Proton-hole states in 57Co studied with the 58Ni(d, 3He) 57Co reaction at 78 MeV

The ⁵⁸Ni(d, ³He)⁵⁷Co reaction was measured at a bombarding energy of 78 MeV. Energy levels up to 7.0 MeV excitation energy in ⁵⁷Co were studied. Angular distributions of the ³He particles, corresponding to transitions to the ground state and to 42 excited states in ⁵⁷Co, were analyzed in the range of θ_lab = 2.7° to 25°. Exact finite-range DWBA calculations were employed to extract l-values and spectroscopic factors. Shell-model calculations were carried out in an fp-shell model space. In addition, calculations of the energy levels in ⁵⁷Co were performed in the SU(6) particle-vibration model (PTQM). Satisfactory agreement is observed between the experimental results and both theoretical predictions.     

3He D-state effects in (d, 3He) reactions

The tensor analysing power of the ²⁷Al(d, ³He)²⁶Mg reaction has been measured at E_d = 12.4 MeV. The results are reproduced by predictions of the DWBA including D-state components in the ³He wave function. The magnitude of the tensor analysing power provides information on the asymptotic D-state to S-state ratio in the ³He wave function. The value obtained for ³He is in agreement with the corresponding value for ³H.     

Analyzing-power and cross-section measurements for 3He(d,d)3He scattering

Complete angular distributions of the differential cross section and all four deuteron-analyzing powers for ³He(d, d)³He scattering have been measured at 14 energies between 1.5 and 11.5 MeV. For all components the major changes in the observables occur below 7 MeV deuteron energy.     

A study of the level properties of 57Co from the (τ, d) reaction on 56Fe

The ⁵⁶Fe(τ, d)⁵⁷Co reaction has been studied at E_τ = 18 MeV using the Tandem Van de Graaff accelerator and the multichannel magnetic spectrograph of the Nuclear Physics Laboratory, Oxford, Angular distributions have been measured for most of the levels up to E_x ≈ 7.8 MeV and are analysed in terms of the DWBA theory of direct reactions. The l_p values and the transition strengths compared with available theories.     

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.     

New highly excited 4He levels found by the 2H(d,p)3H reaction

The differential cross section, the vector- and the tensor-analyzing powers of the reaction ²H($\text{d}$, p)³H have been measured. The polarization data were obtained at 11 energies between 1.0 and 13 MeV at lab angles between 5° and 160°. The data were fitted with Legendre polynomials and the resulting coefficients analyzed for resonances in ⁴He. Overwhelming evidence for a 1^? level at 24.1 MeV and a strong indication of a 4⁺ level at 24.6 MeV excitation energy have been found.     

Study of 74As by the 73Ge(3He,d) reaction

The energy levels of ⁷⁴As have been studied using the ⁷³Ge(³He, d)⁷⁴As reaction at an incident energy of 17 MeV. The overall energy resolution was 30 keV. Twenty-five levels in ⁷⁴As were identified up to 2.2 MeV excitation energy and angular distributions were measured in the interval $\text{3}\text{3}\text{4}\text{°}$ to $\text{86}\text{1}\text{4}\text{°}$. Spectroscopic strengths and l_p values have been extracted for many of the transitions by means of a distorted-wave analysis of the differential cross sections. A comparison with the ⁷⁵As(p, d) data suggests the presence of several unresolved doublets in ⁷⁴As.     

Spectroscopic study of 55Co via the 54Fe(τ, d)55Co and 54Fe(τ, dp̃)54Fe reactions

The ⁵⁴Fe(τ, d)⁵⁵Co reaction has been studied at 25 MeV incident energy with a split-pole spectrometer. About one hundred levels have been observed in ⁵⁵Co up to 10 MeV excitation energy. Angular distributions have been measured and analyzed with DWBA and Gamow functions as form factors for unbound levels. The ⁵⁴Fe(τ,dp?)⁵⁴ reaction has been investigated at 24 MeV incident energy. The angular distributions of the emitted protons were measured in coincidence using method 2 of Litherland and Ferguson, with 0 detection of deuteron groups. Spins, population parameters, branching ratios and proton partial widths for the transitions to the ground and excited states of ⁵⁴Fe were determined from the analysis of the angular correlation data. The results of these two experiments provide a large number ofspectroscopic properties of unbound proton states and in particular of analog states of ⁵⁵Fe low-lying levels. The IAS of the $\text{3}\text{2}{}^{\mathrm{?}}$ ground state of ⁵⁵Fe is observed to be split between two individual levels. The amplitude of neutron coupling to the first 2⁺ excited state of ⁵⁴Fe is obtained for the $\text{lg}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ and $\text{2}\text{d}\text{5}\text{2}$ low-lying parent statfes in ⁵⁵Fe. summed spectroscopic factors and the centroid energies of the proton states in ⁵⁵Co are obtained. A comparison is made with previous (τ, d), (d, p) and (p, p) results.     

Study of the (3He,d) reactions on 58, 60Ni and 56Fe near the Coulomb barrier

Using spectroscopic information gained by earlier measurements of the proton bound states populated by stripping reactions, (³He, d) reactions on ^{58, 60}Ni and ⁵⁶Fe targets are studied at energies near the Coulomb barrier and evaluation is made of the vertex function . This value is then used to determine spectroscopic factors for low-lying states in ⁵⁷Co.     

A study of the 59Co(n,n′γ)59Co reaction

The ⁵⁹Co(n, n'γ)⁵⁹Co reaction has been studied for incident neutron energies ranging from 1.3 to 3.9 MeV. The pulsed-beam time-of-flight technique was employed to discriminate between the inelastically scattered neutrons and the de-excitation γ-rays, which were detected by means of a true-coaxial Ge(Li) detector. Thirty-five levels were identified in this way, and their excitation functions have been extensively compared with the predictions of the statistical theory of the compound nucleus. Possible spin assignements to the levels of ⁵⁹Co are discussed and compared with the results available from previous works.     

Resonances in the reaction 56Fe(p, γ)57Co

Resonances in the reaction ⁵⁶Fe(p, γ)⁵⁷Co have been surveyed over the energy range 1.2 ? E_p ? 1.5 MeV wherein the analogues of the ground state $\text{(J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}^{\mathrm{?}}\text{, 0.014}\text{MeV}$ state $\text{(J}{}^{\mathrm{\pi }}\text{=}\text{3}\text{2}{}^{\mathrm{?}}\text{)}$ and 0.136 MeV state $\text{(J}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{?}}\text{)}$ of ⁵⁷Fe are expected to occur. Gamma-ray angular distributions have been used to establish resonance and bound-state spins, and decay schemes have been determined. The analogue resonances appear to be severely fragmented, however the density of resonances of a given spin correlates quite well with (³He, d) results and with the expected analogue-state positions.     

An investigation of the 144Sm(α, 3He)145Sm reaction

The ¹⁴⁴Sm(α, ³He)¹⁴⁵Sm 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 ¹⁴⁴Sm(d, p)¹⁴⁵Sm reaction the normalization factor for the (α, ³He) reaction is found to depend strongly on the optical model parameters and on the transferred angular momentum l.     

Energy levels,decay scheme, γ-ray branching ratios and lifetimes in 55Fe from the 55Mn(p,nγ)55Fe reaction

The reaction ⁵⁵Mn(p, nγ)⁵⁵Fe has been studied at E_p = 4.0 and 6.0 MeV using a pulsed beam. From the experiments at 6.0 MeV, the energy levels of ⁵⁵Fe up to an excitation of 3810 keV, their decay scheme and the γ-ray branching ratios have been determined. Levels have been identified for the first time in the (p, nγ) reaction. The results have been compared with those available from the literature. From the 4.0 MeV experiment, the mean lifetime of the 1408 keV level has been determined to be 142.7 ± 6.6 ps by direct timing techniques.     

Investigation of the 6Li(d, α)4He reaction between 1.5 and 11.5 MeV

The differential cross section σ₀(θ) and the analysing powers T₁₁(θ), T₂₀(θ), T₂₁(θ) and T₂₂(θ) of the reaction ⁶Li(d, α)⁴He have been measured for twelve energies between 1.5 and 11.5 MeV at c.m. angles between 3.5° and 90°. The results were fitted with Legendre polynomials. The energy dependence of the resulting coefficients indicates resonance-like behaviour at several energies corresponding to excitation between 22 and 32 MeV in ⁸Be. The reaction ⁶Li(d, α)⁴He shows excellent features as an analyser for deuteron vector and tensor polarization over the whole energy range investigated.     

Two-body photodisintegration of 3He and 4He in the Δ(1236) region

Differential cross sections for the reactions ³He(γ, p)d and ⁴He(γ, p)t were measured at proton c.m. angles of 60° and 90° for photon energies ranging from 150–450 MeV with an average resolution of 8 MeV. Bremsstrahlung was used as the photon source; deuterons/tritons were analyzed in a magnetic spectrometer whereas coincident protons were detected in a plastic scintillator telescope. The experimental method includes a calibration by means of ¹H(γ, π⁰)p differential cross section measurement at 90° c.m. in the same photon energy range. The ³He and ⁴He two-body photodisintegration differential cross sections show a monotonically decreasing variation with photon energy. In addition, partial data on the differential cross section of the reaction ⁴He(γ, n)τ at 90° and 120° neutron c.m. angle are given.     

Inelastic processes in the 19F(3He,d)20Ne reaction

We have examined the role of inelastic processes in the ¹⁹F(³He, d)²⁰Ne reaction. By coupling three levels in both the entrance and exit channels it was found that the inelastic processes were able to account for both the magnitude and rather flat shape of the angular distribution for the 4.25 MeV 4⁺ level observed in the ¹⁹F(³He, d)²⁰Ne reaction at 16 MeV bombarding energy. In contrast the DWBA could not account for the data. The magnitude of the inelastic processes was found to be quite sensitive to some of the optical model parameters involved. The DWBA predictions for the 0⁺ and 2⁺ cross sections were modified by the inelastic processes requiring some adjustment of the spectroscopic amplitudes to account for the data.     

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.     

Proton spectroscopy of 96Tc from the (3He,d) reaction

Energy levels of the even-mass odd nucleus ⁹⁶Tc have been populated with the ⁹⁵Mo(³He, d)⁹⁶Tc reaction at a bombarding energy of 33.6 MeV and with 28 keV resolution (FWHM). Thirty levels were observed below 2.10 MeV excitation. Comparison of experimental angular distributions with DWBA calculations allowed l-value assignments and the extraction of spectroscopic factors for most levels. Over eighty-five percent of the observed spectroscopic strength is located in the lowlying $\text{π1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{-}\text{v}\text{2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ configuration multiplet. A simple residual interaction shell model calculation reproduces the observed low-lying positive parity multiplet relatively well although the experimental spectrum indicates much configuration mixing is present.     

The (p,t) reaction on 12C, 54Fe and 208Pb at 80 MeV

Angular distributions have been measured for the low-lying levels of the residual nuclei for the ¹²C, ⁵⁴Fe and ²⁰⁸Pb(p, t) reactions at E_p = 80 MeV. The shapes of these angular distributions are generally well reproduced by the zero-range distorted-wave Born approximation (DWBA). Enhancement factors extracted from the data show that the DWBA predicts relative strengths consistent with those observed at lower bombarding energies. However, the overall empirical DWBA normalization at E_p = 80 MeV is observed to be $\text{1}\text{12}$ ($\text{1}\text{4}$) of that required at 40 MeV for ²⁰⁸Pb (⁵⁴Fe).     

The elastic scattering of polarized 3He by 3He and excitation in the 6Be system

Angular distributions of the polarization in the elastic scattering of ³He by ³He have been measured at eight energies between 18 and 33 MeV, corresponding to excitation of ⁶Be between 20.5 and 28 MeV. The measurements were made using the 33 MeV polarised ³He beam at the University of Birmingham Radial Ridge cyclotron and a small gas target. The data have been analysed in terms of real and complex phase shifts. The deduced phase shift energy dependence cannot be associated with a single isolated level in ⁶Be, however an application of the two-level R-matrix formula reveals some broad L = 3 structures around E_x = 25 MeV.