SVIBOR - Project code: 1-03-100

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Project code: 1-03-100


Pion Absorption and Related Probes


Main researcher: FURIĆ, MIROSLAV (82964)


Assistants
Type of research: basic
Duration from: 01/01/91. to 12/15/96.
Papers on project (total): 0
Institution name: Prirodoslovno-matematički fakultet, Prirodoslovni odjeli, Zagreb (119)
Department/Institute: Department of Physics
Address: Bijenička cesta 32, p.p. 162
City: 10000 - Zagreb, Croatia
Communication
Phone: 385 (0)1 432 482
Fax: 385 (0)1 532 525
E-mail: mfuric@x400.srce.hr
Summary: Pion absorption in nuclei is a dynamic topic with severalimportant aspects unexplored.These issues exist whether one viewsnucleons as the building blocks or one uses the quark-gluonpicture. The role of isospin in pion apsorption is not completelysettled.New absorption mechanisms are also being discovered. Wehave investigated pion absorption first with large-area position-sensitive hodoscopes using double and triple coincidencetechniques. Our studies in A=3 and A=4 nuclei have revealed a newthree-nucleon-absorption (3NA) mechanism.Absolute strengths havebeen determined for both:isoscalar and isovector parts intwo-nucleon absorption (2NA). Later, we have participated in theLADS collaboration (12 european and U.S. institutions) addresingespecially the role of the new mechanisms using 4pidetector,unique in the world,of own construction. Data have beenaccumulated on number of nuclei (D2,He3,He4,N14,...). Our earlierconjuctures on the strenght of the new 3NA mechanism have beenconfirmed.Details of this mechanism are being studied andsearch for new modes is underway. In parallel we haveinvestigated a complementary process of muon capture. Alsoparticipation in search for forbidden muon decay intoelectron-gamma was realized.

Keywords: Pion absorption, isospin ratio, Delta-isobars, three-nucleon absorption, isoscalar absorption, isovector absorption, nuclear wave-functions, muon capture, two-nucleon correlations, Final-State Interactions, Initial-State Interactions, six-quark states, three-nucleon force, multinucleon absorption, large acceptance detector, position sensitive detector, kinematical completeness, testing the Standard Model

Research goals: The starting motivation of our studies have been the unsettled experimental issues in pion absorption dynamics. Two dominant mode of pion being absorbed on two nucleus (2NA) has not been completely explained by total absorption cross section. Also, the role of the isospin, while being important, experimentally did not follow the simple isospin Clebsh-Gordon algebra. To resolve these issues, the systematic program of experimental determination of the total and differential cross section for pion absorption on number of light and some heavier nucleis is conducted. The mechanism of various channels in pion absorption are especialy interesting issues. The hopes are even raised, that some of the features might be explainable with subnucleonic degrees of freedom.

COOPERATION - PROJECTS


  1. Name of project: NSF PN 988 Mechanisms in Medium Energy Processes
    Name of institution: Physics Department, Univ. of Houston, Houston, Texas
    City: Houston, SAD

  2. Name of project: Pion Absorption am Leichten Kernen (Tritium)
    Name of institution: Institut fuer Experimentelle Kernphysik, Kernforschungszentrum, Karlsruhe, Njemačka
    City: Karlsruhe, Njemačka

COOPERATION - INSTITUTIONS


  1. Name of institution: Institut fuer Physik, Universitaet Basel
    Type of institution: Economical/Production
    City: BASEL, Švicarska

  2. Name of institution: Paul Scherrer Institut
    Type of institution: University/Faculty
    City: Villigen, Švicarska

  3. Name of institution: Department of Physics, Massachusets Institut of Technology, Massachusets
    Type of institution: Economical/Production
    City: Cambridge, SAD

  4. Name of institution: Department of Physics, Carnegie Mellon University
    Type of institution: Economical/Production
    City: Pittsburgh, SAD

  5. Name of institution: Los Alamos National Laboratory
    Type of institution: University/Faculty
    City: Los Alamos, SAD

  6. Name of institution: University of Maryland
    Type of institution: Economical/Production
    City: College Park, SAD

  7. Name of institution: University of New Mexico
    Type of institution: Economical/Production
    City: Las Cruces, SAD

  8. Name of institution: National Instituut voor Kernfysica en Hoge-Energiefysica
    Type of institution: University/Faculty
    City: Amsterdam, Nizozemska

  9. Name of institution: National Accelerator Centre
    Type of institution: University/Faculty
    City: Faure, JAR

  10. Name of institution: Stanford University
    Type of institution: Economical/Production
    City: Stanford, SAD

  11. Name of institution: Institut fuer Mittelenergie-Physik
    Type of institution: University/Faculty
    City: Wien, Austrija
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