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Inner-shell soft X-ray lasers in Ne-like ions driven by optical field ionization

Optics Communications 182:1-3 (2000) 209-219

Abstract:

A novel short-wavelength laser based upon monopole excitation of inner-shell electrons in Ne-like ions following optical field ionization with circularly polarized radiation is discussed. Calculations of the small-signal gain are presented for one such ion, Ne-like Ar, for which a small-signal gain of 13.7 cm-1 is predicted on the 2s → 2p hole transition at 15.8 nm for an Ar pressure of 50 mbar. Extensions of this approach to other inner-shell transitions are suggested. © 2000 Elsevier Science B.V. All rights reserved.
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Measurement of the proton structure function F2 at very low Q2 at HERA

Physics Letters B Elsevier 487:1-2 (2000) 53-73

Authors:

ZEUS Collaboration, J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S De Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, H-P Jakob, A Kappes, UF Katz, R Kerger, E Paul, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno, HY Jeoung, JY Kim, JH Lee, IT Lim, KJ Ma, MY Pac, A Caldwell, W Liu, X Liu, B Mellado, S Paganis, S Sampson, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Klimek, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski, B Bednarek, K Jeleń, D Kisielewska, AM Kowal, T Kowalski, M Przybycień, E Rulikowska-Zarȩbska, L Suszycki, D Szuba, A Kotański, LAT Bauerdick, U Behrens, JK Bienlein, C Burgard, D Dannheim, K Desler, G Drews, A Fox-Murphy, U Fricke, F Goebel, P Göttlicher, R Graciani, T Haas, W Hain, GF Hartner, D Hasell, K Hebbel, KF Johnson, M Kasemann, W Koch, U Kötz, H Kowalski, L Lindemann, B Löhr, M Martı́nez, M Milite, T Monteiro, M Moritz, D Notz, F Pelucchi, MC Petrucci, M Rohde, PRB Saull, AA Savin, U Schneekloth, F Selonke, M Sievers, S Stonjek, E Tassi, G Wolf, U Wollmer, C Youngman, W Zeuner, C Coldewey, A Lopez-Duran Viani, A Meyer, S Schlenstedt, PB Straub, G Barbagli, E Gallo, P Pelfer, G Maccarrone, L Votano, A Bamberger, A Benen, S Eisenhardt, P Markun, H Raach, S Wölfle, PJ Bussey, M Bell, AT Doyle, SW Lee, A Lupi, N Macdonald, GJ McCance, DH Saxon, LE Sinclair, IO Skillicorn, R Waugh, I Bohnet, N Gendner, U Holm, A Meyer-Larsen, H Salehi, K Wick, A Garfagnini, I Gialas, LK Gladilin, D Kçira, R Klanner, E Lohrmann, G Poelz, F Zetsche, R Goncalo, KR Long, DB Miller, AD Tapper, R Walker, U Mallik, P Cloth, D Filges, T Ishii, M Kuze, K Nagano, K Tokushuku, S Yamada, Y Yamazaki, SH Ahn, SB Lee, SK Park, H Lim, IH Park, D Son, F Barreiro, G Garcı́a, C Glasman, O González, L Labarga, J del Peso, I Redondo, J Terrón, M Barbi, F Corriveau, DS Hanna, A Ochs, S Padhi, M Riveline, DG Stairs, M Wing, T Tsurugai, A Antonov, V Bashkirov, M Danilov, BA Dolgoshein, D Gladkov, V Sosnovtsev, S Suchkov, RK Dementiev, PF Ermolov, Yu A Golubkov, II Katkov, LA Khein, NA Korotkova, IA Korzhavina, VA Kuzmin, O Yu Lukina, AS Proskuryakov, LM Shcheglova, AN Solomin, NN Vlasov, SA Zotkin, C Bokel, M Botje, N Brümmer, J Engelen, S Grijpink, E Koffeman, P Kooijman, S Schagen, A van Sighem, H Tiecke, N Tuning, JJ Velthuis, J Vossebeld, L Wiggers, E de Wolf, D Acosta, B Bylsma, LS Durkin, J Gilmore, CM Ginsburg, CL Kim, TY Ling, S Boogert, AM Cooper-Sarkar, RCE Devenish, J Große-Knetter, T Matsushita, A Quadt, O Ruske, MR Sutton, R Walczak, A Bertolin, R Brugnera, R Carlin, F Dal Corso, U Dosselli, S Dusini, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, M Turcato, C Voci, L Adamczyk, L Iannotti, BY Oh, JR Okrasiński, WS Toothacker, JJ Whitmore, Y Iga, G D'Agostini, G Marini, A Nigro, C Cormack, JC Hart, NA McCubbin, TP Shah, D Epperson, C Heusch, HF-W Sadrozinski, A Seiden, R Wichmann, DC Williams, N Pavel, H Abramowicz, S Dagan, S Kananov, A Kreisel, A Levy, T Abe, T Fusayasu, K Umemori, T Yamashita, R Hamatsu, T Hirose, M Inuzuka, S Kitamura, T Nishimura, M Arneodo, N Cartiglia, R Cirio, M Costa, MI Ferrero, S Maselli, V Monaco, C Peroni, M Ruspa, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, C-P Fagerstroem, R Galea, T Koop, GM Levman, JF Martin, RS Orr, S Polenz, A Sabetfakhri, D Simmons, JM Butterworth, CD Catterall, ME Hayes, EA Heaphy, TW Jones, JB Lane, BJ West, J Ciborowski, R Ciesielski, G Grzelak, RJ Nowak, JM Pawlak, R Pawlak, B Smalska, T Tymieniecka, AK Wróblewski, JA Zakrzewski, AF Żarnecki, M Adamus, T Gadaj, O Deppe, Y Eisenberg, D Hochman, U Karshon, WF Badgett, D Chapin, R Cross, C Foudas, S Mattingly, DD Reeder, WH Smith, A Vaiciulis, T Wildschek, M Wodarczyk, A Deshpande, S Dhawan, VW Hughes, S Bhadra, C Catterall, JE Cole, WR Frisken, R Hall-Wilton, M Khakzad, S Menary
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Measurement of azimuthal asymmetries in deep inelastic scattering

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 481:2-4 (2000) 199-212

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, E Paul, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno, HY Jeoung, JY Kim, JH Lee, IT Lim, KJ Ma, MY Pac, A Caldwell, W Liu, X Liu, B Mellado, S Paganis, S Sampson, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Klimek, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski

Abstract:

The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron-proton scattering with the ZEUS detector at HERA. Measurements of the dependence of the moments of this distribution on the transverse momenta of the charged hadrons are presented. Asymmetries that can be unambiguously attributed to perturbative QCD processes have been observed for the first time. (C) 2000 Elsevier Science B.V.
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Measurement of inclusive(D(s)(±)) photoproduction at HERA ZEUS collaboration

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 481:2-4 (2000) 213-227

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, E Paul, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno, HY Jeoung, JY Kim, JH Lee, IT Lim, KJ Ma, MY Pac, A Caldwell, W Liu, X Liu, B Mellado, S Paganis, S Sampson, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Klimek, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski

Abstract:

The first measurement of inclusive D(s)(±) photoproduction at HERA has been performed with the ZEUS detector for photon-proton centre-of-mass energies 130 < W < 280GeV. The measured cross section for 3 < p (is perpendicular to)/(D(s)) < 12GeV and |η(D(s))| < 1.5 is σ(ep → D(s)X) = 3.79 ± 0.59(stat.) -0.46/+0.26 (syst.) ± 0.94(br.)nb, where the last error arises from the uncertainty in the D(s)(±) decay branching ratio. The measurements are compared with inclusive D*(±) photoproduction cross sections in the same kinematic region and with QCD calculations. The D(s)(±) cross sections lie above a fixed-order next-to-leading order calculation and agree better with a tree-level O(αα(s)/3) calculation that was tuned to describe the ZEUS D*(±) cross sections. The ratio of D(s)(±) to D*(±) cross sections is 0.41 ± 0.07 (stat.) -0.05/+0.03 (syst.) ± 0.10(br.). From this ratio, the strangeness-suppression factor in charm photoproduction, within the LUND string fragmentation model, has been calculated to be γ(s) = 0.27 ± 0.05 ± 0.07(br.). The cross-section ratio and γ(s) are in good agreement with those obtained in charm production in e+e- annihilation. (C) 2000 Elsevier Science B.V.
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The Q2 dependence of dijet cross sections in γp interactions at HERA

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 479:1-3 (2000) 37-52

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S De Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, E Paul, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno

Abstract:

The dependence of the photon structure on the photon virtuality, Q2, is studied by measuring the reaction e+p → e+ + jet + jet + X at photon-proton centre-of-mass energies 134 < W < 223 GeV. Events have been selected in the Q2 ranges ≃ 0 GeV2, 0.1-0.55 GeV2, and 1.5-4.5 GeV2, having two jets with transverse energy E(T)/(jet) > 5.5 GeV in the final state. The dijet cross section has been measured as a function of the fractional momentum of the photon participating in the hard process, x(γ)/(OBS). The ratio of the dijet cross section with x(γ)/(OBS) < 0.75 to that with x(γ)/(OBS) > 0.75 decreases as Q2 increases. The data are compared with the predictions of NLO pQCD and leading-order Monte Carlo programs using various parton distribution functions of the photon. The measurements can be interpreted in terms of a resolved photon component that falls with Q2 but remains present at values of Q2 up to 4.5 GeV2. However, none of the models considered gives a good description of the data. (C) Copyright 2000 Elsevier Science B.V.
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