D. Kirillov - WASA-at-COSY Collaboration

D. Kirillov
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Publications Authored By D. Kirillov

Exclusive measurements of the quasi-free $pn \to pp\pi^-$ and $pp \to pp\pi^0$ reactions have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $T_p = 0. Read More

The search for 4He-eta bound states was performed with the WASA-at-COSY facility via the measurement of the excitation function for the dd->3He n pi0 and dd->3He p pi- processes. The beam momentum was varied continuously between 2.127 GeV/c and 2. Read More

Using the production reactions $pd\to {}^3\mbox{He}\,\omega$ and $pp\to pp\omega$, the Dalitz plot distribution for the $\omega \to \pi^+ \pi^- \pi^0$ decay is studied with the WASA detector at COSY, based on a combined data sample of $ (4.408\pm 0.042) \times 10^4$ events. Read More

Various theoretical calculations based on QCD or hadronic interactions predict that in addition to the recently observed dibaryon resonance $d^*(2380)$ with $I(J^P) = 0(3^+)$ there should also exist a dibaryon resonance with mirrored quantum numbers $I(J^P) = 3(0^+)$. We report here on a search for such a $NN$-decoupled state in data on the $pp \to pp\pi^+\pi^+\pi^-\pi^-$ reaction. Since no clear-cut evidence has been found, we give upper limits for the production cross section of such a resonance in the mass range 2280 - 2500 MeV. Read More

We report on a high-statistics measurement of the most basic double pionic fusion reaction $\vec{n}p \to d\pi^0\pi^0$ over the energy region of the $d^*(2380)$ resonance by use of a polarized deuteron beam and observing the double fusion reaction in the quasifree scattering mode. The measurements were performed with the WASA detector setup at COSY. The data reveal substantial analyzing powers and confirm conclusions about the $d^*$ resonance obtained from unpolarized measurements. Read More

The WASA-at-COSY experiment has collected $3\times10^{7}$ events with $\eta$-mesons produced via the reaction $pd\rightarrow{^{3}\textrm{He}}\eta$ at $\textrm{T} = 1.0 \textrm{GeV}$. Using this data set, we evaluate the branching ratios of the decays $\eta\to\pi^{+}\pi^{-}\gamma$, $\eta\to e^{+}e^{-}\gamma$, $\eta\to\pi^{+}\pi^{-}e^{+}e^{-}$ and $\eta\to e^{+}e^{-}e^{+}e^{-}$. Read More

Exclusive measurements of the quasi-free $np \to np\pi^0\pi^0$ reaction have been performed by means of $dp$ collisions at $T_d$ = 2.27 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2. Read More

Exclusive and kinematically complete measurements of the double pionic fusion to $^3$He have been performed in the energy region of the so-called ABC effect, which denotes a pronounced low-mass enhancement in the $\pi\pi$-invariant mass spectrum. The experiments were carried out with the WASA detector setup at COSY. Similar to the observations in the basic $pn \to d \pi^0\pi^0$ reaction and in the $dd \to ^4$He$\pi^0\pi^0$ reaction, the data reveal a correlation between the ABC effect and a resonance-like energy dependence in the total cross section. Read More

Authors: P. Adlarson1, W. Augustyniak2, W. Bardan3, M. Bashkanov4, F. S. Bergmann5, M. Berłowski6, H. Bhatt7, M. Büscher8, H. Calén9, I. Ciepał10, H. Clement11, D. Coderre12, E. Czerwiński13, K. Demmich14, E. Doroshkevich15, R. Engels16, A. Erven17, W. Erven18, W. Eyrich19, P. Fedorets20, K. Föhl21, K. Fransson22, F. Goldenbaum23, P. Goslawski24, A. Goswami25, K. Grigoryev26, C. --O. Gullström27, F. Hauenstein28, L. Heijkenskjöld29, V. Hejny30, M. Hodana31, B. Höistad32, N. Hüsken33, A. Jany34, B. R. Jany35, L. Jarczyk36, T. Johansson37, B. Kamys38, G. Kemmerling39, F. A. Khan40, A. Khoukaz41, D. A. Kirillov42, S. Kistryn43, H. Kleines44, B. Kłos45, M. Krapp46, W. Krzemień47, P. Kulessa48, A. Kupść49, K. Lalwani50, D. Lersch51, B. Lorentz52, A. Magiera53, R. Maier54, P. Marciniewski55, B. Mariański56, M. Mikirtychiants57, H. --P. Morsch58, P. Moskal59, H. Ohm60, I. Ozerianska61, E. Perez del Rio62, N. M. Piskunov63, P. Podkopał64, D. Prasuhn65, A. Pricking66, D. Pszczel67, K. Pysz68, A. Pyszniak69, C. F. Redmer70, J. Ritman71, A. Roy72, Z. Rudy73, S. Sawant74, S. Schadmand75, T. Sefzick76, V. Serdyuk77, R. Siudak78, T. Skorodko79, M. Skurzok80, J. Smyrski81, V. Sopov82, R. Stassen83, J. Stepaniak84, E. Stephan85, G. Sterzenbach86, H. Stockhorst87, H. Ströher88, A. Szczurek89, A. Täschner90, A. Trzciński91, R. Varma92, G. J. Wagner93, M. Wolke94, A. Wrońska95, P. Wüstner96, P. Wurm97, A. Yamamoto98, L. Yurev99, J. Zabierowski100, M. J. Zieliński101, A. Zink102, J. Złomańczuk103, P. {Ż}uprański104, M. {Ż}urek105, R. L. Workman106, W. J. Briscoe107, I. I. Strakovsky108
Affiliations: 1WASA-at-COSY Collaboration, 2WASA-at-COSY Collaboration, 3WASA-at-COSY Collaboration, 4WASA-at-COSY Collaboration, 5WASA-at-COSY Collaboration, 6WASA-at-COSY Collaboration, 7WASA-at-COSY Collaboration, 8WASA-at-COSY Collaboration, 9WASA-at-COSY Collaboration, 10WASA-at-COSY Collaboration, 11WASA-at-COSY Collaboration, 12WASA-at-COSY Collaboration, 13WASA-at-COSY Collaboration, 14WASA-at-COSY Collaboration, 15WASA-at-COSY Collaboration, 16WASA-at-COSY Collaboration, 17WASA-at-COSY Collaboration, 18WASA-at-COSY Collaboration, 19WASA-at-COSY Collaboration, 20WASA-at-COSY Collaboration, 21WASA-at-COSY Collaboration, 22WASA-at-COSY Collaboration, 23WASA-at-COSY Collaboration, 24WASA-at-COSY Collaboration, 25WASA-at-COSY Collaboration, 26WASA-at-COSY Collaboration, 27WASA-at-COSY Collaboration, 28WASA-at-COSY Collaboration, 29WASA-at-COSY Collaboration, 30WASA-at-COSY Collaboration, 31WASA-at-COSY Collaboration, 32WASA-at-COSY Collaboration, 33WASA-at-COSY Collaboration, 34WASA-at-COSY Collaboration, 35WASA-at-COSY Collaboration, 36WASA-at-COSY Collaboration, 37WASA-at-COSY Collaboration, 38WASA-at-COSY Collaboration, 39WASA-at-COSY Collaboration, 40WASA-at-COSY Collaboration, 41WASA-at-COSY Collaboration, 42WASA-at-COSY Collaboration, 43WASA-at-COSY Collaboration, 44WASA-at-COSY Collaboration, 45WASA-at-COSY Collaboration, 46WASA-at-COSY Collaboration, 47WASA-at-COSY Collaboration, 48WASA-at-COSY Collaboration, 49WASA-at-COSY Collaboration, 50WASA-at-COSY Collaboration, 51WASA-at-COSY Collaboration, 52WASA-at-COSY Collaboration, 53WASA-at-COSY Collaboration, 54WASA-at-COSY Collaboration, 55WASA-at-COSY Collaboration, 56WASA-at-COSY Collaboration, 57WASA-at-COSY Collaboration, 58WASA-at-COSY Collaboration, 59WASA-at-COSY Collaboration, 60WASA-at-COSY Collaboration, 61WASA-at-COSY Collaboration, 62WASA-at-COSY Collaboration, 63WASA-at-COSY Collaboration, 64WASA-at-COSY Collaboration, 65WASA-at-COSY Collaboration, 66WASA-at-COSY Collaboration, 67WASA-at-COSY Collaboration, 68WASA-at-COSY Collaboration, 69WASA-at-COSY Collaboration, 70WASA-at-COSY Collaboration, 71WASA-at-COSY Collaboration, 72WASA-at-COSY Collaboration, 73WASA-at-COSY Collaboration, 74WASA-at-COSY Collaboration, 75WASA-at-COSY Collaboration, 76WASA-at-COSY Collaboration, 77WASA-at-COSY Collaboration, 78WASA-at-COSY Collaboration, 79WASA-at-COSY Collaboration, 80WASA-at-COSY Collaboration, 81WASA-at-COSY Collaboration, 82WASA-at-COSY Collaboration, 83WASA-at-COSY Collaboration, 84WASA-at-COSY Collaboration, 85WASA-at-COSY Collaboration, 86WASA-at-COSY Collaboration, 87WASA-at-COSY Collaboration, 88WASA-at-COSY Collaboration, 89WASA-at-COSY Collaboration, 90WASA-at-COSY Collaboration, 91WASA-at-COSY Collaboration, 92WASA-at-COSY Collaboration, 93WASA-at-COSY Collaboration, 94WASA-at-COSY Collaboration, 95WASA-at-COSY Collaboration, 96WASA-at-COSY Collaboration, 97WASA-at-COSY Collaboration, 98WASA-at-COSY Collaboration, 99WASA-at-COSY Collaboration, 100WASA-at-COSY Collaboration, 101WASA-at-COSY Collaboration, 102WASA-at-COSY Collaboration, 103WASA-at-COSY Collaboration, 104WASA-at-COSY Collaboration, 105WASA-at-COSY Collaboration, 106SAID Data Analysis Center, 107SAID Data Analysis Center, 108SAID Data Analysis Center

New data on quasifree polarized neutron-proton scattering, in the region of the recently observed $d^*$ resonance structure, have been obtained by exclusive and kinematically complete high-statistics measurements with WASA at COSY. This paper details the determination of the beam polarization, checks of the quasifree character of the scattering process, on all obtained $A_y$ angular distributions and on the new partial-wave analysis, which includes the new data producing a resonance pole in the $^3D_3$-$^3G_3$ coupled partial waves at ($2380\pm10 - i40\pm5$) MeV -- in accordance with the $d^*$ dibaryon resonance hypothesis. The effect of the new partial-wave solution on the description of total and differential cross section data as well as specific combinations of spin-correlation and spin-transfer observables available from COSY-ANKE measurements at $T_d$ = 2. Read More

Charge symmetry breaking (CSB) observables are a suitable experimental tool to examine effects induced by quark masses on the nuclear level. Previous high precision data from TRIUMF and IUCF are currently used to develop a consistent description of CSB within the framework of chiral perturbation theory. In this work the experimental studies on the reaction dd->4He{\pi}0 have been extended towards higher excess energies in order to provide information on the contribution of p-waves in the final state. Read More


Dalitz plot distribution of the $\eta\to\pi^+\pi^-\pi^0$ decay is determined using a data sample of $1.2\cdot 10^7$ $\eta$ mesons from $pd\to ^3\textrm{He}\eta$ reaction at 1 GeV collected by the WASA detector at COSY. Read More


We present new data for angular distributions and on the cross section ratio of the p + d -> 3He + eta reaction at excess energies of Q = 48.8 MeV and Q = 59.8 MeV. Read More


Exclusive measurements of the quasi-free $pn \to pp\pi^0\pi^-$ reaction have been performed by means of $pd$ collisions at $T_p$ = 1.2 GeV using the WASA detector setup at COSY. Total and differential cross sections have been obtained covering the energy region $\sqrt s$ = (2. Read More


An exclusive measurement of the dd -> 3He n \pi 0 reaction was carried at a beam momentum of p = 1.2 GeV/c using the WASA-at-COSY facility. For the first time data on the total cross section as well as differential distributions were obtained. Read More

We present new data for the polarization observables of the final state proton in the $^{1}H(\vec{\gamma},\vec{p})\pi^{0}$ reaction. These data can be used to test predictions based on hadron helicity conservation (HHC) and perturbative QCD (pQCD). These data have both small statistical and systematic uncertainties, and were obtained with beam energies between 1. Read More


Intensive theoretical and experimental efforts over the past decade have aimed at explaining the discrepancy between data for the proton electric to magnetic form factor ratio, $G_{E}/G_{M}$, obtained separately from cross section and polarization transfer measurements. One possible explanation for this difference is a two-photon-exchange (TPEX) contribution. In an effort to search for effects beyond the one-photon-exchange or Born approximation, we report measurements of polarization transfer observables in the elastic $H(\vec{e},e'\vec{p})$ reaction for three different beam energies at a fixed squared momentum transfer $Q^2 = 2. Read More


Among the most fundamental observables of nucleon structure, electromagnetic form factors are a crucial benchmark for modern calculations describing the strong interaction dynamics of the nucleon's quark constituents; indeed, recent proton data have attracted intense theoretical interest. In this letter, we report new measurements of the proton electromagnetic form factor ratio using the recoil polarization method, at momentum transfers Q2=5.2, 6. Read More

This is the summary of the 'International Workshop on eta--Nucleus Physics' held in Juelich, May 8--12, 2006. Each talk is represented by an extended abstract. At the same time the document provides a progress report of the corresponding working group. Read More

Several processes of meson production in proton-deuteron collisions have been measured simultaneously using a calibrated magnetic spectrograph. Among these processes, the $\eta$ meson is seen clearly as a sharp missing--mass peak on a slowly varying background in the $p+d\to ^3\textrm{He} +X$ reaction. Knowing the kinematics of the other reactions with well determined masses, it is possible to deduce a precise mass for the $\eta$ meson. Read More