Observation of double isovector giant dipole resonances from pion double charge exchange

Journal Article · Mon Jan 01 04:00:00 EST 1990 · Physical Review, C (Nuclear Physics); (USA)

DOI:https://doi.org/10.1103/PhysRevC.41.202· OSTI ID:6915635

Mordechai, S ^[1]; Fortune, H T; O'Donnell, J M; Liu, G; Burlein, M; Wuosmaa, A H ^[2]; Greene, S; Morris, C L ^[3]; Auerbach, N ^[4]; Yoo, S H; Moore, C F ^[5]

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1. Ben-Gurion University of the Negev, Beer-Sheva 84105, (Israel) University of Texas at Austin, Austin, Texas 78712 (USA)
2. University of Pennsylvania, Philadelphia, Pennsylvania 19104 (USA)
3. Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (USA)
4. Tel Aviv University, Tel Aviv, (Israel)
5. University of Texas at Austin, Austin, Texas 78712 (USA)

We report the observation of double isovector giant dipole resonances in ({pi}{sup +},{pi}{sup {minus}}) and, for the first time, also in ({pi}{sup {minus}},{pi}{sup +}) double-charge-exchange reactions at {ital T}{sub {pi}}=292 MeV. The resonances have been observed on nine targets covering a wide range of mass at {ital Q} values around {approx}{minus}50 MeV in ({pi}{sup +},{pi}{sup {minus}}), but at significantly lower energy ({ital Q}={minus}33.8 MeV) in the inverse reaction on {sup 56}Fe. The centroid energies in both reactions are very close to the energies at which the {Delta}{ital T}{sub {ital z}}={plus minus}2 double giant dipole ({ital J}{sup {pi}}=0{sup +},2{sup +},{Delta}{ital T}=2) states are expected to appear. Angular distributions have been measured for the ({pi}{sup +},{pi}{sup {minus}}) resonances on {sup 40}Ca,{sup 56}, Fe, and {sup 93}Nb and each is observed to have a quadrupole shape. Based on their energies, angular distributions, cross sections, and the comparison between the ({pi}{sup +},{pi}{sup {minus}}) and ({pi}{sup {minus}},{pi}{sup +}) data on {sup 56}Fe, we identify the resonances as double giant dipole states (i.e. states arising from a charge-exchange dipole operator acting twice on the ground-state wave function). The data from the present and recent observations indicate that the newly discovered resonance is a general collective feature of all nuclei.

• OSTI ID: 6915635
• Journal Information: Physical Review, C (Nuclear Physics); (USA), Journal Name: Physical Review, C (Nuclear Physics); (USA) Vol. 41:1; ISSN 0556-2813; ISSN PRVCA
• Country of Publication: United States
• Language: English

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73 NUCLEAR PHYSICS AND RADIATION PHYSICS
ACCELERATORS
ANGULAR DISTRIBUTION
ANGULAR MOMENTUM
CALCIUM 40 TARGET
CHARGE-EXCHANGE REACTIONS
CHARGED-PARTICLE REACTIONS
CROSS SECTIONS
DATA
DIPOLE MOMENTS
DISTRIBUTION
ENERGY
ENERGY RANGE
EXPERIMENTAL DATA
FUNCTIONS
GIANT RESONANCE
HADRON REACTIONS
INFORMATION
IRON 56 TARGET
LAMPF LINAC
LINEAR ACCELERATORS
MESON FACTORIES
MESON REACTIONS
MEV RANGE
MEV RANGE 100-1000
NIOBIUM 93 TARGET
NUCLEAR REACTIONS
NUMERICAL DATA
PARITY
PARTICLE PROPERTIES
PION MINUS REACTIONS
PION PLUS REACTIONS
PION REACTIONS
Q-VALUE
RESONANCE
SPIN
TARGETS
WAVE FUNCTIONS