Abstract
Reported are measurements of angular distributions of resonance-energy positive and negative pions exciting approximately 40 states in Mg24 and Mg26. These include the (ground state, 0+), (1.36 MeV, 2+), (4.14, 2+), (5.93, 4+), (6.44, 0+), (7.34), (7.55, 3-), (8.33, 3-), (9.32, 4+), (9.97, 5-), (11.08, 3-), (12.06), (13.26), (13.96, 3-), (15.1, T=1, 6-), and (15.4) states in Mg24 and the (ground state, 0+), (1.81, 2+), (2.92, 2+), (3.59, 0+), (4.31, 2++4+), (4.90, 4+), (5.31, 2+), (5.44, 4+), (5.69, 4+), (6.86, 3-), (7.33, 3-), (7.79, 3-), (8.17, 3-), (9.2, possible 6-), (10.30, 4+), and (18.1, T=2, 6-) states in Mg26. The distorted-wave impulse approximation with a Kisslinger form for the optical potential using a -nucleon t matrix at a shifted energy of -25 MeV was found to explain the elastic scattering data from Mg24,26 in the energy range 116-292 MeV that is spanned by these data. Inelastic distorted-wave impulse approximation calculations employing collective-model deformation parameters were simultaneously fitted to the + and - data for each state. The deformation parameters and matrix elements in most cases compare favorably with results from other studies. Published s-d shell-model calculations using one value for the effective charges were found to reproduce the trend of both the strengths and ratios of neutron-to-proton matrix elements for the 2+ and 4+ states. The data at the first maximum in the inelastic angular distributions for Mg24 and that from other studies for C12, Si28, and Ca40 show that the cross section for + scattering is equal to that for - scattering, which forces the proton deformation parameters to be greater than the neutron deformation parameters and gives a ratio of neutron-to-proton elements to be less than unity. This difference from unity is interpreted as a measure of the failure of the model and a systematic error of 11% is assumed to dominate the errors in the results for Mg26. Coupled-channels calculations employing monopole form factors are compared to data for low-lying 0+ states in Mg24 and Mg26.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1625-1636 |
| Number of pages | 12 |
| Journal | Physical Review C |
| Volume | 41 |
| Issue number | 4 |
| DOIs | |
| State | Published - 1990 |
Fingerprint
ASJC Scopus subject areas
- Physics and Astronomy(all)
- Nuclear and High Energy Physics
Cite this
Pion elastic and inelastic scattering from Mg24 and Mg26. / Blanpied, G. S.; Hernandez, J.; Mishra, C. S.; Mize, W. K.; Whisnant, C. S.; Ritchie, Barry; Morris, C. L.; Seestrom-Morris, S. J.; Moore, C. Fred; Seidl, P. A.; Lindgren, R. A.; Wildenthal, B. H.; Gilman, R.
In: Physical Review C, Vol. 41, No. 4, 1990, p. 1625-1636.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Pion elastic and inelastic scattering from Mg24 and Mg26
AU - Blanpied, G. S.
AU - Hernandez, J.
AU - Mishra, C. S.
AU - Mize, W. K.
AU - Whisnant, C. S.
AU - Ritchie, Barry
AU - Morris, C. L.
AU - Seestrom-Morris, S. J.
AU - Moore, C. Fred
AU - Seidl, P. A.
AU - Lindgren, R. A.
AU - Wildenthal, B. H.
AU - Gilman, R.
PY - 1990
Y1 - 1990
N2 - Reported are measurements of angular distributions of resonance-energy positive and negative pions exciting approximately 40 states in Mg24 and Mg26. These include the (ground state, 0+), (1.36 MeV, 2+), (4.14, 2+), (5.93, 4+), (6.44, 0+), (7.34), (7.55, 3-), (8.33, 3-), (9.32, 4+), (9.97, 5-), (11.08, 3-), (12.06), (13.26), (13.96, 3-), (15.1, T=1, 6-), and (15.4) states in Mg24 and the (ground state, 0+), (1.81, 2+), (2.92, 2+), (3.59, 0+), (4.31, 2++4+), (4.90, 4+), (5.31, 2+), (5.44, 4+), (5.69, 4+), (6.86, 3-), (7.33, 3-), (7.79, 3-), (8.17, 3-), (9.2, possible 6-), (10.30, 4+), and (18.1, T=2, 6-) states in Mg26. The distorted-wave impulse approximation with a Kisslinger form for the optical potential using a -nucleon t matrix at a shifted energy of -25 MeV was found to explain the elastic scattering data from Mg24,26 in the energy range 116-292 MeV that is spanned by these data. Inelastic distorted-wave impulse approximation calculations employing collective-model deformation parameters were simultaneously fitted to the + and - data for each state. The deformation parameters and matrix elements in most cases compare favorably with results from other studies. Published s-d shell-model calculations using one value for the effective charges were found to reproduce the trend of both the strengths and ratios of neutron-to-proton matrix elements for the 2+ and 4+ states. The data at the first maximum in the inelastic angular distributions for Mg24 and that from other studies for C12, Si28, and Ca40 show that the cross section for + scattering is equal to that for - scattering, which forces the proton deformation parameters to be greater than the neutron deformation parameters and gives a ratio of neutron-to-proton elements to be less than unity. This difference from unity is interpreted as a measure of the failure of the model and a systematic error of 11% is assumed to dominate the errors in the results for Mg26. Coupled-channels calculations employing monopole form factors are compared to data for low-lying 0+ states in Mg24 and Mg26.
AB - Reported are measurements of angular distributions of resonance-energy positive and negative pions exciting approximately 40 states in Mg24 and Mg26. These include the (ground state, 0+), (1.36 MeV, 2+), (4.14, 2+), (5.93, 4+), (6.44, 0+), (7.34), (7.55, 3-), (8.33, 3-), (9.32, 4+), (9.97, 5-), (11.08, 3-), (12.06), (13.26), (13.96, 3-), (15.1, T=1, 6-), and (15.4) states in Mg24 and the (ground state, 0+), (1.81, 2+), (2.92, 2+), (3.59, 0+), (4.31, 2++4+), (4.90, 4+), (5.31, 2+), (5.44, 4+), (5.69, 4+), (6.86, 3-), (7.33, 3-), (7.79, 3-), (8.17, 3-), (9.2, possible 6-), (10.30, 4+), and (18.1, T=2, 6-) states in Mg26. The distorted-wave impulse approximation with a Kisslinger form for the optical potential using a -nucleon t matrix at a shifted energy of -25 MeV was found to explain the elastic scattering data from Mg24,26 in the energy range 116-292 MeV that is spanned by these data. Inelastic distorted-wave impulse approximation calculations employing collective-model deformation parameters were simultaneously fitted to the + and - data for each state. The deformation parameters and matrix elements in most cases compare favorably with results from other studies. Published s-d shell-model calculations using one value for the effective charges were found to reproduce the trend of both the strengths and ratios of neutron-to-proton matrix elements for the 2+ and 4+ states. The data at the first maximum in the inelastic angular distributions for Mg24 and that from other studies for C12, Si28, and Ca40 show that the cross section for + scattering is equal to that for - scattering, which forces the proton deformation parameters to be greater than the neutron deformation parameters and gives a ratio of neutron-to-proton elements to be less than unity. This difference from unity is interpreted as a measure of the failure of the model and a systematic error of 11% is assumed to dominate the errors in the results for Mg26. Coupled-channels calculations employing monopole form factors are compared to data for low-lying 0+ states in Mg24 and Mg26.
UR - http://www.scopus.com/inward/record.url?scp=0000028485&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0000028485&partnerID=8YFLogxK
U2 - 10.1103/PhysRevC.41.1625
DO - 10.1103/PhysRevC.41.1625
M3 - Article
AN - SCOPUS:0000028485
VL - 41
SP - 1625
EP - 1636
JO - Physical Review C - Nuclear Physics
JF - Physical Review C - Nuclear Physics
SN - 0556-2813
IS - 4
ER -