J.A. Faucett

Measurements of ΔσL (np) between 500 and 800 MeV

Abstract A measurement of Δσ L (np), the difference between neutron-proton total cross sections in pure longitudinal spin states, is described. Data were taken for five energies between 500 and 800 MeV, with statistical errors of ≈ 1.5 mb and an estimated normalization error of 6%. The data, combined with other results, show some evidence for an elastic I =0 spin-singlet resonance with mass ∼ 2213 MeV and width ∼ 74 MeV, or a coupled-triplet resonance with similar mass and width.

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 neutron hodoscope for medium energy np scattering experiments

Abstract A 24-element plastic scintillation counter hodoscope for np elastic and total cross section measurements at LAMPF is described. Details of construction, electronics, calibration with cosmic ray muons, and a determination of absolute detection efficiency at 289 and 435 MeV are presented.

Pion-nucleus elastic scattering on {sup 12}C, {sup 40}Ca, {sup 90}Zr, and {sup 208}Pb at 400 and 500 MeV

Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at energies where second-order corrections to impulse approximation calculations should be small. The results are compared with other data sets at similar energies, and with four different first-order impulse approximation calculations. Significant disagreement exists between the calculations and the data from this experiment.

Pion - nucleus elastic scattering on C-12, Ca-40, Zr-90, and Pb-208 at 400-MeV and 500-MeV

Pion-nucleus elastic scattering at energies above the Delta(1232) resonance is studied using both pi+ and pi- beams on 12C, 40Ca, 90Zr, and 208Pb. The present data provide an opportunity to study the interaction of pions with nuclei at energies where second-order corrections to impulse approximation calculations should be small. The results are compared with other data sets at similar energies, and with four different first-order impulse approximation calculations. Significant disagreement exists between the calculations and the data from this experiment.

Pion elastic scattering from polarized [sup 13]C in the energy region of the [ital P][sub 33] resonance

Analyzing powers [ital A][sub [ital y]] were measured for [pi][sup +] and [pi][sup [minus]] elastic scattering from polarized [sup 13]C at incident pion energies [ital T][sub [pi]] near the [ital P][sub 33] [pi]-nucleon resonance. At [ital T][sub [pi]]=130 MeV, the values of [ital A][sub [ital y]] are significantly different from zero for [pi][sup [minus]] scattering. For [pi][sup +] at [ital T][sub [pi]]=130 MeV and for both [pi][sup [minus]] and [pi][sup +] at all other energies, the [ital A][sub [ital y]] are mostly consistent with zero. Elastic differential cross sections were measured using an unpolarized [sup 13]C target. Both the analyzing-power and cross-section data were compared with predictions using a variety of nuclear structure and reaction models. The analyzing power was found to be strongly sensitive to the quadrupole spin-flip part of the transition. The data of this work complement measurements of the magnetic form factor by electron scattering. The pion [ital A][sub [ital y]] data are not reproduced by calculations using wave functions that fit the magnetic form factor at low momentum transfers.

Pion double charge exchange on sup 42,44,48 Ca for 300 le T sub. pi. le 550 MeV

Measurements of cross sections for pion-induced double-charge-exchange reactions to the double-isobaric-analog state for {sup 42,44,48}Ca at incident pion energies of 300--550 MeV at {theta}{sub lab}=5{degree} are reported, together with upper limits for cross sections for transitions to the residual ground states for {sup 44,48}Ca. The data are fitted with a two-amplitude model which gives expressions for cross sections for both transitions. The fit overpredicts the ground-state cross sections, indicating a failure of the model in this energy range.

Pion double charge exchange on Ca 4 2 , 4 4 , 4 8 for 300≤ T π ≤550 MeV

Measurements of cross sections for pion-induced double-charge-exchange reactions to the double-isobaric-analog state for {sup 42,44,48}Ca at incident pion energies of 300--550 MeV at {theta}{sub lab}=5{degree} are reported, together with upper limits for cross sections for transitions to the residual ground states for {sup 44,48}Ca. The data are fitted with a two-amplitude model which gives expressions for cross sections for both transitions. The fit overpredicts the ground-state cross sections, indicating a failure of the model in this energy range.

Pion double charge exchange onCa42,44,48for 300≤Tπ≤550 MeV

Measurements of cross sections for pion-induced double-charge-exchange reactions to the double-isobaric-analog state for {sup 42,44,48}Ca at incident pion energies of 300--550 MeV at {theta}{sub lab}=5{degree} are reported, together with upper limits for cross sections for transitions to the residual ground states for {sup 44,48}Ca. The data are fitted with a two-amplitude model which gives expressions for cross sections for both transitions. The fit overpredicts the ground-state cross sections, indicating a failure of the model in this energy range.