Fabiola Gianotti.

“The new management inherits a laboratory in great shape. For that I would like to thank Rolf Heuer and his team along with all staff, users and Member States,” said incoming Director-General Fabiola Gianotti. “We have a great legacy to build on, and a very bright future ahead.”

The CERN Council also praised the efforts made towards the Organization’s geographical enlargement over recent years, during which time CERN has welcomed Israel as a new Member State. Romania and Serbia are expected to join as Member States in the near future. Pakistan and Turkey became Associate Member States in 2015, and links with many other countries have been strengthened.

The LHC has now shut down for its traditional winter technical stop and will restart in March 2016. Its smooth running during 2015 augurs well for a successful run in 2016, which should enable the experiments to collect a substantial amount of new data, and promises a bright future for the LHC.

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.