Particle-hole multiplets in 40Ca observed in the 41Ca(τ, α) reaction

Energy levels in ⁴⁰Ca up to 10.2 MeV have been studied in the neutron pickup reaction ⁴¹Ca(τ, α)⁴⁰Ca with 20 MeV bombarding energy. Thirty excited states have been identified and angular distributions have been measured in the interval from 5° to 40° by means of a split-pole magnetic spectrometer. The angular distributions together with DW calculations have been used to extract l_n values and spectroscopic factors. The l_n = 2 strength distribution for the $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$ particle-hole levels is compared to the l_p = 3 strength distribution from pr stripping data.     

Study of the 91Zr(d, 3He)90Y reaction

The ⁹¹Zr(d, ³He) reaction was studied at a deuteron energy of 28 MeV. Angular distributions were measured from 13° to 47°; l_p values were extracted for the prominent lines of ⁹⁰Y. The l_p values and transition strengths were determined by DWBA analysis. The angular distributions for the $\text{(π}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{)(ν}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ doublet (g.s. and 0.20 MeV state) exhibit the characteristic l = 1 shape. States at 1.42, 1.57, 1.64 and 1.81 MeV were also populated strongly in the (d, ³He) reaction; the 1.42, 1.57 and 1.81 MeV levels contain l= 1 transition strength and are most likely members of the $\text{(π}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{)(ν}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ multiplet. The 2.03 MeV state has a characteristic l = 3 angular distribution and is suggested to be the only member of the $\text{(π}\text{f}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{)(ν}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)}$ sextet to be unambiguously observed in this study, most probably the 5^? or 4^? member. The members of the $\text{(π}\text{g}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)(ν}\text{d}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{)}$ sextet were populated weakly (less than 100 μb/sr) in this reaction.     

Study of 11B at high excitations with the 9Be(3He,p)11B and 9Be(α, d)11B reactions

The nucleus ¹¹B has been studied over the excitation energy range from 8.5 MeV to 21.5 MeV with the ⁹Be(³He, p)¹¹B / reaction at / E_{³He = 38 MeV}. The analogs of the parent states in ¹¹Be have been located at 12.56, 12.92, 14.40, 16.44, 17.69, 18.0, 19.15 and 21.27 MeV. A complementary measurement with the ⁹Be(α, d)¹¹B reaction at E_α = 48 MeV demonstrates that the 16.44, 17.69, 18.0 and 19.15 MeV resonances have rather pure isospin $\text{T}{}_{\mathrm{f}}\text{=}\text{3}\text{2}$. The 14.40 MeV state is a strongly isospin-mixed analog of the $\text{5}\text{2}{}^{\mathrm{+}}\text{1.78}\text{MeV}$ state in ¹¹Be. It is argued that spin S = 1 transfer is involved in the excitation of the 16.44 MeV state and its 3.887 MeV parent in ¹¹Be in a two-step stripping process. The $\text{T}{}_{\mathrm{f}}\text{=}\text{1}\text{2}$ states and the lowest three $\text{T}{}_{\mathrm{f}}\text{=}\text{3}\text{2}$ states are compared with the predictions of DWBA utilizing shell-model form factors. It is concluded that the $\text{T}{}_{\mathrm{f}}\text{=}\text{1}\text{2}$ strength is more strongly fragmented than is implied by the calculations of Teeters and Kurath.     

Structure study of 12B from the elastic scattering of neutrons from 11B

Differential cross sections for neutrons scattered from ¹¹B have been measured for 2.2 MeV < E_n < 4.5 MeV. The differential cross section σ(θ) is fitted reasonably well by R-matrix parameters for broad states in ¹²B with assignments 1 ^? and (1) ⁺ at excitation energies E_x = 5.8 and 6.8 MeV respectively. The broad 1 ^? state has not been previously observed and is believed to be the 1 ^? member of the $\text{1}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ particle-hole multiplet predicted to exist by earlier shell model calculations. Its existence completes the identification of all of the levels of this multiplet (3 ^?, 2 ^?, 4 ^?, 1 ^?). The broad (1)⁺ level at E_x = 6.8 MeV has not been previously observed. States at excitation energies E_x = 5.61, 5.73 and 6.6 MeV have been assigned spins and parities of 3⁺, 3^? and (1)⁺ respectively. These states had previously been assigned spins of 2, 3 and $\text{≧ 1}$ respectively. Work on T = 1 states in ¹²C¹ has been compared with the present work.     

Electromagnetic transitions in 51Mn

The nuclear structure of ⁵¹₂₅Mn was studied by γ-ray spectroscopy in the ⁵⁴Fe(p, α)⁵¹ Mn reaction (E_p = 9.0–13.2 MeV) and the ¹⁴N+³⁹K, ¹⁶O+⁴⁰Ca and ¹⁴N+⁴⁰Ca fusion-evaporation reactions (E_beam = 36 MeV). In the ⁵⁴Fe(p, αγ)⁵¹Mn reaction γ-rays were detected in coincidence with α-particles emitted near 180°; mean lifetimes and γ-ray mixing and branching ratios were deduced from Doppler shift attenuation and α-γ angular correlation measurements, respectively. Definite spin assignments are: 237 and 2416 keV, $\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}$; 1140 keV, $\text{9}\text{2}$^?; 1488 keV, $\text{11}\text{2}$^?; 1825 and 2140 keV, $\text{3}\text{2}$^?. The results for other states below 3 MeV are consistent with the existence of rotational bands (/kh²/2/OI/t~ 95 keV) built on the ($\text{3}\text{2}$⁺) 1817 keV and $\text{1}\text{2}$⁺ 2276 keV hole states. The various measurements together with an earlier value for the lifetime of the first-excited state determine unambiguously the B(M1) and B(E2) values for all of the decay branches of the $\text{7}\text{2}$^?, $\text{9}\text{2}$^? and $\text{11}\text{2}$^? lowest three excited states. From the γ-singles and γ-γ coincidence observations with fusion-evaporation reactions, the yrast cascade proceeds through these three states and higher states at 2957, 3250,3680 and 4139 keV which are suggested to have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{13}\text{2}{}^{\mathrm{?}}$, $\text{15}\text{2}$^?,$\text{15}\text{2}$^? and $\text{19}\text{2}$^?, respectively. The various experimental results for the $\text{5}\text{2}$^? → ($\text{19}\text{2}$^?) yrast states are in good overall agreement with shell-model calculations in the (f_{$\text{7}\text{2}$}¹ space.     

High-resolution proton scattering on 46Ti

Differential cross sections were measured for ⁴⁶Ti(p, p) and ⁴⁶Ti(p, p₁) at four angles between E_p = 1.5 and 3.1 MeV, with an overall energy resolution of about 300 eV. Spins, parities, total and partial widths were extracted for 144 resonances. Six analogue states were identified. The s-wave states have expected spacing and width distributions, while the $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ states behave anomalously. The $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ strength functions were determined.     

Study of proton transfer reactions to low-lying multiplets in 90Y and 92Nb

The (d, ³He) and (α, t) proton transfer reactions on ⁹¹Zr were studied at incident energies of 24.3 and 35.4 MeV, respectively. Angular distributions were measured from 6° to 50° (⁹⁰Y) and 60° (⁹²Nb). High detection efficiency and good energy resolution were obtained by using a magnetic spectrograph in connection with a multiwire proportional chamber. For the low-lying multiplet levels in both nuclei angular momentum transfers and spectroscopic factors were determined by DWBA analysis. In ⁹²Nb the states at 0, 0.135, 0.29, 0.36 and the sum of the states at 0.48 and 0.50 MeV show typical l = 4 shapes. They belong to the ($\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{π}$)($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) sextet. The corresponding multiplet in ⁹⁰Y is weakly populated ($\text{dσ}\text{dΩ}\text{≦ 20 μb/sr}$), and l = 4 shapes are found for the levels at 0.68, 0.78, 0.95, 1.05 and 1.30 MeV proving previous assignments. The members of the low-lying ($\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{π}$)($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) doublets in ⁹⁰Y and ⁹²Nb exhibit a characteristic l = 1 angular shape. The levels at 1.42, 1.57, 1.64, 1.76 and 1.81 MeV in ⁹⁰Y are excited both by l = 1 and l = 3 resulting from a strong mixing of the ($\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{π}$)^?1($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) and $\text{(1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{π)}{}^{\mathrm{?1}}$ ($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) multiplets. Only the level at 2.03 MeV displays a pure l = 3 shape. From the spectroscopic information on the ($\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{π}$)($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) and ($\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{π}$)($\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν}$) multiplets in ⁹⁰Y and ⁹²Nb the g.s. configuration mixing in ⁹¹Zr is deduced.     

Study of the 58Ni(τ, α)57Ni reaction at 25 MeV

The ⁵⁸Ni(τ, α)⁵⁷Ni reaction has been studied at 25 MeV incident energy. Angular distributions have been measured from 5° to 50° with a split-pole spectrometer up to 13.5 MeV excitation energy. A local zero-range DWBA analysis has been carried out, allowing l-assignments for about eighty levels, most of them previously unknown. An isospin-dependent potential has been used in the calculation of the neutron form factor for both T_<and T_> states, and the C²S values deduced using this procedure are compared to those obtained with the usual separation energy method. Analog states of eleven ⁵⁷Co levels have been identified and the eventuality for isospin mixing in ⁵⁷Ni has been discussed. A sum rule analysis has been carried out and energy centroids of hole states have been determined. About 60% of the $\text{1}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{and}\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{T}{}_{\mathrm{<}}$ strengths and the full $\text{1}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole strengths are observed. It is shown that the two excess neutrons in the ⁵⁸Ni ground state mainly populate the $\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{, 1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ orbitals, whereas the occupancy number of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ subshell is found to be smaller than 0.1%. Some non-pickup angular distributions have also been observed and a CRC analysis assuming two-step processes in the (τ, α) reaction and weak-coupling wave functions for final states has been attempted. Assignments of J^π values are proposed for four ⁵⁷Ni levels, based on this analysis.     

Direct transfer and two-step processes in the 42Ca(α, 3He)43Ca reaction

The ⁴²Ca(α, ³He)⁴³Ca reaction has been studied at 36 MeV incident energy. Angular distributions have been measured from 4° to 42° using a split-pole spectrometer and position sensitive Si detectors, for about 40 levels located up to 6 MeV excitation energy. A local zero-range DWBA analysis has been carried out; l = 3 and 4 assignments are tentatively proposed for levels located above 4 MeV excitation energy, indicating a strong fragmentation of the $\text{1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ strength between 4 and 6 MeV and the location of the main component of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ strength above 6 MeV. A number of weakly excited levels cannot be reproduced by DWBA analysis. Their angular distributions have been compared with the results of coupled-reaction-channel calculations assuming two-step excitation of weak coupling states with a [⁴²Ca¹ ? $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ structure. A reasonable agreement has been obtained, confirming that the two-step process cannot be neglected in the analysis of the (α, ³he) reaction.     

Nuclear reaction studies of 168Tm

The intrinsic structure of ¹⁶⁸Tm has been studied using the (³He, d) and (α, t) proton stripping reactions as well as the (d, t) and (³He, α) neutron pick-up reactions. The beams of 24 MeV ³He particles, 25 MeV α-particles and 12 MeV deuterons were obtained from the McMaster tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions. The spectra have been interpreted in terms of the coupling of an odd proton and an odd neutron, each moving independently in a spheroidal potential, which gives rise to intrinsic two-quasiparticle states with $\text{K = ¦Ω}{}_1\text{±Ω}{}_2\text{¦}$. The identification of the intrinsic states was made by comparing the experimental cross-section patterns with those predicted with the aid of Coriolis coupling and distorted-wave Born approximation (DWBA) calculations. Rotational bands superimposed on the K^π = 3⁺ and $\text{K}{}^{\mathrm{\pi }}\text{= 4}{}^{\mathrm{+}}\text{, {}\text{7}\text{2}{}^{\mathrm{+}}\text{[633]}{}_{\mathrm{n}}\text{±}\text{1}\text{2}{}^{\mathrm{+}}\text{[411]}{}_{\mathrm{p}}\text{}}$ configurations, the first of which is the ground state, ha been observed in the spectra of all four reactions. New assignments have been made for configurations resulting from coupling the $\text{1}\text{2}$^? [541], $\text{7}\text{2}$⁺ [404], $\text{5}\text{4}$⁺ [402] and $\text{1}\text{2}$^? [530] p to the $\text{7}\text{2}$⁺ [633] neutron state. The neutron pick-up measurements confirmed the earlier assignments based on (d, t) reaction studies and suggested tentative assignments for the {$\text{1}\text{2}$⁺ [400]_n±$\text{1}\text{2}$⁺ [411]_p} and {$\text{3}\text{2}$⁺ [402]_n±$\text{1}\text{2}$⁺ [411]_p}     

High-resolution proton scattering on 50Ti

Differential cross sections were measured for ⁵⁰Ti(p, p) at four angles for E_p = 1.83 to 2.97 MeV, with an overall energy resolution of about 350 eV. Spins, parities and total widths were extracted for 212 levels. An energy region near E_p = 1.37 MeV was also examined in order to study the analogue of the ground state of ⁵Ti. Coulomb energies and spectroscopic factors were determined for the analogues of the ground and first excited states of ⁵¹Ti. The latter analogue was highly fragmented. The s-wave spacing and width distributions were analyzed and the number of missing levels estimated. The $\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ proton strength functions were determined.     

Spectroscopy of 42Ca from 41Ca(d,p)

Energy levels in ⁴²Ca up to 7.8 MeV have been studied in the neutron capture reaction ⁴¹Ca(d, p)⁴²Ca with 12 MeV bombarding energy. Ninety-four excited states have been identified and angular distributions have been measured in the interval from 5° to 110° by means of a broad-range magnetic spectrograph. The angular distributions together with DW calculations have been used to determine I_n values and spectroscopic factors. The $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ strength sum agrees with shell-model expectations if the f_{$\text{7}\text{2}$} spectroscopic factors are renormalized by $\text{1}\text{0.75}$, in line with other $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$. transfer experiments on ⁴⁰Ca and ⁴¹Ca. A similar renormalization of the l_n = 1 spectroscopic factors brings this strength sum in accordance with the shell-model calculations. The effective ($\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^2$) matrix elements for ⁴²Ca are compared with the corresponding matrix elements of ⁴²Sc and ⁴⁸Sc. The differences between the three sets of matrix elements are of the order of a few hundred keV or less. The monopole centroid energy of the ($\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{)}{}^2$ multiplet is shifted downwards in the mass-42 nuclei compared to ⁴⁸Sc, possibly indicating the importance of the monopole pairing force near ⁴⁰Ca.     

The reaction π−p → ηn up to pη1 = 450 MeV/c: experimental results and partial-wave analysis

An accurate measurement of $\text{d}\text{σ}\text{d}\text{Ω}\text{(π}{}^{\mathrm{?}}\text{p}\text{→ η}\text{n}\text{)}$ at 1531 MeV total energy (expanded) up to l = 4 Legendre polynomials) requires reconsideration of previous angular distribution fits which were expanded only up to l = 2 and of subsequent partial-wave analysis. An energy-dependent partial-wave analysis has been performed here for $\text{p}{}_{\mathrm{\eta }}{}^1$ up to 450 MeV/c. In addition to the well-known S₁₁ (1520 MeV) resonance, either the P₁₁ (1532 MeV) or the P₁₃ (1530 MeV) resonance is found to be strongly coupled to the η-n channel. In both cases, the P₁₁ (1729 MeV) resonance is needed as is the weakly coupled D₁₃ (1525 MeV) resonance. The decay states in the ηn channelare compared to the SU(3) and SU(6)_W predictions.     

Interference effects in 12C(p, γ)13N and direct capture to unbound states

Excitation functions of the capture reaction ¹²C(p, γ₀)¹³N have been obtained at θ_γ = 0° and 90° and E_p = 150–2500 keV. The results can be explained if a direct radiative capture process, E1(s and d → p), to the ground state in ¹³N is included in the analysis in addition to the two well-known resonances in this beam energy range $\text{[E}{}_{\mathrm{p}}\text{= 457(}\text{1}\text{2}{}^{\mathrm{+}}\text{)}$ and 1699 $\text{(}\text{3}\text{2}{}^{\mathrm{?}}\text{) keV]}$. The direct capture component is enhanced through interference effects with the two resonance amplitudes. From the observed direct capture cross section, a spectroscopic factor of C²S(l = 1) = 0.49 ± 0.15 has been deduced for the $\text{1}\text{2}{}^{\mathrm{?}}$ ground state in ¹³N. Excitation functions for the reaction ${}^{12}\text{C(p,γ}{}_1\text{p}{}^1\text{)}{}^{12}\text{C}$ have been obtained at θ_γ = 0° and 90° and E_p = 610–2700 keV. Away from the 1699 keV resonance the capture γ-ray yield is dominated by the direct capture process E1 (p → s) to the $\text{2366 (}\text{1}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound state. Above E_p = 1 MeV, the observed excitation functions are well reproduced by the direct capture theory to unbound states (bremsstrahlung theory). Below E_p = 1 MeV, i.e., E_p → 457 keV, the theory diverges in contrast to observation. This discrepancy is well known in bremsstrahlung theory as the “infrared problem”. From the observed direct capture cross sections at $\text{E}{}_{\mathrm{p}}\text{? 1 MeV}$, a spectroscopic factor of C²S(l = 0) = 1.02 ± 0.15 has been found for the $\text{2366 (}\text{1}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound state. A search for direct capture transitions to the $\text{3512 (}\text{3}\text{2}{}^{\mathrm{?}}\text{)}$and $\text{3547 (}\text{5}\text{2}{}^{\mathrm{+}}\text{) keV}$ unbound states resulted in upper limits of C²S(l = 1) ≦ 0.5 and C²S(l = 2) ? 1.0, respectively. The results are compared with available stripping data as well as shell-model calculations. The astrophysical aspect of the ¹²C(p, γ₀)¹³N reaction also is discussed.     

Experimental and shell-model studies of the reactions 91Zr(d,p)92Zr and 90Zr(t,p)92Zr

The results of high-resolution studies of the ⁹¹Zr(d, p) reaction at E_d = 12 MeV and the ⁹⁰Zr(t, p) reaction at E_t = 11.85 MeV are presented. Absolute cross sections have been measured for both reactions and (d, p) spectroscopic factors determined. A comparison of these results with earlier data has been made, and although many of the previous assignments have been confirmed, many new features concerning the structure of ⁹²Zr have been discovered. Shell-model calculations have been performed for ⁹¹Zr and ⁹²Zr using a neutron space which includes the $\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$, $\text{3}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$, $\text{2}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, $\text{1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ and $\text{1}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}$ orbits and a proton space comprising the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ and $\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ orbits. Realistic proton-neutron and neutron-neutron interactions based on the Sussex matrix elements were used in the calculations. Spectroscopic factors have been calculated for the ⁹⁰Zr(d, p) and ⁹¹Zr(d, p) reactions and cross sections calculated for the ⁹⁰Zr(t, p) reaction. In general, good agreement between the theoretical and the experimental results has been obtained.     

Low-lying levels of 140Pr

The doubly odd nucleus ¹⁴⁰Pr has been investigated by means of the ¹⁴¹Pr(d, t)¹⁴⁰Pr and ¹⁴⁰Ce(p, nγ)¹⁴⁰Pr reactions. Twenty-eight levels, up to 1300 keV excitation, were observed in the pickup study. DWBA analysis was used to determine l-values and spectroscopic factors for all but a few which are very weakly populated. Gamma-ray angular distributions, measured at E_p = 4.78 MeV for the five strongest γ-rays, show appreciable nuclear alignment and demonstrate the feasibility of such experiments in this mass region. Taken together, the two studies have permitted the identification of the 12 levels expected from the low-lying ($\text{π2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν2}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$), ($\text{π2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{ν3}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$), ($\text{π1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{ν2}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$) and (π1g_{$\text{7}\text{2}$}ν3s_{$\text{1}\text{2}$}^?1) configurations. Tenta assignments for the strong odd-parity states are suggested on the basis of their spectroscopic factors.     

The γ-decay of the 1g92 and 2p inner-hole states in 111Sn via the 112Sn(3He, αγ) reaction at 32 MeV

The γ-decay of the deeply-bound hole states in ¹¹¹Sn has been investigated at 32 MeV incident energy by means of the ¹¹²Sn(³He, αγ) reaction. The α-particles emitted near 0° were detected in a Si counter located at the image plan of the superconducting solenoidal spectrometer SOLENO. The γ-rays in coincidence with the α-particles were detected by two Ge(Li) detectors located at 90° and 142° with respect to the beam direction, respectively. Energies, spins and decay schemes have been established for the low-lying states up to 2.5 MeV excitation energy in ¹¹¹Sn. The γ-decay of the broad bump, located around 4.2 MeV and previously attributed to neutron pick-up from the inner $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{,}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ neutron. Subshells, reveals the importance of quasiparticle-phonon m the spreading mechanism of the inner-hole strengths. The $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ and 2p strength functions have been deduced from the α-decay of the enhanced structures (3 ≦ E_x≦ 8 MeV). They are compared to the ones measured in previous inclusive neutron pick-up experiments and to those calculated in the framework of the quasiparticle-phonon nuclear model.     

12C(7Li,t)16O and stellar helium fusion

The reaction ¹²C(⁷Li, t)¹⁶O has been studied at $\text{E(}{}^7\text{Li}\text{) = 34}\text{MeV}$ with the LASL tandem accelerator and QDDD magnetic spectrometer. Angular distributions to levels with E_x < 11 MeV have been obtained from 0° to 90°, including 0°. The results have been analyzed with finite-range distorted-wave Born approximation theory. The α-particle spectroscopic factors and reduced widths obtained are compared with those calculated with group theory (SU(3)) and other models. The analysis of data for the 7.1 and 9.6 MeV J^π = 1^? levels, which are of great importance in stellar helium buring, yields a ratio, R, of dimensionless reduced α-widths $\text{θ}{}^2{}_{\mathrm{<mtext>a</mtext>}}\text{(7.1}\text{MeV}\text{)}\text{θ}{}^2{}_{\mathrm{<mtext>a</mtext>}}\text{(9.6}\text{MeV}\text{)}\text{= 0.35b ± 0.13}$. The observed line width of the 9.6 MeV level (Γ_c.m. = 390 ± 60 keV) is less than the accepted value (Γ_c.m. = 510 ± 60 keV) and implies θ²_a(9.6 MeV) ≈ 0.6. These results as well as data for the 6.92 MeV J^π = 2⁺ and 10.35 MeV J^π = 4⁺ “α-cluster” states indicate 0.09 < θ²_a(7.1 MeV) < 0.33 with a mean value θ²_a(7.1 MeV) = 0.14 ± 0.04. The implication for stellar helium burning is discussed.     

The separation of proton and deuteron spin-dependent effects in the 116Sn(d,p)117Sn reaction

The cross section, vector analyzing power, and proton polarization have been measured for the l_n = 0 reaction ¹¹⁶Sn(d, p)¹¹⁷Sn(g.s.) at 8.22 MeV. In addition, cross section and analyzing power data have been obtained at 8.22 MeV for ${}^{116}\text{Sn}\text{(}\text{d}\text{,}\text{d}\text{)}{}^{116}\text{Sn}$ and for ¹¹⁶Sn(d, p)¹¹⁷Sn leading to excited states of ¹¹⁷Sn at 0.159, 0.317, 1.020, 1.179, 1.308 and 1.497 MeV. The cross section and analyzing power for ${}^{117}\text{Sn}\text{(}\text{p}\text{,}\text{p}\text{)}\text{Sn}$ and for ${}^{117}\text{Sn}\text{(}\text{p}\text{,}\text{d}\text{)}{}^{116}\text{Sn}$ leading to the 1.294 MeV state of ¹¹⁶Sn have also been measured at 12.91 MeV. The data for ¹¹⁶Sn(d, p)¹¹⁷Sn(g.s.) have been used to separate the contributions to the analyzing power arising from spin-dependent forces in the proton and deuteron channels. A similar analysis is presented for an $\text{l}{}_{\mathrm{n}}\text{= 0}{}^{90}\text{Zr}\text{(}\text{d, p}\text{)}{}^{91}\text{Zr}$ transition at 11 MeV. Optical-model analyses have been performed for the elastic scattering data. The reaction data have been compared with distorted-wave calculations in order to investigate the validity of various deuteron potentials, as well as to extract spectroscopic information.     

The 54Fe(3He,t)54Co reaction at 70 MeV,Gamow-Teller strength

The ⁵⁴Fe(³He, t)⁵⁴Co reaction has been studied at 70 MeV with an energy resolution around 70 keV (FWHM). The triton spectra are characterized by sharp peaks up to 10 MeV excitation energy superimposed on a continuum. Most of the sharp peaks have a forward-peaked angular distribution and 38 peaks or groups of peaks are found to have an angular distribution corresponding to an angular momentum transfer of 2. Model considerations lead to the conclusion that most of these states are 1⁺ states. A shell-model calculation with parameters that account for the Gamow-Teller strength distribution in ⁴⁸Ca-⁴⁸Sc divides the β-strength in ⁵⁴Co in a ratio 5.7:6.8:1.3 for the T = 0, 1 and 2 states. A comparison is made with the 1⁺ spectrum in ⁵⁴Mn (T = 2 states) and a tentative assignment of T = 2 states in ⁵⁴Co is reached. The cross section has been calculated for the 0⁺, 1⁺ and 3⁺ states in ⁵⁴Co assuming a pure ($\text{π}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{ν}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$) configuration finite-range DWBA is used and the conclusions are that the (³He, α, t) and (³He, d, t) processes give significant contributions to the cross sections.