Coherent π0 electroproduction on 4He in the Δ region

✍ Scribed by M.J.M. van Sambeek; T. Botto; T. Bauer; H.P. Blok; D. Boersma; G.E. Dodge; D. Groep; P. Heimberg; W.H.A. Hesselink; D.W. Higinbotham; C.W. de Jager; E. Jans; T.J. Ketel; D.J.J. de Lange; L. Lapikás; B.E. Norum; I. Passchier; V.M. Pugatch; M.F.M. Steenbakkers; J.J.M. Steijger; L. Todor; P. Ulmer; H. de Vries; K. Wang

• Publisher: Elsevier Science
• Year: 1998
• Tongue: English
• Weight: 274 KB
• Volume: 631
• Category: Article
• ISSN: 0375-9474
• DOI: 10.1016/s0375-9474(98)00065-7

✦ Synopsis

Coherent 7c ° electroproduction on 4He was studied using the internal target facility of the AmPS electron storage ring at NIKHEF. This 4He(e,e'4He)Tr° experiment is the first on exclusive 7c ° electroproduction on a complex nucleus. The experiment was performed at a luminosity of about 1033 cm-2s -~ with a stored beam of about 150 mA 676 MeV electrons and a 4He gas target of 1015 atoms/cm 2. The observation of neutral pions was avoided by detecting in coincidence with scattered electrons the recoiling 4He nuclei with a dedicated detector. A clear signature for 7r ° knockout was achieved and the differential cross sections were measured as a function of the 7r ° CM-angle over the full A-resonance region at two values of Q2 of 0.07 and 0.15 (GeV/c) 2.