TY - JOUR
T1 - Observation of double isovector giant dipole resonances from pion double charge exchange
AU - Mordechai, S.
AU - Fortune, H. T.
AU - Odonnell, J. M.
AU - Liu, G.
AU - Burlein, M.
AU - Wuosmaa, A. H.
AU - Greene, S.
AU - Morris, C. L.
AU - Auerbach, N.
AU - Yoo, S. H.
AU - Moore, C. Fred
PY - 1990/1/1
Y1 - 1990/1/1
N2 - We report the observation of double isovector giant dipole resonances in (+,-) and, for the first time, also in (-,+) double-charge-exchange reactions at T=292 MeV. The resonances have been observed on nine targets covering a wide range of mass at Q values around -50 MeV in (+,-), but at significantly lower energy (Q=-33.8 MeV) in the inverse reaction on Fe56. The centroid energies in both reactions are very close to the energies at which the "Tz=2 double giant dipole (J=0+,2+,"T=2) states are expected to appear. Angular distributions have been measured for the (+,-) resonances on Ca40,56, Fe, and Nb93 and each is observed to have a quadrupole shape. Based on their energies, angular distributions, cross sections, and the comparison between the (+,-) and (-,+) data on Fe56, 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.
AB - We report the observation of double isovector giant dipole resonances in (+,-) and, for the first time, also in (-,+) double-charge-exchange reactions at T=292 MeV. The resonances have been observed on nine targets covering a wide range of mass at Q values around -50 MeV in (+,-), but at significantly lower energy (Q=-33.8 MeV) in the inverse reaction on Fe56. The centroid energies in both reactions are very close to the energies at which the "Tz=2 double giant dipole (J=0+,2+,"T=2) states are expected to appear. Angular distributions have been measured for the (+,-) resonances on Ca40,56, Fe, and Nb93 and each is observed to have a quadrupole shape. Based on their energies, angular distributions, cross sections, and the comparison between the (+,-) and (-,+) data on Fe56, 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.
UR - http://www.scopus.com/inward/record.url?scp=0000785577&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.41.202
DO - 10.1103/PhysRevC.41.202
M3 - Article
AN - SCOPUS:0000785577
SN - 0556-2813
VL - 41
SP - 202
EP - 212
JO - Physical Review C - Nuclear Physics
JF - Physical Review C - Nuclear Physics
IS - 1
ER -