A useful spectroscopic tool: The (7Li, 6He) reaction

Angular distribution measurements for the reactions ²⁴Mg(⁷Li, ⁶He)²⁵ Al and ⁵²Cr(⁷Li, ⁶He)⁵³ Mn at$\text{E(}{}^7\text{Li) = 34}$ MeV show that for angles less than 15°, the shapes of the measured angular distributions allow $\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ or $\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$, and $\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$ or $\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ final-state configurations to be distinguished when compared with finite-range DWBA calculations.     

Very light neutron-rich nuclei studied via the (6Li, 8B) reaction

Results from investigations of the $\text{T}{}_{\mathrm{z}}\text{=}\text{3}\text{2}$ nuclei ⁵H, ⁷He and ⁹Li and of the T = 1 nuclide ⁴H employing the (⁶Li, ⁸B) reaction at 80 and 93 MeV are presented. In ⁹Li the locations of several low-lying Ip shell levels are indicated; in ⁷He and ⁴H the ground states are clearly observed. No evidence is found for the formation of a narrow ⁵H ground state.     

Linear momentum transfer in the reaction 232Th(14N,light particles) AT 208 MeV

The longitudinal momentum transferred to a target nucleus (ΔP) has been studied for light-particle emission in the ¹⁴N-induced reaction on ²³²Th at 208 MeV. The transferred momentum was deduced by measuring folding angles between two fission fragments resulting from the sequential decay of the target-like nucleus. It was found that the fraction $\text{?}{}_2\text{=}\text{(〈ΔP〉 + P}{}_{\mathrm{<mtext>out</mtext>}}{}^{\mathrm{\parallel }}\text{)}\text{P}{}_{\mathrm{<mtext>beam</mtext>}}$ averaged over light-particle energy was about 0.68, almost independent of light-particle species and detection angle, where P_beam is the initial momentum of the beam particle and P_out^∥, the momentum component parallel to the beam carried away by the observed light particle. A possible mechanism for describing the phenomena is discussed.     

Fragmentation of relativistic heavy ions

The “incoherent droplet model” is used to explain recent experiments on the fragmentation of ¹⁶O during high energy collision with a Be target. In the ¹⁶O rest frame the fragments have a universal iso tropic Gaussian momentum distribution, independent to the masses of the fragments. The half-width of the Gaussian is $\text{〈p〉 (}\text{A}\text{3}{}_{\mathrm{n}}\text{)}$, where, A is the mass number of the nucleus, n is the total number of fragments, and 〈p²〉 is the mean square momentum of individual nucleons in the fragmenting nucleus.     

Alpha-deuteron structure of 6Li as predicted by a separable-potential three-body model

Schroedinger's equation with separable n-p (³S₁) and $\text{n}\text{-α (}{}^2\text{P}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}$ potentials solved to obtain a three-body model of the ⁶Li ground-state wave function. This model predicts the α-n-p binding energy of ⁶Li to be 4.67 MeV [Exp.: 4.53 MeV = 3.697 + 0.834 (Coulomb)], the asymptotic normalization constant of the d-α tail to be 2.39, and the amount of d+α component to be 65%. The ⁶Li→α+d vertex function is slightly more momentum dependent than present experiments suggest.     

The differential cross section and polarization quantities in the 4He(d,p)n4He and 2H(α, n)p4He reactions

The differential cross section and the polarization quantities (T₁₁, T₂₀, T₂₁, T₂₂, P_γ') in the deuteron breakup reaction by an α-particle are calculated in the framework of the recently developed three-body model. All values are discussed under the incomplete kinematical condition. All polarization quantities are caused by the difference of the potential between $\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ waves of the N-α interaction. Results of the calculation are compared with the available measurement of (i) the differential cross section and the deuteron vector analysing power in the ⁴He($\text{d}$, p)n⁴He reaction and (ii) the differential cross section and neutron polarization in the ²H(α, $\text{n}$)p⁴He reaction. The agreement with experiment is very satisfactory in each case. Among the tensor analysing powers of the deuteron the absolute value of T₂₀ is very large. Observables at the FSI peak corresponding to ⁵He_g.s. are discussed systematically in the energy region of 5.4–20 MeV of the incident deuteron in the ⁴He(d, p)n⁴He reaction. Although the differential cross section is not sensitive to the energy of the three-body resonance, the polarization quantities T₁₁, T₂₀, P_γ' are quite sensitive to it.     

An anomalous M1 transition in 38Cl

The observed enchangement of the M1 transition in ³⁸Cl between the 3^? state of the “$\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{-}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ multiplet” and the 4^? state of the “ mumultiplet” is explained.     

Structure of positive parity states in 29P and two-step processes in (p,t) reactions

From a study of (p,t) reactions on ³¹P and ³⁰Si it is suggested that in ²⁹P the states with $\text{J}{}^{\mathrm{\pi }}\text{=}\text{1}\text{2}{}_1{}^{\mathrm{+}}$ and $\text{1}\text{2}{}_2{}^{\mathrm{+}}$, the pair $\text{3}\text{2}{}_2{}^{\mathrm{+}}$, $\text{5}\text{2}{}_1{}^{\mathrm{+}}$, and the pair $\text{7}\text{2}{}_3{}^{\mathrm{+}}$, $\text{9}\text{2}{}_1{}^{\mathrm{+}}$ are related by weak coupling of a s${}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ proton with the states 0₁⁺, 0₂⁺, 2₁⁺ and 4₁⁺ respectively of ²⁸Si. Completely atypical L = 2 angular distributions have been obtained for the $\text{3}\text{2}{}_1{}^{\mathrm{+}}$ and $\text{5}\text{2}{}_2{}^{\mathrm{+}}$ states in ²⁹P and it is suggested that this is due to contribution by two-step processes.     

Stark mixing spectroscopy in cesium

We present a new technique for selectively populating excited states which are inaccessible by dipole excitation from the ground state. The method uses a static electric field to introduce a component of a dipole-allowed state into the state of interest. We have applied the method to cesium to measure lifetimes and a Stark mixing coefficient. The results are $\text{τ(6}{}^2\text{D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)=64(2) ns}$, $\text{τ(7}{}^2\text{D}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{)=92.5(15) ns}$, and <6²D_{$\text{5}\text{2}$}|;ez |7²P_{$\text{3}\text{2}$}>/(E_7P?E_6D)=0.7(3)×10^?3 where is in kV/cm. 141     

Radiative lifetimes in MoI using a novel atomic beam source

Radiative lifetimes of the 4d⁵ (a⁶S)5pz ⁷P^o levels and the 4d⁵ (a⁶S)5pz⁵P^o levels in MoI are reported as follows: $\text{τ(}\text{z}{}^7\text{P}{}_4{}^{\mathrm{<mtext>O</mtext>}}\text{) = 15.9}\text{ns}$, $\text{τ(}\text{z}{}^7\text{P}{}_3{}^{\mathrm{<mtext>O</mtext>}}\text{) = 17.0}\text{ns}$, $\text{τ(}\text{z}{}^7\text{P}{}_2{}^{\mathrm{<mtext>O</mtext>}}\text{) = 17.1}\text{ns}$, $\text{τ(}\text{z}{}^5\text{P}{}_3{}^{\mathrm{<mtext>O</mtext>}}\text{) = 22.3}\text{ns}$, $\text{τ(}\text{z}{}^5\text{P}{}_2{}^{\mathrm{<mtext>O</mtext>}}\text{) = 22.1}\text{ns}$, and $\text{τ(}\text{z}{}^5\text{P}{}_1{}^{\mathrm{<mtext>O</mtext>}}\text{) = 21.7}\text{ns}$ (±5%). The lifetimes are measured using time resolved laser induced fluorescence and a novel atomic beam source. This novel hollow cathode effusive beam source produces an intense beam of ground state Mo atoms and metastable Mo atoms. Our measurements on the z ⁷P^O levels are in agreement with earlier lifetime measurements. Our measurements on the z ⁵P^O levels are the first direct radiative lifetime measurements of these levels; the z ⁵P^O measurements are of particular interest because the a⁵S → z⁵P^O multiplet is used to determine the solar abundance of Mo.     

Decays of 185m + gHg: Low-spin levels of 185Au as a test of nuclear models

The decay of ^{185m + g}Hg has been studied on-line with mass-separated sources from the ISOCELE facility. Precise conversion-electron measurements were performed with a 180° spectrograph. The $\text{13}\text{2}{}^{\mathrm{+}}$ isomeric state of ¹⁸⁵Hg ($\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 28 ± 5 s}$) was located with respect to the $\text{1}\text{2}$^? ground state ($\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 55 ± 10 s}$). A level scheme of ¹⁸⁵Au has been established. Two abnormally converted M1 transitions de-excite a state local at 330.2 keV. Excited states of ¹⁸⁵Au have been discussed in the framework of a “quasi-particle + axial rotor” approach, quasi-particle states being issued from Hartree-Fock plus BCS calculations using the SIII Skyrme force. Most of the low-spin negative-parity levels have been identified as h_{$\text{9}\text{2}$} + f _{$\text{5}\text{2}$} or p_{$\text{3}\text{2}$} + f_{$\text{7}\text{2}$} mixed states. The h_{$\text{11}\text{2}$} system has also been discussed using a model of asingle-j quasi-particle coupled to a triaxial rotor.     

Level structure of 100Tc

Gamma and electron spectra following thermal neutron capture on ⁹⁹Tc have been studied with a bent-crystal spectrometer, Ge(Li) and Si(Li) detectors and a magnetic spectrometer. Prompt and delayed γ-γ coincidences with Ge(Li) detectors have been performed. A level scheme is proposed for ¹⁰⁰Tc comprising 21 excited states up to 640 keV. The binding energy of the last neutron in ¹⁰⁰Tc was deduced. For most levels, spin and parity values were assigned. Two isometric transitions of respective half-lives 10.2 and 4.6 μs have been identified using the ¹⁰⁰Mo(d, 2n)¹⁰⁰Tc reaction with a pulsed beam of deuterons. From the comparison of the present (n, γ) study and the collaborative study of the ⁹⁹Tc(d, p) reaction, several members of the multiplets $\text{π}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{ν}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}$, $\text{π}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{ν}\text{g}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$, $\text{π}\text{g}{}_{\mathrm{<mtext>9</mtext><mtext>2</mtext>}}\text{ν}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ and $\text{π}\text{p}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{ν}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$ have been identified.     

A numerical estimate of deviations from the exponential decay law for the transition 2P12→1S12 in hydrogen

The deviations from the exponential decay law of the $\text{2}\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ states of the Dirac hydrogen atom with respect to the transition $\text{2}\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{→1}\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ are numerically estimated. We find |a₀(t) ? exp(?λt)|?2.5 × 10^?4 for all t, where a₀(t) is the “exact” decay amplitude and λ is a complex constant such that (2Re λ)^?1 is the “natural lifetime” of the $\text{2}\text{P}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ states with respect to the spontaneous transition to $\text{1}\text{S}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$.     

Beta decay studies in the vicinity of 13250Sn82: Excited states in 13051Sb, 13052Te and 13252Te

Using the OSIRIS on-line isotope separator facility, the decays of ¹³⁰Sn and ^{130, 132}Sb have been studied. On the basis of singles γ and γ-γ coincidence Ge(Li) spectra and conversion electron Si(Li) measurements, level schemes for ¹³⁰Sb, ¹³⁰Te and ¹³²Te have been constructed. The corresponding half-lives have been measured using multiscaling technique. The 3.8 min ground state of ¹³⁰Sn populates only positive parity states in the πν^?3 nucleus ¹³⁰Sb: the energetically lowest 5⁺ state with the $\text{(π1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, ν2}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{)}$ configuration assignment; the $\text{T}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}\text{= 3.6 ± 0.3}\text{ns}\text{4}{}^{\mathrm{+}}$ state at 70.0 keV; the 2⁺ state at 262.5 keV; the (0, 1)⁺ state at 697.2 keV; the 3⁺ state at 813.1 keV and the 1⁺ state at 1042.3 keV excitation energy. A 1.7 min isomeric state in ¹³⁰Sn, with the tentative spin assignment (7^?), populates several odd parity levels in ¹³⁰Sb. These arise from the $\text{(π1}\text{g}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, ν1}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}{}^{-1}\text{)}$ and/or $\text{(π2}\text{d}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}\text{, ν1}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}{}^{-1}\text{)}$ configurations and are located 84.7 keV (6^?), 144.9 keV (7^?), 688.5 keV and 1044.0 keV above the 40 min 8^? β- decaying state. No transitions between odd and even parity states have been observed.The most important excited states in ¹³⁰Te found in the β^? decay of the 6.6 min ¹³⁰Sb 5⁺ state are: 839.4 keV, 2⁺; 1632.8 keV, 4⁺; 1815.1 keV, 6⁺; 2100.8 keV, 5^?.Levels in the π²ν^?2 nucleus ¹³²Te were observed in the β^? decays of the 2.8 min ¹³²Sb (4⁺) and the 4.2 min ¹³²Sb (8^?) states. Unique spin and parity assignments have been given to the following states: 973.9 keV, 2⁺; 1670.7 keV, 4⁺; 1774.1 keV, 6⁺; 1924.7 keV, 7^?; 2053.0 keV, 5^?.     

Level structure of 48Sc from the 48Ca(p,nγ) reaction

Levels of ⁴⁸Sc up to 3.33 MeV excitation were studied by the reaction ⁴⁸Ca(p,nγ)⁴⁸Sc employing a variety of experimental techniques. A level scheme of ⁴⁸Sc comprising 29 excited states and 54 transitions were determined from the measurements of γ-γ coincidences and γ-ray excitation functions. Within the framework of the statistical compound nucleus model spins and parities of the ⁴⁸Sc levels were assigned from the angular distributions and linear polarizations of the de-excitation γ-rays as well as the excitation functions of the residual levels. From the present experimental results and other available data we tentatively identified some of the levels of the ($\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^9$, $\text{1}\text{d}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}\text{)}$, ($\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^9\text{, 2}\text{s}{}_{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$), ($\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^7\text{, 2}\text{p}{}_{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$) and ($\text{1}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^7\text{, 1}\text{f}{}_{\mathrm{<mtext>5</mtext><mtext>2</mtext>}}$) configurations in addition to the well-known ($\text{π}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}\text{, v}\text{f}{}_{\mathrm{<mtext>7</mtext><mtext>2</mtext>}}{}^{\mathrm{?1}}$) multiplet.     

Rotational bands in the odd-odd 152Eu nucleus

The ¹⁵⁰Nd(⁷Li, 5n) reaction has been used to study the high-spin states in the odd-odd nucleus ¹⁵²Eu. Two rotational bands of different behaviour have been identified: a rather regular band based on the I^π = 8^? isomeric state of configuration $\text{[413}\text{5}\text{2}\text{]}{}_{\mathrm{<mtext>p</mtext>}}\text{[505}\text{11}\text{2}\text{]n}$ and a strongly decoupled system belonging to the configuration $\text{[}\text{h}{}_{\mathrm{<mtext>11</mtext><mtext>2</mtext>}}\text{]}{}_{\mathrm{<mtext>p</mtext>}}\text{[i}{}_{\mathrm{<mtext>13</mtext><mtext>2</mtext>}}\text{]}{}_{\mathrm{<mtext>n</mtext>}}$.It is shown in this work that the aligned angular momentum carried by each two-quasiparticle configuration in ¹⁵²Eu is the sum of the alignment of the odd neutron and odd proton, which indicates a negligible influence of the neutron-proton residual interaction. Particular attention has been focused on the strong deviations of the moment of inertia of the core when different quasiparticle configurations are involved.     

β-delayed charged particles from 9Li and 11Li

β-delayed emission of α-particles from ⁹Li and of both α and ⁶He particles from ¹¹Li is observed. Singles energy spectra and two-dimensional energy spectra of coincident particles are measured. A time-of-flight versus energy measurement is used to identify the mass of the particle. New β-branches are observed which populate high-energy levels in the daughter nuclei. The branching ratios are measured and the β-delayed neutron emission probabilities $\text{P}{}_{\mathrm{<mtext>n</mtext>}}\text{for}{}^9\text{Li and}\text{P}{}_{\mathrm{3n}}\text{for}{}^{11}\text{Li}$ are deduced.     

Φecчet ДИLcy;н boЛн Л sИЛ osцИЛЛЯtoΦo b ДЛЯ ИЗoЭЛeКtponnoЙ ПosЛeДoBateЛЬn ostИ Li

ФeйnмanoBsкaя диaгpaмnaя teчnи кa пpимenena для pasЧeta длen Bo лn и sил osцилляtopoB osnBoг и nикoto pыч neжnич Boэбyждennыч sstoяn ий Li-пoдoбnыч иonoB. passЧиtanы Bклaды ot диaгp aмм пepBыч пopядкoB длк nepeляtи Bиstsкoй эnepгии, peляtиBиstsкич пoпpaBoк и дипoл ьnыч matpиЧnыч matpиЧnыч элeme ntoB. Для pasЧeta peляtиBиstsкич пoпpaBoк был иsпoльэoBan oпepat op Бpeйta. pяд пo $\text{1}\text{z}$ для эnepгии пpe дstaBлen B sлeдyющeem Bидe

$\text{E = E}{}_0\text{z}{}^2\text{+ΔE}{}_1\text{z+}\text{1}\text{z}\text{ΔE}{}_3\text{+}\text{α}{}^2\text{4}\text{(E}{}_0{}^{\mathrm{p}}\text{z}{}^4\text{+ ΔE}{}_1{}^{\mathrm{p}}\text{z}{}^3\text{),}$

для дипoльnoгo matpиЧoгo элe

$\text{P =}\text{a}\text{z}\text{1+}\text{τ}{}_1\text{z}\text{+}\text{τ}{}_2\text{z}{}^2\text{.}$

ПoлyЧennыe Чиsлennяe эnaЧennы e эnaЧenия кoэффициentoB пpи z^k дaли Boэmoжnostь passЧиtatь длиnы Boлn и sилы osцилляtopoB пe peчoдoB 1s²2s ? 1s²2p, 1s²2s ? 1s²3p, 1s²2p ? 1s²3s, 1s²2p ? 1s²3d, 1s²3s ? 1s²3p, 1s²3p ? 1s²3d для Li-п oдoбnыч иonoB. peэyльtatы pasЧe ta spaBnиBaюtsя s экsпepиmentaльныmи для иэoэлeкtpnnoй пoлeдoBat eльnostи Li. Чopoшee soглasиe s экsпepиment aльnыmи (0,01–0,1%) дaet Boэmoжnostь naдetьsя, Чto pяд пo $\text{1}\text{z}$ sчoдиtsя д ostatoЧno быstpo.Feynman diagram techniques have been applied to the calculation of wavelengths and oscillator strengths of the ground state and of a number of low-lying excited states for Li-like ions (1s²2l, 1s²3l). Contributions have been calculated to the first order for the nonrelativistic energy, relativistic corrections and dipole matrix elements. Relativistic corrections have been obtained by computing the active 〈H_B〉 matrix. Numerical results for the $\text{1}\text{z}$ expansion are presented in the following form: for the energy,

$\text{E = E}{}_0\text{z}{}^2\text{+ΔE}{}_1\text{z+}\text{1}\text{z}\text{ΔE}{}_3\text{+}\text{α}{}^2\text{4}\text{(E}{}_0{}^{\mathrm{p}}\text{z}{}^4\text{+ ΔE}{}_1{}^{\mathrm{p}}\text{z}{}^3\text{),}$

for the dipole matrix elements,

$\text{P =}\text{a}\text{z}\text{1+}\text{τ}{}_1\text{z}\text{+}\text{τ}{}_2\text{z}{}^2\text{.}$

The results were used for calculations of the wavelengths and oscillator ofthe transitions 1s²2s ? 1s²2p, 1s²2s ? 1s²3p, 1s²2p ? 1s²3s, 1s²2p ? 1s²3d, 1s²3s ? 1s²3p, 1s²3p ? 1s²3d for Li-like ions. Results are compared with experimental data for the isoelectronic sequence of Li (Li I-SX IV). Good agreement with experimental data (0·01–0·1%) suggests that the $\text{1}\text{z}$-expansion converges rapidly.