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1.	Erni, W., et al. (author) Technical design report for the PANDA (AntiProton Annihilations at Darmstadt) Straw Tube Tracker 2013 In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 49:2 Journal article (peer-reviewed)abstract This document describes the technical layout and the expected performance of the Straw Tube Tracker (STT), the main tracking detector of the PANDA target spectrometer. The STT encloses a Micro-Vertex-Detector (MVD) for the inner tracking and is followed in beam direction by a set of GEM stations. The tasks of the STT are the measurement of the particle momentum from the reconstructed trajectory and the measurement of the specific energy loss for a particle identification. Dedicated simulations with full analysis studies of certain proton-antiproton reactions, identified as being benchmark tests for the whole PANDA scientific program, have been performed to test the STT layout and performance. The results are presented, and the time lines to construct the STT are described.
2.	Singh, B. P., et al. (author) Experimental access to Transition Distribution Amplitudes with the PANDA experiment at FAIR 2015 In: European Physical Journal A. Hadrons and Nuclei. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 51:8 Journal article (peer-reviewed)abstract Baryon-to-meson Transition Distribution Amplitudes (TDAs) encoding valuable new information on hadron structure appear as building blocks in the collinear factorized description for several types of hard exclusive reactions. In this paper, we address the possibility of accessing nucleon-to-pion (pi N) TDAs from (p) over barp -> e(+)e(-)pi(0) reaction with the future PANDA detector at the FAIR facility. At high center-of-mass energy and high invariant mass squared of the lepton pair q(2), the amplitude of the signal channel (p) over barp -> e(+)e(-)pi(0) admits a QCD factorized description in terms of pi N TDAs and nucleon Distribution Amplitudes (DAs) in the forward aid backward kinematic regimes. Assuming the validity of this factorized description, we perform feasibility studies for measuring (p) over barp -> e(+)e(-)pi(0) with the PANDA detector. Detailed simulations on signal reconstruction efficiency as well as on rejection of the most severe background channel, i.e. (p) over barp -> pi(+)pi(-)pi(0) were performed for the center-of-mass energy squared s = 5 GeV2 and s = 10 GeV2, in the kinematic regions 3.0 < q(2) < 4.3 GeV2 and 5 < q(2) < 9 GeV2, respectively, with a neutral pion scattered in the forward or backward cone vertical bar cos theta(pi 0)vertical bar > 0.5 in the proton-antiproton center-of-mass frame. Results of the simulation show that the particle identification capabilities of the PANDA detector will allow to achieve a background rejection factor of 5 . 10(7) (1 . 10(7)) at low (high) q(2) for s = 5 GeV2, and of 1 . 10(8) (6 . 10(6)) at low (high) q(2) for s = 10 GeV2, while keeping the signal reconstruction efficiency at around 40%. At both energies, a clean lepton signal can be reconstructed with the expected statistics corresponding to 2 of integrated luminosity. The cross sections obtained from the simulations are used to show that a test of QCD collinear factorization can be done at the lowest order by measuring scaling laws and angular distributions. The future measurement of the signal channel cross section with PANDA will provide a new test of the perturbative QCD description of a novel class of hard exclusive reactions and will open the possibility of experimentally accessing pi N TDAs.
3.	Adare, A., et al. (author) Charged hadron multiplicity fluctuations in Au plus Au and Cu plus Cu collisions from s(NN)=22.5 to 200 GeV 2008 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 78:4 Journal article (peer-reviewed)abstract A comprehensive survey of event-by-event fluctuations of charged hadron multiplicity in relativistic heavy ions is presented. The survey covers Au+Au collisions at s(NN)=62.4 and 200 GeV, and Cu+Cu collisions at s(NN)=22.5,62.4, and 200 GeV. Fluctuations are measured as a function of collision centrality, transverse momentum range, and charge sign. After correcting for nondynamical fluctuations due to fluctuations in the collision geometry within a centrality bin, the remaining dynamical fluctuations expressed as the variance normalized by the mean tend to decrease with increasing centrality. The dynamical fluctuations are consistent with or below the expectation from a superposition of participant nucleon-nucleon collisions based upon p+p data, indicating that this dataset does not exhibit evidence of critical behavior in terms of the compressibility of the system. A comparison of the data with a model where hadrons are independently emitted from a number of hadron clusters suggests that the mean number of hadrons per cluster is small in heavy ion collisions.
4.	Adare, A., et al. (author) Cold nuclear matter effects on J/psi production as constrained by deuteron-gold measurements at root S-NN=200 GeV 2008 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:2, s. 15-024912 Journal article (peer-reviewed)abstract We present a new analysis of J/psi production yields in deuteron-gold collisions at root s(NN) =200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/psi data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (R-dAu). A suppression of J/psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial-state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/psi (or precursor) breakup cross section is added. Breakup cross sections of sigma(breakup)=2.8(-1.4)(+1.7) (2.2(-1.5)(+1.6)) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross-section values are consistent within large uncertainties with the 4.2 +/- 0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.
5.	Adare, A., et al. (author) Direct photon production in d+Au collisions at root s(NN)=200 GeV 2013 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 87:5 Journal article (peer-reviewed)abstract Direct photons have been measured in root s(NN) = 200 GeV d + Au collisions at midrapidity. A wide p(T) range is covered by measurements of nearly real virtual photons (1 < p(T) < 6 GeV/c) and real photons (5 < p(T) < 16 GeV/c). The invariant yield of the direct photons in d + Au collisions over the scaled p + p cross section is consistent with unity. Theoretical calculations assuming standard cold-nuclear-matter effects describe the data well for the entire p(T) range. This indicates that the large enhancement of direct photons observed in Au + Au collisions for 1.0 < p(T) < 2.5 GeV/c is attributable to a source other than the initial-state nuclear effects.
6.	Adare, A., et al. (author) System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at root S-NN 200 and 62.4 GeV 2007 In: Physical Review Letters. - 1079-7114. ; 98:23 Journal article (peer-reviewed)abstract We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at root s(NN)=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
7.	Adler, S. S., et al. (author) Azimuthal angle correlations for rapidity separated hadron pairs in d+Au collisions at root s(NN)=200 GeV 2006 In: Physical Review Letters. - 1079-7114. ; 96:22 Journal article (peer-reviewed)abstract Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at root s(NN)=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x similar to 0.1 to similar to 0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.
8.	Adler, S. S., et al. (author) Centrality dependence of charged hadron production in deuteron plus gold and nucleon plus gold collisions at root S-NN=200 GeV 2008 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 77:1 Journal article (peer-reviewed)abstract We present transverse momentum (p(T)) spectra of charged hadrons measured in deuteron-gold and nucleon-gold collisions at root s(NN)=200 GeV for four centrality classes. Nucleon-gold collisions were selected by tagging events in which a spectator nucleon was observed in one of two forward rapidity detectors. The spectra and yields were investigated as a function of the number of binary nucleon-nucleon collisions, nu, suffered by deuteron nucleons. A comparison of charged particle yields to those in p+p collisions show that yield per nucleon-nucleon collision saturates with nu for high momentum particles. We also present the charged hadron to neutral pion ratios as a function of p(T).
9.	Adler, S. S., et al. (author) Centrality dependence of pi(0) and eta production at large transverse momentum in root s(NN) = 200 GeV d+Au collisions 2007 In: Physical Review Letters. - 1079-7114. ; 98:17 Journal article (peer-reviewed)abstract The dependence of transverse momentum spectra of neutral pions and eta mesons with p(T) < 16 GeV/c and p(T) < 12 GeV/c, respectively, on the centrality of the collision has been measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) in d + Au collisions at root s(NN) = 200 GeV. The measured yields are compared to those in p + p collisions at the same root s(NN) scaled by the number of underlying nucleon-nucleon collisions in d + Au. At all centralities, the yield ratios show no suppression, in contrast to the strong suppression seen for central An + Au collisions at RHIC. Only a weak p(T) and centrality dependence can be observed.
10.	Adler, S. S., et al. (author) Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at root(NN)-N-S=200 GeV 2006 In: Physical Review Letters. - 1079-7114. ; 97:5 Journal article (peer-reviewed)abstract Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at root s(NN)=200 GeV. The distribution of jet-associated partner hadrons (1.0 < p(T)< 2.5 GeV/c) per trigger hadron (2.5 < p(T)< 4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.
11.	Adler, S. S., et al. (author) Detailed study of high-p(T) neutral pion suppression and azimuthal anisotropy in Au plus Au collisions at root s(NN) =200 GeV 2007 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 76:3 Journal article (peer-reviewed)abstract Measurements of neutral pion (pi(0)) production at midrapidity in root s(NN)=200 GeV Au+Au collisions as a function of transverse momentum, p(T), collision centrality, and angle with respect to reaction plane are presented. The data represent the final pi(0) results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of 3 increase in statistics over previously published results for p(T)>6 GeV/c. We evaluate the suppression in the yield of high-p(T) pi(0)'s relative to pointlike scaling expectations using the nuclear modification factor R-AA. We present the p(T) dependence of R-AA for nine bins in collision centrality. We separately integrate R-AA over larger p(T) bins to show more precisely the centrality dependence of the high-p(T) suppression. We then evaluate the dependence of the high-p(T) suppression on the emission angle Delta phi of the pions with respect to event reaction plane for seven bins in collision centrality. We show that the yields of high-p(T) pi(0)'s vary strongly with Delta phi, consistent with prior measurements 1,2. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane, whereas the yield of pi(0)'s produced perpendicular to the reaction plane is suppressed by a factor of similar to 2. We analyze the combined centrality and Delta phi dependence of the pi(0) suppression in different p(T) bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.
12.	Adler, S. S., et al. (author) Evidence for a long-range component in the pion emission source in Au plus Au collisions at root s(NN)=200 GeV 2007 In: Physical Review Letters. - 1079-7114. ; 98:13 Journal article (peer-reviewed)abstract Emission source functions are extracted from correlation functions constructed from charged pions produced at midrapidity in Au+Au collisions at s(NN)=200 GeV. The source parameters extracted from these functions at low k(T) give first indications of a long tail for the pion emission source. The source extension cannot be explained solely by simple kinematic considerations. The possible role of a halo of secondary pions from resonance emissions is explored.
13.	Adler, S. S., et al. (author) High transverse momentum eta meson production in p+p, d+Au, and Au+Au collisions at root s(NN)=200 GeV 2007 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:2 Research review (peer-reviewed)abstract Inclusive transverse momentum spectra of eta mesons in the range p(T)approximate to 2-12 GeV/c have been measured at midrapidity (vertical bar eta vertical bar < 0.35) by the PHENIX experiment at RHIC in p+p,d+Au, and Au+Au collisions at root s(NN)=200 GeV. The eta mesons are reconstructed through their eta ->gamma gamma channel for the three colliding systems as well as through the eta ->pi(0)pi(+)pi(-) decay mode in p+p and d+Au collisions. The nuclear modification factor in d+Au collisions, R-dAu(p(T))approximate to 1.0-1.1, suggests at most only modest p(T) broadening ("Cronin enhancement"). In central Au+Au reactions, the eta yields are significantly suppressed, with R-AuAu(p(T))approximate to 0.2. The ratio of eta to pi(0) yields is approximately constant as a function of p(T) for the three colliding systems in agreement with the high-p(T) world average of R-eta/pi(0)approximate to 0.5 in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions for a wide range of center-of-mass energies (root sNN approximate to 3-1800 GeV) as well as, for high scaled momentum x(p), in e(+)e(-) annihilations at root s=91.2 GeV. These results are consistent with a scenario where high-p(T) eta production in nuclear collisions at the Relativistic Heavy Ion Collider is largely unaffected by initial-state effects but where light-quark mesons (pi(0),eta) are equally suppressed due to final-state interactions of the parent partons in the dense medium produced in Au+Au reactions.
14.	Adler, S. S., et al. (author) Jet properties from dihadron correlations in p plus p collisions at root s=200 GeV 2006 In: Physical Review D (Particles, Fields, Gravitation and Cosmology). - 1550-2368. ; 74:7 Journal article (peer-reviewed)abstract The properties of jets produced in p+p collisions at root s=200 GeV are measured using the method of two-particle correlations. The trigger particle is a leading particle from a large transverse momentum jet while the associated particle comes from either the same jet or the away-side jet. Analysis of the angular width of the near-side peak in the correlation function determines the jet-fragmentation transverse momentum j(T). The extracted value, root < j(T)(2)>=585 +/- 6(stat)+/- 15(sys) MeV/c, is constant with respect to the trigger particle transverse momentum, and comparable to the previous lower root s measurements. The width of the away-side peak is shown to be a convolution of j(T) with the fragmentation variable, z, and the partonic transverse momentum, k(T). The < z > is determined through a combined analysis of the measured pi(0) inclusive and associated spectra using jet-fragmentation functions measured in e(+)e(-) collisions. The final extracted values of k(T) are then determined to also be independent of the trigger particle transverse momentum, over the range measured, with value of root < k(T)(2)>=2.68 +/- 0.07(stat)+/- 0.34(sys) GeV/c.
15.	Adler, S. S., et al. (author) Jet structure from dihadron correlations in d+Au collisions at root S-NN=200 GeV 2006 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 73:5 Journal article (peer-reviewed)abstract Dihadron correlations at high transverse momentum p(T) in d+Au collisions at root s(NN)=200 GeV at midrapidity are measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. From these correlations, we extract several structural characteristics of jets: the root-mean-squared transverse momentum of fragmenting hadrons with respect to the jet root < j(T)(2)>, the mean sine-squared of the azimuthal angle between the jet axes < sin(2)phi(jj)>, and the number of particles produced within the dijet that are associated with a high-p(T) particle (dN/dx(E) distributions). We observe that the fragmentation characteristics of jets in d+Au collisions are very similar to those in p+p collisions and that there is little dependence on the centrality of the d+Au collision. This is consistent with the nuclear medium having little influence on the fragmentation process. Furthermore, there is no statistically significant increase in the value of < sin(2)phi(jj)> from p+p to d+Au collisions. This constrains the effect of multiple scattering that partons undergo in the cold nuclear medium before and after a hard collision.
16.	Adler, S. S., et al. (author) Measurement of density correlations in pseudorapidity via charged particle multiplicity fluctuations in 2007 In: Physical Review C - Nuclear Physics. - 0556-2813. ; 76 Journal article (peer-reviewed)
17.	Adler, S. S., et al. (author) Measurement of direct photon production in p+p collisions at root s=200 GeV 2007 In: Physical Review Letters. - 1079-7114. ; 98:1 Journal article (peer-reviewed)abstract Cross sections for midrapidity production of direct photons in p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are reported for transverse momenta of 3 < p(T)< 16 GeV/c. Next-to-leading order perturbative QCD (pQCD) describes the data well for p(T)> 5 GeV/c, where the uncertainties of the measurement and theory are comparable. We also report on the effect of requiring the photons to be isolated from parton jet energy. The observed fraction of isolated photons is well described by pQCD for p(T)> 7 GeV/c.
18.	Adler, S. S., et al. (author) Measurement of single muons at forward rapidity in p+p collisions at root s=200 GeV and implications for charm production 2007 In: Physical Review D - Particles, Fields, Gravitation and Cosmology. - 1550-2368. ; 76:9 Journal article (peer-reviewed)abstract Muon production at forward rapidity (1.5 <=\|eta\|<= 1.8) has been measured by the PHENIX experiment over the transverse momentum range 1 <= p(T)<= 3 GeV/c in root s=200 GeV p+p collisions at the Relativistic Heavy Ion Collider. After statistically subtracting contributions from light hadron decays an excess remains which is attributed to the semileptonic decays of hadrons carrying heavy flavor, i.e. charm quarks or, at high p(T), bottom quarks. The resulting muon spectrum from heavy flavor decays is compared to PYTHIA and a next-to-leading-order perturbative QCD calculation. PYTHIA is used to determine the charm quark spectrum that would produce the observed muon excess. The corresponding differential cross section for charm quark production at forward rapidity is determined to be d sigma(c (c) over bar)/dy\|(y=1.6)=0.243 +/- 0.013(stat.)+/- 0.105(data syst.)(-0.087)(+0.049)(PYTHIA syst.) mb.
19.	Adler, S. S., et al. (author) Nuclear effects on hadron production in d plus Au collisions at root S-NN=200 GeV revealed by comparison with p plus p data 2006 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 74:2 Journal article (peer-reviewed)abstract PHENIX has measured the centrality dependence of midrapidity pion, kaon, and proton transverse momentum distributions in d+Au and p+p collisions at root s(NN) = 200 GeV. The p+p data provide a reference for nuclear effects in d+Au and previously measured Au+Au collisions. Hadron production is enhanced in d+Au, relative to independent nucleon-nucleon scattering, as was observed in lower energy collisions. The nuclear modification factor for (anti)protons is larger than that for pions. The difference increases with centrality but is not sufficient to account for the abundance of baryon production observed in central Au+Au collisions at the BNL Relativistic Heavy Ion Collider (RHIC). The centrality dependence in d+Au shows that the nuclear modification factor increases gradually with the number of collisions encountered by each participant nucleon. We also present comparisons with lower energy data as well as with parton recombination and other theoretical models of nuclear effects on particle production.
20.	Adler, S. S., et al. (author) Production of omega mesons at large transverse momenta in p+p and d+Au collisions at root S(NN) = 200 GeV 2007 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 75:5 Journal article (peer-reviewed)abstract The PHENIX experiment at RHIC has measured the invariant cross section for omega-meson production at midrapidity in the transverse momentum range 2.5 < p(T)< 9.25 GeV/c in p+p and d+Au collisions at root s(NN) = 200 GeV. Measurements in two decay channels (omega ->pi(0)pi(+)pi(-) and omega ->pi(0)gamma) yield consistent results, and the reconstructed omega mass agrees with the accepted value within the p(T) range of the measurements. The omega/pi(0) ratio is found to be 0.85 +/- 0.05(stat)+/- 0.09(sys) in p+p and 0.94 +/- 0.08(stat)+/- 0.12(sys) in d+Au collisions, independent of p(T). The nuclear modification factor R-dA(omega) is 1.03 +/- 0.12(stat)+/- 0.21(sys) and 0.83 +/- 0.21(stat)+/- 0.17(sys) in minimum bias and central (0-20%) d+Au collisions, respectively.
21.	Adler, S. S., et al. (author) Transverse-energy distributions at midrapidity in p plus p, d plus Au, and Au plus Au collisions at root s(NN)=62.4-200 GeV and implications for particle-production models 2014 In: Physical Review C (Nuclear Physics). - 0556-2813. ; 89:4 Journal article (peer-reviewed)abstract Measurements of the midrapidity transverse-energy distribution, dE(T)/d eta, are presented for p + p, d+Au, and Au+Au collisions atv root s(NN) = 200 GeV and additionally for Au+Au collisions atv root s(NN) = 62.4 and 130 GeV. The dE(T)/d eta distributions are first compared with the number of nucleon participants N-part, number of binary collisions N-coll, and number of constituent-quark participants N-qp calculated from a Glauber model based on the nuclear geometry. For Au+Au, < dE(T)/d eta >/N-part increases with N-part, while < dE(T)/d eta >/N-qp is approximately constant for all three energies. This indicates that the two-component ansatz, dE(T)/d eta alpha (1 - x)N-part/2 + xN(coll), which was used to represent E-T distributions, is simply a proxy for N-qp, and that the N-coll term does not represent a hard-scattering component in E-T distributions. The dE(T)/d eta distributions of Au+Au and d+Au are then calculated from the measured p + p E-T distribution using two models that both reproduce the Au+Au data. However, while the number-of-constituent-quark-participant model agrees well with the d+Au data, the additive-quark model does not.
22.	Bakchinov, A.A., et al. (author) An experimental study on the incipient spot and turbulent spot origination 1997 In: In Proc. of the Third Int. Conf. on Experimental Fluid Mechanics, Korolev, Moscow region, Russia. ; , s. 45- Conference paper (other academic/artistic)
23.	Bakchinov, A.A., et al. (author) Experimental study of the K-regime of breakdown in straight and swept wing boundary layers 2000 In: Abstracts of 53rd Ann. Meeting of the Div. of Fluid Dyn. APS, Washington, DC. Conference paper (other academic/artistic)abstract Experiments on the stability of three-dimensional boundary layers on the straight and swept airfoils have been conducted. Detailed measurements of the streamwise velocity field in (Y, Z) planes, as well as the 3D frequency-wavenumber spectra have revealed linear and non-linear evolutions of the disturbances generated by an external acoustic field in the airfoil boundary layers. The Tollmien-Schlichting waves, excited by the sound, were dominant in both configurations, and the disturbance flow field was found to remain highly deterministic and periodic both in time and space until the latest stages of the transition. To control a spanwise variation of the disturbance flow field roughness elements were placed on the surface and equidistantly aligned along the airfoil leading edge. The K-type transition was identified with the aligned order of so-called Lambda-patterns at non-linear stage of the transition. The experiment was conducted in a closed-circuit wind-tunnel at the department of Thermo and Fluid Dynamics, Calmers. This work was supported by the Royal Swedish Academy of Sciences (KVA).
24.	Bakchinov, Andrey, 1967, et al. (author) Patterns of streamwise lambda structures mapped with Mini-CTA hot wire anemometry 2000 In: Dantecs booklet. Journal article (other academic/artistic)
25.	Chernoray, Valery, 1975, et al. (author) Effect of riblets on nonlinear disturbances in the boundary layer 2006 In: Thermophysics and Aeromechanics. ; 13:1, s. 67-74 Journal article (peer-reviewed)abstract Results of experimental investigations of the nonlinear stage of sinusoidal and varicose instability of a streaky structure, which leads to multiplication of streaky structures and origination of coherent structures (such as Λ-structures), are presented. Riblets suppress the intensity of streaky structures, stabilize the flow against the development of the secondary high-frequency instability of streaky structures, and, for this reason, delay spatial turbulization of the flow. The results of these investigations can be useful for understanding the flow structure in such situations and for possible controlling of the coherent structures aimed at flow stabilization
26.	Chernoray, Valery, 1975, et al. (author) Experimental study of K-regime of breakdown in straight and swept wing boundary layers 2000 In: In Proc. Int. Conf. on Methods of Aerophys. Research, Novosibirsk, Russia. ; 2, s. 65-70 Conference paper (other academic/artistic)
27.	Chernoray, Valery, 1975, et al. (author) Experimental study of the K-regime of breakdown in straight and swept wing boundary layers 2001 In: Physics of Fluids. ; 13:7, s. 2129-2132 Journal article (peer-reviewed)abstract In this Brief Communication, the nonlinear evolution of periodical disturbances generated by an external sound field in a swept wing boundary layer is presented. All experimental results are compared with corresponding data for a straight wing configuration. The Tollmien-Schlichting instability has been studied, and it was found that the disturbance flow field remained highly deterministic and periodic in both time and space until the latest stages of the transition. A frequency-wave number Fourier analysis shows that the disturbance spectra comprise only the fundamental wave and its higher harmonics. The K-type breakdown scenario was observed, and the nonsymmetry of flow patterns in the swept wing boundary layer was found to be due to the presence of the cross flow.
28.	Chernoray, Valery, 1975, et al. (author) Experiments on secondary instability of streamwise vortices in a swept wing boundary layer 2005 In: Journal of Fluid Mechanics. ; 534, s. 295-325 Journal article (peer-reviewed)abstract A detailed experimental study on the formation of crossflow vortex mode packets and their high-frequency secondary instability in a swept-wing boundary layer was carried out. Stationary vortex packets are most likely to be generated under natural flight conditions and transition to turbulence is quickest within these disturbances. In the present experiments, different methods of controlled excitation are used so that the crossflow vortex packets are generated by surface-roughness elements and by localized continuous suction. It is found that as the stationary disturbance reaches a significant amplitude, of about 10% of the free-stream velocity, while being below the saturation level, high-frequency secondary instabilities start to grow. Influence of the crossflow vortex packet magnitude on the development of the secondary instability is investigated in detail and below its threshold the crossflow vortex packet was found to be nearly neutrally stable. By studying the unstable packets, the frequency of natural secondary perturbations was identified and the travelling disturbances were forced in a controlled manner by periodic blowing-suction applied locally under the stationary vortex. Two modes of secondary instability were found to develop and the preferred mode was dependent on the properties of the primary stationary disturbance. Additionally, the underlying physics of the process of nonlinear formation and development of the vortices in the boundary layer is clarified. It was observed that the large-amplitude co-rotating vortices may interact, thus reducing their amplitude. Also a large-scale excitation by an isolated roughness element produced two individual stationary crossflow vortex packets at its tips, each with different preferred secondary instability modes.
29.	Chernoray, Valery, 1975, et al. (author) Features of laminar-turbulent transition of adverse pressure gradient flows at low and high Reynolds numbers 2006 In: Proc. of the 6th Euromech Fluid Mechanics Conference, 2006, Stockholm, Sweden. ; , s. 82- Conference paper (other academic/artistic)abstract Recent experimental studies of laminar-turbulent transition are presented withfocus on adverse pressure gradient flows. New developments in secondary instabilityof streaks and separation control are reported. In the first part of the presentation thestudies of laminar-turbulent transition in non-swept and swept wing boundary layersare discussed, and in the second part the investigations of separated flows on wingswith ordinary (plain) and modified (wavy-shaped) surfaces are considered. The role ofthree-dimensional velocity perturbations such as streamwise vortices and streaks in thelaminar-turbulence transition process is demonstrated, and the importance ofsecondary instability mechanisms is outlined. For a straight wing, the experimentalstudies of the nonlinear varicose secondary instability are compared at zero andadverse streamwise pressure gradients. Results obtained testify to the strong influenceof the pressure gradient upon the breakdown of streaks with developed instability [1].For the swept wings, the stationary vortex packets are most likely to be generatedunder natural flight conditions and transition to turbulence is known to be thequickest within these disturbances. Two modes of the secondary instability are foundto develop and the preferred mode is dependent on the properties of the primarystationary disturbance. The instability modes studied are the 'y' and 'z' high-frequencysecondary instability modes, which are investigated separately and also theirinteraction under fully controlled experimental conditions [2]. Furthermore, theinfluence of wing surface modifications on the wing performance and drag is studied.The results testify that for the low-Reynolds-number flow conditions the critical angleof attack of a wing with a wavy-shaped surface can be up to 1.5 times or more thanthat of a similar plane-surface-wing, and for the attack angles in the range between 5and 20 degrees the wing with a modified surface reveal higher aerodynamic qualityowing to decreased size of the separated zones [3].1 Litvinenko et al., Phys. Fluids 17, 118106 (2005).2 Chernoray et al., J. Fluid Mech. 534, 295 (2005).3 Kozlov et al., Proc. EUCASS Conf. Moscow, Russia, Paper 2.11.07 (2005).
30.	Chernoray, Valery, 1975, et al. (author) Generation of the localized disturbances by the vibrating surface 2000 In: Thermophysics and Aeromechanics. ; 7:3, s. 329-339 Journal article (peer-reviewed)abstract Appearance and development of disturbances generated by 3-D vibrating surface in Blasius boundary layer are studied experimentally. The experiments were conducted under the controlled conditions where the preservation of phase information made it possible to obtain profound and accurate data, qualitative as well as quantitative, on the object under study. Surface vibration was provided by the loudspeaker working in the blowing-suction regime. Detailed hot-wire measurements showed that in case when the surface produces oscillations of low frequency and small amplitude, the packet of disturbances with the characteristics of Tollmien - Schlichting (TS) waves is observed downstream. When the effective amplitude is increased two times "blowing" leads to the appearance of the new type of disturbances: "puff"-structures, which have other characteristics of development in the boundary layer than Tollmien - Schlichting waves.
31.	Chernoray, Valery, 1975, et al. (author) Hot wire visualization of turbulization of complex flows 2006 In: Thermophysics and Aeromechanics. ; 13:2, s. 1-9 Journal article (peer-reviewed)
32.	Chernoray, Valery, 1975, et al. (author) Hot wire visualizations of breakdown to turbulence in complex flows 2005 In: Proc. of EUCASS conf., Moscow, Russia. ; , s. 211-216 Conference paper (other academic/artistic)
33.	Chernoray, Valery, 1975, et al. (author) Influence of an unfavourable pressure gradient on the breakdown of boundary layer streaks 2007 In: Journal of Visualization. - 1343-8875 .- 1386-6478. ; 10:2, s. 217-225 Journal article (peer-reviewed)abstract Breakdown of boundary layer streaks is studied experimentally and compared at zero and adverse (positive) streamwise pressure gradients on a wing under fully controlled experimental conditions. The varicose mode of streak breakdown is found to be a dominant mode in the case of the adverse pressure gradient. A strong influence of pressure gradient upon the development of the streak and the secondary instability is revealed. The unfavourable pressure gradient is shown to alter the critical streak amplitude, the dispersion properties of the streak and the secondary disturbance, as well as attained maximum amplitudes for both the streak and the secondary disturbance.
34.	Chernoray, Valery, 1975, et al. (author) Instability of a swept-wing boundary layer modulated by stationary flow perturbations 2013 In: Visualization of Mechanical Processes: An International Online Journal. - 2152-209X. ; 3:1 Journal article (peer-reviewed)abstract A collection of illustrations of swept-wing boundary layer secondary instability at low subsonic flow velocities is presented in this paper. The experimental results, obtained by hot-wire "visualization," provide detailed insight into the spatio-temporal structure and evolution of oscillations in the three-dimensional laminar boundary layer disturbed by longitudinal vortices and streaky structures.
35.	Chernoray, Valery, 1975, et al. (author) Longitudinal structures in the near field of the plane wall-jet 2007 In: Thermophys. Aeromech.. - 1531-8699. ; 14:4, s. 545-553 Journal article (peer-reviewed)
36.	Chernoray, Valery, 1975, et al. (author) On K-type transition in swept wing boundary layer in the presence of an acoustic field 2000 In: In Proc. of the 7th Int. Conf. on Stability of Homogeneous and Heterogeneous Flows, Novosibirsk, Russia. ; , s. 141-144 Conference paper (other academic/artistic)
37.	Chernoray, Valery, 1975, et al. (author) Riblet-assisted control of transformation of the Λ-structure into a turbulent spot 2005 In: Thermophysics and Aeromechanics. - 0869-8643. ; 12:4, s. 539-548 Journal article (peer-reviewed)abstract Experimental results are presented on transformation of a solitary Λ-structure into a turbulent spot and control of this process by means of riblets on the wetted surface in the boundary layer on a flat plate. It is shown that riblets exert a stabilizing effect on transformation of the Λ-structure into a turbulent spot. The Λ-structure on a smooth surface is shown to stretch in the streamwise direction and transform into a hairpin vortex, which becomes a turbulent spot further downstream. The intensity of the Λ-structure on riblets first increases and then decays further downstream, reaching less than half its value on a smooth surface. Finally, the Λ-structure decays on riblets without forming a turbulent spot.
38.	Chernoray, Valery, 1975, et al. (author) Secondary instability of a swept-wing boundary layer disturbed by controlled roughness elements 2010 In: Journal of Visualization. - : Springer Science and Business Media LLC. - 1343-8875 .- 1386-6478 .- 1875-8975. ; 13:3, s. 251-256 Journal article (peer-reviewed)abstract Wind-tunnel data on velocity perturbations evolving in a laminar swept-wing flow under low subsonic conditions are reported. The focus of the present experiments are secondary disturbances of the boundary layer which is modulated by stationary streamwise vortices. Both the stationary vortices and the secondary oscillations of interest are generated in a controlled manner. The experimental data are obtained through hot-wire measurements. Thus, evolution of the vortices, either isolated or interacting with each other, is reconstructed in detail. As is found, the secondary disturbances, initiating the laminar-flow breakdown, are strongly affected by configuration of the stationary boundary-layer perturbation that may have an implication to laminar-turbulent transition control.
39.	Chernoray, Valery, 1975, et al. (author) Secondary instability of stationary vortex packets in a swept wing boundary layer 2004 In: In Proc. of XXI International Congress of Theoretical and Applied Mechanics, Warsaw, Poland. Conference paper (other academic/artistic)abstract The fact is that stationary vortex packets are most likely to be generated under natural flight conditions on the wing and these disturbances lead to breakdown the fastest. A detailed experimental study on the formation of crossflow vortex mode packets and their secondary instability in a swept wing boundary layer was carried out.
40.	Chernoray, Valery, 1975, et al. (author) Secondary oscillations of a swept-wing flow perturbed by stationary streamwise vortices 2010 In: Proc. of 13th Asian Congress of Fluid Mech. ; 1, s. 224-227 Conference paper (other academic/artistic)
41.	Chernoray, Valery, 1975, et al. (author) Spatial hot-wire visualization of the Lambda-structure transformation into the turbulent spot on the smooth flat plate surface and riblet effect on this process 2010 In: Journal of Visualization. - : Springer Science and Business Media LLC. - 1343-8875 .- 1386-6478 .- 1875-8975. ; 13:2, s. 151-158 Journal article (peer-reviewed)abstract Evolution of the Lambda-vortex and its transformation into the turbulent spot in a flat plate boundary layer are investigated experimentally. Extensive measurements visualizing the Lambda-structure transformation into the turbulent spot on the smooth and ribbed surfaces of the flat plate are presented. The flow behavior in the course of spatial evolution of the Lambda-structure and turbulent spot is discussed. Specific features of the downstream evolution of Lambda-structure and turbulent spot on the smooth and ribbed surfaces are demonstrated, such as suppression by riblets of the Lambda-vortex transformation into the turbulent spot, appearance of the coherent structures of Lambda-vortex within ensemble-averaged turbulent spot, and oblique waves generation both by the Lambda-vortex and turbulent spot.
42.	Chernoray, Valery, 1975, et al. (author) Study of the incipient spot breakdown controlled by riblets 2011 In: Progress in flight physics. Eds. Ph. Reijasse, D. Knight, M. Ivanov, and I. Lipatov EUCASS advances in aerospace sciences book ser. - 9782759806744 ; , s. 519-530 Book chapter (other academic/artistic)
43.	Chernoray, Valery, 1975, et al. (author) Study of the Incipient Spot Breakdown Controlled by Riblets 2012 In: EUCASS Book Series on Advances in Aerospace Sciences, Vol. 3, Progress in Flight Physics, [Edited by Ph. Reijasse, D. Knight, M. Ivanov, and I. Lipatov]. ; , s. 545-556 Book chapter (other academic/artistic)
44.	Chernoray, Valery, 1975, et al. (author) Study of the incipient spot breakdown controlled by riblets 2009 In: Proc. of EUCASS conf., Versailles, France. Conference paper (other academic/artistic)
45.	Chernoray, Valery, 1975, et al. (author) Study of the nonlinear instability of a longitudinal structure generated by a roughness element in the boundary layer of a straight wing 2007 In: Thermophys. Aeromech.. - 1531-8699. ; 14:3, s. 343-358 Journal article (peer-reviewed)abstract The results of experimental study of a nonlinear varicose instability of the streaky structure generated by roughness element in unswept-wing boundary layer are presented. Features of the varicose breakdown of longitudinal steady streaky structure such as modulation of structure in transverse and streamwise directions by secondary disturbance, occurrence of the new streaky structures and Lambda-structures downstream are shown. Spatio-temporal pictures of the hot-wire visualization of flow during spatial evolution of the streaky structures under influence of secondary high-frequency disturbance are discussed. Features of the adverse pressure gradient influence upon processes of the nonlinear varicose instability evolution and flow structure are revealed. Essential influence of the adverse pressure gradient on evolution of disturbances is shown. Comparison of varicose instability of the streaky structures generated in two different ways (the roughness element as in the given work, and continuous air blowing as in the earlier published work) is the carried out.
46.	Chernoray, Valery, 1975, et al. (author) The role of streamwise structures in the near-field entrainment of plane jet 2001 In: Euromech and Ercoftac colloquium 426, Bergen-Tromsø, Norway. ; , s. 9-10 Conference paper (other academic/artistic)
47.	Chernoray, Valery, 1975, et al. (author) Visualization of sinusoidal and varicose instabilities of streaks in a boundary layer 2006 In: ERCOFTAC SIG 33 Workshop, Stockholm. ; , s. 29-30 Conference paper (peer-reviewed)
48.	Chernoray, Valery, 1975, et al. (author) Visualization of sinusoidal and varicose instabilities of streaks in a boundary layer 2006 In: Journal of Visualization. - 1343-8875 .- 1386-6478. ; 9:4 Journal article (peer-reviewed)abstract Nonlinear instabilities of boundary layer streaks are investigated experimentally. Extensive measurements visualizing the sinusoidal and varicose instabilities of streaky structures at nonlinear stage of the breakdown process in boundary layer are presented. The flow behaviour in the course of spatial evolution of the streaky structures with a secondary high-frequency disturbance generated on them is discussed. Various scenarios of origination and development of coherent vortex structures examined in physical experiments are considered. Specific features of the development of sinusoidal and varicose cases of destruction of the steady streamwise streaks are demonstrated, such as transverse and streamwise modulations of the streak by the secondary-disturbance frequency, appearance of new streaky structures in the downstream direction, and emergence and evolution of unsteady Λ-shaped structures localized in space in both cases.
49.	Gorev, V.N., et al. (author) Experimental research of streamwise vortices in a swept-wing boundary layer and its secondary instability 2009 In: Proc. of EUCASS conf., Versailles, France. Conference paper (other academic/artistic)
50.	Grek, G.R., et al. (author) Experimental study of a Λ-structure development and its transformation into the turbulent spot 2000 In: Current Science. - 0011-3891. ; 79:6, s. 781-789 Journal article (peer-reviewed)abstract This paper presents the results of experimental research on the characteristics of Λ-structures, their development, and the mechanism of their transformation into turbulent spots. It has been shown that an isolated Λ-structure can damp as well as increase downstream and transform into a turbulent spot. The structure of the associated disturbances consists of two counter-rotating vortices (the "legs" of disturbance) closed by a "head" at the leading edge. The difference between the two types is that the Λ-structure that damps is a kind of a hairpin vortex which does not cross the upper boundary layer edge; the "head" of the increasing Λ-structure crosses the upper boundary layer edge and the disturbance attains the form of the Greek letter Λ. It has been proposed that the increasing Λ-structure is connected with the development of secondary high frequency disturbances on the "legs" of the structure. The reason for this is probably the local transverse velocity gradient ∂u / ∂z on the "legs" of the Λ-structure, which creates conditions for the development of secondary disturbances in it. It has also been shown that the frequency of the secondary disturbance decreases because of the continuous extension of a localized disturbance under its downstream propagation. Secondary high frequency breakdown of structures is also observed when there is periodical generation.

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