Skobeltsyn Institute of Nuclear Physics

Moscow, Russia

Skobeltsyn Institute of Nuclear Physics

Moscow, Russia

Time filter

Source Type

News Article | December 22, 2016
Site: www.eurekalert.org

A member of the Lomonosov Moscow State University together with his colleagues, using new interaction between neutrons, have theoretically justified the low-energy tertaneutron resonance obtained recently experimentally. This proves the existence for a very short period of time of a particle consisting of four neutrons. According to the supercomputer simulations, the tetraneutron lifetime is 5×10-22 sec. The research results are published in a top-ranked journal Physical Review Letters. A team, consisting of Russian, German and American scientists, and among them Andrey Shirokov, Senior Researcher at the Skobeltsyn Institute of Nuclear Physics, has calculated the energy of the resonant tetraneutron state. Their theoretical computations, based on a new approach and new interaction between neutrons, correlate with the results of the experiment in which the tetraneutron has been produced. A neutron lives about 15 min before it decays producing a proton, electron and antineutrino. There is also another known stable system consisting of a huge number of neutrons - a neutron star. Scientists have aimed to find out whether there are other systems, even short-lived, composed purely of neutrons. A system made up of two neutrons doesn't form even a short-lived state. Due to multi-year experimental and fundamental researches, scientists conclude that there are no such states in a system made up of three neutrons. Searches for a tetraneutron, a cluster of four neutrons, have been conducted for more than 50 years. These searches were fruitless until 2002 when a group of French researchers in an experiment at the Large Heavy Ion National Accelerator (Grand accélérateur national d'ions lourds - GANIL) in Caen has found 6 events which could be interpreted as the tetraneutron production. However, the reproduction of this experiment failed, and some scientists suppose that at least a part of the original data analysis was incorrect. A new phase of the tetraneutron searches takes place at the Radioactive Ion Beam Factoryin the RIKEN Institute, Japan, where a high-quality beam of 8He nuclei is available. The 8He nucleus consists of an α-particle (the 4He nuclei) and four neutrons. A few research teams from different countries have proposed the tetraneutron searches in RIKEN. In the first of these experimental searches, the 8He nuclei were bombarding the 4He target. As a result of the collision, the α-particle was knocked out from 8He leaving the system of 4 neutrons. Four events interpreted as the short-lived tetraneutron resonant statehave been detected. This experiment of the Japanese group has been published at the beginning of this year, and it will be continued. The scientist from Lomonosov Moscow State University and his collaborators have published in their article theoretical evaluations of the tetraneutron resonant state energy and its lifetime. They have contributed to the preparation of one of the proposed experimental searches for the tetraneutron when a group of experimentalists from Germany asked for the assistance. Andrey Shirokov, the first author of the article, says: "Such evaluations were made by us in different models, and the obtained results were used to support the experiment application. Afterwards, we thoroughly elaborated thetheoretical approach and performed numerous simulations on supercomputers. The results have been published in our paper in Physical Review Letters". The theoretical results for the energy of tetraneutron resonance of 0.84 MeV correlate well with the Japanese experimental findingof 0.83 MeV which is however characterized by a large uncertainty (about ±2 MeV). The calculated width of the resonant tetraneutron state is 1.4 MeV which corresponds to the lifetime of about 5×10-22 sec. Andey Shirokov continues: "It's worth noting that none of theoretical papers up to now has predicted the existence of the resonant tetraneutron state at such low energies of about 1 MeV". The new theoretical result probably stems from a new theoretical approach to the studies of resonant states in nuclear systems developed by the scientists. This approach has been carefully tested on model problems and in less complicated systems and only afterwards applied to the tetraneutron studies accounting for the specifics of the four-particle decay of this system. Andrey Shirokov however indicates an alternative possibility: "Another possible reason is the fact that we've used a new interaction between neutrons elaborated by our team. Our tetraneutron studies will be continued, we'll perform simulations with other more traditional interactions. At the same time, our French colleagues are going to study thetetraneutron with our interaction within their approach. Of course, all of us are looking forward for the results of new experimental tetraneutron searches". The research has been conducted by a large international team of theorists with Russia been represented by scientists not only from the Lomonosov Moscow State University, but also from the Pacific National University (Khabarovsk). This team includes also collaborators from USA and Germany. Researchers from South Korea are joining the group for future studies. The Russian side has been at the forefront of this research leading the elaboration of the theoretical approach to the resonant states and the design of the new interaction between particles in atomic nuclei.


Flash Physics is our daily pick of the latest need-to-know developments from the global physics community selected by Physics World's team of editors and reporters An atom could be made to emit an optical signal that is usually associated with another type of atom, according to calculations done by Andre Campos, Denys Bondar, Herschel Rabitz and Renan Cabrera at Princeton University in the US. When an atom is illuminated with light it can absorb energy and give off light at a set of frequencies distinct to that type of atom – which forms the basis of optical spectroscopy. However, if the atom is illuminated by an intense and complex optical signal it should be possible – in principle – to control the quantum states of the atom and cause the emission of light at frequencies not normally seen from that atom. Unlike conventional spectroscopy, a measurement of such a spectrum would not reveal the type of the atom – unless the experimenter knew the precise nature of the complex optical signal. Previous attempts to calculate the exact nature of such an optical signal has proven very difficult. But now, the team has come up with a successful scheme that involves both bound and ionized quantum states of an atom. Writing in Physical Review Letters, the team points out that some of the experimental techniques needed to carry out its scheme have already been demonstrated in the lab. A quantum chromodynamics (QCD) calculation involving five loops has been made for the first time by physicists in Russia and Germany. QCD describes the strong nuclear force between the quarks that make up protons, neutrons and other heavy particles. It is notoriously difficult to calculate the properties of systems governed by QCD because of the enormous strength of the strong nuclear force and the fact that calculations must consider large numbers of virtual quark–antiquark pairs that pop into and out of existence. As a result, physicists have struggled to calculate the properties of even simple objects such as the proton. Since the early 1970s, physicists have shown that QCD calculations can be made as a series of corrections to a leading-order calculation. These corrections are called loops, and physicists had been able to calculate one-, two-, three- and four-loop corrections. However, progress had been stuck at four loops since 1997. Now, Andrey Baikov at the Skobeltsyn Institute of Nuclear Physics in Moscow and Konstantin Chetyrkin and Johann Kühn of the Karlesruhe Institute of Technology have extended calculations to five loops. Writing in Physical Review Letters, the trio use five loops to calculate several properties of the Higgs boson. A new "supermaterial" has been made that can bend and shape sound waves using specially designed bricks. Scientists at the University of Sussex and the University of Bristol in the UK have developed an acoustic device that can transform incoming sound waves into any required sound field. Sound manipulation is useful for many applications including ultrasound imaging, loudspeaker design and acoustic levitation. Current approaches use fixed lenses and expensive phased arrays. In contrast, this latest device comprises small, 3D-printed metamaterial bricks. These slow down incoming sound by directing it through meandering channels. The tailored geometries of the channels delay the wave phase to create the desired sound field. Gianluca Memoli from the Sussex team describes the device as a "do-it-yourself acoustics kit”, as the bricks are easily made and can be arranged in arrays specific to the application requirements. The new material could be used on a large scale to direct and focus sound to form an audio hotspot. It could also be suitable for small-scale applications such as focusing high-intensity ultrasound waves to destroy tumours within the body. The material is presented in Nature Communications.


Kuznetsov N.V.,Skobeltsyn Institute of Nuclear Physics | Nikolaeva N.I.,Skobeltsyn Institute of Nuclear Physics
Advances in Space Research | Year: 2010

The proton fluxes from the low-Earth orbital satellites databases (NPOES-17 and CORONAS-F) were analyzed for the quiet geomagnetic period in April 2005. The satisfactory consent was found between the experimental and the AP8 model fluxes of the trapped protons with energy more than ∼10 MeV. At the same time, trapped proton fluxes with energy less than 10 MeV measured by LEO satellites were higher than the ones predicted by the AP8 model in the region of the SAA (drift shell L < 1.5). © 2010 COSPAR.


Belyaeva T.L.,National Autonomous University of Mexico | Danilov A.N.,RAS Research Center Kurchatov Institute | Demyanova A.S.,RAS Research Center Kurchatov Institute | Goncharov S.A.,Skobeltsyn Institute of Nuclear Physics | And 2 more authors.
Physical Review C - Nuclear Physics | Year: 2010

Evidence of the 3α-particle condensate character of the Hoyle state (the 02+ state at 7.65 MeV in C12) implies not only an enhanced radius of C12 in this state, which was established by many theoretical calculations and confirmed by the recent diffraction model analysis, but also zero relative angular momenta between clusters. We performed coupled-channels model calculations of the angular distributions of α+12C elastic and inelastic (to the 4.44-MeV 2⊃+, 7.65-MeV 02+, and 9.65-MeV 31- states) scattering at 110 MeV and found the ratio of the empirical spectroscopic factors S(L). As the differential cross sections of these reactions are characterized by pronounced enhancement and strong oscillations at large angles, we assumed a potential scattering in the forward hemisphere and the direct transfer of a Be8 cluster at θc.m. 90⊃° and took into account the direct transfer of Be8 in the ground state and in the first excited 2⊃+ and 4⊃+ states. We found that the cluster configuration with L=0 dominates in the 02+ state, being more than three times larger than that in the ground state. This result provides additional evidence of the condensed structure of the Hoyle state in C12 with a dominance of zero relative angular momentum. The negative-parity 31- excited state in C12 observed above the 3α threshold is also considered to have the 3α-cluster structure. The present calculations described well the structure of the large-angle cross section on this state. We found a positive interference for all allowed α+8Be configurations with a dominance of the p-orbital (69%)α+8Be motion and confirmed the exotic, but hardly a condensed, structure of this state. © 2010 The American Physical Society.


Leonov S.B.,Russian Academy of Sciences | Firsov A.A.,Russian Academy of Sciences | Shurupov M.A.,Russian Academy of Sciences | Michael J.B.,Princeton University | And 3 more authors.
Physics of Plasmas | Year: 2012

The use of a low energy, high peak intensity (>100TW/cm2) femtosecond laser pulse is investigated for guiding and control of a sub-microsecond high voltage discharge. Study of the laser induced plasma channel and measurements of the field required for breakdown in air and nitrogen at atmospheric pressure are presented. Direct imaging of the dynamics of the discharge breakdown shows effective laser guiding. The effectiveness of laser guiding is shown to be critically dependent on the laser focusing geometry, timing, and location relative to the electrodes. © 2012 American Institute of Physics.


News Article | December 23, 2016
Site: phys.org

A team consisting of Russian, German and American scientists, including Andrey Shirokov, senior researcher at the Skobeltsyn Institute of Nuclear Physics, has calculated the energy of the resonant tetraneutron state. Their theoretical computations, based on a new approach and new interaction between neutrons, correlate with the results of an experiment in which a tetraneutron was produced. A neutron lives about 15 minutes before it decays, producing a proton, electron and an antineutrino. There is also another known stable system consisting of a huge number of neutrons—neutron stars. Scientists have aimed to find out whether there are other systems, even short-lived, composed purely of neutrons. A system made up of two neutrons doesn't form even a short-lived state. After multi-year experimental and fundamental studies, scientists concluded that there are no such states in a system made up of three neutrons. Searches for a tetraneutron, a cluster of four neutrons, has proceeded for more than 50 years. These searches were fruitless until 2002, when a group of French researchers in an experiment at the Large Heavy Ion National Accelerator in Caen found six events that could be interpreted as tetraneutron production. However, the reproduction of this experiment failed, and some scientists believe that at least a part of the original data analysis was incorrect. A new phase of the tetraneutron searches took place at the Radioactive Ion Beam Factoryin the RIKEN Institute, Japan, which operates a high-quality beam of 8He nuclei. The 8He nucleus consists of an α-particle (the 4He nuclei) and four neutrons. A few research teams had proposed the tetraneutron searches in RIKEN. In the first of these experiments, the 8He nuclei bombarded the 4He target. As a result of the collision, the α-particle was knocked from the 8He, leaving behind the system of four neutrons. Four events interpreted as the short-lived tetraneutron resonant state have been detected. This experiment was reported at the beginning of 2016, and continues. The researchers from Lomonosov Moscow State University published in their article on theoretical evaluations of the tetraneutron resonant state energy and its lifetime. They contributed to the preparation of one of the proposed experimental searches for the tetraneutron when a group of experimentalists from Germany asked for the assistance. Andrey Shirokov, the first author of the article, says: "We made such evaluations in different models, and the obtained results were used to support the experiment. Afterwards, we thoroughly elaborated the theoretical approach and performed numerous simulations on supercomputers. The results have been published in our paper in Physical Review Letters." The theoretical results for the energy of tetraneutron resonance of 0.84 MeV correlate well with the Japanese experimental finding of 0.83 MeV, which is, however, characterized by a large uncertainty (about ±2 MeV). The calculated width of the resonant tetraneutron state is 1.4 MeV, which corresponds to the lifetime of about 5×10-22 sec. Shirokov says, "It's worth noting that none of the previous theoretical papers has predicted the existence of the resonant tetraneutron state at such low energies of about 1 MeV." The new result probably stems from a new theoretical approach to the studies of resonant states in nuclear systems developed by the scientists. This approach has been carefully tested on model problems and in less complicated systems, and only afterwards applied to the tetraneutron studies accounting for the specifics of the four-particle decay of this system. Shirokov, however, indicates an alternative possibility: "Another possible reason is the fact that we've used a new interaction between neutrons elaborated by our team. Our tetraneutron studies will continue, we'll perform simulations with other more traditional interactions. At the same time, our French colleagues are going to study the tetraneutron with our interaction within their approach. Of course, all of us are looking forward to the results of new experimental tetraneutron searches." Explore further: Physicists demonstrate existence of new subatomic structure More information: A. M. Shirokov et al, Prediction for a Four-Neutron Resonance, Physical Review Letters (2016). DOI: 10.1103/PhysRevLett.117.182502


Home > Press > Prototype device for measuring graphene-based electromagnetic radiation created: Russian scientists have created a prototype device for measuring graphene-based electromagnetic radiation Abstract: Bolometer is a device for measuring electromagnetic radiation energy flow based on measurement of variations of physical parameters of thermosensitive element as a result of heating by absorption of radiation energy. "We studied thermal and optical properties of the carbon structures derived from the reduced graphene oxide in a wide range of wavelengths from visible to infrared. In addition to the optical and thermal properties of the carbon structures, we have demonstrated the bolometer prototype that operates at room temperature without additional cooling", says Stanislav Evlashin, the first author of the article, the researcher of the Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University (SINP MSU), PhD in Physico-Mathematical Sciences. Synthesis and investigations of the new materials for bolometric sensors have a great scientific and practical importance. Such materials should possess a high effective absorption over a wide spectral range, high stable thermoresistive effect (change in electrical conductance with temperature), and, of course, they must be cheap to manufacture. To create bolometer prototype the water solution of graphene oxide was used, which was obtained by the standard method of graphite oxidation, which is known and widely used. The resulting suspension of graphene oxide was deposited on the substrate for subsequent laser microstructuring. Laser treatment causes partial reduction of graphene oxide film and changes morphology, consequently, it changes optical and thermal properties of graphene oxide. The material synthesis and development of the bolometer prototype was held at SINP MSU. Studies on the optical properties were carried out at Physics Department of Moscow State University. Research on the thermal properties were carried out at LPI RAS. "Laser microstructuring of graphene oxide opens up the possibility of selective creation of antireflective, thermally-conductive and electrically-conductive coatings. Developed method is quite cheap, compatible with conventional semiconductor technology and allows you to create antiabsorbing coatings that would cover large areas on almost any surface. The observed properties of reduced graphene oxide partially show the prospects of it's use in bolometric matrices and other IR devices," - says Stanislav Evlashin. For more information, please click If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


News Article | October 28, 2016
Site: www.cemag.us

A prototype device called a bolometer measures electromagnetic radiation energy flow based on physical parameter variations of thermosensitive elements as a result of heating by absorption of radiation energy. "We studied thermal and optical properties of the carbon structures derived from reduced graphene oxide in a wide range of wavelengths from visible to infrared. In addition to the optical and thermal properties of the carbon structures, we have demonstrated the bolometer prototype that operates at room temperature without additional cooling," says Stanislav Evlashin, the first author of the article, the researcher of the Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University (SINP MSU), PhD in Physico-Mathematical Sciences. Synthesis and investigations of the new materials for bolometric sensors have great scientific and practical importance. Such materials should possess a high effective absorption over a wide spectral range, high stable thermoresistive effect (change in electrical conductance with temperature), and they must be cheap to manufacture. To create the bolometer prototype, the researchers used a water solution of graphene oxide, which was obtained by the widely used method of graphite oxidation. The resulting suspension of graphene oxide was deposited on the substrate for subsequent laser microstructuring. Laser treatment causes the partial reduction of graphene oxide film and changes the morphology. Consequently, it changes optical and thermal properties of graphene oxide. The material synthesis for the bolometer prototype was developed at SINP MSU. Studies on the optical properties were carried out at the Physics Department of Moscow State University. Research on the thermal properties was carried out at LPI RAS. "Laser microstructuring of graphene oxide opens the possibility of selective creation of antireflective, thermally conductive and electrically conductive coatings. The method is quite cheap, compatible with conventional semiconductor technology and produces antiabsorbing coatings that would cover large areas on almost any surface. The observed properties of reduced graphene oxide partially show the prospects of its use in bolometric matrices and other IR devices," says Evlashin.


News Article | October 27, 2016
Site: www.eurekalert.org

Bolometer is a device for measuring electromagnetic radiation energy flow based on measurement of variations of physical parameters of thermosensitive element as a result of heating by absorption of radiation energy. "We studied thermal and optical properties of the carbon structures derived from the reduced graphene oxide in a wide range of wavelengths from visible to infrared. In addition to the optical and thermal properties of the carbon structures, we have demonstrated the bolometer prototype that operates at room temperature without additional cooling", says Stanislav Evlashin, the first author of the article, the researcher of the Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University (SINP MSU), PhD in Physico-Mathematical Sciences. Synthesis and investigations of the new materials for bolometric sensors have a great scientific and practical importance. Such materials should possess a high effective absorption over a wide spectral range, high stable thermoresistive effect (change in electrical conductance with temperature), and, of course, they must be cheap to manufacture. To create bolometer prototype the water solution of graphene oxide was used, which was obtained by the standard method of graphite oxidation, which is known and widely used. The resulting suspension of graphene oxide was deposited on the substrate for subsequent laser microstructuring. Laser treatment causes partial reduction of graphene oxide film and changes morphology, consequently, it changes optical and thermal properties of graphene oxide. The material synthesis and development of the bolometer prototype was held at SINP MSU. Studies on the optical properties were carried out at Physics Department of Moscow State University. Research on the thermal properties were carried out at LPI RAS. "Laser microstructuring of graphene oxide opens up the possibility of selective creation of antireflective, thermally-conductive and electrically-conductive coatings. Developed method is quite cheap, compatible with conventional semiconductor technology and allows you to create antiabsorbing coatings that would cover large areas on almost any surface. The observed properties of reduced graphene oxide partially show the prospects of it's use in bolometric matrices and other IR devices," - says Stanislav Evlashin.


News Article | October 28, 2016
Site: phys.org

"We studied thermal and optical properties of the carbon structures derived from reduced graphene oxide in a wide range of wavelengths from visible to infrared. In addition to the optical and thermal properties of the carbon structures, we have demonstrated the bolometer prototype that operates at room temperature without additional cooling," says Stanislav Evlashin, the first author of the article, the researcher of the Skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State University (SINP MSU), PhD in Physico-Mathematical Sciences. Synthesis and investigations of the new materials for bolometric sensors have great scientific and practical importance. Such materials should possess a high effective absorption over a wide spectral range, high stable thermoresistive effect (change in electrical conductance with temperature), and they must be cheap to manufacture. To create the bolometer prototype, the researchers used a water solution of graphene oxide, which was obtained by the widely used method of graphite oxidation. The resulting suspension of graphene oxide was deposited on the substrate for subsequent laser microstructuring. Laser treatment causes the partial reduction of graphene oxide film and changes the morphology. Consequently, it changes optical and thermal properties of graphene oxide. The material synthesis for the bolometer prototype was developed at SINP MSU. Studies on the optical properties were carried out at the Physics Department of Moscow State University. Research on the thermal properties was carried out at LPI RAS. "Laser microstructuring of graphene oxide opens the possibility of selective creation of antireflective, thermally conductive and electrically conductive coatings. The method is quite cheap, compatible with conventional semiconductor technology and produces antiabsorbing coatings that would cover large areas on almost any surface. The observed properties of reduced graphene oxide partially show the prospects of its use in bolometric matrices and other IR devices," says Stanislav Evlashin. Explore further: New technique integrates graphene, graphene oxide and reduced graphene oxide onto silicon chips at room temperature More information: Stanislav Evlashin et al, Controllable Laser Reduction of Graphene Oxide Films for Photoelectronic Applications, ACS Applied Materials & Interfaces (2016). DOI: 10.1021/acsami.6b10145

Loading Skobeltsyn Institute of Nuclear Physics collaborators
Loading Skobeltsyn Institute of Nuclear Physics collaborators