Particle physics

14 September 2017

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The hard worker from Val Mesolcina

Matter and Material Research Using Muons Particle Physics

For Aldo Antognini, physics and conviviality are in the blood

PSI researcher Aldo Antognini has received more than 2.2 million Swiss francs from the EU for his latest experiment. He wants to find out how magnetism is distributed in the proton. The particle physicist will be able to apply not only his scientific and technical talents, but his social flair as well.

9. March 2016

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Five hundred thousand times less likely than winning the lottery

Media Releases Large Research Facilities Research Using Muons Particle Physics

Measuring the rarity of a particle decay
In the so-called MEG experiment at the PSI, researchers are searching for an extremely rare decay signature from a certain kind of elementary particles known as muons. More precisely, they are quantifying its improbability. According to their latest number, this decay occurs less than once in 2.4 trillion events. By means of this result, theoretical physicists can sort out which of their approaches to describing the universe will hold up against reality.

8. December 2015

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Measuring the simultaneity

Research Using Muons Particle Physics

What does a physicist do when his experiment needs an extremely precise time measurement? So precise that existing electronics cannot help him? A scientist from the Paul Scherrer Institute PSI simply decided to develop his own solution. The result is called DRS4, a high-precision electronic chip that could unlock the physics of our entire universe. As an additional benefit, the chip is already helping doctors to localise brain tumours with great accuracy.

2. October 2015

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New method will enable most accurate neutron measurement yet

Media Releases Research Using Neutrons Particle Physics

Our universe consists of significantly more matter than existing theories are able to explain. This is one of the great puzzles of modern science. One way to clarify this discrepancy is via the neutron’s so-called electric dipole moment. In an international collaboration, researchers at PSI have now devised a new method which will help determine this dipole moment more accurately than ever before.

24. February 2014


The proton accelerator at the Paul Scherrer Institute: forty years of top-flight research

Media Releases Large Research Facilities Research Using Muons Research Using Neutrons Particle Physics Matter and Material

Materials research, particle physics, molecular biology, archaeology – for the last forty years, the Paul Scherrer Institute’s large-scale proton accelerator has made top-flight research possible in a number of different fields.

31. October 2013


Rare particle decays support standard model

Matter and Material Particle Physics

Researchers from the Paul Scherrer Institute have observed for the first time the extremely rare decay of the Bs meson into two muons. They have determined its decay frequency with sufficient accuracy using data collected by the CMS detector at CERN. Their result agrees with the predictions of the standard model of particle physics.

1. October 2013


The quest for an elusive white crow of particle physics

Research Using Muons Particle Physics

A very rare process in nature should best decide on how we should describe our universe in the future. It is the particular decay of a particular type of elementary particle: the muon. These particles are short-lived and decay into a variety of other particles. According to one theoretical model, a very particular decay process is practically forbidden, whereas according to another it should be allowed. Which theory is correct? By observing many hundreds of trillions of muon decays very precisely, physicists at the Paul Scherrer Institut have come a step closer to solving this puzzle. They have now published their results in the journal Physical Review Letters.

20. June 2013


Searching for the Higgs boson: “PSI inside”

Matter and Material Particle Physics

“Higgs Particle Found” announced the media triumphantly in July 2012. But for Roland Horisberger, particle physicist at PSI, this was a premature conclusion: “It will take at least another five years before we can be sure of that”. Whatever the findings – whether this is the original Higgs boson, or only one of the theoretical “Higgs-like” particles – one can surely put a tag on them that reads “PSI inside.”

25. January 2013


Proton size puzzle reinforced!

Media Releases Particle Physics Research Using Muons Large Research Facilities Matter and Material

An international team of scientists confirmed the surprisingly small value of the proton radius with laser spectroscopy of exotic hydrogen. The experiments were carried out at PSI which is the only research institute in the world providing the necessary amount of muons for the production of the exotic hydrogen atoms made up of a muon and a proton.

7. January 2013


The weak side of the proton

Media Releases Matter and Material Research Using Muons Particle Physics

An international research team has determined with a high level of accuracy, how the proton participates in the weak interaction – one of the fundamental forces of nature. Their results confirm the predictions of the Standard Model of particle physics. The experiment observed the probability of muon capture by protons – a process governed by the weak interaction. The experiment was conducted at the Paul Scherrer Institute, the only institute in the world with an accelerator capable of generating enough muons for carrying out this project in a realistic timeframe.

4. July 2012


Observation of a New Particle

Media Releases Matter and Material Particle Physics

In a joint seminar today at CERN and the ICHEP 2012 conference in Melbourne, researchers of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) presented their preliminary results on the search for the standard model (SM) Higgs boson in their data recorded up to June 2012.

23. November 2011


Erkenntnis aus dem Nichts

Media Releases Matter and Material Particle Physics Research Using Muons

Zwei Experimente mit massgeblicher Beteiligung von Forschern des Paul Scherrer Instituts PSI liefern wichtige Ergebnisse bei der Suche nach der richtigen Beschreibung der Welt der kleinsten Teilchen. In den Experimenten haben die Physiker nach sehr seltenen Teilchenzerfällen gesucht. In beiden Fällen konnte der gesuchte Zerfall nicht beobachtet werden wodurch bestimmte Modelle der Teilchenphysik ausgeschlossen werden konnten.
This news release is only available in German.

25. January 2011


How strong is the weak force?

Media Releases Matter and Material Research Using Muons Particle Physics

A new measurement of the muon lifetime – the most precise determination of any lifetime – provides a high-accuracy value for a crucial parameter determining the strength of weak nuclear force. The experiments were performed by an international research team at the accelerator facility of the Paul Scherrer Institute.

8. July 2010

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Protons – smaller than we thought

Media Releases Matter and Material Research Using Muons Particle Physics

The proton – one of the smallest building-blocks of all matter – is even smaller than had previously been assumed. This discovery is the result of experiments carried out at the Paul Scherrer Institute (PSI) in Villigen, Switzerland, by an international research team.

3. March 2010

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Technology from the Paul Scherrer Institute detects proton collisions at unprecedented levels of energy

Media Releases Particle Physics Matter and Material

CERN has been able to take the first measurements of collisions between the highest-energy particles ever generated. These collisions were performed at CERN's new LHC accelerator and recorded with the CMS Experiment, which involved a key component (the barrel pixel detector) contributed by the Paul Scherrer Institute in collaboration with Swiss Universities. The first LHC operation in Dezember 2009 has now resulted in a first particle physics publications of the CMS experiment. This is after a remarkable short time , given the compexity and the size of this gigantic experiment with over 3000 physicists and engineers from close to 40 countries.

1. December 2009

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The PSI proton accelerator

Matter and Material Research Using Synchrotron Light Research Using Neutrons Research Using Muons Large Research Facilities Particle Physics

The neutrons and muons used for experiments at PSI are all produced by a beam of fast protons colliding with a target – made of lead in the case of the SINQ neutron source and of carbon in the case of the SμS muon source. For that purpose, the protons are accelerated to 80% of the speed of light at PSI's accelerator facility. The facility has been in operation since 1974. After numerous improvements, it provides the most intense proton beam in the world.

1. December 2009

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Service to the scientific community

Matter and Material Research Using Synchrotron Light Research Using Muons Research Using Neutrons Large Research Facilities Particle Physics

Neutrons, synchrotron light and muons are very useful for researchers in a variety of disciplines. Using these probes, we can determine the structure of crystals, they help us understand magnetic processes, or they can reveal the structures of biological materials. However, producing these probes is so difficult that most research groups will not have a neutron, muon or synchrotron light at their own scientific centre.

27. November 2007

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Excursion in the wondrous Mirror World

Matter and Material Particle Physics

In physics, mirror matter, is a hypothetical counterpart to ordinary matter and not be mixed up with antimatter. It could explain symmetry violations observed in several processes of ordinary elementary particles. Symmetry could be restored by so called mirror particles with exactly the same mass as ordinary elementary particles.