NMR relaxation at low temperature in one dimensional antiferromagnets: Comparison between S = 12 and S = 52

The proton spin-lattice relaxation time T₁ has been measured at low temperatures in spin $\text{5}\text{2}$ (CH₃)₄NMnCl₃ (TMMC) and spin $\text{1}\text{2}$ CuCl₂2NC₅H₅ (CuPC). The two systems have very different temperature dependences which we attribute to the different spin values.     

Resonance magnetic field shift induced by electric field for the +12→-12 transition relativistic approach

The resonance magnetic field shift induced by an electric field for the $\text{+}\text{1}\text{2}\text{→-}\text{1}\text{2}$ transition has been interpreted using a relativistic spin motion equation. Two examples are reported.     

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.     

Construction of a unitary analytic amplitude for the scattering of spin-12 particles

We study the existence, the uniqueness and the construction of unitary analytic amplitudes for $\text{spin}\text{1}\text{2}\text{?}\text{1}\text{2}$ scattering, in the framework previously introduced by Atkinson-Mahoux-Ynduráin for spin 0-0, and $\text{spin}\text{0?}\text{1}\text{2}$ scattering.     

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.     

Spin selectivity of the polarised (d, 2p) reaction

Tensor polarisation observables in intermediate energy $\text{(}\text{d}\text{, 2}\text{p}\text{)}$ charge exchange on 0⁺ nuclei are investigated. It is shown that for small excitation energies of the di-proton the polarisation can help to distinguish between 0^?, 1^? and 2^? final nuclear states produced through ΔL = 1, ΔS = 1 transitions. The information to be obtained is similar to that inherent in $\text{(}\text{p}\text{,}\text{n}\text{)}$ spin transfer experiments but the deutron-induced experiments should have much higher efficiency.     

On spin-52 gauge fields

We present and discuss the theory of free, massless gauge fields with spin $\text{5}\text{2}$.     

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 ${}^{56}\text{Co}\text{: 3.54}\text{MeV}\text{, 7}{}^{\mathrm{+}}\text{; 4.44}\text{MeV}\text{, 7}{}^{\mathrm{+}}\text{; 5.14}\text{MeV}\text{, 5}{}^{\mathrm{+}}$.     

Production and decay properties of possible spin 32 leptons

A systematic study of production and decay properties of hypothetical charged spin $\text{3}\text{2}$ leptons is presented. These particles are assumed to occur in each lepton family. The simplest V ± A currents constructed with these particle fields and the corresponding spin $\text{1}\text{2}$ neutrinos are assumed to be coupled to the familiar V ? A lepton charged weak currents. Our results are independent from structure models and indicate ways for an experimental search for these particles.     

Isospin-forbidden d1 production in the 4He(d,pαn reaction with tensor-polarized beam

The ${}^4\text{He}\text{(}\text{d}\text{,}\text{p}\text{α)}\text{n}$ reaction has been studied in a kinematically complete experiment using a tensor-polarized deuteron beam to investigate the isospin-forbidden pn final-state interaction. A clear dependence of the cross section near E_pn = 0 on the spin state of the incoming deuterons has been found as expected if the bumps observed by several authors at small pn relative energies are indeed due to the isospin-forbidden proton-neutron FSI in the ¹S₀, T = 1 state.     

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.     

Decay pathways and entry-state population in (α, xnγ) and (3He, xnγ) reactions on 150Nd

Exclusive neutron spectra and angular distributions have been measured by n-γ coincidence techniques for $\text{(α, x}\text{n}\text{γ)}\text{and}\text{(}{}^3\text{He}\text{, x}\text{n}\text{γ)}$ reactions on ¹⁵⁰Nd in the 25–44 MeV range. The results show that pre-equilibrium processes dominate low-energy light-ion induced reactions at certain beam energies. Analysis of the yrast γ-ray cascades in the residual nuclei shows that a well-defined minimum entry-state spin exists in final nuclei populated by pre-equilibrium processes. This in turn implies the existence of a minimum classical impact parameter for these reactions. These results are discussed in terms of phenomenological models of the reaction mechanisms.     

Spin alternation in one-dimensional exchange-coupled systems: Magnetic behaviour of the (12−1)N chain

We report on the magnetic behaviour of exchange-coupled closed chains (rings) of increasing length made of two alternating spin sublattices $\text{S}{}_{\mathrm{<mtext>a</mtext>}}\text{=}\text{1}\text{2}\text{, S}{}_{\mathrm{<mtext>b</mtext>}}\text{= 1}$. Taking into account the geometrical and spin space symmetries of such syste the problem is shown to be tractable up to 10 spins for distinct values of the g_a/g_b ratio between Landé factors; the results are discussed for an antiferromagnetic coupling. The limiting behaviour for the infinite chain is determined by extrapolation of the data obtained for finite rings. At very low temperatures, the analogy with the regular $\text{S =}\text{1}\text{2}$ ferromagnetic chain is underlined.     

Integral representation for the spin 12 Ising ferromagnet

A simpler derivation is given for a recently discovered integral representation for the spin $\text{1}\text{2}$ Ising ferromagnet.     

Measuring the P-odd asymmetry in electroproduction of the δ(32, 32 resonance at low energies

We show that measurements of the P-odd asymmetry in the reaction $\text{e}{}^{\mathrm{?}}\text{+}\text{N}\text{→}\text{e}{}^{\mathrm{?}}\text{+δ(}\text{2}\text{2}\text{,}\text{3}\text{2}$ at low energies might determine the combination $\text{α}\text{～}\text{+(1.0–1.2γ}\text{β}\text{～}$ of the isovector phenomenological couplings, characterizing the parity nonconserving electron-quark neutral current interaction at presently accessible energies. They may provide also a very accurate determination of the parameter sin²θ_W of the standard electroweak gauge theory.     

The U(612) supersymmetric limit of the interacting Boson-Fermion Model

The $\text{U(}\text{6}\text{12}\text{)}$ dynamical supersymmetry of the Interacting Boson-Fermion Model, appropriate for nuclei where the odd nucleon can occupy the single-particle orbits $\text{J =}\text{1}\text{2}\text{,}\text{3}\text{2}\text{,}\text{and}\text{5}\text{2}$ is analyzed. The subgroup structure of $\text{U(}\text{6}\text{12}\text{)}$ is discussed and the generators and Casimir operators of these subgroups are given. In each of the three dynamical symmetries of $\text{U(}\text{6}\text{12}\text{)}$ the energy formulas, reduction rules, and wave functions are obtained and closed expressions for E2 transition rates and one-nucleon transfer intensities are derived. Examples of $\text{U(}\text{6}\text{12}\text{)}$ symmetries are presented.     

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.     

Quasiquadrupolar echoes in solids containing spins-12 triads undergoing hindered reorientation

The spin echo responses to resonant 90⁰-τ-β_φ⁰ rf pulse sequences in solids containing spin-$\text{1}\text{2}$ triads undergoing hindered rotations, are shown to be predicted by a model of dipolar coupled quasiparticles of spin-$\text{3}\text{2}$.     

Polarization dynamics for spin 12-spin I systems with Breit-Rabi interaction

We study the full polarization dynamics of two interacting systems of spin $\text{1}\text{2}$ and spin I for the Breit-Rabi hamiltonian, the sum of contact hyperfine and Zeeman terms. We obtain the time dependence of the polarizations by solving the eigenvalue problems for the interaction hamiltonian and discuss some applications.     

The rotational bands 12+[411]and 12−[541]in 175Lu

In a study of the γ-radiation emitted in the reaction ¹⁷⁶Yb(p, 2n) excited states of the nucleus ¹⁷⁵Lu up to spin I = $\text{13}\text{2}$ have been investigated. The main results concern the rotational bands $\text{1}\text{2}$⁺ [411]and $\text{1}\text{2}$^? [541]with the corresponding band heads found at 626.60 and 370.88 keV, respectively. The half-life of the $\text{1}\text{2}$⁺[411] level has been determined to be $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 10.7±0.5}\text{ns}$. Furthermore, the band heads $\text{3}\text{2}$^?[532]and $\text{3}\text{2}{}^{\mathrm{+}}$[411]are proposed at energies of 999.0 and 1150.8 keV, respectively. Experimental E1 transition probabilities between both $\text{K =}\text{1}\text{2}$ bands are compared with calculations including the Coriolis and pairing effects, as well as theoretically deduced quadrupole deformation parameters.