Progress of the Volume FEL (VFEL) experiments in millimeter range

Use of non one-dimensional distributed feedback in VFEL gives possibility of frequency tuning in wide range. In present work dependence of lasing process on the angle between resonant diffraction grating grooves and direction of electron beam velocity is discussed.Comment: LaTeX, 9 eps figures, to be presented at FEL2002 Conferenc

Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL

Current status of turbulent dynamo theory: From large-scale to small-scale dynamos

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of the turbulence, power develops on large scales, which is not present in non-helical small-scale turbulent dynamos. At small length scales, differences occur in connection with the dissipation cutoff scales associated with the respective value of the magnetic Prandtl number. These differences are found to be independent of whether or not there is large-scale dynamo action. However, large-scale dynamos in homogeneous systems are shown to suffer from resistive slow-down even at intermediate length scales. The results from simulations are connected to mean field theory and its applications. Recent work on helicity fluxes to alleviate large-scale dynamo quenching, shear dynamos, nonlocal effects and magnetic structures from strong density stratification are highlighted. Several insights which arise from analytic considerations of small-scale dynamos are discussed.Comment: 36 pages, 11 figures, Spa. Sci. Rev., submitted to the special issue "Magnetism in the Universe" (ed. A. Balogh

First Observation of the Cabibbo-suppressed Decays Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+ and Measurement of their Branching Ratios

We report the first observation of two Cabibbo-suppressed decay modes, Xi_c+ -> Sigma+ pi- pi+ and Xi_c+ -> Sigma- pi+ pi+. We observe 59+/-14 over a background of 87, and 22+/-8 over a background of 13 events, respectively, for the signals. The data were accumulated using the SELEX spectrometer during the 1996-1997 fixed target run at Fermilab, chiefly from a 600GeV/c Sigma- beam. The branching ratios of the decays relative to the Cabibbo--favored Xi_c+ -> Xi- pi+ pi+ are measured to be B(Xi_c+ -> Sigma+ pi- pi+)/B(Xi_c+ -> Xi- pi+ pi+) = 0.48+/-0.20, and B(Xi_c+ -> Sigma- pi+ pi+)/B(Xi_c+ -> Xi- pi+ pi+) = 0.18+/-0.09, respectively. We also report branching ratios for the same decay modes of the Lambda_c+ relative to Lambda_c+ -> p K- pi+.Comment: 15 pages, 5 figures, version 2 as accepted in PL

Nuclear Dependence Of Charm Production

Using data taken by SELEX during the 1996-1997 fixed target run at Fermilab, we study the production of charmed hadrons on copper and carbon targets with ∑ -, p, π -, and π + beams. Parametrizing the dependence of the inclusive production cross section on the atomic number A as A α, we determine α for D +, D 0, D s +, D +(2010), Λ c +, and their respective anti-particles, as a function of their transverse momentum p t and scaled longitudinal momentum x F . Within our statistics there is no dependence of α on x F for any charm species for the interval 0.1<x F <1.0. The average value of α for charm production by pion beams is α meson=0.850±0.028. This is somewhat larger than the corresponding average α baryon=0.755±0.016 for charm production by baryon beams (∑ -, p). © 2009 Springer-Verlag/Società Italiana di Fisica.644637644Cobbaert, H., (1987) Phys. Lett. B, 191, p. 456. , 10.1016/0370-2693(87)90639-3 1987PhLB.191.456CCobbaert, H., (1988) Phys. Lett. B, 206, p. 546. , 10.1016/0370-2693(88)91627-9Cobbaert, H., (1988) Phys. Lett. B, 213, p. 395. , 10.1016/0370-2693(88)91783-2 1988PhLB.213.395CLeitch, M.J., (2000) Phys. Rev. Lett., 84, p. 3256. , 10.1103/PhysRevLett.84.3256 2000PhRvL.84.3256L arXiv:nucl-ex/9909007Alessandro, B., Alexa, C., Arnaldi, R., Atayan, M., Baglin, C., Baldit, A., Beole, S., Willis, N., Charmonium production and nuclear absorption in p-A interactions at 450 GeV (2004) European Physical Journal C, 33 (1), pp. 31-40. , DOI 10.1140/epjc/s2003-01539-yAbt, I., (2009) Eur. Phys. J. C, 60, p. 525. , 10.1140/epjc/s10052-009-0965-7 2009EPJC.60.525A arXiv:0812.0734 [hep-ex]Heller, K.J., (1977) Phys. Rev. D, 16, p. 2737. , 10.1103/PhysRevD.16.2737 1977PhRvD.16.2737HSkubic, P., (1978) Phys. Rev. D, 18, p. 3115. , 10.1103/PhysRevD.18.3115 1978PhRvD.18.3115SAleev, A.N., (1987) Sov. J. Nucl. Phys., 46, p. 657. , [Yad. Fiz. 46, 1127 (1987)]Vecko, M., (1989) Czech. J. Phys. B, 39, p. 297. , 10.1007/BF01597781 1989CzJPh.39.297VAdamovich, M., (1992) Phys. Lett. B, 284, p. 453. , 10.1016/0370-2693(92)90460-L 1992PhLB.284.453AAlves, G.A., (1993) Phys. Rev. Lett., 70, p. 722. , 10.1103/PhysRevLett.70.722 1993PhRvL.70.722AAlves, G.A., (1994) Phys. Rev. D, 49, p. 4317. , 10.1103/PhysRevD.49.R4317 1994PhRvD.49.4317ALeitch, M.J., (1994) Phys. Rev. Lett., 72, p. 2542. , 10.1103/PhysRevLett.72.2542 1994PhRvL.72.2542LAdamovich, M., (1997) Nucl. Phys. B, 495, p. 3. , 10.1016/S0550-3213(97)00223-X 1997NuPhB.495.3AApanasevich, L., (1997) Phys. Rev. D, 56, p. 1391. , 10.1103/PhysRevD.56.1391 1997PhRvD.56.1391A arXiv:hep-ex/9702014Abt, I., (2007) Eur. Phys. J. C, 52, p. 531. , 10.1140/epjc/s10052-007-0427-z 2007EPJC.52.531A arXiv:0708.1443 [hep-ex]Duffy, M.E., (1985) Phys. Rev. Lett., 55, p. 1816. , 10.1103/PhysRevLett.55.1816 1985PhRvL.55.1816DVogt, R., The A dependence of open charm and bottom production (2003) International Journal of Modern Physics E, 12 (2), pp. 211-269. , DOI 10.1142/S0218301303001272Lourenco, C., Wohri, H.K., Heavy-flavour hadro-production from fixed-target to collider energies (2006) Physics Reports, 433 (3), pp. 127-180. , DOI 10.1016/j.physrep.2006.05.005, PII S0370157306001815Frawley, A.D., Ullrich, T., Vogt, R., (2008) Phys. Rept., 462, p. 125. , 10.1016/j.physrep.2008.04.002 2008PhR.462.125F arXiv:0806.1013 [nucl-ex]Russ, J.S., (1998) Proceedings of the 29th International Conference on High Energy Physics II World Scientific Singapore, 1259. , A. Astbury (eds), et al. arXiv:hep-ex/9812031Russ, J.S., (1998) Proceedings of the 29th International Conference on High Energy Physics, 2, p. 1259. , ed. by A. Astbury, et al. (World Scientific, Singapore) arXiv:hep-ex/9812031Engelfried, J., (1999) Nucl. Instrum. Methods A, 431, p. 53. , 10.1016/S0168-9002(99)00043-1 1999NIMPA.431.53E arXiv:hep-ex/9811001Kushnirenko, A., Alkhazov, G., Atamantchouk, A.G., Balatz, M.Y., Bondar, N.F., Cooper, P.S., Dauwe, L.J., Vishnyakov, V.E., Precision measurements of the ∧c+ and D 0 lifetimes (2001) Physical Review Letters, 86 (23), pp. 5243-5246. , DOI 10.1103/PhysRevLett.86.5243Garcia, F.G., (2002) Phys. Lett. B, 528, p. 49. , 10.1016/S0370-2693(01)01484-8 2002PhLB.528.49S arXiv:hep-ex/0109017Kaya, M., (2003) Phys. Lett. B, 558, p. 34. , 10.1016/S0370-2693(03)00246-6 2003PhLB.558.34S arXiv:hep-ex/0302039Brodsky, S.J., Kopeliovich, B., Schmidt, I., Soffer, J., (2006) Phys. Rev. D, 73, p. 113005. , 2006PhRvD.73k3005B arXiv:hep-ph/0603238Adamovich, M.I., (2003) Eur. Phys. J. C, 26, p. 357. , 10.1140/epjc/s2002-01073-6 2003EPJC.26.357WA. Blanco-Covarrubias, et al. (SELEX Collaboration), in preparatio

ПОВЫШЕНИЕ КАЧЕСТВА ПРОВЕДЕНИЯ ЗАНЯТИЙ ПО ДИСЦИПЛИНЕ "СУДЕБНАЯ МЕДИЦИНА"_

Article is devoted to the pedagogical experiment made when teaching discipline «Forensic medicine». The new type of a task on the sequence of actions at survey of a corpse (scene) which is used in educational process at department of forensic medicine and the medical right of MGMSU of A.I. Evdokimov is developed and offered. Results of the made pedagogical experiment are presented.Статья посвящена педагогическому эксперименту, проведенному при преподавании дисциплины «Судебная медицина». Разработан и предложен новый тип задачи на последовательность действий при осмотре трупа (места происшествия), который используется в учебном процессе на кафедре судебной медицины и медицинского права МГМСУ им. А.И. Евдокимова. Представлены результаты проведенного педагогического эксперимента