Reaction mechanism and nuclear correlations study by low energy pion double charge exchange

Thesis/Dissertation · Tue Jun 01 04:00:00 EDT 1993

OSTI ID:10165050

Weinfeld, Z

In pion double-charge-exchange (DCX) reactions, a positive (negative) pion is incident on a nucleus and a negative (positive) pion emerges. These reactions are of fundamental interest since the process must involve at least two nucleons in order to conserve charge. Although two nucleon processes are present in many reactions they are usually masked by the dominant single nucleon processes. DCX is unique in that respect since it is a two nucleon process in lowest order and thus may be sensitive to two-nucleon correlations. Measurements of low energy pion double-charge-exchange reactions to the double-isobaric-analog-state (DIAS) and ground-state (GS) of the residual nucleus provide new means for studying nucleon-nucleon correlations in nuclei. At low energies (T{sub {pi}} <65 MeV) the {pi}N interaction is relatively weak thus simplifying the theoretical treatment of the problem. Also, isobaric-analog-state (IAS) transitions are suppressed near 50 MeV due to destructive s-p wave interference in the {pi}N scattering amplitude leading to enhancement of DIAS transitions through non-analog intermediate states. Theoretical studies by several groups have shown that, while transitions through the analog route involve relatively large nucleon-nucleon distances, those through the non-analog intermediate states involve distances of the order 1 to 2 fm. Therefore, DCX reactions at low incident pion energies provide a way to study the short-range part of the nucleon-nucleon correlations. The author presents measured DCX cross sections of DIAS and GS transitions for several nuclei in the f{sub 7/2} shell at energies ranging from 25 to 65 MeV. Cross sections were measured on {sup 42,44,48}Ca, {sup 46,50}Ti and {sup 54}Fe. The calcium isotopes make a good set of nuclei on which to study the effects of correlations in DCX reactions.

• Research Organization: Los Alamos National Lab., NM (United States)
• Sponsoring Organization: USDOE, Washington, DC (United States)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 10165050
• Report Number(s): LA--12560-T; ON: DE93015863
• Country of Publication: United States
• Language: English

Related Subjects

663460
663540
73 NUCLEAR PHYSICS AND RADIATION PHYSICS
A = 39-58
ANGULAR DISTRIBUTION
CALCIUM 42 TARGET
CALCIUM 44 TARGET
CALCIUM 48 TARGET
CHARGE-EXCHANGE REACTIONS
CHROMIUM 46
CHROMIUM 50
CORRELATIONS
DIFFERENTIAL CROSS SECTIONS
F STATES
INTERFERENCE
IRON 54 TARGET
ISOBARIC ANALOGS
MESON- AND HYPERON-INDUCED REACTIONS AND SCATTERING
MEV RANGE 10-100
NICKEL 54
NUCLEAR REACTION KINETICS
NUCLEON-NUCLEON POTENTIAL
PION PLUS REACTIONS
PIONS MINUS
TITANIUM 42
TITANIUM 44
TITANIUM 46 TARGET
TITANIUM 48
TITANIUM 50 TARGET