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Multi-(K)over-bar (hyper)Nuclei and Kaon Condensation
Gazda, Daniel; Mareš, Jiří; Friedman, E.; Gal, A.
2010 - English
We report on recent relativistic mean-field calculations of multi-(K) over bar nuclei(1,2) which were performed fully and self-consistently across the periodic table. The (K) over bar separation energy B-(K) over bar as well as the nuclear and (K) over bar -meson densities were found to saturate with the number of antikaons in the nuclear medium. Saturation appears robust against a wide range of variations, including the nuclear model used and the type of boson fields mediating the strong interactions. In addition, we have explored properties of kaonic hypernuclei strange systems made of nucleons, hyperons and K- mesons. We observed saturation also in these objects. Since the (K) over bar separation energy B-(K) over bar does not exceed 200 MeV, multi-(K) over bar nuclei lie energetically well above multi-hyperonic nuclei and it is unlikely that kaon condensation could occur in strong-interaction self-bound hadronic matter.
Keywords:
Kaonic nuclei; relativistic mean field model; kaon condensation
Available at various institutes of the ASCR
Multi-(K)over-bar (hyper)Nuclei and Kaon Condensation
We report on recent relativistic mean-field calculations of multi-(K) over bar nuclei(1,2) which were performed fully and self-consistently across the periodic table. The (K) over bar separation ...
Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques
Rogante, M.; Mikula, Pavol; Vrána, Miroslav
2010 - English
The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, thus, a substantial contribution in justifying different cases of failure or else bad performance of coated components due to e.g. the coating delamination or to other occurrences which are not simply interpretable via the conventional mechanical tests or microstructure analyses. The adoption of both neutron diffraction (ND) and X-ray diffraction (XRD) techniques has revealed its usefulness in assessing the RS values in proximity of the coating interface area, respectively, without any layer removal or hole drilling at the extreme surface.
Keywords:
Polysrystalline materials; Residual stress; Neutron diffraction
Available at various institutes of the ASCR
Residual Stresses Assessment in Coated Materials: Complementarity between Neutron and X-Ray Techniques
The residual stress (RS) status induced in the substrate of coated materials by the coating process plays frequently a major role in lending the component’s characteristics. RS assessment can give, ...
Renaissance of Nuclear Energy, year 2008
Janouch, František
2010 - English
Each year, a few scientific issues are selected and experts are invited to present contrasting views during the plenary multidisciplinary sessions of the seminar. General debates soon follow. These sessions offer a unique opportunity for specialists to broaden their perspectives after being confronted with ideas and suggestions from high level scientists in complementary domains of science. Associated workshops allow the experts to further refine and process the ideas evoked during the seminar. This year's topics are focused on the World Energy Crisis and more specifically on the future of nuclear power, the sustainability of biofuels and nuclear waste. On Global Monitoring of the Planet we have focused on the climate change issue and specifically on the theoretical basis for model calculations, on vector-borne and air-borne particulates disseminating diseases and the crisis in internet security. A full day session was devoted to the Disarmament and Proliferation Regime, in collaboration with the Government of Italy and international institutions.
Keywords:
nuclear energy
Available at various institutes of the ASCR
Renaissance of Nuclear Energy, year 2008
Each year, a few scientific issues are selected and experts are invited to present contrasting views during the plenary multidisciplinary sessions of the seminar. General debates soon follow. These ...
Application of Pulse-Shape Discrimination Method for Wide Aperture Si-Detectors
Sobolev, Yuri, G.; Tyurin, G. P.; Damyanova, A. S.; Danilov, A.; Khlebnikov, S. V.; Kugler, Andrej; Ogloblin, A. A.; Penionzhkevich, Y. E.; Trzaska, W. H.
2010 - English
A method for the identification of charged particles by wide aperture Si -detectors has been investigated based on the employment of pulse -shape discrimination in a silicon p-i-n detector.
Keywords:
exotic nuclei; neutron reach nuclei; cross section
Available at various institutes of the ASCR
Application of Pulse-Shape Discrimination Method for Wide Aperture Si-Detectors
A method for the identification of charged particles by wide aperture Si -detectors has been investigated based on the employment of pulse -shape discrimination in a silicon p-i-n detector.
First measurement of the O-18(p, alpha)N-15 cross section at astrophysical energies
La Cognata, M.; Spitaleri, C.; Mukhamedzhanov, A.; Tribble, R. E.; Al-Abdullah, T.; Banu, A.; Cherubini, S.; Coc, A.; Crucilla, V.; Goldberg, V.; Gulino, M.; Irgaziev, B.; Kiss, G. G.; Lamia, L.; Mrázek, Jaromír; Pizzone, R. G.; Puglia, S. M. R.; Rapisarda, G. G.; Romano, S.; Sergi, M. L.; Tabacaru, G.; Trache, L.; Trzaska, W.; Tudisco, S.; Tumino, A.
2010 - English
The O-18(p, alpha)N-15 reaction rate has been deduced by means of the Trojan horse method. For the first time the contribution of the 20 keV resonance has been directly evaluated, giving a value about 35% larger than the one in the literature. Moreover, the present approach has allowed to improve the accuracy by a factor 8.5, as it is based on the measured strength instead of spectroscopic measurements. The contribution of the 90 keV resonance has been also determined, which turned out to be of negligible importance to astrophysics.
Keywords:
spectroscoic measurements; astrophysics; resonance
Available at various institutes of the ASCR
First measurement of the O-18(p, alpha)N-15 cross section at astrophysical energies
The O-18(p, alpha)N-15 reaction rate has been deduced by means of the Trojan horse method. For the first time the contribution of the 20 keV resonance has been directly evaluated, giving a value about ...
Neutral Kaon Photoproduction at LNS, Tohoku University
Kaneta, M.; Chiga, N.; Beckford, B.; Ejima, M.; Fujii, T.; Fujii, Y.; Fujibayashi, T.; Gogami, T.; Futatsukawa, K.; Hashimoto, O.; Hosomi, K.; Hirose, K.; Iguchi, A.; Kameoka, S.; Kanda, H.; Kawama, D.; Kawasaki, T.; Kimura, C.; Kiyokawa, S.; Koike, T.; Kon, T.; Ma, Y.; Maeda, K.; Maruyama, N.; Matsumura, A.; Miyagi, Y.; Miura, Y.; Miwa, K.; Nakamura, S. N.; Nomura, H.; Okuyama, A.; Ohtani, A.; Otani, T.; Sato, M.; Shichijo, A.; Shirotori, K.; Takahashi, T.; Tamura, H.; Taniya, N.; Tsubota, H.; Tsukada, K.; Terada, N.; Ukai, M.; Uchida, D.; Watanabe, T.; Yamamoto, T.; Yamauchi, H.; Yokota, K.; Ishikawa, T.; Kinoshita, T.; Miyahara, H.; Nakabayashi, T.; Shimizu, H.; Suzuki, K.; Tamae, T.; Terasawa, T.; Yamazaki, H.; Han, Y. C.; Wang, T. S.; Sasaki, A.; Konno, O.; Bydžovský, Petr; Sotona, Miloslav
2010 - English
The elementary photo-strangeness production process has been intensively studied based on the high-quality data of the charged kaon channel, gamma + p -> K+ + Lambda(Sigma(0)). However, there had been no reliable data for the neutral kaon channel gamma + n -> K-0 Lambda(Sigma(0)) and the theoretical investigations suffer seriously from the lack of the data. In order to have reliable data for the neutral kaon photo-production data, substantial effort has been made to measure the gamma + n -> K-0 + A process in the pi(+)pi(-) decay channel, using a liquid deuterium target and a tagged photon beam (E-gamma = 0.8-1.1 GeV) in the threshold region at the Laboratory of Nuclear Science (LNS), Tohoku University. We have taken exploratory data quite successfully with the use of Neutral Kaon Spectrometer (NKS) at LNS-Tohoku in 2003 and 2004. The data is compared to theoretical models and it indicates a hint that the K-0 differential cross section has a backward peak in the energy region. The second generation of the experiment, NKS2, is designed to extend the NKS experiment by considerably upgrading the original neutral kaon spectrometer, fully replacing the spectrometer magnet, tracking detectors and all the trigger counters. The new spectrometer NKS2 has significantly larger acceptance for neutral kaons compared with NKS, particularly covering forward angles and much better invariant mass resolution. The estimated acceptance of NKS2 is three (ten) times larger for K-S(0)(Lambda) than that of NKS. The spectrometer is newly constructed and installed at the Laboratory of Nuclear Science, Tohoku University in 2005. The deuterium target data was taken with tagged photon beam in 2006-2007. We will report recent results of NKS2 in this paper. Additionally, a status of the upgrade project that gives us larger acceptance and capability of K-0 + A coincidence measurement will be presented.
Keywords:
strangeness; photoproduction
Available at various institutes of the ASCR
Neutral Kaon Photoproduction at LNS, Tohoku University
The elementary photo-strangeness production process has been intensively studied based on the high-quality data of the charged kaon channel, gamma + p -> K+ + Lambda(Sigma(0)). However, there had been ...
High-resolution Hypernuclear Spectroscopy Electron Scattering at JLab, Hall A
Garibaldi, F.; Cisbani, E.; Cusanno, F.; Frullani, S.; Iodice, M.; Urciuoli, G.M.; De Leo, R.; Lagamba, L.; Marrone, S.; LeRose, J. J.; de Jager, C.W.; Feuerbach, R. J.; Higinbotham, D. W.; Reitz, B.; Acha, A.; Markowitz, P.; Bydžovský, Petr; Sotona, Miloslav; Chang, C. C.; Millener, J.
2010 - English
The characteristics of the Jefferson LAB electron beam, together with those of the experimental equipments, offer a unique opportunity to study hypernuclear spectroscopy via electromagnetic induced reactions. Experiment 94-107 started a systematic study on 1p-shell targets, C-12, Be-9 and O-16. We present the results from C-12, O-16 and very preliminary results from Be-9. For C-12 for the first time measurable strength in the core-excited part of the spectrum between the ground state and the p(Lambda) state was shown in B-12(Lambda) for the first time. A high-quality N-16(Lambda) spectrum was produced for the first time with sub-MeV Energy resolution. A very precise B-Lambda value for N-16(Lambda), calibrated against the elementary (e,e'K+) reaction on hydrogen, has also been obtained. Final data on Be-9 will be available soon. The missing energy resolution is the best ever obtained in hypernuclear production experiments.
Keywords:
electromagneti production; Jefferson laboratory; stangeness
Available at various institutes of the ASCR
High-resolution Hypernuclear Spectroscopy Electron Scattering at JLab, Hall A
The characteristics of the Jefferson LAB electron beam, together with those of the experimental equipments, offer a unique opportunity to study hypernuclear spectroscopy via electromagnetic induced ...
QCD factorization at forward rapidities
Nemchik, J.; Šumbera, Michal
2010 - English
We analyze several reactions on nuclear targets at forward rapidities and different energies (at smallest experimentally accessible Bjorken x(2) in the target). Nuclear effects are then usually interpreted as a result of shadowing or the Color Glass Condensate. QCD factorization of soft and hard interactions requires the nucleus to be an universal filter for different Fock components of the projectile hadron. We demonstrate, however, that this is not the case in the vicinity of the kinematic limit, Feynman x(F) -> 1, where sharing of energy between the projectile constituents becomes an issue. The rise of suppression with x(F) is confirmed by the E772 and E886 data on the Drell-Yan and heavy quarkonium production. We show that this effect can be treated alternatively as an effective energy loss proportional to initial energy. This leads to a nuclear suppression at any energy, and predicts x(F) scaling of the suppression. We demonstrate also that the same kinematic limit can be approached in transverse momentum when the Cronin enhancement of particle production at medium-high p(T) switches to a suppression at larger p(T) violating thus QCD factorization. Such an unexpected effect seems to be confirmed by the RHIC data for pion production in d+A collisions, and even for direct photons in Au+Au collisions.
Keywords:
suppression; collisions
Available at various institutes of the ASCR
QCD factorization at forward rapidities
We analyze several reactions on nuclear targets at forward rapidities and different energies (at smallest experimentally accessible Bjorken x(2) in the target). Nuclear effects are then usually ...
Spectral flux of the p-Li-7(C) Q-M neutron source measured by proton recoil telescope
Novák, Jan; Bém, Pavel; Fischer, U.; Götz, Miloslav; Honusek, Milan; Simakov, S. P.; Šimečková, Eva; Štefánik, Milan
2010 - English
The cyclotron-based fast neutron source at NPI produces mono-energetic neutron fields up to 35 MeV neutron energy using the p + 7Li(carbon backing) reactions. To be applied for activation cross-section measurements, not only the intensity of neutron peak, but also the contribution of low-energy continuum in the spectra must be well determined. Simulations of the spectral flux from present source at a position of irradiated samples were performed using CYRIC TOF-data validated in the present work against LA150h by calculations with the transport Monte Carlo code MCNPX.
Keywords:
MCNPX; TOF; neutron source
Available at various institutes of the ASCR
Spectral flux of the p-Li-7(C) Q-M neutron source measured by proton recoil telescope
The cyclotron-based fast neutron source at NPI produces mono-energetic neutron fields up to 35 MeV neutron energy using the p + 7Li(carbon backing) reactions. To be applied for activation ...
Chiral model for (K)over-barN interactions and its pole content
Cieplý, Aleš; Smejkal, J.
2010 - English
We use chirally motivated effective meson-baryon potentials to describe the low energy (K) over barN data including the characteristics of kaonic hydrogen. Our results are examined in comparison with other approaches based on the unitarity and dispersion relation for the inverse of the T-matrix. We demonstrate that the movements of the poles generated by the model upon varying the model parameters can serve as a tool to get additional insights on the dynamics of the strongly coupled pi Sigma-(K) over barN system.
Keywords:
chiral Lagrangians; coupled channels; meson-baryon interactions
Available at various institutes of the ASCR
Chiral model for (K)over-barN interactions and its pole content
We use chirally motivated effective meson-baryon potentials to describe the low energy (K) over barN data including the characteristics of kaonic hydrogen. Our results are examined in comparison with ...
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