Proton excitations in 44Ca

A comparison of the results of the ⁴⁰Ar(⁶Li, d)⁴⁴Ca reaction with previous results for ⁴²Ca(t, p)⁴⁴Ca is used to investigate core-excited 0⁺ states in ⁴⁴Ca.     

Analogue states in 47Ca

The ⁴⁸Ca(³He, ⁴He)⁴⁷Ca and ⁴⁸Ca(p, d)⁴⁷Ca reactions were used to observe six levels in ⁴⁷Ca above 12 MeV excitation. Analysis of the data has yielded precise excitation energies for the lowest $\text{T =}\text{9}\text{2}$ levels in ⁴⁷Ca; which are analogs of low-lying levels in ⁴⁷K. Comparison of experimental and calculated Coulomb displacement energies for the K-Ca isotopes is made.     

On the Yrast levels of106–108Sn

The isotope shift in the Ca-intercombination line withλ=6,573 Å was measured for all isotopes between⁴⁰Ca and⁴⁸Ca with the only exception of 47Ca. The combination of the results with muonic x-ray data yields highly accurate values for the changes of the mean square nuclear charge radii. In addition, the nuclear quadrupole moments of the three isotopes⁴¹Ca,⁴³Ca and⁴⁵Ca have been determined from the hyperfine structure splitting of the 4s 4p ³ P ₁ state.     

Spectroscopy of neutron-deficient nuclei around 36Ca

An experiment was performed to extend the knowledge of excited states in neutron-deficient Ca isotopes. In particular, the first excited state in ³⁶Ca was searched for to obtain information on the isospin dependence of the nucleon-nucleon interaction near the proton drip line from a comparison with its stable mirror nucleus, ³⁶S. The ³⁶Ca ions were produced using a two-step fragmentation technique with a ³⁷Ca secondary beam, and in-beam γ-rays were measured. First results are the energy of the first 2⁺ state in ³⁶Ca, E(2⁺)=3036(11) keV, and the cross section for the reaction ³⁷Ca → ³⁶Ca at 61.A MeV. In addition, the de-excitaion of the first 2⁺ state in ²⁸S has been observed.     

Biological fractionation of stable Ca isotopes in Göttingen minipigs as a physiological model for Ca homeostasis in humans

In order to investigate fractionation of calcium (Ca) isotopes in vertebrates as a diagnostic tool to detect Ca metabolism dysfunction we analyzed the Ca isotopic composition (δ^44/40Ca?=?[(⁴⁴Ca/⁴⁰Ca)_sample/(⁴⁴Ca/⁴⁰Ca)_reference]?1) of diet, faeces, blood, bones and urine from Göttingen minipigs, an animal model for human physiology. Samples of three groups were investigated: 1. control group (Con), 2. group with glucocorticosteroid induced osteoporosis (GIO) and 3. group with Ca and vitamin D deficiency induced osteomalacia (?CaD). In contrast to Con and GIO whose average δ^44/40Ca_faeces values (0.39?±?0.13‰ and 0.28?±?0.08‰, respectively) tend to be lower than their diet (0.47?±?0.02‰), δ^44/40Ca_faeces of ?CaD (?0.27?±?0.21‰) was significantly lower than their δ^44/40Ca_diet (0.37?±?0.03‰), but also lower than δ^44/40Ca_faeces of Con and GIO. We suggest that the low δ^44/40Ca_faeces of ?CaD might be due to the contribution of isotopically light Ca from gastrointestinal fluids during gut passage. Assuming that this endogenous Ca source is a common physiologic feature, a fractionation during Ca absorption is also required for explaining δ^44/40Ca_faeces of Con and GIO. The δ^44/40Ca_urine of all groups are high (>2.0‰) reflecting preferential renal reabsorption of light Ca isotopes. In Göttingen minipigs we found a Ca isotope fractionation between blood and bones (Δ^44/40Ca_blood-bone) of 0.68?±?0.15‰.     

Study of 51Ca via three-neutron transfer

Low-lying levels in ⁵¹Ca have been studied via the reaction ⁴⁸Ca(¹⁸O, ¹⁵O)⁵¹Ca at a beam energy of 108 MeV. Recoiling ⁵¹Ca nuclei were detected in coincidence with ¹⁵O ejectiles, largely removing the substantial background from target contaminants that was encountered in previous work. The lowest ⁵¹Ca level identified is 1.01 ±0.11 MeV less bound than the ground state, according to a recent measurement of the ground state mass using the ⁴⁸Ca(¹⁴C, ¹¹C)⁵¹Ca reaction. Consider- ations of the difficulty in identifying the ground state peak suggest that published values of the mass excess should be viewed with caution, and that a definitive mass measurement is still required in order to resolve questions on the structure of the neutron-rich calcium isotopes. A total of six energy levels in ⁵¹Ca have been identified, and their mass excesses measured. Only two of these levels have been observed previously, via the (¹⁴C, ¹¹C) reaction. Striking differences in selectivity between the (¹⁸O, ¹⁵O) and (¹⁴C, ¹¹C) transfer reactions are discussed.     

The photonuclear cross sections of 48Ca

The sum of the photoneutron and photoproton cross sections of ⁴⁸Ca (⁴⁸Ca(γ, n + p)), has been deduced from an activation yield curve measurement using bremsstrahlung. In a separate experiment the ⁴⁸Ca(γ, p) and partial photoproton cross sections to the ground and first excited states of ⁴⁷K have been deduced from measured photoproton spectra recorded from the electro-disintegration of ⁴⁸Ca. The ⁴⁸Ca(γ, n) cross section is estimated from these data. A statistical decay model is used to estimate the ⁴⁸Ca(γ, 2n) cross section. These reported cross sections are used to determine the relative strengths and energy distributions of the isospin components of the GDR states, and to compare these with theoretical predictions.     

Isotope shift of calcium isotopes withA=40, 42, 43, 44, 46 and 48 by laser spectroscopy

Isotope shifts of all the stable Ca isotopes in the intercombination lineλ=6573Å have been studied by laser spectroscopy. The nuclear volume effect for⁴³Ca and⁴⁶Ca could be evaluated from the measurements and the quadrupole moment of⁴³Ca was obtained.     

Production of neutron-rich Ca isotopes in transfer-type reactions

The production cross sections of neutron-rich isotopes ^{52, 54, 56, 58, 60}Ca in the diffusive nucleon transfer reactions ⁴⁸Ca + ¹⁹⁷Au and ⁴⁸Ca + ²³⁸U at incident energies close to the Coulomb barrier are predicted. The global trend of production cross-section with respect to the charge (mass) number of target in reactions with ⁴⁸Ca beam is analysed for the future experiments.     

Symmetric splitting of very light systems in the coalescence and reseparation model

The coalescence and reseparation model has been used to calculate trajectories of the ¹²C + ⁴⁰Ca, ⁹Be + ⁴⁰Ca and ⁶Li + ⁴⁰Ca collisions which lead to symmetric splitting. A fusion-fission mechanism is suggested by the model. Comparison with experimental data locates the reaction angular momentum window in the region of superdeformed nuclei.     

Energy and angular momentum dependence of heavy ion optical potentials

The influence of bombarding energy and angular momentum on the depth and shape of the real part of the optical ion-ion potential is studied in a model which uses oscillator wave functions for the ground states of the interacting nuclei and takes into account the relative motion of the nuclei by a multiplication with a plane wave factor. The calculations were done for α+α,¹⁶O+¹⁶ O,⁴⁰Ca+⁴⁰Ca,α +¹⁶O,α +⁴⁰Ca and¹⁶ O +⁴⁰Ca with the Skyrme force as interaction.     

The reactions48Ca(d,t)47Ca and48Ca(3He, α)47Ca

The reactions⁴⁸Ca(d, t)⁴⁷Ca and⁴⁸Ca(³He, α)⁴⁷Ca have been measured at incident energies of 17 and 18 MeV, respectively and analysed by DWBA. Besides strong transitions to the groundstate and two unresolved states at aboutE _x =2.60 MeV relatively strong transitions withl=2 are observed at higher excitation energies in the (³He, α) reaction. The observedl=1 and higherl=3 transitions are rather weak indicating that particle-hole components in the⁴⁸Ca groundstate are relatively small.     

Mass dependence of calcium isotope fractionations in crown-ether resin chromatography

Benzo 18-crown-6-ether resin was synthesised by the phenol condensation polymerisation process in porous silica beads, of which particle diameter was ca 60μ Calcium adsorption chromatography was performed with the synthesised resin packed in a glass column. The effluent was sampled in fractions, and the isotopic abundance ratios of ⁴²Ca, ⁴³Ca, ⁴⁴Ca, and ⁴⁸Ca against ⁴⁰Ca were measured by a thermo-ionisation mass spectrometer. The enrichment of heavier calcium isotopes was observed at the front boundary of calcium adsorption chromatogram. The mass dependence of mutual separation of calcium isotopes was analysed by using the three-isotope-plots method. The slopes of three-isotope-plots indicate the relative values of mutual separation coefficients for concerned isotopic pairs. The results have shown the normal mass dependence; isotope fractionation is proportional to the reduced mass difference, (M – M′)/MM′, where M and M′ are masses of heavy and light isotope, respectively. The mass dependence clarifies that the isotope fractionations are originated from molecular vibration. The observed separation coefficient ? is 3.1×10^?3 for the pair of ⁴⁰Ca and ⁴⁸Ca. Productivity of enriched ⁴⁸Ca by crown-ether-resin was discussed as the function of the separation coefficient and the height equivalent to the theoretical plate.     

Isotope shift and hyperfine structure of43Ca by laser spectroscopy

The isotope shift⁴⁰Ca-⁴³Ca in the 4s ^{2 1} S ₀-4s4p ³ P ₁ intercombination line as well as the hyperfine structure splitting of the 4s4p ³ P ₁ state of⁴³Ca have been remeasured by saturation spectroscopy with a tunable stabilizedcw dye laser and an atomic beam of natural Ca as absorber. The nuclear charge radius of⁴³Ca obtained here reconciles our result with the radius obtained from measurements in muonic Ca-atoms and in the Ca resonance line. It reconfirms the fact that the charge radius of⁴³Ca is considerably smaller than the ones of both neighbouring even isotopes. The discrepancy of our previous measurement for this charge radius was due to a wrong assignment of so far unobserved absorption lines of probably molecular origin occuring in the neighbourhood of the atomic resonances under study.     

Isospin aspects in nuclear reactions involving Ca beams at 25 MeV/nucleon

Isospin dependence of dynamical and thermodynamical properties observed in reactions ⁴⁰Ca+ ^40,48Ca and ⁴⁰Ca + ⁴⁶Ti at 25 MeV/nucleon has been studied. We used the CHIMERA multi-detector array. Strong isospin effects are seen in the isotopic distributions of light nuclei and in the competition between different reaction mechanisms in semi-central collisions. We will show also preliminary results obtained in nuclear collision ⁴⁸Ca + ⁴⁸Ca at 25MeV/nucleon, having very high N/Z value in the entrance channel (N/Z = 1.4). The enhancement of evaporation residue production confirms the strong role played by the N/Z degree of freedom in nuclear dynamics.     

Cross sections and thermonuclear reaction rates for 42Ca(p, γ)43Sc, 44Ca(p, γ) 45Sc, 44Ca(p,n) 44Sc and 45Sc(p,n)45Ti

The yield of γ-rays from the reaction ⁴²Ca(p, γ)⁴³Sc has been measured as a function of bombarding energy over the range 0.63–3.01 MeV, from ⁴⁴Ca(p, γ)⁴⁵Sc over the range 0.775–4.00 MeV, from ⁴²Ca(p, p'γ)⁴²Ca over the range 2.24–3.01 MeV, and from ⁴⁴Ca(p, p'γ)⁴⁴Ca over the range 1.90–5.03 MeV. The cross section of the reaction ⁴⁴Ca(p, n)⁴⁴Sc has been measured from threshold to a bombarding energy of 5.05 MeV by observation of the 1157 keV γ-ray associated with the residual ⁴⁴Sc activity, and the cross section of the reaction ⁴⁵Sc(p, n)⁴⁵Ti has been measured from threshold to a bombarding energy of 4.00 MeV both by observation of the annihilation radiation associated with the residual ⁴⁵Ti activity and by measurement of the total neutron yield with a wide-angle BF₃ tube and paraffin detector. All these data are compared with statisticalmodel calculations and satisfactory agreement is achieved. Thermonuclear reaction rates for the (p, γ) and (p, n) reactions are calculated for the temperature range 5 × 10⁸-10¹⁰K and the significance of these results for explosive nucleosynthesis in stars is discussed.     

The Ca(t,d0)Ca reaction near the coulomb barrier

Angular distributions of the ⁴⁰Ca(t, d₀)⁴¹Ca reaction have been measured at energies near the Coulomb barrier at 2.0, 2.5, 3.0 and 3.5 MeV. A DWBA analysis of the data gives a value of the spectroscopic factor of 0.80 ± 0.03, in good agreement with the results of ⁴⁰Ca(d, p₀)⁴¹Ca, experiments. The sensitivity of our result to variations in the optical-model parameters and bound-state neutron radius is discussed.     

Development of multiple laser frequency control system for Ca<Superscript>+</Superscript> isotope ion cooling

We here developed and evaluated a laser frequency control system which synchronizes the laser frequency to the resonance of target Ca ⁺ isotope ion whose having more than 8 GHz of isotope shift based on the Fringe Offset Lock method for simple operation of ICPMS-ILECS (Inductively Coupled Plasma Mass Spectrometry - Ion trap Laser Cooling Spectroscopy) The system fulfilled the minimum requirements of four slave lasers stability for Doppler cooling of Ca ⁺ ions. A performance of the system was evaluated by cooling ⁴⁰Ca ⁺ ions with the stabilized slave lasers. All the stable even Ca ⁺ isotope ions were trapped and their fluorescence was observed by switching laser frequencies using the system. An odd calcium isotope ⁴³Ca ⁺cooling was also succeeded by the control system.     

Sequential and simultaneous transfer in the reactions 18O(p,t)16O, 48Ca(t,p)50Ca and 90Zr(t,p)92Zr

The effects of sequential transfer of a pair of neutrons in the reactions ¹⁸O(p, t)¹⁶O, ⁴⁸Ca(t, p)⁵⁰Ca and ⁹⁰Zr(t, p)⁹²Zr are found to be sizeable. Channel spin-orbit distortion is an important feature of the calculations of the ¹⁸O and the ⁴⁸Ca reactions.     

Nuclear sizes of 40,48Ca and 32,34S isotopes determined from 1 GeV proton elastic scattering

Differential cross sections for 1 GeV proton elastic scattering from ^40,48Ca and ^32,34S have been measured. The parameters of the nucleon distributions were obtained from an analysis of the experimental data. The difference between the neutron distributions in ⁴⁰Ca and ⁴⁸Ca is discussed in particular.