Non-statistical effects for inelastic proton amplitudes in49V

The magnitudes and relative signs of inelastic proton-channel amplitudes have been measured for 71 3/2^? resonances in⁴⁹V. The measured quantitiesγ _c ² ,γ _c′ ² , andγ _c γ _c′ provide distributions of reduced widths, distribution of the relative sign between reduced width amplitudes, and correlations between reduced widthsρ(γ _c ² ,γ _c′ ² ) and between amplitudesρ(γ _c ,γ _c′ ). A variety of non-statistical effects are observed, including one case in which the effect occurs only in the signs, and not in the magnitudes of the amplitudes.     

Collective states in 48V

The low-lying positive parity states of ⁴⁸V have been studied in the framework of deformed configuration mixing model calculations based on projected Hartree-Fock theory, within the full fp shell space. The modified Kuo-Brown effective interaction has been used. The calculated spectrum and the electromagnetic properties of these states are in good agreement with the experiment. The calculation predicts an excited low-lying collective K = 2⁺ band in the spectrum of ⁴⁸V and accounts for the observed breakdown of the “signature” selection rule arising in the shell-model calculation within the ($\text{f}\text{7}\text{2}\text{)}{}^{\mathrm{nd}}$ space. It does not favour a 5⁺ assignment to the observed 1.099 MeV level. Two sets of proton and neutron effective charges (i) e_p = 1.32e and e_n = 0.89e and (ii) Kuo and Osnes charges e_p = 1.25e and e_n = 0.47e were employed. The observed decay properties appear to favour the latter charges. Our model also explains in a semiquantitative way the observed K-value, moment of inertia parameter and the intrinsic quadrupole moment of the K = 1^?1 rotational band.     

Cross-section measurements and thermonuclear reaction rates for 46Ti(p, γ)47V, 47Ti(p, γ)48V, 47Ti(p,n)47V and 48Ti(p, γ)49V

The yield of γ-rays from the reaction ⁴⁶Ti(p, γ)⁴⁷V has been measured as a function of bombarding energy over the range 0.72–3.00 MeV, from ⁴⁷Ti(p, γ)⁴⁸V over the range 0.74–3.50 MeV, and from ⁴⁸Ti(p, γ)⁴⁹V over the range 0.72–4.40 MeV. The yields of γ-rays following (p, p') reactions on all three targets were also measured and (p, p') cross sections were deduced for the first excited state proton groups for ⁴⁶Ti and ⁴⁸Ti and for the first ten proton groups for ⁴⁷Ti. The yield of neutrons from the reaction ⁴⁷Ti(p, n)⁴⁷V has been measured over the range from threshold to 4.40 MeV. All these data are compared with statistical-model calculations, and good agreement is achieved. Thermonuclear reaction rates for the (p, γ) and (p, n) reactions are calculated for the temperature range 5 × 10⁸–10¹⁰ K which includes the range of temperatures of interest in nucleosysnthesis calculations.     

A study of 50V using the direct reactions 49Ti (3He,d) and 51V(d,t)

Energy levels in ⁵⁰V up to 4.3 MeV have been studied using the ⁴⁹Ti(³He, d)⁵⁰V and ⁵¹V(d,t)⁵⁰V reactions with ³He particles of 22 MeV and deuterons of 19.5 MeV incident energy. More than eighty levels are seen, with angular distributions taken for forty-one levels in the (³He, d) reaction and for the ten lowest levels in the (d, t) reaction. The angular distributions are compared with the distorted-wave Born approximation (DWBA) to extract the l-values of the transferred nucleons and obtain the spectroscopic strengths. In the stripping reaction, a small amount of l = 0 and l = 2 strength is seen, indicating the presence of s and d proton holes in the g.s. of ⁴⁹Ti. The results are compared with a recent shell-model calculation based on an $\text{(}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{n}}$ configuration, and show qualitative agreement.     

Shell model calculations of inelastic electron scattering from 51V and effective charges

Form factors for inelastic electron scattering for the excitation of the $\text{3}\text{2}{}^{\mathrm{?}}$, $\text{5}\text{2}{}^{\mathrm{?}}$, $\text{9}\text{2}{}^{\mathrm{?}}$, $\text{11}\text{2}{}^{\mathrm{?}}$ and $\text{15}\text{2}{}^{\mathrm{?}}$ members of the ($\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{)}{}^3$ configuration in ⁵¹V are studied by considering the effect of configuration mixing in the shell model. The inclusion of the highly excited configurations which does not contribute to the γ-transitions is shown to give rise to significant modifications of the form factors in large momentum transfer regions. Under the assumption of the static central potential as the residual interactions between protons, good agreement with the experimental data on form factors is obtained by the ordinary force as well as smaller effective charges than the bare charge for higher multipole transitions.     

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.     

Interference effects in inelastic proton scattering on 28Si

Interference effects in ²⁸Si(p, p') inelastic scattering are studied in the Coulomb barrier region. The interference occurs between compound contributions and direct inelastic transitions. The asymmetric resonance shape is analysed to extract the intrinsic shape of the excited target nucleus.     

The β-decay of 47V

The γ-rays emitted following the β-decay of ⁴⁷V have been studied with a 65 cm³ Ge(Li) detector. Direct β-branches were observed to the following levels in ⁴⁷Ti (log ft values in parentheses): ground state (4.9); 1550 keV (6.0); 1794 keV (5.1); 2163 keV (5.3); 2167 keV (6.2); 2526 keV (5.4); 2549 keV (5.7); 2793 keV (5.0). The branches to the last four levels have not been reported previously. In addition, a newγ-decay branch, 2163 → 160 keV, was observed. These results, together with information from reaction studies, permit the assignment of spin and parity $\text{3}\text{2}{}^{\mathrm{?}}$ to the 2163 keV level, and $\text{5}\text{2}{}^{\mathrm{?}}$ to the 2167 keV level. The half-life of the ⁴⁷V decay was measured to be 32.6±0.3 min.     

The 51V(n, γ)52V reaction studied with polarized neutrons and polarized vanadium nuclei

Circular polarization of γ- radiation following capture of polarized thermal neutrons by unoriented nuclei and the angular distribution of such radiation, using polarized neutrons and polarized nuclei, made it possible to assign spins to 13 levels of ⁵²V. In addition the admixtures of spin-3 and spin-4 reaction channels could be derived for 20 primary γ-ray transitions. With this information interference phenomena in the ⁵¹V(n, γ) reaction were studied. The low-lying levels of ⁵²V are compared with shell-model calculations. The capture mechanism is discussed in terms of a doorway-state model.     

Decay of the mirror nuclide 45V

The β⁺ decay of ⁴⁵V $\text{(J}{}^{\mathrm{\pi }}\text{, T=}\text{7}\text{2}{}^{\mathrm{?}}\text{,}\text{1}\text{2}\text{)}$ has been observed. The half-life was found to be 539 ± 18 ms; in addition to the superallowed transition to the mirror state (⁴⁵Ti ground state), it exhibits a (4.3 ± 1.5)% allowed branch to the $\text{5}\text{2}{}^{\mathrm{?}}$ state at 40.1 keV in ⁴⁵Ti. Decay data for the complete $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ shell series of mirror nuclei are presented.     

Non-energy-weighted sum rule analysis of one nucleon transfer data on 41Ca, 43Ca, 45Se, 49Ti and 51V and the validity of the shell model

Spin-dependent sum rules for spectroscopic factors have been fitted to experimental data for the transfer of f_{$\text{7}\text{2}$} nucleons. The fits give the error in absolute normalizations in terms of the percentage error, σ, in relative spectroscopic factors, and evidence is presented that standard distorted wave Born approximation analyses of light-ion induced reactions give σ < 10%. The sum rule analyses then imply f_{$\text{7}\text{2}$} occupancies m agreement with simple shell-model expectations to an accuracy of about 10%. The f_{$\text{7}\text{2}$} occupancy deduced for ⁵¹V is completely inconsistent with the results of a Hartree-Fock-Bogolyubov calculation.     

A study of the 51V(6Li,d)55Mn reaction

Alpha particle spectroscopic strengths extracted for transitions to low-lying levels in ⁵⁵Mn observed in a study of the ⁵¹V(⁶Li, d) reaction at 32 MeV are compared with the results of shell-model calculations. These reproduce well the relative strengths of the levels.     

Photonuclear reactions in medium weight nuclei 51V, 55Mn and Cu

New results on the photospallation of the medium weight nuclei ⁵¹V, ⁵⁵Mn and Cu at maximum bremsstrahlung energy between 2 and 5 GeV are presented. The yields of residual nuclei were measured by the activation method using a Ge(Li) detector. The results are analyzed with the empirical Rudstam formula and compared with data obtained in lower energy photon and proton induced reactions.     

Possible mesonic effects on inelastic proton scattering to the 10.24 MeV 1+ state in 48Ca

Differential cross sections and analyzing powers were measured for inelastic scattering of 160 MeV protons to the ⁴⁸Ca 10.24 MeV, 1⁺ state. DWIA calculations with shell-model wave functions which fit inelastic electron scattering form factors predict too much cross section at small q and too little at large q for inelastic proton scattering. These results are consistent with the q-dependent modification of magnetic transitions anticipated from mesonic effects such as virtual Δ(1232)-hole excitations.     

51V nuclear magnetic resonance in polycrystalline ferroelastic BiVO4

Nuclear magnetic resonance studies on polycrystalline ferroelastic BiVO₄ indicate that the ⁵¹V electric field gradient asymmetry parameter is an order parameter in the ferroelastic transition. Using ∩ = A(T?T_c)^B, B is found to be 0.48(5), in good agreement with earlier studies of this material. Near the phase transition above and below, the vanadium nuclear quadrupole coupling is constant with a value of 4.8(1) MHz.     

Microscopic study of elastic 28Si28Si scattering and intermediate structure resonances in 56Ni

Elastic ²⁸Si²⁸Si scattering has been studied microscopically with special emphasis on quasimolecular and barrier resonances in high partial waves. Schematic application of the double resonance mechanism predicts intermediate structures in the excitation functions in qualitative agreement with the experimental data.     

Decay of 48K, 49K and 50K

The ⁴⁸K, ⁴⁹K and ⁵⁰K nuclides have been produced in high energy fragmentation and analyzed by mass spectroscopy techniques. Their half-lives have been measured as 6 ± 1 s, 1.1 ± 0.3 s and and 0.7 ± 0.3 s, respectively. The γ-rays from their radioactive decay have been observed and the corresponding γ-intensities measured. The nuclide ⁵⁰K is shown to be a delayed neutron emitter. The antianalog states in the daughter Ca nuclei with a $\text{(1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}{}^{\mathrm{?}}$ neutron configuration, preferentially populated in the β-decay, have been located. The corresponding $\text{1d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ neutron single-particle energy is found to remain approximately constant for these neutron-rich Ca isotopes.     

A Kπ = 4− rotational band in 48V

From γ-ray linear polarization measurements, γ-ray angular distributions and γ?γ coincidences, the following levels were identified in ⁴⁸V (E_Xin keV): 4^? at 1099, (5^?) at 1685, (6^?) at 2397, (7^?) at 3171 and (8^?) at 3976. This sequence of states is interpreted as a K^π = 4^? rotational band.     

A study of the (α, t) reaction on 19F, 27Al, 51V and 59Co

The angular distributions of tritons from the (α, t) reaction on ¹⁹F, ²⁷Al, ⁵¹V and ⁵⁹Co nuclei corresponding to the (0⁺) ground states and (2⁺) excited states in the final nuclei have been measured in the angular range between 15° and 170° at α-particle energies of 25 MeV. For reactions on ²⁷Al and ⁵¹V nuclei, the differential excitation functions have also been obtained at different angles of outgoing tritons at E_α from 20 to 25 MeV. The experimental angular distributions are analysed by the DWBA approximation on the assumption of a nucleon stripping mechanism. The analyses of the present results and the data obtained earlier for the (α, t) reaction on the 1 p shell nuclei, A ? 30, reveal that the distinguishing feature of the reaction under study is the presence of backward angle peaks in the reaction cross section, which appear to be associated with exchange processes. For the (α, t) reaction on the heavier nuclei (A > 30), the dominant mechanism is nucleon stripping.