Dynamical supersymmetry in 196Pt and 197Au

The excitation energies, reduced E2 transition probabilities and spectroscopic factors in the (${}^3\text{He, d}$) reaction for the levels with positive parity in ${}^{197}\text{Au}$ up to about 1 MeV, together with the corresponding data for ${}^{196}\text{Pt}$, are shown to be in overall agreement with the predictions of a dynamical supersymmetry scheme recently proposed for nuclei in this mass region.     

20Ne + n → 21Ne(T = 32) resonances

$\text{T =}\text{3}\text{2}$ resonances in ²¹Ne have been studied in measurements of the total neutron cross section of ²⁰Ne using the 190 m neutron time-of-flight facility of the Karlsruhe Isochronous Cyclotron. The high time-of-flight resolution of 6.6 ps/m enabled the study of sharp $\text{T =}\text{3}\text{2}$ resonances in ²¹Ne with an effective energy resolution of up to 4000. Five $\text{T =}\text{case3}\text{2}$ levels have been observed as sharp resonances allowing the precise determination of total width Λ, partial decay with Λ_no and resonance energy E_R. The c.m. resonance parameters of the first $\text{T =}\text{3}\text{2}$ state in ²¹Ne are E_R = 2098.6 ± 0.3 keV, Λ = 2.2 ± 0.5 keV and Λ_no = 0.21 ± 0.05 keV. Upper limits for the partial decay widths are deduced for those $\text{T =}\text{3}\text{2}$ levels which do not appear as resonance anomalies. A search for additional $\text{T =}\text{3}\text{2}$ states was undertaken. The resonance energies are discussed in the framework of the isbobaric mass multiplet equation. The decay widths are compared with shell-model predictions of isospin mixing and the systematics of isospin-non-conserving particle decays.     

The 238U(n, α)235Th reaction with thermal neutrons

The thermal neutron induced (n, α) reaction cross section of ²³⁸U was measured using the highly pure thermal neutron beam from the 87 m curved neutron guide at the High Flux Reactor of the ILL (Grenoble). The energy spectrum showed an α-particle line with E_α = 9.05±0.06 MeV and σ(n, α) = 1.3±0.6 μb. The α-particle energy was used to calculate the ²³⁵Th mass of 235.04700±0.00008 amu, the Q_α value of 9.20±0.06 MeV for the ${}^{238}\text{U(n}\text{, α)}{}^{235}\text{Th}$ reaction and the Q_β value of 1.44±0.08 MeV for the β-decay of ²³⁵Th. The cross-section data are compared with the results obtained with the statistical model calculation.     

Spectroscopic investigations of the decay 223Ra → 219Rn

Internal conversion electron spectra of the transitions 4.4 keV, 10.0 keV, 14.4 keV, and 324.1 keV in the decay ²²³Ra → ²¹⁹Rn were measured. E2/M1 mixing ratios of these γ-transitions were deduced from conversion electron intensity ratios: δ² = 3.8(4) · 10^?3, 2.35(18) · 10^?3, 12.85(36) · 10^?3, 0.23(3). The half-lives of the 4.4 keV and 14.4 keV levels were determined as $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 15.4(1.3)}$ nsec and 0.875(30) nsec. Reduced transition probabilities were calculated and compared to the Weisskopf estimates. αγ angular correlation measurements of the transitions 269.6 keV, 324.1 keV, and 338.6 keV and an αγ linear polarization measurement of the 269.6 keV transition were performed for spin determination. We assign $\text{I =}\text{7}\text{2}$ to the ²¹⁹Rn ground state and $\text{I =}\text{5}\text{2}$ or $\text{9}\text{2}$ to the 269.6 keV state. All other low excitations including the 338.6 keV level have spins $\text{I =}\text{5}\text{2}$, $\text{7}\text{2}$, or $\text{9}\text{2}$. The spins of the states 158.7 keV and 14.4 keV are equal. The ²²³Ra ground state spin is $\text{I =}\text{7}\text{2}$ or $\text{9}\text{2}$. The possibility of an interpretation of the transitional nucleus ²¹⁹Rn in the frame of the collective model is discussed.     

On the β-decay 210Bi(RaE) → 210Po(RaF)

It was the aim of the present work to extract nuclear wave functions directly from experimental data of β-transitions. As a favourable example the 1^? (1.153 MeVβ^?)0⁺ β-transition of ²¹⁰Bi(RaE) was studied. The results obtained are compared with theoretical wave functions and good quantitative agreement, especially for the ground state of the daughter nucleus ²¹⁰Po, was found. It is explicitely demonstrated how, in this case, the higher order terms of the transition matrix elements contribute. The results for the matrix element ratios μ and Λ are discussed. In particular it is shown that it is not possible to test CVC theory by examining Λ.     

40Ca(d, α)38K and isospin

We investigate the ⁴⁰Ca(d, α_{0, 1, 2, 4})³⁸K reactions for E_d = 4.00–4.61 MeV. The α₁ and α₄ transitions are isospin forbidden. The resonant-like structures observed in the α₀, α₁, α₂, and α₄ transitions are consistent with Ericson theory. In addition we can fit a portion of the α₁, data with a few interfering Breit-Wigner resonances. The level parameters for the corresponding ⁴²Sc levels are given.     

Measurement of coherent pion-photoproduction on the 3He/3H isodoublet

Neutral and charged pion-photo production on ${}^3\text{H}$ and ${}^3\text{He}$ nuclei have been observed in the Δ(1232) resonance region. Resonance averaged cross-sections are presented as functions of momentum transfer.     

The 16O + p → 17F (T = 32) resonances at Ep = 11.26,12.71 and 14.57 MeV

Excitation functions for ¹⁶O+p reactions have been measured with high energy resolution in the region of the first, second and seventh $\text{T =}\text{3}\text{2}$ resonances in ¹⁷F at extreme backward angles. The observed resonance shapes have been analyzed with a single-level resonance formula taking the off-resonance spin-flip amplitude into account. The resonance parameters of the ¹⁷F first $\text{T =}\text{3}\text{2}$ state studied with special emphasis are E_x = 11193.3 ± 2.3 keV, Γ = 200 ± 40 eV and Γ_p0 = 19 ± 3 eV. This result and other results are compared with previous studies and theoretical predictions. The comparison with data of the mirror nucleus ¹⁷O is discussed with respect to the observed charge asymmetry of the isospin-forbidden particle decay widths.     

Spin assignments for 16O + 12C resonances at low energies

Spin and parity values have been determined for sub-Coulomb resonances of the ${}^{16}\text{O}\text{+}{}^{12}\text{C}$ system.     

Spin assignments in 63Ni through 62Ni(d,p)63Ni

Angular distributions of vector analyzing power have been measured for the reaction ${}^{62}\text{Ni}\text{(}\text{d, p}\text{)}{}^{63}\text{Ni}$ at a beam energy of 10 MeV. The observed j-dependence of vector analyzing power allows unambiguous spin assignments to be made for the following states in ⁶³Ni (excitation energies in MeV): $\text{0,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{0.087,}\text{5}\text{2}{}^{\mathrm{?}}$; $\text{0.155,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{0.515,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{1.003,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{2.297,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{2.700,}\text{1}\text{2}{}^{\mathrm{?}}$; $\text{2.953,}\text{1}\text{2}{}^{\mathrm{+}}$; $\text{3.292,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{3.932,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{3.951,}\text{5}\text{2}{}^{\mathrm{+}}$; $\text{4.387,}\text{5}\text{2}{}^{\mathrm{+}}$. An assignment of $\text{9}\text{2}{}^{\mathrm{+}}$ is suggested for the state at 2.519 MeV. The data for the unresolved l_n = 4, 1 doublet (1.294, 1.327) MeV indicate the $\text{3}\text{2}{}^{\mathrm{?}}$ spin assignment for the 1.327 MeV state. The main features for all the data are in agreement with DWBA calculations.     

The 7Li(d, n0)8Be reaction with polarized 800 keV deuterons

The analysing power of the ${}^7\text{Li}\text{(}\text{d}\text{, n}{}_0\text{)}{}^8\text{Be}$ reaction for vector and tensor polarization of an 800 keV deuteron beam, as well as the relative cross section for the unpolarized beam were measured at 7 to 9 angles between 0° and 160°, using a thick target. Analysis in terms of (l, s, J^π) matrix elements shows that two intermediate states with $\text{J}{}^{\mathrm{\pi }}\text{=}\text{3}\text{2}{}^{\mathrm{+}}$ and $\text{J}{}^{\mathrm{\pi }}\text{=}\text{5}\text{2}{}^{\mathrm{?}}$ present, strongly interfering with each other. Assignments to known ⁹Be levels and to threshold resonances as suggested by Hackenbroich and Seligman are briefly discussed. The magnitude of the vector analysing power makes the reaction interesting as a monitor for the vector polarization of low-energy deuteron beams.     

Spin-parity combinations in 16N from the 18O(d,α)16N reaction

The reaction ¹⁸O(d, α)¹⁶N has been studied using a tensor-polarized deuteron beam at incident energies of 8.50, 9.25, 10.00, 10.30, 10.75 and 11.30 MeV. From measurement of the tensor analysing power of the reaction when the α-particles are emitted near 0°, spin-parity combinations have been deduced for thirteen levels in ¹⁶N up to 6.2 MeV excitation. These results, together with previous work, lead to new and unambiguous spin and parity assignments for four of these levels.     

Molecular three-body approach to Λ9Be and Σ9Be hypernuclei

The dependence of the low-lying spectra of ${}_{\mathrm{\Lambda ,\; \Sigma }}{}^9\text{Be}$ hypernuclei on hyperon-α interaction in the molecular α + α + Λ(Σ) scheme has been studied. A suggestion is made for obtaining the strengths of both p-wave and spin-orbit Λ-α interactions from the experimental ${}_{\mathrm{\Lambda }}{}^9\text{Be}$ spectrum. A relation between the Σ⁰-binding energies $\text{B}{}_{\mathrm{\Sigma }}\text{(}{}_{\mathrm{\Sigma }}{}^9\text{Be}\text{)}$ and $\text{B}{}_{\mathrm{\Sigma }}\text{(}{}_{\mathrm{\Sigma }}{}^9\text{He}\text{)}$ has been established and on its basis a prediction is made about a possible binding energy of ${}_{\mathrm{\Sigma }}{}^5\text{He}$.     

Spin determinations from the 58Ni(d→, α)56Co reaction at 80 MeV

Vector analyzing power angular distributions for the ${}^{58}\text{Ni}\text{(}\text{d}\text{→}\text{,a)}{}^{56}\text{Co}$ reaction have been measured at 80 MeV bombarding energy. They exhibit large differences between the possible transferred total angular momenta J=L+1, J=L and J=L ? 1, thus allowing unique spin determinations of the levels in the residual nucleus ⁵⁶Co. This has led to new spin assignments for the following high-spin states in ${}^{56}\text{Co}\text{: 3.54}\text{MeV}\text{, 7}{}^{\mathrm{+}}\text{; 4.44}\text{MeV}\text{, 7}{}^{\mathrm{+}}\text{; 5.14}\text{MeV}\text{, 5}{}^{\mathrm{+}}$.     

Spin assignments in 59Ni from the 58Ni(d, p)59Ni reaction

Angular distributions of the vector analyzing power and the absolute cross section were measured for the ⁵⁸Ni(d, p)⁵⁹Ni reaction at a deuteron energy of 10 MeV. The observed j-dependence of the vector analyzing power allowed unambiguous spin assignments for the following states in ⁵⁹Ni with excitation energies in $\text{MeV}\text{: 0.0,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 0.341,}\text{5}\text{2}{}^{\mathrm{?}}$; $\text{0.465,}\text{1}\text{2}{}^{\mathrm{?}}\text{; 0.879,}\text{3}\text{2}{}^{\mathrm{?}}$; $\text{1.303,}\text{1}\text{2}{}^{\mathrm{?}}\text{; 1.686,}\text{5}\text{2}{}^{\mathrm{?}}\text{; 3.454,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 3.858,}\text{3}\text{2}{}^{\mathrm{?}}\text{; 4.495,}\text{5}\text{2}{}^{\mathrm{+}}$. The data are well reproduced by DWBA calculations employing deuteron and proton optical model parameters obtained from analyses of elastic scattering cross sections and polarizations. A tentative spin assignment of $\text{9}\text{2}{}^{\mathrm{+}}$ is made for the level at 3.061 MeV. A $\text{5}\text{2}{}^{\mathrm{+}}$ assignment to the level at 3.538 MeV is suggested on the basis of the empirical behavior of the j-dependence of the vector analyzing power for l = 2 transitions. Measurements of the vector analyzing power for the four low-lying ⁵⁹Ni states formed by l = 1 transfer were made for angles from 2.5° to 15° using a magnetic spectrograph. A very strong j-dependence was observed for these far-forward-angle measurements in agreement with DWBA predictions.     

The decay process 11ΛB → π− + 11C

The branching ratios are calculated for ¹¹_ΛB decay to the ¹¹C ground and excited states below 8 MeV for two possible spin values of ¹¹_ΛB. It is found that the decay rate to the ¹¹C^★ state at E^★ = 6.48 MeV is comparable in magnitude to that leading to the ¹¹C ground state if $\text{J(}{}^{11}{}_{\mathrm{\Lambda }}\text{B}\text{) =}\text{5}\text{2}$ is assumed. This result, unlike the branching ratios calculated for the $\text{J(}{}^{11}{}_{\mathrm{\Lambda }}\text{B}\text{) =}\text{7}\text{2}$ case, is in accord with experiment and lends support to the assumption that $\text{J =}\text{5}\text{2}$ holds for ¹¹_ΛB. The necessity of the reinterpretation of some of the so-called ¹³_ΛC events in terms of ${}^{11}{}_{\mathrm{\Lambda }}\text{B}\text{→ π}{}^{\mathrm{?}}\text{+}{}^{11}\text{C}{}^1$ is indicated.     

ESR spectra of the OD radical in the 2Π32, J = 32 state, v = 0–5 levels

The paramagnetic resonance absorption spectrum of the OD radical in the excited vibrational levels up to v = 5 of the ground ${}^2\text{Π}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, $\text{J =}\text{3}\text{2}$ state has been observed at X-band frequencies. The theory of the Zeeman effect of a paramagnetic ²Π state of a light diatomic molecule has been applied to analyze the spectrum. The Λ-doubling frequencies, the molecular g factors, coefficients of the second order Zeeman effect, and the hyperfine interaction constants were determined for each of the vibrational levels. The experimental results agree reasonably well with the values calculated from (a) optical data and (b) ab initio data. The experimental determinations are still much better than theoretical calculations.     

Spin of deep-hole states in 111Sn via the 112Sn(d, t) reaction

Analyzing powers measured in the study of ${}^{112}\text{Sn}\text{(}\text{d}\text{,}\text{t}\text{)}\text{at}\text{40}\text{MeV}$ bombarding energy show strong J-dependence and have been used to clearly assign the spin of a number of low-lying states in the residual nucleus. At high excitation energy (3.5–6 MeV). the inner-hole strength is shared between clearly isolated peaks on one hand and a fragmented structure on the other. This work reports on the determination of the spin of the inner-hole states and consequently on a more precise measurement of the overlapping regions between $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{, 2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ Subshell components. The analyzing power data shows that the group of peaks located between 3.4 and 4.5 MeV consist of spins $\text{J =}\text{9}\text{2}\text{+}\text{1}\text{2}$, in agreement with the excitation of the $\text{1}\text{g}\text{1}\text{2}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ inner- hole strengths in ¹¹¹Sn. In addition a substantial amount of the $\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ component is observed between 4.5 and 6.0 MeV.The results of the data analysis allow us to clearly eastablish the spreading of the $\text{1}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}$ innerhole strength and to a lesser extent the strong fragmentation of the $\text{2}\text{p}\text{1}\text{2}\text{and}\text{2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ inner-hole subshells.     

Investigation of the 29Si(n, γ)30Si reaction with non-polarized and polarized thermal neutrons

The γ-radiation following capture of non-polarized as well as polarized thermal neutrons in ²⁹Si has been investigated. All but one of the 56 γ-rays ascribed to the ²⁹Si(n, γ) reaction could be placed into a ³⁰Si decay scheme. The excitation energies of 21 bound states, three of which have not been reported previously, have been determined with 0.14 ± 0.8 keV errors. The spin and parity of the E_x = 8.16 MeV level have been determined as 1^?. The thermal-neutron capture cross sections of ²⁸Si and ²⁹Si are 160 ± 18 mb and 101 ± 14 mb, respectively. The (n, γ) reduced primary transition probabilities are strongly correlated with the (d, p) spectroscopic factors for l_n(d, p) = 1 levels. A simple shell-model calculation supports the experimentally founded assumption that, in addition to the E_x = 8.16 MeV level, there are one or more other levels with J^π = 1^? and with rather large relative $\text{2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{2}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ strength.