Double-Pionic Fusion of Nuclear Systems and the 'ABC' Effect: Approaching a Puzzle by Exclusive and Kinematically Complete Measurements

Journal Article · Fri Feb 06 04:00:00 EST 2009 · Physical Review Letters

DOI:https://doi.org/10.1103/PHYSREVLETT.102.052301· OSTI ID:21180180

Bashkanov, M; Clement, H; Doroshkevich, E; Khakimova, O; Kren, F; Meier, R; Pricking, A; Skorodko, T; Wagner, G J ^[1]; Bargholtz, C; Geren, L; Lindberg, K; Tegner, P -E; Zartova, I ^[2]; Berlowski, M; Stepaniak, J ^[3]; Bogoslawsky, D; Ivanov, G; Jiganov, E; Morosov, B ^[4]

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1. Physikalisches Institut der Universitaet Tuebingen, D-72076 Tuebingen (Germany)
2. Department of Physics, Stockholm University, Stockholm (Sweden)
3. Soltan Institute of Nuclear Studies, Warsaw and Lodz (Poland)
4. Joint Institute for Nuclear Research, Dubna (Russian Federation)

The ABC effect--a puzzling low-mass enhancement in the {pi}{pi} invariant mass spectrum, first observed by Abashian, Booth, and Crowe--is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn{yields}d{pi}{sup 0}{pi}{sup 0} at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a ({pi}{pi}){sub I=L=0} channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a {delta}{delta} system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.

• OSTI ID: 21180180
• Journal Information: Physical Review Letters, Journal Name: Physical Review Letters Journal Issue: 5 Vol. 102; ISSN 0031-9007; ISSN PRLTAO
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
ABC EFFECT
ENERGY DEPENDENCE
GEV RANGE 01-10
INTEGRAL CROSS SECTIONS
INTERMEDIATE STATE
MASS SPECTRA
PAIR PRODUCTION
PIONS NEUTRAL
PROTON-NEUTRON INTERACTIONS
S CHANNEL