The recoil detection method has been used to measure the differential cross sections at nucleon backward angles, 160 degrees-180 degrees (cm), for the C-12,C-13(p,p)C-12,C-13 and C-12,C-13(p,n)N-12,N-13 reactions at an incident proton energy of 200 MeV. These are the first reported data in this angular region. The elastic scattering cross sections show a shallow minimum at 180 degrees and are about a factor of 15 larger than those predicted by optical model calculations using standard parameters. The (p,n) cross sections are lower than the (p,p), flat within the rather limited statistics, and about a factor of 5 greater than predicted. The backward-angle elastic scattering cross sections are selectively sensitive to the real central potential and can be brought into fairly good agreement with experiment without destroying the fit at more forward angles by greatly reducing both its depth and diffuseness. Adding a Majorana exchange term in the real central and spin orbit potential to a phenomenological potential that fits previously reported lower-angle C-12 elastic scattering data does not significantly alter these fits while introducing a peak at 180 degrees.

A system for the measurement of medium-energy, high-momentum transfer reactions via detection of the heavier ion products has been developed. The system consists of a parallel grid avalanche counter, a proportional counter, and a large-area microstrip silicon detector array, all attached to a large-gap dipole magnet that bends the primary beam through 6° and sweeps the recoil ions into the detection system. The detector stack measures the energy, time-of-flight, nuclear charge, mass, and angle of recoil-ion emission products. Ray tracing gives the emission angle of the recoil ions at the target. The system was installed at the Indiana Cooler Ring and its advantages and use in a storage ring environment are discussed. Preliminary results of differential cross section measurements for the reaction 12C(p, π+)13C at Tp = 166 and 294 MeV are presented.

Differential cross sections and analyzing powers for the <(p)over right arrow p> --> d pi(+) reaction have been measured to within T-pi(cm) = 85 keV of threshold. The S-wave strength is extracted and found to be similar to 13% larger than that determined from recent measurements of np --> d pi(0). Both the analyzing power and the anisotropy in the angular distribution show the expected energy dependence and these data are used to obtain values for the two contributing P-wave amplitudes.

Analyzing powers and total cross sections for the p(p↘,π+)d reaction near threshold have been measured at the Indiana University Cyclotron Facility Cooler. The analyzing power follows a sin θcm distribution. These preliminary results are consistent with the calculated factor of two enhancement of the s‐wave cross section from heavy meson exchange currents. (AIP)

A readout system for Si microstrip detectors has been developed in which inductors are placed between each strip thus forming an LC delay line with the detector's intrinsic capacitance. Each strip in a 50-strip detector is resolved and a time resolution of 800 ps is obtained with 5.49 MeV alpha particles. Only two fast signals and an energy signal are needed from an entire detector in order to determine a particle's time of arrival, position and energy. The system requires little power and is made of components that are available commercially.

Studies of (p,pi) and (p,2pi) reactions on the Indiana cooler ring using recoil-ion detection

The nucleus $^{43}\mathrm{Ti}$ has been studied by prompt and delayed $n\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences in the bombardment of $^{40}\mathrm{Ca}$ with 20-MeV $\ensuremath{\alpha}$ particles. A cascade of three $\ensuremath{\gamma}$ rays with energies of 114.7, 1094.0, and 1857.7 keV has been observed. The $\ensuremath{\gamma}$ cascade is emitted by an isomeric state of 3066.4-keV excitation energy; its mean life has been determined to be $\ensuremath{\tau}=810\ifmmode\pm\else\textpm\fi{}50$ nsec. By measuring the relative intensities of the three $\ensuremath{\gamma}$ rays the sequence in the $\ensuremath{\gamma}$ decay has been established. The close resemblance of this $\ensuremath{\gamma}$ cascade to the one in the mirror nucleus $^{43}\mathrm{Sc}$ leads to the conclusion that the 3066.4-keV state in $^{43}\mathrm{Ti}$ is an isomeric 19/${2}^{\ensuremath{-}}$ state which has the decay scheme ${\frac{19}{2}}^{\ensuremath{-}}\underset{114.7}{\ensuremath{\rightarrow}}{\frac{15}{2}}^{\ensuremath{-}}(2952.7)\underset{1094.0}{\ensuremath{\rightarrow}}{\frac{11}{2}}^{\ensuremath{-}}(1857.7)\ensuremath{\rightarrow}{\frac{7}{2}}^{\ensuremath{-}}(0)$. This conclusion is in agreement with the results of measured excitation functions which show that the maximum yield of the 1857.7-keV $\ensuremath{\gamma}$ occurs at the lowest \ensuremath{\alpha} energy and that of the 114.7-keV $\ensuremath{\gamma}$ at the highest. The $B(E2)$ value of the 19/${2}^{\ensuremath{-}}$\ensuremath{\rightarrow}15/${2}^{\ensuremath{-}}$ transition in $^{43}\mathrm{Ti}$ is larger by nearly a factor of 2 than the corresponding transition in $^{43}\mathrm{Sc}$. The slightly lower excitation energy (56.9 keV) of the 19/${2}^{\ensuremath{-}}$ state in $^{43}\mathrm{Ti}$ with respect to the corresponding state in $^{43}\mathrm{Sc}$ seems to be at least partially due to Coulomb shifts arising from the two valence protons in $^{43}\mathrm{Ti}$.NUCLEAR REACTIONS $^{40}\mathrm{Ca}(\ensuremath{\alpha},n\ensuremath{\gamma})$; prompt and delayed $n\ensuremath{-}\ensuremath{\gamma}$ and $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ coincidences with ${E}_{\ensuremath{\alpha}}=20$ MeV. Singles $\ensuremath{\gamma}$-ray spectra: $\frac{d\ensuremath{\sigma}}{d\ensuremath{\Omega}}=f({E}_{\ensuremath{\alpha}},{E}_{\ensuremath{\gamma}})$. Deduced for $^{43}\mathrm{Ti}:{\frac{19}{2}}^{\ensuremath{-}}(3066.4 \mathrm{keV})\ensuremath{\rightarrow}{\frac{15}{2}}^{\ensuremath{-}} (2951.7 \mathrm{keV})\ensuremath{\rightarrow}{\frac{11}{2}}^{\ensuremath{-}}(1857.7 \mathrm{keV})\ensuremath{\rightarrow}{\frac{7}{2}}^{\ensuremath{-}}(0)$, ${\frac{19}{2}}^{\ensuremath{-}}$ state: $\ensuremath{\tau}=(810\ifmmode\pm\else\textpm\fi{}50)$ nsec.

The scattering of neutrons from 148Sm and from 154Sm has been studied at 6.25 MeV. Evidence is presented that the main effect of nuclear deformation on neutron elastic scattering is to decrease appreciably the scattering at back angles.