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The empirical distribution of Gamow-Teller strengths in /sup 98/Tc and /sup 115/Sn have been obtained via the (p,n) reaction at E/sub p/ = 120 MeV and E/sub p/ = 200 MeV on /sup 98/Mo and /sup 115/In targets. This information is used to calculate the cross section for absorption of solar neutrinos in /sup 98/Mo and /sup 115/In, nuclides which are being considered as neutrino detectors to accomplish solar neutrino spectroscopy.

The fusion cross section for the 16O + 16O reaction has been measured with a time-of-flight technique at energies Elab = 35, 45, 52, 60, 70 and 80 MeV. Excitation functions for the total fusion and for the individual evaporation residues have been deduced from one-angle measurements of mass yields as a function of energy by normalizing to the energies given above. The 16O + 12C reaction has been studied by the same method at energies of 45, 52, 70 and 80 MeV, and fusion cross sections and mass distributions are given. Small amplitude oscillations are observed in the fusion cross section for the 16O + 16O reaction and are explained as effects of the individual grazing angular momenta. The measured fusion cross section is compared with a TDHF calculation of this quantity. A possible low angular momentum cut for fusion as predicted by the TDHF calculation is examined.

The 41 Ca(d, t) 40 Ca and 41 Ca(d, τ) 40 K reactions have been investigated at a bombarding energy of 40 MeV. A distorted-wave analysis of the measured angular distributions and a sum-rule analysis of the resulting spectroscopic factors has enabled the identification of members of various particle-hole multiplets. Values obtained for the matrix elements of the 1 f 7 2 − 1 d 3 2 −1 effective interaction are in poor agreement with values obtained from other nuclei, but are reasonably well reproduced by calculations with a simple force.

Differential cross sections and analyzing powers for the (p\ensuremath{\rightarrow},n) reaction on carbon isotopes have been measured for angles up to ${\ensuremath{\theta}}_{\mathrm{lab}=50}$\ifmmode^\circ\else\textdegree\fi{} using 160 MeV protons. The angular distributions for the stronger transitions are compared with the results of distorted-wave impulse approximation calculations which utilize transition densities from existing shell model calculations. The total observed Gamow-Teller strength is also compared with the shell model predictions. In addition, the shapes of these angular distributions are discussed emphasizing decomposition into longitudinal, transverse, and non-normal-parity-transfer components. Some comparisons of the present (p,n) data with corresponding (p,p') data and with other relevant (p,n) data are also made.

The Gamow-Teller strength function in $^{71}\mathrm{Ge}$ has been measured by use of the reaction $^{71}\mathrm{Ga}(p, n)$ at ${E}_{p}=120 \mathrm{and} 200$ MeV. While a significant fraction of the total strength is associated with excited states located below particle-emission threshold, the first excited state exhibits little strength. Excited-state contributions to the total solar-neutrino capture rate for a $^{71}\mathrm{Ga}$ detector are about 14 solar neutrino units for the neutrino spectrum of the standard solar model and about 3-4 solar neutrino units for representative nonstandard solar models.

Recent (p, n) experiments at intermediate energies have shown the existence of spin-isospin collective modes in nuclei. From the zero degree spectra Gamow-Teller strength can be deduced and only half the sumrule limit is observed. Recent (p, p') experiments at 200 MeV on a number-of nuclei from 5, 1 V to 140 Ce have found resonances that are interpreted as collective M1 states

The first measurements of the transverse spin-transfer coefficient D/sub N/N(0/sup 0/) for intermediate-energy (p,n) reactions to well-resolved nuclear states are reported. Results are presented for (p/sub pol/,n/sub pol/) reactions on /sup 6,7/Li, /sup 12,13,14/C, and /sup 90/Zr at E/sub p/ = 160 MeV. The average value of D/sub N/N(0/sup 0/) for pure Gamow-Teller transitions at this energy is shown to be close to the expected value of approx. =-(1/3). The utility of spin-transfer measurements for investigation of aspects of the nuclear spin-dependent response not otherwise observable is pointed out.

Data are presented for the 12 C(p, n) 12 N reaction at 120, 160 and 200 MeV. Angular distributions at 160 MeV show that the spectrum between 2 and 17 MeV excitation energy is dominated by l = 1 spin excitations. The (p, n) spectrum for l = 1 transitions is calculated based on a Cohen-Kurath type of shell-model calculation. The shape of the calculated spectrum agrees well with the experimental spectrum, but with a factor of 2 larger cross section. This is consistent with electron-scattering data for the 19.4 MeV state in 12 C, the analogue of the 4.2 MeV state in 12 N. Two broad structures at 4 and 7 Me V are identified as being mainly 2 − and 1 − states.

Differential cross sections for the (p, n) reaction on 52, 54Cr and 57, 58Fe have been measured for angles up to θlab = 10.5° and 14.6°, respectively, using 120 MeV protons. The observed angular distributions are used to evaluate the location and strength of Gamow-Teller resonances. A shell-model calculation of this strength distribution is presented and compared with the experimental results. The M1 strength for 52Cr is also calculated and compared with available results from (e, e') and (p, p') experiments. A comparison is made with other If 7 2 nuclei.

The effects of Δ (1232) and L = 1 baryon resonances on the quenching of spin-dipole (rY1 σ) excitation are studied based on the quark model. The couplings between L = 1 baryon resonances and nucleons are shown to be minor effects. The Δ-hole coupling decreases the transition strengths of spin-dipole states, but to a lesser extent than the case of Gamow-Teller (l = 0) strengths.

Data from recent (p, n) and (3He, t) experiments at intermediate energies are presented. The reactions show a spectacular selectivity for excitation of isospin-spin modes in nuclei. From the zero degree (p, n) spectra Gamov-Teller strength can be deduced, and only half the sumrule strength is observed. The very general nature of the sumrule for charge exchange modes suggests that internal degrees of freedom of the nucleon could be involved. The (3He, t) reaction at 2 GeV shows a strong excitation of the Δ-resonance, indicating that this resonance could be important for the isospin-spin excitations in nuclei.

The analogue states of the low-lying levels in 47 Ca are studied via the (p, p) and (p, p′) reactions on 46 Ca. Resonances seen at bombarding energies of 1.863, 2.768 and 3.95 MeV are identified as analogue states to the 2.013, 2.878 and 4.049 MeV excited states in 47 Ca. For analogue resonances below the neutron threshold the compound elastic scattering has been taken into account. It is shown that by including the compound elastic contribution the shape of the resonance determines not only the l -value but also the spin. Partial and total widths are given and spectroscopic factors are calculated. The elastic proton widths Λ p correspond well with the results obtained from the 46 Ca(d, p) reaction. From the inelastic widths we get new information about the structure of the states in 47 Ca.

The γ-decay from three fine-structure components of the 49 Ca ground state analogue has been investigated. Angular distributions have been measured for the decay from the strongest component. Absolute γ-widths are found from the γ-spectra, and the proton and neutron widths from fits to the 48 Ca(p, p) and (p, n) excitation functions. A group of eight states with E x around 7 MeV is found to carry a significant part of the M1 strength. A comparison with the β-decay from 49 Ca has been made.

A system is described, which makes it possible to take into account the slow variations (

The γ-decay from the analogue state of the 51 Ti g.s. is studied. It is shown that most of the T > strength is concentrated in a single state. Absolute widths for the transitions from the analogue state to 17 lower-lying states in 51 V are given. Strong dipole transitions are observed to a group of states around 5 MeV below the analogue state. It is believed that the transitions are M1 transitions and that the states carry a significant part of the Gamow-Teller strength. The absolute widths for the transitions to the first and second excited states are compared with the ft values for the corresponding β-decay of 51 Ti.

Fine structure of analogue resonances is studied by elastic proton scattering on 44 Ca and 50 Ti. The analogue state corresponding to the 1.90 MeV excited state in 45 Ca is observed at bombarding energies around 1.65 MeV with its strength distributed over six resonances. The energy resolution was about 600 eV. The analogue state corresponding to the first excited state ( E ex = 1.16 MeV) in 51 Ti is distributed over at least eight components, which appear in the excitation function around 2.55 MeV. The data are analysed in terms of a one-channel multilevel formula. On the basis of a particular model, the average cross section is calculated. It is shown that in the gross structure, the compound elastic scattering must be taken into account. Analogue widths are deduced, and spectroscopic factors are calculated by two methods.

Angular distributions have been measured in the range from 5° to 50° for the 48 Ca( 6 Li, 6 He) 48 Sc reaction at E( 6 Li) = 34 MeV in a magnetic spectrograph. A rather clean spectrum of 6 He particles was obtained by using a sonic spark counter as the position defining device together with three proportional counters in an anticoincidence set-up. A microscopic description of the reaction has been used to predict absolute cross sections for the unnatural parity states of the ( f 7 2 ) 2 multiplet. A calculation of the configuration mixing shows that the cross section to especially the 1 + state is strongly dependent on such a mixing. A number of states with excitation energies above 2.5 MeV are excited with cross sections similar to the low lying states. Comparison with DWBA calculations puts limits on the spins of the final states.

The transverse polarization transfer for the $^{90}\mathrm{Zr}$(p,n) reaction has been measured for ${E}_{\mathrm{p}=160}$ MeV and theta=0\ifmmode^\circ\else\textdegree\fi{}. A sequence of alternating unnatural parity and natural parity excitations is clearly revealed. Some of the observed features are consistent with the known or predicted excitation energies of \ensuremath{\Delta}L=0 and \ensuremath{\Delta}L=1 resonances.

The probability for γ-transitions from the 6.92 MeV 2 + state in O 16 to the 6.06 MeV 0 + state has been measured relative to the probability for ground-state transitions. The branching ratio obtained is R = (2.7±0.7)×10 −4 , in agreement with an earlier result.

Analogue states have been identified as resonances in (p, p) and (p, p′) reactions on Ca, Ni, Zn and Ge isotopes. The proton widths Γp relative to single-particle widths calculated from a real Saxon-Woods potential are compared with (d, p) results.

The 144 Sm(α, 3 He) 145 Sm stripping reaction has been studied up to 3 MeV excitation energy with a 40 MeV α-beam. Angular distributions have been recorded, and spectroscopic factors are deduced using a standard DWBA procedure. The reaction favours high- l transfers, and is found to be very useful for the investigation of large- j states. From a comparison with the spectroscopic factors known from the 144 Sm(d, p) 145 Sm reaction the normalization factor for the (α, 3 He) reaction is found to depend strongly on the optical model parameters and on the transferred angular momentum l .

The study of Δ-excitations in a nucleus is a natural extension of the study of nuclear structure. The A is however not identical with the nucleons in a nucleus, and the Pauli-principle will have a very different effect on the Δ. The properties of the nuclear medium in the presence of a Δ is therefore different from normal nuclear matter.

Put rather high energy w (30~120MeV) and high momentum q (1.0~2.5 fm−1) together with spin and isospin into nucleus and see how it responds. This is one of the main subjects of this meeting. Inelastic and charge exchange scatterings of nuclear probes are very promising tools for this purpose. If a probe interacts a nucleon inside the nucleus almost freely, one expects the broad bump with the peak at ω = q2/2m (m being the nucleon mass). This bump region is called the quasi-free region.

Excitation of the Δ resonance is observed for the first time with heavy ions. It is very strong in the two mirror charge-exchange reactions ( 20 Ne , 20 F ) and ( 20 Ne , 20 Na ) at 950 MeV per nucleon. With similar incident energies per nucleon, the Δ is weakly excited with a 14 N beam and nearly absent with a 12 C beam. The role of the ejectile bound states is discussed.

The recent (p, n) experiments at intermediate energy at the Indiana University Cyclotron1–6 have led to a major breakthrough in the understanding of spin correlations in nuclei. The (p,n) reaction for bombarding energies between 100 and 200 MeV has proven to be a unique tool for the study of spin excitations in nuclei. Fig.1 shows zero degree neutron spectra for Ep=200 MeV. 5 The spectra are seen to be dominated by a single peak which is interpreted as a collective l+-state, the giant Gamow-Teller state, the isospin-spin nuclear sound. The collective state carries a large fraction of the total Gamow-Teller strength, i.e. strength associated with the operator σμt_ that governs Gamow-Teller β-decay. The concentration of strength into a collective state was first discussed by K. Ikeda, S. Fujii and J.I. Fujita as early as 1963.7 In a shell model picture of e.g. 208Pb the G.T. operator has non-zero matrix elements with all 44 excess neutrons (and the 12 h11/2 neutrons in the next lower shell). The collective state then corresponds to a transition where all these nucleons coherently change direction of spin and isospin.

The excitation mechanisms and properties of broad hadronic resonances in nuclei, which are intimately related with nuclear medium response on high energy excitations, have attracted much attention during last decade.