Neutron-hole strengths and isobaric analog states in 95Zr

The ⁹⁶Zr(τ, α)⁹⁵Zr reaction at 39 MeV incident energy was used to populate both the low-lying and highly excited (up to an excitation energy of 18 MeV) analog states in ⁹⁵Zr and some low-lying levels in other Zr isotopes. The main components of the 2d_{$\text{5}\text{2}$}. and 1g_{$\text{9}\text{2}$}. hole strengths and the analogs of the 2p_{$\text{1}\text{2}$}., 2p_{$\text{3}\text{2}$}. and 1f_{$\text{3}\text{2}$}. proton hole states in ⁹⁵Y have been observed in this work. Angular distributions of transitions to 27 levels in ⁹⁵Zr have been extracted and analysed with DWBA calculations to yield spectroscopic factors. Between the excitation energies of 1 and 3 MeV in ⁹⁵Zr a number of levels with l = 2, 4 and 5 angular distributions have been identified. These are associated with the 2d_{$\text{3}\text{2}$}, 1g_{$\text{7}\text{2}$} and 1h_{$\text{11}\text{2}$} components already observed in the previous study of the ⁹⁴Zr(d, p) and (α, τ) reactions. The total strength and center of gravity for levels assigned to the (1g_{$\text{9}\text{2}$})^?1 configurations in ⁹⁵Zr are presented and compared to the results obtained from the studies of neutron pick-up reaction on ⁹¹Zr and ⁹⁸Mo. For the isobaric analog states observed between the excitation energies of 15 and 17 MeV, total widths, Coulomb displacement energies and spectroscopic factors are also determined from this experiment and the results compared with the properties of the low-lying proton hole states in the ⁹⁵Y parent nucleus.     

Analogue states in 61Cu

Resonances in the reaction ⁶⁰Ni(p, γ)⁶¹Cu have been studied in the energy region E_p ≈ 1550–1950 keV. Decay schemes and branching ratios are presented for 12 resonances and the resonance strength has been determined for most of these. Gamma-ray angular distribution measurements on two resonances yield the following spin assignments $\text{(E}{}_{\mathrm{<mtext>p</mtext>}}\text{(}\text{keV}\text{; J): (1668;}\text{5}\text{2}\text{), (1850;}\text{3}\text{2}\text{,}\text{5}\text{2}\text{)}$. Several of the resonances studied are identified as fragments of the analogue states of the ground and first two excited states in ⁶¹Ni. M1 transitions strengths to the corresponding antianalogue candidates have been measured.     

207Pb(p,p') measurements at 135 and 61 MeV,the effective interaction and core polarization

Data at Einp = 61 and 135 MeV for neutron-hole transitions are used to study the proton-neutron part of the assumed NN force. Collective core-polarization strengths (A_L) from the present fits at 135 MeV are consistent with those extracted from the (e, e') reaction for two L = 2 transitions and one L = 4 transition. This is not the case at 61 MeV where the A_L values needed to fit the (p, p') data are much smaller for transitions to the $\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{and}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ hole states. A fully microscopic DWBA fit is successful for the L = 3 transition to the doublet at 2.64 MeV of excitation at E_p = 61 MeV, but fails at 135 MeV; a fully microscopic DWIA calculation provides a reasonable fit to the data at 135 MeV.     

Particle coupling to the octupole state in 89Sr from 88Sr(p,p')88Sr analog resonances and 88Sr(d,p)89Sr

A study has been made of the six most pronounced isobaric analog resonances in the ⁸⁸Sr(p, p')⁸⁸Sr (3^?) excitation function at E_p = 7.65, 7.80, 7.92, 8.78, 9.75, and 9.90 MeV. They are believed to have a simple structure in the parent nucleus ⁸⁹Sr consisting of the lowlying positive-parity, single-neutron spectrum of ⁸⁹Sr weakly coupled to the collective 3^? state in ⁸⁸Sr. A high-resolution ⁸⁸Sr(d, p)⁸⁹Sr experiment was performed to locate small 2f and 3p admixed fragments in ⁸⁹Sr which would allow these analog resonances their entrance widths. In addition, on-resonance ⁸⁸Sr(p, p')⁸⁸Sr (3^?) angular distributions were measured in order to determine the partial waves involved in the exit channel. Results are compared to a particlephonon coupling model, and overall selectivity, strengths, and angular distributions of the (p, p') analog resonances are consistent with the above interpretation.     

The reaction 36S(p, γ)37Cl: (II). Lifetimes,spins and parities of 37Cl levels

Analysis of the γ-ray angular distributions measured at 16 ³⁶S(p, γ)³⁷Cl resonances yields the spins and/or parities of 21 bound states of ³⁷Cl in addition to the resonance spins. Among the latter are four $\text{J =}\text{1}\text{2}$ resonances. For several other bound states the possible spins have been restricted. Multipolarity mixing ratios have been deduced from the same data. Lifetimes (or lifetime limits) of 29 bound states have been deduced from DSA measurements.This extensive experimental information allows a comparison with the results of a shell-model calculation for both the even- and odd-parity states of ³⁷Cl. In this calculation either zero, one or two particles are promoted from the 2s_{$\text{1}\text{2}$} or 1d_{$\text{3}\text{2}$} to the 1f_{$\text{7}\text{2}$} or 2p_{$\text{3}\text{2}$} subshells. Up to an excitation energy of about 5 MeV a one-to-one correspondence is found between experimental and calculated levels.     

Neutron scattering from 26Mg

Elastic and inelastic cross sections have been measured for 24 MeV neutrons incident on ²⁶Mg using the time-of-flight technique. These cross sections and existing proton data were analyzed in terms of a Lane-consistent optical potential. Distorted-wave and coupled-channel calculations are presented. Deformation parameters for the first 2⁺ state (1.81 MeV) and the second 2⁺ state (2.94 MeV) derived from both the (n, n') and (p, p') data are used to obtain the ratio of neutron and proton transition matrix elements M_n(E2) and M_p(E2) for these states. Comparison of results for $\text{M}{}_{\mathrm{<mtext>n</mtext>}}\text{(}\text{E}\text{2)}\text{M}{}_{\mathrm{<mtext>p</mtext>}}\text{(}\text{E}\text{2)}$ with those obtained from pion work, from electromagnetic (EM) rates and theoretical evaluations are presented.     

Particle-hole states in 42K studied by the 44Ca(d, α)42K reaction

The ⁴⁴Ca(d, α)⁴²K reaction was studied at a bombarding energy of 11 MeV using a broadrange magnetic spectrograph and solid-state detectors. About thirty energy levels were identified in ⁴²K, up to an excitation energy of 3.5 MeV. Excitation functions corresponding to some of the low-lying energy states of ⁴²K were measured in the incident energy range from 10.4 to 11.6 MeV. Angular distributions of the α-particle groups corresponding to the excitation of about twenty energy levels in ⁴²K have been measured. DWBA calculations were performed and L-values for most of the above transitions were deduced. The results were compared with previous information and possible spin and configuration assignments are proposed for some of the states. Centroids of states interpreted as belonging to the (1d_{$\text{3}\text{2}$}^?1)_p (1f_{$\text{7}\text{2}$}³)_n, (2s_{$\text{1}\text{2}$}^?1)_p (1f_{$\text{7}\text{2}$}³)_n and the (1d_{$\text{3}\text{2}$}^?1)_P (1d_{$\text{3}\text{2}$}^?1 1f_{$\text{7}\text{2}$}⁴)_n configurations were found to be in good agreement with calculations based on the weak-coupling model.     

Proton induced resonances on 21Ne

Excitation curves for the ${}^{21}\text{Ne}\text{(}\text{p}\text{, γ)}{}^{22}\text{Na}\text{,}{}^{21}\text{Ne}\text{(}\text{p, p}\text{′γ)}{}^{21}\text{Ne and}{}^{21}\text{Ne}\text{(}\text{p, p}\text{)}{}^{21}\text{Ne}$ reactions have been obtained for E_p = 0.4–1.6 MeV. Neon gas enriched to 92 % in ²¹Ne was recirculated in a differentially pumped gas target system. The fifteen previously reported (p, γ) resonances were established and nineteen new (p, γ) resonances found. Anomalies in the elastic scattering yield were observed for fourteen resonances. The reported state at E_x = 7278 ± 7 keV in ²²Na was resolved into a doublet separated by 1 keV. All unbound states in ²²Na, observed previously in other reactions, have been confirmed as resonance states in the energy range covered, with the exception of the E_x = 7942 ± 7 keV state. The new E_p = 663, 694, 1235, 1432 and 1543 keV resonances correspond to new unbound states in ²²Na. Excitation energies, γ-ray decay schemes, resonance widths and strengths as well as limits on J^π assignments are reported for all the resonances. From the Coulomb excitation of the E_x = 350 keV, first excited state in ²¹Ne a value of B(E2) = 0.014 ± 0.002 e² · b² is deduced. The astrophysical as well as the nuclear structure implications of the present results are discussed.     

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.     

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.     

Isospin effects upon the decay of highly excited nuclear states

It is proposed that T_< states which strongly mix with analog states to give states of mixed isospin results in the enhancement of the probability of proton decay from highly excited nuclear states. Such considerations are shown to explain the anomalies observed in the ($\text{p, n}\text{p}$) reactions.     

High resolution proton scattering from 42Ca

Differential cross sections were measured for ⁴²Ca(p, p) at four angles between E_p = 1.2 and 3.0 MeV, with an overall energy resolution of 325 eV. Spins, parities and proton widths were extracted for 170 resonances. Two analogue states were identified and spectroscopic factors determined. The nearest neighbor spacing distributions were analyzed. Proton strength functions were determined for $\text{1}\text{2}$⁺, $\text{1}\text{2}$^? and $\text{3}\text{2}$^? resonances.     

A study of some resonances in the 54Fe(p, γ)55Co reaction

Excitation functions for the ⁵⁴Fe(p, γ)⁵⁵Co reaction have been recorded in the energy region E_p = 1100–1760 keV. The decay schemes and branching ratios of ten resonances have been investigated. Angular distributions of primary γ-rays have been measured for three resonances to establish resonance spins. Resonance strengths for six resonances and gamma widths for three resonances have been determined. The isobaric analogues of the ground ($\text{J}{}^{\mathrm{\pi }}\text{=}\text{7}\text{2}{}^{\mathrm{?}}\text{)}\text{and}\text{1919}\text{keV}$$\text{J}{}^{\mathrm{\pi }}\text{=}\text{3}\text{2}$^?) states of the parent nucleus ⁵⁵Fe have been identified at 4722 and 6712 keV respectively in ⁵⁵Co. The Coulomb displacement energies of the observed analogue pairs (0–4722 keV) and (1919–6712 keV) have been obtained. The strengths of the possible analogue-antianalogue transitions for the proton capture state at E_p = 1679 keV have also been determined.     

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.     

Spin assignments from the 142Nd(7Li, 6He)143Pm and 144Sm(7Li, 6He)145Eu reactions at 52 MeV

Angular distributions have been measured for transitions to low-lying states in ¹⁴³Pm and ¹⁴⁵Eu populated by the ¹⁴²Nd(⁷Li, ⁶He)¹⁴³ and the ¹⁴⁴Sm(⁷Li, ⁶He)¹⁴⁵Eu reactions at $\text{E(}{}^7\text{Li}\text{) = 52}$ MeV. Elastic scattering of ⁷Li at 52 MeV on ¹⁴²Nd and ¹⁴⁴Sm, and ⁶Li at 46 MeV on ¹⁴²Nd and at 45 MeV on ¹⁴⁴Sm, were measured. Optical-model parameters extracted from fits to the scattering data were used in a finite-range DWBA analysis of the angular distributions for levels below 1.40 MeV excitation energy in ¹⁴³Pm and 1.84 MeV in ¹⁴⁵Eu. The reaction cross sections forward of 6° c.m. allow unambiguous distinction to be made between 2d_{$\text{5}\text{2}$} and 2d_{$\text{3}\text{2}$} final states. Final-state spins have been assigned to d-states in ¹⁴³Pm at 1.40 MeV($\text{3}\text{2}$⁺)and in ¹⁴⁵Eu at 1.042 MeV ($\text{3}\text{2}$⁺). Existing assignments to other levels in both residual nuclei have been confirmed.     

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.     

Analyzing power of the neutron continuum spectrum for the 93Nb(→p, nX) reaction at 65 MeV and a DWBA analysis

The analyzing power of neutron continuum spectrum for the ⁹³Nb($\text{→p}$, nX) reaction at 65 MeV was measured for a wide angular range ?_n = 20° – 130°. The analyzing powers are positive and large at large angles ?_n > 40°. The characteristic features in the analyzing power for the ⁹³Nb($\text{→p, nX}$) reaction are very similar to those for the ⁹³Nb($\text{→p}$, p'X) reaction indicating the importance of a common reaction mechanism for both reactions. A DWBA calculation was performed and compared with the data. The calculation for E_X = 14 MeV reproduced the cross sections but failed to reproduce the analyzing powers.     

An amplitude analysis of the K+K− system produced in the reaction π−p→K+K−n at 10 GeV/c

We present results on an amplitude analysis of the K⁺K^? system produced in the reaction π^?p→K⁺K^?n from threshold up to 2.2 GeV. The branching ratios of f⁰ and f' to K$\text{K}$ have been determined. In the low mass region of the K$\text{K}$ system the observation of an S-wave enhancement at 1.3 GeV and the interference of the f⁰-A₂-f' mesons are studied. We observe a 3^? structure in the mass region of 1.7 GeV which is consistent with g⁰ production. With this interpretation the branching ratio $\text{g→}\text{K}\text{K}$ has been determined. Evidence for a new structure in the J^p = 2⁺ wave around 1.8 GeV with a width of ～200 MeV is presented.     

Das Niveauschema von 47V aus dem γ-zerfall von Analogresonanzen

A high-accuracy investigation of the level scheme of ⁴⁷V has been performed using the ⁴⁶Ti(p, γ)⁴⁷V reaction. The γ-decay schemes of the strong (p, γ) resonances at E_p = 1546, 1549, 1565 and 1572 keV lead to 17 new energy levels in ⁴⁷V with excitation energies between 2.7 and 5.1 MeV. From the (p,γ) angular distributions mixing ratios of the primary γ-transitions and J^π values of the resonances and of many states populated in the γ-decay have been determined. The total width of the E_p = 1549, 1565 and 1572 keV resonances for γ-decay are found to be Γ_γ = 0.12, 0.15 and 0.03 eV, respectively. The Q-value of the ⁴⁶Ti(p,γ)⁴⁷V reaction is found to be 5168.6 keV. The two resonances at E_p = 1549 and 1565 keV, which have $\text{J}{}^{\mathrm{\pi }}\text{=}\text{3}\text{2}{}^{\mathrm{?}}$, are interpreted as fine structure components of the analogue state of the $\text{E}{}^1\text{= 2.545}\text{MeV}\text{J}{}^{\mathrm{\pi }}\text{=}\text{3}\text{2}{}^{\mathrm{?}}$ level in ⁴⁷Ti while the ($\text{7}\text{2}$) resonance at E_p = 1546 keV might correspond to the $\text{E}{}^1\text{= 2.615}\text{MeV}\text{7}\text{2}{}^{\mathrm{?}}$ parent state in ⁴⁷Ti. The analogue-antianalogue M1 transition strength of the split $\text{3}\text{2}{}^{\mathrm{?}}$ analogue state is 0.01 single-particle units and fits well into our systematics of IAS → AIAS transitions in fp-shell nuclei.