Fine structure of analogue states in 45Sc

Differential cross sections were measured for ⁴⁴Ca(p, p′) and ⁴⁴Ca(p, p') at four angles between E_p = 1.5 and 3.0 MeV, with an overall energy resolution of about 325 eV. Spins, parities, total and partial widths were extracted for 429 resonances. Five analogue states were identified and fits to the fine structure were obtained for four of these analogues.     

Inelastic proton amplitudes forf-wave resonances in55Co

The measurement of inelastic proton channel amplitudes has been extended tof-wave resonances. Ten resonances were studied in the⁵⁴Fe(p, p′γ) reaction, All were established to haveJ ^π = 5/2^?, and inelastic decay amplitudes were determined for these resonances. Elastic and inelastic spectroscopic factors were determined for the 5/2^? analogue state atE _p =3.80 MeV.     

Entrance channel correlations for 2+ resonances inp+27Al

Angular distributions for²⁷Al(p, α ₀) and excitation functions for²⁷Al(p, p ₀) and²⁷Al(p, α ₀) have been measured for 2⁺ resonances in thep+²⁷Al system. For 10 of these resonances, partial widths have been determined for three proton channels, and the relative sign between the reduced width amplitudes in two of these channels has been deduced. Linear correlation coefficients between reduced widths and between reduced width amplitudes in different channels have been calculated. The amplitudes appear consistent with the expected Gaussian distribution.     

Possible higher order processes seen in four-nucleon transfer

Coupled Channels calculations have been performed for the reaction⁴⁰Ca(⁶Li,d)⁴⁴Ti(3^?)_3.94 assuming coupling of α-transfer with inelastic scattering in both the entrance and the exit channels. The effect of several competing transition routes is discussed. A relative spectroscopic factor (⁴⁴Ti(3^?);⁴⁰Ca(3^?), α) is derived.     

Electromagnetic decay of fragmented analogue states in 45Sc

The ⁴⁴Ca(p, γ) reaction was studied for 45 resonances for E_p = 1.6?2.2 MeV. The overall proton energy resolution was 300–350 eV; the γ-rays were detected with both NaI(T1) and Ge(Li) detectors. Partial and total γ-ray widths were measured for each of the fine structure states of the $\text{3}\text{2}{}^{\mathrm{?}}$ and $\text{1}\text{2}{}^{\mathrm{?}}$ analogue states at E_p = 1.65 and 2.04 MeV, respectively. The data are examined for correlations between the partial widths (Γ_p, Γ_p′, Γ_γi, Γ_γ^total) in different channels. The γ-ray intensities are compared with (τ, d) spectroscopic factors.     

Amplitude correlations for inelastic proton scattering from48Ti

The magnitudes and relative signs of inelastic proton channel amplitudes were determined for three decay channels for 45 5/2⁺ resonances in⁴⁹V. The reduced widths in each channel follow a Porter-Thomas distribution, but extremely large amplitude correlations are observed — for one pair of channel amplitudes the relative sign is positive for 43 of 45 resonances. These results provide the first direct test of the Krieger-Porter reduced width amplitude distribution.     

Investigation of22Na excited states

Fourteen²¹Ne(p, γ)²²Na resonances have been observed in the rangeE _p =300–1,300 keV. Theγ-decay of all these resonances has been investigated by means of a 38 cm³ Ge(Li) detector. Energies and branching ratios of several bound states have been determined. TheQ-value was determined as 6,738.5±1.7 keV. Lifetimes of seven states were determined with the Doppler-shift attenuation method. The observed upper limit (τ _m ≦4 fs) of the lifetime for the 4,071 keV state, regarded as the analogue of the third excited state in²²Ne, and the transition observed from this state to the 1,528 keV state do not support the proposed rotational band structure of the²²Na low-lying states.     

Excitation of giant multipole resonancesL=1,2 and 3 in the16O(p,2p) reaction

The¹⁶O(p,2p) quasi elastic reaction at 45 MeV is investigated in the framework of the antisymmetrized distorted wave approximation (DWA). The inclusion of a direct and exchange two step core polarization mechanism, virtually exciting giant multipole resonances was consistently applied as in the (p, p′) non normal parity transition of¹⁶O. Thus utilizing the same renormalized effective two nucleont-matrix as in the inelastic transition a good fit to the data was obtained. It is suggested by the present analyses that corepolarization must be fully included for (p, 2p) like for inelastic scattering in the intermediate energy range.     

Angular momentum and temperature dependence of fission barriers with a realistic force

Angular distributions and excitation functions were measured for 30 2⁺ resonances in the³⁹K(p,p₀) and₃₉K(p, α⁰) reactions. Partial reduced widths have been extracted for three proton channels; the relative signs of the reduced width amplitudes for two of these channels were also determined. Reduced widths are generally consistent with a Gaussian distribution for the reduced width amplitudes, but the amplitudes themselves are not. These data represent the first measurement of correlation coefficients in an entrance channel and suggest that the large correlations previously observed in exit channels are generic features of this mass region.     

Competition between fission and neutron emission by diffusion model

Magnitudes and relative signs of amplitudes for three inelastic proton channels have been determined for 42 3/2⁺ resonances in⁵⁷Co in the rangeE _p =3.1–4.0 MeV. Amplitude and width channel correlations have been obtained for each pair of channels. One of the amplitude correlations is large and highly significant. Comparisons between these data and statistical theories of nuclear levels are presented for both widths and products of amplitudes; in general, agreement is good. The widths for one channel and amplitude products for one pair of channels appear energy-dependent, with most of the strength concentrated in the lowest 200 keV.     

Study of proton elastic and inelastic scattering from 74Se at the isobaric analogue resonances

Excitation functions of proton elastic and inelastic scattering from ⁷⁴Se were measured to investigate the isobaric analogue resonances (IAR) in ⁷⁵Br. Observed IAR correspond to the parent states of ⁷⁵Se in excitation energy from 0.29 to 1.8 MeV. For eleven resonances, resonance parameters were determined from the analysis of the elastic scattering. For three of these resonances, inelastic widths to the 2⁺ (0.635 MeV) state in ⁷⁴Se were obtained from the analysis of the angular distributions of inelastically scattered protons. Spectroscopic factors obtained from the elastic scattering were compared with those from the ⁷⁴Se(d, p)⁷⁵Se reaction. There is good agreement between the corresponding Spectroscopic factors except for the states with l_n = 1 where they were much smaller than the (d, p) ones. For the inelastic scattering, it was proved that the compound process via IAR play an important role and the analysis including the compound process explained the experimental results reasonably well.     

The gamma decay of analogue states in61Cu

Resonances in the reaction⁶⁰Ni(p, γ)⁶¹Cu have been studied in the proton energy rangesE _p=1840–1880 keV and 2220–2300 keV. Decay schemes and branching ratios have been determined for a number of resonances, three of which are identified as analogue fragments of the 283 keV (1/2^?) and 656 keV (3/2^?) states in⁶¹Ni. The split analogue components of the 283 keV state atE _x≈6.6 MeV are seen to decay significantly to a group of states in the region of excitation 3–4 MeV. Gamma ray angular distributions yield the following resonance spins:E _p=2248 keV,J=3/2;E _p=2263 keV,J=5/2. Also, the⁶¹Cu ground stateβ ⁺ decay to parent levels in⁶¹Ni has been compared to the respective analogue stateM1 gamma decay to the⁶¹Cu ground state.     

Internal electron-positron pair production from electric monopole transitions

The yield curve of the reaction⁵⁶Fe(p,γ)⁵⁷Co has been measured over the energy rangeE _p =1,300–1,900 keV and the decay of nine resonances has been investigated. For twelve of the resonances the strengths have been determined. The angular distributions of the gamma rays have been recorded for resonances atE _p =1,599, 1,623, 1,643 and 1,649 keV, giving spin-parity assignmentsJ ^π=3/2^? for all four resonances. The resonances atE _p =1,623, 1,643 and 1,649 keV have been identified as the split analogue resonances of the 367 (J ^π=3/2^?) states in⁵⁷Fe. TheM1 transition strengths to the corresponding antianalogue states have been measured and compared with theoretical predictions.     

Isobaric analogue states excited in the59Co(p, γ)60Ni reaction

The⁵⁹Co(p, γ)⁶⁰Ni reaction has been investigated in the proton energy regionE _p=1365–2150 keV. Decay schemes and branching ratios have been determined for ten resonances, five of which have been identified as possible analogues or fragments of analogues of the ground state (5⁺) and the 58.6 keV (2⁺), 277.1 keV (4⁺), 288.4 keV (3⁺), and 435.7 keV (5⁺) levels in⁶⁰Co. At eight of the resonances most of the decay seems to go via a group of states with an excitation energy of 5–9 MeV. The investigated analogue states give a Coulomb displacement energy of 9118±7 keV.     

Spectroscopy of 41Sc by resonant scattering of protons: Observation of an intermediate structure

Excitation functions of elastic and inelastic scattering of protons on ⁴⁰Ca have been measured for incident proton energies between 4.8 and 8.2 MeV. Spin and parity assignments and partial width determinations of ⁴¹Sc states between 5.8 and 8.7 MeV excitation energy have been made on the basis of quantitative analyses of the data for the different inelastic channels. Intermediate structure has been identified in the excitation function for the inelastic scattering to the 3^? (3.73 MeV) state in ⁴⁰Ca. This has been interpreted as being due to the presence of a state in ⁴¹Sc which consists primarily of the core nucleus ⁴⁰Ca in its 3^? state with a 2p particle weakly coupled to it.     

The 25Mg(p, γ)26Al and 25Mg(p,p′) resonances for Ep = 0.31–1.84 MeV

Thin target yield curves with good statistics have been measured for the ²⁵Mg(p, γ)²⁶Al and ²⁵Mg(p, p′)²⁵Mg reactions in the E_p = 310–1845 keV region. Altogether 76 resonances have been observed, of which 45 only in (p, γ), 30 in both (p, γ) and (p, p′), and one only in (p, p′). Several of these resonances had not been observed previously in either of the two reactions, and several of the previously observed resonances turned out to be doublets. All 39 ²⁵Mg(p, p₀)²⁵Mg resonances found previously in the E_p = 700–1845 keV region resonate in (p, γ) and many also in (p, p′). Resonance strengths have been derived relative to that of the E_p = 593 keV resonance.The analysis of weak (p, p₁) and (p, p₂) resonance yields has been supported by a calculation of the yields in the continuum (in between resonances) due to the Breit-Wigner tails of strong and broad resonances in the neighbourhood (with interference between resonances with the same J^π; T taken into account), and to Coulomb excitation.     

Structure of the deformed terms of the rotational-model optical potential (II)

The microscopic optical matrix potential (OMP^m) for rotational nuclei is constructed. The structure of the non-diagonal elements of OMP^m is investigated and compared with the deformed part of the phenomenological optical potential (OMP^p) employed in analyses of nucleon inelastic scattering data. The deformed form of OMP^p relates the real parts of the phenomenological form factors. This relation is shown to be approximately satisfied by the microscopic form factors. It is proved that the decay amplitudes of complicated compound states to similar channels are correlated, which we call the similar channels effect (SCE). Some channels are similar since the rotational states of the target are obtained from the same intrinsic state. The commonly used deformed imaginary part of OMP^p at very low energies (few MeV or Iess) may be justified as being due to the similar channels effect.     

High resolution proton inelastic scattering from 50Cr

Resonances in the ⁵⁰Cr(p, p′γ) reaction were investigated with the TUNL high resolution system. All previously observed p-wave resonances between Ep = 2.00 and 3.03 MeV were studied. Measurement of the p' and the γ-ray angular distributions provides sufficient information to determine unambiguously the J-value of the resonance and the magnitude and relative phase of the inelastic decay amplitudes. Expressions are given for the appropriate angular distributions and for the transformation between the channel spin and the total angular momentum representation. Experimental results are presented for 24 p-wave resonances in ⁵¹Mn including decay amplitudes and relative phases for $\text{16}\text{3}\text{2}{}^{\mathrm{?}}$ resonances. Six resonances formerly assigned $\text{1}\text{2}{}^{\mathrm{?}}$ are reassigned $\text{3}\text{2}{}^{\mathrm{?}}$. Inelastic spectroscopic factors were determined for two analogue states. Proton strength functions were evaluated from both the elastic and inelastic data.     

Statistical properties of 3/2− resonances in45Sc and51Mn

Magnitudes and relative signs of reduced width amplitudes for two inelastic decay channels were obtained for 3/2^? resonances in⁴⁵Sc and⁵¹Mn. Width and amplitude correlations were determined, and the first large amplitude correlation has been observed forl=1 resonances over a broad energy range. These results are consistent with the large amplitude correlations previously observed for 3/2⁺ and 5/2⁺ resonances.