Integral cross sections for the scattering of pions by protons into angles greater than 30 degrees (lab) have been measured at a wide range of energies spanning the delta resonance using liquid hydrogen targets. Cross sections were measured for nip scattering at 40 energies from 39.8 to 283.9 MeV and for pi(-)p at 15 energies from 80.0 to 283.9 MeV. Comparisons with phase shift predictions from the Karlsruhe group show good agreement on resonance but significant deviations below 100 MeV. [S0556-2813(99)02903-9].

Ratios of double-differential cross sections for incident 500-MeV pions are presented for (π+,π+p) and (π+,π−p) reactions on 12,13C, 90Zr, and 208Pb. A comparison with intra-nuclear cascade-model calculations suggest that the outgoing pion spectra show a feature consistent with quasi-free scattering from the Δ− component of the nuclear ground state wave function.

An argument is given that the mechanism of charge polarization cannot give rise to E1 radiation in the H-2(d, gamma)He-4 reaction. It then follows that E1 radiation produced in this reaction probably arises from the spin-dependent part of the E1 operator, although small E1 admixtures have been shown to arise in coupled-channels calculations as a result of Coulomb-induced isospin mixing in H-3 and He-3. A proper calculation of this reaction should consider meson-exchange currents and remains to be performed.

An argument is given that the mechanism of charge polarization cannot give rise to E1 radiation in the 2H(d, Υ)4He reaction. It then follows that E1 radiation produced in this reaction probably arises from the spin-dependent part of the E1 operator, although small E1 admixtures have been shown to arise in coupled-channels calculations as a result of Coulomb-induced isospin mixing in 3H and 3He. A proper calculation of this reaction should consider mesonexchange currents and remains to be performed.

Experimental differential cross sections for [pi][sup +] and [pi][sup [minus]] elastic scattering on [sup 28]Si at an incident pion energy of 400 meV are reported. The data fall above the predictions of a calculation using a momentum-space first-order optical potential. The behavior is similar to earlier results for pion scattering at [ital T][sub [pi]]=672 meV and to [ital K][sup +] nucleus scattering in this energy range, suggesting that there may be a common origin for the observed discrepancy that is not yet understood.

Experimental differential cross sections for pi+ and pi- elastic scattering on Si-28 at an incident pion energy of 400 MeV are reported. The data fall above the predictions of a calculation using a momentum-space first-order optical potential. The behavior is similar to earlier results for pion scattering at T(pi) = 672 MeV and to K+ nucleus scattering in this energy range, suggesting that there may be a common origin for the observed discrepancy that is not yet understood.

Pion-deuteron integral cross sections have been measured at LAMPF for both {pi}{sup +} and {pi}{sup -} scattering, at incident pion energies from 100 to 260 MeV. The measurements were made for scattering outside of a 30{degrees} forward angle in the laboratory system in a transmission experiment. A quantity less effected by systematics is the asymmetry between {pi}{sup +}p and {pi}{sup -}p scattering. The asymmetry is sensitive to the splitting of the {Delta}{sub 3.3} resonance due to isospin dependence of the interaction. A multiple scattering calculation in which the series is summed exactly will be compared to this data.

Non-charge-exchange inclusive cross sections have been measured at 500 MeV incident pion energy at quasifree scattering kinematics for both positive and negative pion charges. Peaks identified with quasifree knockout are seen at momentum transfers from 314 to 724 MeV/c. The widths and sizes of the peaks seen are consistent with the knockout of single nucleons from the nuclear surface. The data are consistent with no softening of the pion quasifree response at high momentum transfer, in contrast to the result seen in 500-MeV pion charge exchange data.

Inclusive double-differential cross sections for 500-MeV pions are presented for C(pi+/-, pi+/-) at theta(lab) of 30-degrees, 40-degrees, 50-degrees, 70-degrees, and 90-degrees; and for C(pi-, pi-) at 110-degrees. We compare the 50-degrees and 70-degrees data with C(e, e') data at nearly the same momentum transfer. These spectra from very different probes are more similar than expected from an intranuclear cascade calculation, which includes the strong rescattering of pions that have energies near 180 MeV. Agreement of the calculated spectra and the pion data is improved if the nucleus is assumed to be nearly transparent to these pions.

The Neutral Meson Spectrometer (NMS) is currently being built at LAMPF. This spectrometer is designed to obtain approximately 300 keV resolution, thus facilitating nuclear reaction and structures studies which require the identification of specific discrete states. In the summer of 1992 the two arm assembly (one converter plane and a complete calorimeter in each arm) was tested. Using this assembly, IAS data were collected for {sup 13}C, {sup 48}Ca, {sup 18}O and {sup 208}Pb for zero degrees scattering. These data show remarkable improvement over data obtained with the already existing {pi}{sup 0} spectrometer. In this talk the IAS spectra obtained using NMS will be compared against old {pi}{sup 0} spectra and the authors expectations of its performance in 1993 will be discussed.

Tensor and vector analyzing powers for the H-2(d, gamma)He-4 reaction have been obtained as a function of angle at E(d)(lab) = 20, 30, and 50 MeV. Differential cross sections were extracted at 30 and 50 MeV. Data for A(yy)(theta) and A(y)(theta) were obtained at all three energies, while T20(theta) was also measured at E(d)(lab) = 50 MeV. A direct capture calculation was performed and compared to the data. This calculation assumes point deuterons and that the reaction proceeds primarily via E2 radiation in this energy region. A value of 4% for the D-state probability arising from two-deuteron relative motion in the He-4 wave function was extracted by fitting the predictions of this model to the data. This calculation indicates that g-wave capture is significant at the energies of the present experiment, a result which is supported by a transition matrix element analysis of the data. The results of a microscopic 7-channel resonating group model (MCRGM) calculation are also compared to the data. This model takes all amplitudes having incoming angular momenta l less-than-or-equal-to 2 into account as well as the couplings to the n-He-3 and p-T channels. This microscopic calculation, which has produced reasonable agreement with the previous low energy data, predicts a value of 2.2% for the two-deuteron component of the D state in He-4. There is qualitative agreement with the present data.

A state-of-the-art radiation detection system for real-time and simultaneous spectroscopy of beta-particles and gamma-rays has been developed. The system utilizes a triple-layer phoswich detector and a customized Digital Pulse Processor (DPP) designed and built in our laboratory. The DPP board digitally captures the analog signal pulses and, following several digital preprocessing steps, transfers valid pulses to the host computer for further digital processing. A resolving algorithm also was developed to digitally discriminate beta and gamma events, and reconstruct separate beta and gamma-ray energy spectra with minimal crosstalk. The spectrometer has proven to be an effective tool for recording separate beta and gamma-ray spectra from mixed radiation fields. The system as a beta–gamma spectrometer will have broad-ranging applications in nuclear non-proliferation, radioactive waste management, worker safety, systems reliability, dose assessment, and risk analysis.

A multiplexing scheme for cathode strip chamber readouts which is cost-effective and efficient is described. This scheme provides an inexpensive alternative to individual-wire readout schemes, while not compromising the attractive qualities of cathode-strip chambers. A chamber with an area of 72×36 cm was built and tested. A position resolution of 130±50 μm (FWHM) was obtained with the multiplexing scheme. Details of the construction and operation of the cathode-strip chamber and its response to cosmic rays are presented here.

Measurements of the tensor and vector analyzing powers, Ayy(130°) and Ay(130°), have been obtained for the 2H(d,γ )4He reaction for energies ranging from Ed(lab) = 0.3 MeV to Ed(lab) = 50 MeV. The Ayy(130°) data are sensitive to the D-state present in the ground state of 4He and are observed to have their maximum value near Ed = 30 MeV. The vector analyzing power data show a maximum near Ed = 3 MeV. The data are compared to the results of a microscopic multi-channel resonating group model calculation.

New high spin states in $^{25}\mathrm{Mg}$ (up to 13.3 MeV in excitation) have been located using the $^{12}\mathrm{N}$,p\ensuremath{\gamma}${)}^{25}$Mg reaction at a laboratory beam energy of 23.5 MeV. Gamma decay from 28 neutron unbound levels has been observed (24 of which are reported here for the first time) up to 7 MeV above the neutron drip line. Tentative identification of the yrast line up to ${(17/2}^{+}$ has been made, along with an extension of the ground-state rotational band up to ${(15/2}^{+}$ and the location of several other states with ${J}^{\ensuremath{\pi}}$${=(11/2}^{+}$ and ${(15/2}^{+}$. Extensive comparison with the s-d shell model and the cranked Nilsson-Strutinsky model has been made for the states in $^{25}\mathrm{Mg}$. Very good agreement is observed between the shell model and experimental level energies and \ensuremath{\gamma}-decay branches. Potential energy surfaces for ${J}^{\ensuremath{\pi}}$${=(11/2}^{+}$, ${(13/2}^{+}$, and ${(17/2}^{+}$ in the cranked Nilsson-Strutinsky model show a noncollective oblate local minimum at (${\ensuremath{\epsilon}}_{2}$,\ensuremath{\gamma})=(0.34,60\ifmmode^\circ\else\textdegree\fi{}) for ${(11/2}^{+}$ and prolate configurations at (0.2,-120\ifmmode^\circ\else\textdegree\fi{}) for ${(13/2}^{+}$ and ${(17/2}^{+}$. These states compete with the collective ground-state band members at \ensuremath{\gamma}\ensuremath{\approxeq}0\ifmmode^\circ\else\textdegree\fi{} and become yrast for ${(17/2}^{+}$. The stabilization of these prolate aligned states relative to more deformed, collective states of the same spin results from shell effects at high spin in the cranking model, and provides a description of the configuration in the yrast ${8}^{+}$; ${(11/2}^{+}$, ${(13/2}^{+}$, and ${(17/2}^{+}$; and ${4}^{+}$ states in $^{24}\mathrm{Mg}$, $^{25}\mathrm{Mg}$, and $^{26}\mathrm{Mg}$, respectively.