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Abashian-Booth-Crowe resonance structure in the double pionic fusion to $^{4}$ He

P. Adlarson¹, W. Augustyniak², W. Bardan³, M. Bashkanov^4,5, T. Bednarski³, F. S. Bergmann⁶, M. Berłowski⁷, H. Bhatt⁸, K.-T. Brinkmann⁹ et al. (WASA-at-COSY Collaboration)

K.-T. Brinkmann⁹, M. Büscher^10,11, H. Calén¹, H. Clement^4,5, D. Coderre^10,11,12, E. Czerwiński³, K. Demmich⁶, E. Doroshkevich^4,5, R. Engels^10,11, W. Erven^13,11, W. Eyrich¹⁴, P. Fedorets^10,11,15, K. Föhl¹⁶, K. Fransson¹, F. Goldenbaum^10,11, P. Goslawski⁶, K. Grigoryev^10,11,17, C.-O. Gullström¹, F. Hauenstein¹⁴, L. Heijkenskjöld¹, V. Hejny^10,11, F. Hinterberger⁹, M. Hodana^3,10,11, B. Höistad¹, C. Husmann⁶, A. Jany³, B. R. Jany³, L. Jarczyk³, T. Johansson¹, B. Kamys³, G. Kemmerling^13,11, F. A. Khan^10,11, A. Khoukaz⁶, S. Kistryn³, J. Klaja³, H. Kleines^13,11, B. Kłos¹⁸, W. Krzemień³, P. Kulessa¹⁹, A. Kupść¹, K. Lalwani^8,*, D. Lersch^10,11, L. Li¹⁴, B. Lorentz^10,11, A. Magiera³, R. Maier^10,11, P. Marciniewski¹, B. Mariański², M. Mikirtychiants^12,17, H.-P. Morsch², P. Moskal³, B. K. Nandi⁸, S. Niedźwiecki³, H. Ohm^10,11, I. Ozerianska^3,10,11, C. Pauly^10,11,†, E. Perez del Rio^4,5, Y. Petukhov²⁰, P. Pluciński^1,‡, P. Podkopał^3,10,11, D. Prasuhn^10,11, A. Pricking^4,5, D. Pszczel⁷, K. Pysz¹⁹, A. Pyszniak^1,3, C. F. Redmer^1,§, J. Ritman^10,11,12, A. Roy²¹, Z. Rudy³, S. Sawant^8,10,11, S. Schadmand^10,11, A. Schmidt¹⁴, V. Serdyuk^10,11,22, N. Shah^8,∥, R. Siudak¹⁹, T. Skorodko^4,5, M. Skurzok³, J. Smyrski³, V. Sopov¹⁵, R. Stassen^10,11, J. Stepaniak⁷, G. Sterzenbach^10,11, H. Stockhorst^10,11, H. Ströher^10,11, A. Szczurek¹⁹, T. Tolba^10,11,¶, A. Trzciński², R. Varma⁸, P. Vlasov⁹, G. J. Wagner^4,5, W. Węglorz¹⁸, M. Wolke¹, A. Wrońska³, P. Wüstner^13,11, P. Wurm^10,11, A. Yamamoto²³, X. Yuan²⁴, L. Yurev²², J. Zabierowski²⁵, C. Zheng²⁴, M. J. Zieliński³, W. Zipper¹⁸, J. Złomańczuk¹, and P. Żuprański² (WASA-at-COSY Collaboration)

¹Division of Nuclear Physics, Department of Physics and Astronomy, Uppsala University, Box 516, 75120 Uppsala, Sweden
²Nuclear Physics Division, National Centre for Nuclear Research, ul. Hoza 69, 00-681 Warsaw, Poland
³Institute of Physics, Jagiellonian University, ul. Reymonta 4, 30-059 Kraków, Poland
⁴Physikalisches Institut, Eberhard-Karls-Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany
⁵Kepler Center for Astro and Particle Physics, University of Tübingen, Auf der Morgenstelle 14, 72076 Tübingen, Germany
⁶Institut für Kernphysik, Westfälische Wilhelms-Universität Münster, Wilhelm-Klemm-Strasse 9, 48149 Münster, Germany
⁷High Energy Physics Department, National Centre for Nuclear Research, ul. Hoza 69, 00-681 Warsaw, Poland
⁸Department of Physics, Indian Institute of Technology Bombay, Powai, Mumbai 400076, Maharashtra, India
⁹Helmholtz-Institut für Strahlen und Kernphysik, Rheinische Friedrich-Wilhelms-Universität Bonn, Nußallee 14-16, 53115 Bonn, Germany
¹⁰Institut für Kernphysik, Forschungszentrum Jülich, 52425 Jülich, Germany
¹¹Jülich Center for Hadron Physics, Forschungszentrum Jülich, 52425 Jülich, Germany
¹²Institut für Experimentalphysik I, Ruhr-Universit¨ Bochum, Universitätsstrasse 150, 44780 Bochum, Germany
¹³Zentralinstitut für Elektronik, Forschungszentrum Jülich, 52425 Jülich, Germany
¹⁴Physikalisches Institut, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erwin-Rommel-Strasse 1, 91058 Erlangen, Germany
¹⁵Institute for Theoretical and Experimental Physics, State Scientific Center of the Russian Federation, Bolshaya Cheremushkinskaya 25, 117218 Moscow, Russia
¹⁶II. Physikalisches Institut, Justus-Liebig-Universität Gießen, Heinrich-Buf-Ring 16, 35392 Giessen, Germany
¹⁷High Energy Physics Division, Petersburg Nuclear Physics Institute, Orlova Rosha 2, 188300 Gatchina, Russia
¹⁸August Chełkowski Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice, Poland
¹⁹The Henryk Niewodniczański Institute of Nuclear Physics, Polish Academy of Sciences, 152 Radzikowskiego Street, 31-342 Kraków, Poland
²⁰Veksler and Baldin Laboratory of High Energiy Physics, Joint Institute for Nuclear Physics, Joliot-Curie 6, 141980 Dubna, Russia
²¹Department of Physics, Indian Institute of Technology Indore, Khandwa Road, Indore 452017, Madhya Pradesh, India
²²Dzhelepov Laboratory of Nuclear Problems, Joint Institute for Nuclear Physics, Joliot-Curie 6, 141980 Dubna, Russia
²³High Energy Accelerator Research Organisation KEK, Tsukuba, Ibaraki 305-0801, Japan
²⁴Institute of Modern Physics, Chinese Academy of Sciences, 509 Nanchang Road, 730000 Lanzhou, China
²⁵Department of Cosmic Ray Physics, National Centre for Nuclear Research, ul. Uniwersytecka 5, 90-950 Łódź, Poland

^*Present address: Department of Physics & Astrophysics, University of Delhi, Delhi 110007, India.
^†Present address: Fachbereich Physik, Bergische Universität Wuppertal, Gaußstrasse 20, 42119 Wuppertal, Germany.
^‡Present address: Department of Physics, Stockholm University, Roslagstullsbacken 21, AlbaNova, 10691 Stockholm, Sweden.
^§Present address: Institut für Kernphysik, Johannes Gutenberg-Universität Mainz, Johann-Joachim-Becher Weg 45, 55128 Mainz, Germany.
^∥Present address: Department of Physics and Astronomy, University of California, Los Angeles, California 90045.
^¶Present address: Albert Einstein Center for Fundamental Physics, Fachbereich Physik und Astronomie, Universität Bern, Sidlerstrasse 5, 3012 Bern, Switzerland.

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Phys. Rev. C 86, 032201(R) – Published 7 September, 2012

DOI: https://doi.org/10.1103/PhysRevC.86.032201

Abstract

Exclusive and kinematically complete high-statistics measurements of the double pionic fusion reaction $d d \to^{4} He π^{0} π^{0}$ have been performed in the energy range 0.8–1.4 GeV covering thus the region of the Abashian-Booth-Crowe effect, which denotes a pronounced low-mass enhancement in the $π π$ invariant mass spectrum. The experiments were carried out with the WASA detector setup at the cooler synchrotron at Forshungszentrum Julich GmbH. Similar to the observation in the basic $p n \to d π^{0} π^{0}$ reaction, the data reveal a correlation between the ABC effect and a resonancelike energy dependence in the total cross section. The maximum occurs at $m = 2.37$ GeV $+$ 2 $m_{N}$ , i.e., at the same position as in the basic reaction. The observed resonance width $Γ \approx 160$ MeV can be understood from broadening due to Fermi motion of the nucleons in initial and final nuclei together with collision damping. Differential cross sections are described equally well by the hypothesis of a $p n$ resonance formation during the reaction process.