News from FZU

Autumn events for public with FZU

News: Institute of Physics - Tue, 09/03/2019 - 22:21

The first month of autumn at the Institute of Physics of the Czech Academy of Sciences will be marked with a sequence of events intended for general public. Apart from the annual events such as the Science Festival or Researchers‘ Night, the Institute of Physics will participate in a neighbourhood fest entitled Different City Experience. All events will be free of charge, for information about the programme and how to sign up please continue reading.

The series of events will be started by the Science Festival on Wednesday, Sept 4, taking place at “Kulaťák” in Dejvice, Prague, offering its visitors a full day programme which will be extended for the first time until as late as 7 p.m. The morning programme is usually visited by classroom trips as a perfect complimentary program to start the new academic year. General public is, however, welcome anytime throughout the day.

This year, the booth of the Institute of Physics will give its visitors a detailed presentation of its research section, focusing on particle physics and astrophysics, and of a discipline referred to as astroparticle physics, a field connecting both aforementioned disciplines, being the FZU‘s field of excellence. Do come and unveil the mystery of this scientific cross-field! Learn about the particles reaching the Earth in huge amounts and - going unnoticed – landing on us and on everything around us – with us you will have the opportunity to observe them! To do so, we are going to bring our brand new cloud chamber to the site. Additionally, you will learn which are the international observatories we participate in; how Czech scientists contribute to the research at CERN, and finally, who the scientists from the CEICO group are that examine the development and the building stones of the entire universe.

Particle tracks in a cloud chamber - what do they mean and could be dangerous?

On Saturday, Sept 21st, the Institute of Physics will take part in a neighbourhood fest in Cukrovarnická street in Střešovice, Prague. The event will take place directly in front of the historical site of this Institute‘s facility as part of the Different City Experience. The concept of the Different City Experience is to improve the awareness of the value of public space and to enable active citizens to meet under the lead of local organisers and volunteers.

“The Institute of Physics and our workers will join the Different City Experience by introducing interesting physical experiments or a cloud chamber. We will make part of our premises accessible to a historical tour,” says Dr. Michal Dušek, the head of the FZU facility at Cukrovarnická street. At the end of the evening, we will show a short amateur historical film that recalls with humorous nostalgia of the times when a screwdriver, a solder and a volmeter were a must-have for every physicist.

Historical image of a main building at Cukrovarnická (1920s).

The last event to take place in September will be the Researchers’ Night. It will take place on Friday, Sept. 27th at 51 locations around the Czech Republic, including three facilities of the Institute of Physics. Every year, the programme includes the participation of research institutes, universities and observatories that offer their visitors an opportunity to encounter both the fascinating world of science and the people doing science.

At this occasion, you will also be able to take part in thematic tours featuring special alloys with shape memory and electron microscopy at the facility of the Institute of Physics at Na Slovance (Prague 8 – Ládví). The facility in Cukrovarnická street (Prague 6 – Střešovice) will present its research to students with serious interest in physics and potential collaborators, showing not only top technologies and procedures but also entertaining experiments and refreshments. A comprehensive programme will traditionally be offered be the renown ELI Beamlines and HiLASE laser centres in Dolní Břežany. Detailed information and how to sign up for individual sites is available in detailed programme.

Experience the unique atmosphere of Researchers' Night!

If you do not make it in September, do not worry! You can look forward to visiting the Week of Science and Technology (November 11th – 17th) hosting also our Open Days – more information about the event and how to sign up will follow at our website during September.

Categories: News from FZU

Scientists from the Institute of Physics facilitated the miniaturization of electric circuits

News: Institute of Physics - Tue, 07/16/2019 - 16:20

Recently scientists all over the world have been examining components of ever smaller, virtually molecular dimensions. An international team from the Institute of Physics of the Czech Academy of Sciences and the Tokyo Institute of Technology has developed a new method which will contribute to the miniaturization of electric circuits in electronics. They have published their discovery in the prestigious scientific journal Chemical Science.

When examining the properties of molecules potentially useable in miniature circuits, scientists encounter a number of problems. One of them is understanding the configuration of molecule contacts with the metal surfaces of electrodes that influences important properties of junctions, e.g. their conductance. The international team established in collaboration between the Institute of Physics of the Czech Academy of Sciences and the Tokyo Institute of Technology has managed to significantly contribute to addressing this obstacle.

“The new method will enable to check the geometry of the interface between metal electrodes and a molecule. We have thus taken a step towards overcoming one of the main challenges in the realization of stable and reproducible single molecule circuits,” says the leader of the Czech team from the Department of Thin Films and Nanostructures of the Institute of Physics Héctor Vázquez. “The success has been achieved in collaboration with our Japanese colleagues whose measurements we have identified with specific types of bond using numerical simulations. It is the combination of different techniques that forms the basis of the successful new method.”

Fig. 1. Experimental setup where there are two golden electrodes linked by a single “conduction” molecule (a single molecule junction).

The linking of the molecule to source and drain electrodes is done via chemical bonds established between linking functional groups on a molecule (linkers) and atoms of golden electrodes. The properties of the junction (including the important conductance) are strongly affected by the details of the bonding geometry. This is particularly relevant for the most commonly used linkers containing sulphur.

This geometry, however, changes quickly in the conditions under which experiments are conducted most frequently – in solution or in ambient conditions, and at room temperature – and cannot be detected easily. The changes in geometry then lead to significant variations (up to 2 orders of magnitude) in conductance of the junction and thus significantly impede the investigation of molecule suitability for the use in microelectronics.

Through the combination of different techniques, the scientists managed to distinguish between three binding configurations of a molecule (see Fig. 2) – bridge, hollow or atop conformations.

Fig. 2. Simulation of three stable binding configurations of a molecule (from the left– bridge, hollow or atop conformations).

The group of Manabu Kiguchi at the Tokyo Institute of Technology performed simultaneous surface enhanced Raman scattering and current-voltage measurements. The group of Héctor Vázquez at the Institute of Physics carried out density functional theory (DFT) based simulations. Variations in conductance and in Raman frequencies characteristic of the molecule measured experimentally were thus matched to specific configurations. By applying a small voltage, the scientists also managed to induce transitions between the different binding sites.

Based on article “Identifying the molecular adsorption site of a single molecule junction through combined Raman and conductance studies”, published in Chemical Science, Issue 25, 2019. Authors of the study:

Satoshi Kaneko1, Enrique Montes2, Sho Suzuki1, Shintaro Fujii1, Tomoaki Nishino1, Kazuhito Tsukagoshi3, Katsuyoshi Ikeda4, Hideaki Kano5, Hisao Nakamura6, Héctor Vázquez2 and Manabu Kiguchi1

Chem. Sci. 10, 6261-6269 (2019), DOI: 10.1039/C9SC00701F
1Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-10 Ookayama, Meguro-ku, Tokyo 152-8511, Japan.
2Institute of Physics, Czech Academy of Sciences, Cukrovarnická 10, Prague CZ-162 00, Czech Republic.
3International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan.
4Graduate School of Engineering, Nagoya Institute of Technology, Gokiso, Showa, Nagoya 466-8555, Japan.
5Institute of Applied Physics, University of Tsukuba Tennodai 1-1-1, Tsukuba 305-8573, Japan.
6CD-FMat, National Institute of Advanced Industrial Science and Technology (AIST), Central 2, Umezono 1-1-1, Tsukuba, Ibaraki 305-8568, Japan.

Categories: News from FZU

Exploring the extreme Universe: International collaboration for a new gamma-ray observatory launched

News: Institute of Physics - Tue, 07/02/2019 - 14:04

On July 1st 2019, 36 research institutions from nine countries officially signed the agreement for the creation of a new international R&D collaboration for a future wide field-of-view gamma ray observatory in the southern hemisphere. The founding countries of the newly created Southern Wide field-of-view Gamma-ray Observatory (SWGO) are Argentina, Brazil, Czech Republic, Germany, Italy, Mexico, Portugal, the United Kingdom and the United States of America, creating a world-wide community around the project. SWGO unifies different communities that were already involved in R&D in this field. The signature of the agreement comes after a successful meeting of the scientists from the different countries, held in Lisbon in May.

The new observatory is planned to be installed in the Andes, at an altitude above 4.4 km, to detect the highest energy gamma rays — particles of light billion or trillions of times more energetic than visible light. It will probe the most extreme phenomena and environments to address some of the most compelling questions about our Universe, from the origin of high-energy cosmic rays to searching for dark matter particles and for deviations from Einstein’s theory of relativity. Its location in the southern hemisphere will allow the most interesting region of our galaxy to be observed directly, in particularly the Galactic Centre, hosting a black hole four million times the mass of the sun. Wide field-of-view observations are ideal to search for transient sources but also to search for very extended emission regions, including the ‘Fermi Bubbles’ or annihilating dark matter, as well as to discover unexpected phenomena.

”The new observatory will be a powerful time-variability explorer, filling an empty space in the global multi-messenger network of gravitational, electromagnetic and neutrino observatories. It will also be able to issue alerts and be fully complementary to the next generation imaging atmospheric Cherenkov telescope array, CTA”, explains Jakub Vícha from the Institute of Physics of the Czech Academy of Sciences, the country representative of the Czech Republic.

Gamma-ray sky image as seen by the (current) HAWC and (future) SWGO observatories (Credits: Richard White, MPIK).

The baseline for the new observatory will be the approach of the current ground-based gamma-ray detectors, namely HAWC in Mexico and LHAASO in China. In particular, water Cherenkov detectors will be used to sample the particle showers produced by gamma rays in the atmosphere, by recording the light produced when particles pass through tanks full of purified water. New layouts and technologies will however be explored in order to increase the sensitivity and lower the energy threshold of the observatory.

The first very-high-energy gamma-ray emission was observed only 30 years ago, from the Crab Nebula. Hundreds of sources have been discovered since then at these extreme energies. Many extragalactic and some galactic sources present variability, and the duration of flares and transients can be days, hours, minutes or even just a few seconds. The study of these phenomena requires instruments such as SWGO, able to monitor in a continuous way large portions of the sky, sensitive to energies above the reach of satellite-based experiments, and operating in a multi-messenger context: able to alert and to follow up on neutrino and gravitational wave detections as well as other photon observatories.

Direct detection of primary gamma-rays is only possible with satellite-based detectors, such as Fermi. However, the cost of space technology limits the size of satellite-borne detectors, and thus their sensitivity, as fluxes become too small at higher energies. In the atmosphere, gammas interact creating a shower of particles. These showers can be studied in observatories of two complementary types: imaging atmospheric Cherenkov telescopes, pointing instruments such as CTA, and high altitude air shower arrays, such as SWGO. Cherenkov telescopes are highly sensitive pointing detectors, with high precision but limited duty cycle and narrow field-of-view, benefiting from pointing alerts provided by complementary observatories. Wide field-of-view observations from the ground have the highest energy reach, and are ideal to search for transient sources and for emissions from very extended regions of the sky.

Illustration of the complementary detection techniques of high-energy gamma rays on ground (Credits: A. Albert et al.).

Categories: News from FZU