Peter A. Seidl

Systematics of pion double-charge-exchange reactions on T = 0 nuclei

Abstract Pion induced double charge exchange on 12 C, 16 O, 24 Mg, 28 Si, 32 S, and 40 Ca exhibits forward-angle cross sections that vary rapidly with pion energy and fall off roughly as A −4 3 . Angular distributions at 164 MeV appear diffractive for targets of 12 C, 16 O, and 40 Ca.

The energy dependence of 18O(π+, π−)18Ne(gs)☆

Abstract Eight angular distributions measured for 18(π+, π−)18Ne(gs) across the Δ33 resonance show the details of the energy dependence of the reaction. At higher energies, the maximum is at q ≅ 0.85 fm−1, in agreement with simple sequential scattering models, but a lower energies it is at q ≅ 0.5 fm−1, with the transition occuring over a narrow energy range.

Angular distributions for /sup 14/C,/sup 26/Mg(. pi. /sup +/,. pi. /sup -/)

Cross sections at theta = 5/sup 0/ (lab) were obtained at seven energies for /sup 14/C(..pi../sup +/,..pi../sup -/) /sup 14/ O(g.s.) and at four energies for /sup 26/Mg(..pi../sup +/,..pi../sup -/) /sup 26/ Si(g.s.). Angular distributions have been measured for both reactions at energies of 140 and 200 MeV. The results are compared to previous angular distributions at other energies on these two nuclei, and to a series of angular distributions measured for /sup 18/O(..pi../sup +/,..pi../sup -/).

A range-nuclear-interaction absorber for rejecting muons at EPICS

Abstract A range-nuclear-interaction absorber for rejecting muons in the focal plane of the EPICS spectrometer is described. This absorber rejects 95% of the muons in the focal plane, while rejecting fewer than 4% of the pions.

Two-amplitude model of pion DCX applied to the 18O angular distribution and excitation function☆

Abstract An earlier model developed to fit the DCX excitation function of 18O has been extended to account for the T π = 164 MeV 18 O DCX angular distribution in terms of that for 16O and a double-isobaric-analog transition.

A large-angle pion-nucleus scattering facility for EPICS at LAMPF

Abstract A facility has been constructed to extend the measurements of pion-nucleus scattering with the EPICS system at LAMPF into the angular range of 115 to 180°. The design of the system is described, and results of tests on it are given. Comparisons of measurements of elastic scattering cross sections with previous data are presented.

Pion scattering to 6- stretched states in Mg24 and Mg26

Inelastic {pi}{sup {plus minus}} cross-section measurements at pion incident energies of 150 and 180 MeV were made on 6{sup {minus}} states in {sup 24,26}Mg. In particular, we have determined the ({ital f}{sub 7/2}{ital d5/2}{sup {minus}1}){sub 6}{sup {minus}} isoscalar {ital Z}{sub 0}=0.21{plus minus}0.02 strength for the strongest {ital T}=0, {ital J} {sup {pi}}=6{sup {minus}} state located at 12.11{plus minus}0.05 MeV in {sup 24}Mg, and the isoscalar {ital Z}{sub 0}=0.17{plus minus}0.04 and isovector {ital Z}{sub 1}=0.21{plus minus}0.02 strength for the strongest {ital T}=1, {ital J} {sup {pi}}=6{sup {minus}} state located at 9.18 MeV in {sup 26}Mg. The distorted-wave impulse-approximation pion cross-section calculations required a multiplicative normalization factor of 1.2{plus minus}0.1 in order to reproduce the pure isovector strength deduced from electron scattering for the well-known {ital T}=1, {sup {pi}}=6{sup {minus}} state at 15.15 MeV in {sup 24}Mg and the {ital T}=2, {ital J} {sup {pi}}=6{sup {minus}} state at 18.05 MeV in {sup 26}Mg.

Pion scattering to 6 sup minus stretched states in sup 24 Mg and sup 26 Mg

Inelastic {pi}{sup {plus minus}} cross-section measurements at pion incident energies of 150 and 180 MeV were made on 6{sup {minus}} states in {sup 24,26}Mg. In particular, we have determined the ({ital f}{sub 7/2}{ital d5/2}{sup {minus}1}){sub 6}{sup {minus}} isoscalar {ital Z}{sub 0}=0.21{plus minus}0.02 strength for the strongest {ital T}=0, {ital J} {sup {pi}}=6{sup {minus}} state located at 12.11{plus minus}0.05 MeV in {sup 24}Mg, and the isoscalar {ital Z}{sub 0}=0.17{plus minus}0.04 and isovector {ital Z}{sub 1}=0.21{plus minus}0.02 strength for the strongest {ital T}=1, {ital J} {sup {pi}}=6{sup {minus}} state located at 9.18 MeV in {sup 26}Mg. The distorted-wave impulse-approximation pion cross-section calculations required a multiplicative normalization factor of 1.2{plus minus}0.1 in order to reproduce the pure isovector strength deduced from electron scattering for the well-known {ital T}=1, {sup {pi}}=6{sup {minus}} state at 15.15 MeV in {sup 24}Mg and the {ital T}=2, {ital J} {sup {pi}}=6{sup {minus}} state at 18.05 MeV in {sup 26}Mg.

Pion scattering to6−stretched states inMg24andMg26

Inelastic {pi}{sup {plus minus}} cross-section measurements at pion incident energies of 150 and 180 MeV were made on 6{sup {minus}} states in {sup 24,26}Mg. In particular, we have determined the ({ital f}{sub 7/2}{ital d5/2}{sup {minus}1}){sub 6}{sup {minus}} isoscalar {ital Z}{sub 0}=0.21{plus minus}0.02 strength for the strongest {ital T}=0, {ital J} {sup {pi}}=6{sup {minus}} state located at 12.11{plus minus}0.05 MeV in {sup 24}Mg, and the isoscalar {ital Z}{sub 0}=0.17{plus minus}0.04 and isovector {ital Z}{sub 1}=0.21{plus minus}0.02 strength for the strongest {ital T}=1, {ital J} {sup {pi}}=6{sup {minus}} state located at 9.18 MeV in {sup 26}Mg. The distorted-wave impulse-approximation pion cross-section calculations required a multiplicative normalization factor of 1.2{plus minus}0.1 in order to reproduce the pure isovector strength deduced from electron scattering for the well-known {ital T}=1, {sup {pi}}=6{sup {minus}} state at 15.15 MeV in {sup 24}Mg and the {ital T}=2, {ital J} {sup {pi}}=6{sup {minus}} state at 18.05 MeV in {sup 26}Mg.