<Superscript>4</Superscript>He<Superscript>3</Superscript>H<Superscript>2</Superscript>H three-body model of the <Superscript>9</Superscript>Be nucleus

Within the framework of the single-channel approximation, an {αtd} model of the ⁹ Be nucleus is presented. A comparative analysis of the t ⁶ Li wave functions describing relative motion of bound states constructed in {ααn} and {αtd} cluster representations is carried out on the example of calculations of the ⁹ Be(γ,t₀)⁶ Li process characteristics. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 85–89, January, 2008.     

Spectroscopic investigation of thallium 6<Emphasis Type="Italic">s</Emphasis>6<Emphasis Type="Italic">p</Emphasis><Superscript>2</Superscript> configuration at electron-atom collisions: I. Spectra

Thallium emission spectra in the 115–300 nm range excited by electron-atom collisions at electron energies of 12–300 eV are investigated. A number of weak lines that cannot be unidentified using spectroscopic tables are found in the 140–170 nm range. Two of them (144.9 and 148.0 nm) are attributed to the radiative decay of levels that belong to the 6s6p ² configuration and that lie above the ionization potential. A weak emission with an excitation threshold of about 9 eV is revealed in the vicinity of the Tl II resonance line at 132.2 nm. The excitation function of the emission is measured for electron energies below 15.5 eV. It is found that the emission consists of two lines, which also appear due to the excitation of the 6s6p ² configuration and correspond to the radiative decay of levels that are common with the lines at 144.9 and 148.0 nm mentioned above. Their calculated wavelengths are 130.2 and 132.7 nm, respectively.     

Total strength of the magnetic dipole resonance in <Superscript>31</Superscript>P

The γ decay of the resonance-like structure observed in the ³⁰Si(pγ)³¹P reaction in the energy range E _p = 1.4–2.7 MeV of accelerated protons has been investigated. The excitation function of this reaction and the spectra and angular distributions of the γ rays formed in the decay of resonances with E _p = 1482, 2350, and 2505 keV have been measured. The M1 resonance on the ground and the first excited states of ³¹P with E _p = 1266 keV is identified. The total strength of the M1 resonance on the ground state of this nucleus is determined. The position and total strength of this resonance on the ground state are explained taking into account pairing forces.     

Charge distribution studies in the fast-neutron-induced fission of <Superscript>232</Superscript>Th, <Superscript>238</Superscript>U, <Superscript>240</Superscript>Pu and <Superscript>244</Superscript>Cm

Charge distribution studies for heavy-mass fission products were carried out in the fast-neutron-induced fission of ²³²Th, ²³⁸U, ²⁴⁰Pu and ²⁴⁴Cm using radiochemical and gamma-ray spectrometric techniques. The width parameter( σ_Z/σ_A), the most probable charge/mass ( Z _P/A _P), the charge polarization (ΔZ) and the slope of charge polarization [ δ(ΔZ)/δA ^′] as a function of the fragment mass (A ^′) were deduced. The average charge dispersion parameter ( 〈σ_Z〉) and proton odd-even effect ( δ_p) were also obtained for these fissioning systems. The 〈σ_Z〉 and δ_p values in the fissioning systems ²⁴¹Pu ^* and ²⁴⁵Cm ^* were determined for the first time. The δ(ΔZ)/δA ^′ value is also determined for the first time in the fissioning systems ²³⁹U ^* , ²⁴¹Pu ^* and ²⁴⁵Cm ^* . These data along with the literature data for even-Z fissioning systems such as ²³⁰Th ^* , ²³²Th ^* , ²³³U ^* , ²³⁴U ^* , ²³⁶U ^* , ²³⁸U ^* , ²³⁹Pu ^* , ²⁴⁰Pu*, ²⁴²Pu ^* , ²⁴⁶Cm ^* , ²⁵⁰Cf ^* and ²⁵²Cf(SF) are discussed in terms of nuclear structure effect and dynamics of descent from the saddle to the scission point. The role of the excitation energy in low-energy fission is also discussed. Received: 26 July 2002 / Accepted: 3 December 2002 / Published online: 3 April 2003 RID="a" ID="a"Present address: Emeritus Scientist (CSIR) Bhabha Atomic Research Centre, Nuclear Recycle Group, WIP Building, Trombay, Mumbai-400085, India; e-mail: rhiyer@magnum. barc.ernet.in Communicated by D. Schwalm     

Cluster radioactivity leading to doubly magic <Superscript>100</Superscript>Sn and <Superscript>132</Superscript>Sn daughters

Decay of neutron-deficient ^{128 − 137}Gd parents emitting ⁴He to ³²S clusters are studied within the Coulomb and proximity potential model. The predicted half-lives are compared with other models and most of the values are well within the present experimental limit for measurements (T _1/2 < 10³⁰ s). The lowest T _1/2 value for ²⁸Si emission from ¹²⁸Gd indicates the role of doubly magic ¹⁰⁰Sn daughter in cluster decay process. It is also found that neutron excess in the parent nuclei slows down the cluster decay process. Geiger–Nuttal plots for all clusters are found to be linear with different slopes and intercepts. The α-decay half-lives of ^{148 − 152}Gd parents are computed and are in agreement with experimental data. The role of doubly magic ¹³²Sn daughter in cluster decay process is also examined for various neutron-rich Ba, Ce, Nd, Sm and Gd parents emitting clusters ranging from ⁴He to ³²Si. Alpha-like structures are most probable in the decays leading to ¹⁰⁰Sn, while non-α-like structures are probable in the decays leading to ¹³²Sn. The neutron–proton asymmetry in parent and daughter nuclei is responsible for the reduced decay rate in the decay leading to ¹³²Sn.     

The pp→K<Superscript>+</Superscript><Emphasis Type="Italic">Σ</Emphasis><Superscript>+</Superscript>n cross-section from missing-mass spectra

We utilize existing inclusive data on K⁺-meson momentum spectra of the reaction pp→K ⁺ X at T _p = 2.3-2.85GeV to deduce total cross-sections for pp→K ⁺ Σ ⁺ n. The method used to extract those cross-sections is explained and discussed in detail. Our result for T _p = 2.85GeV is consistent with the data point from a direct measurement at the same beam energy. The cross-section obtained for T _p = 2.3GeV is with 13.7±2.3μb considerably smaller than the value found in a recent experiment by the COSY-11 Collaboration at a somewhat lower beam energy, indicating that the pp→K ⁺ Σ ⁺ n reaction cross-section could exhibit a rather unusual energy dependence.     

Partial-wave analysis for elastic <Emphasis Type="Italic">p</Emphasis><Superscript>13</Superscript>C scattering at astrophysical energies

A standard partial-wave analysis was performed on the basis of known measurements of differential cross sections for elastic p ¹³C scattering at energies in the range 250–750 keV. This analysis revealed that, in the energy range being considered, it is sufficient to take into account the ³ S ₁ wave alone. A potential for the triplet ³ S ₁-wave state of the p ¹³C system in the region of the J ^p T = 1⁻¹ resonance at 0.55 MeV was constructed on the basis of the phase shifts obtained from the aforementioned partial-wave analysis.     

Saturation of Coulomb sum rules in the <Superscript>6</Superscript>Li case

The Coulomb sums S _L(q) of the ⁶Li nucleus have been obtained from electron scattering measurements at 3-momentum transfers q = 1.125–1.625 fm⁻¹. It is found that at q > 1.35 fm⁻¹ the Coulomb sum of the nucleus becomes saturated: S _L(q) = 1 .     

Phase analysis and potential description of elastic <Superscript>4</Superscript>He<Superscript>12</Superscript>С scattering at low energies

Based on experiments on elastic ⁴Не¹²С scattering at energies of 1.5–6.5 MeV, a phase analysis is performed and results obtained are compared with the available data. The parameters of ⁴Не¹²С interactions are refined to reproduce more correctly the energy of bound energy levels of the ¹⁶О nucleus required for calculations of the astrophysical S-factors.     

Interaction of intermediate-energy protons with <Superscript>20</Superscript>Ne and <Superscript>24</Superscript>Mg nuclei within the multiple-scattering model

Observables of the elastic and inelastic scattering of 800- and 250-MeV protons on ²⁰Ne and ²⁴Mg nuclei were calculated on the basis of the theory of multiple diffractive scattering and the dispersive α-cluster model. The ²⁰Ne and ²⁴Mg nuclei were assumed to consist of a core (¹⁶O nucleus) and additional alpha-particle clusters, which could be situated with the highest probability both in the vicinity of the center of mass of the core and outside the core. The multiparticle densities of these nuclei and single-particle nucleon-distribution densities as obtained from the dispersive α-cluster model were used in the calculations. The differential cross sections and polarizations for elastic and inelastic p ²⁰Ne and p ²⁴Mg scattering at the energy of 800 MeV are in better agreement with experimental data than the analogous calculations at the energy of 250 MeV. The spin-rotation functions calculated in the singleparticle approximation for elastic p ²⁰Ne and p ²⁴Mg scattering at these two energy values differ qualitatively from their counterparts calculated on the basis of the dispersive α-cluster model.     

Pre-irradiation with low-dose <Superscript>12</Superscript>C<Superscript>6+</Superscript> beam significantly enhances the efficacy of <Emphasis Type="Italic">AdCMV-p53</Emphasis> gene therapy in human non-small lung cancer

The combination of ionizing radiation and gene therapy has been investigated. However, there are very few reports about the combination of heavy-ion irradiation and gene therapy. To determine if the pre-exposure to low-dose heavy ion beam enhances the suppression of AdCMV-p53 on non-small lung cancer (NSLC), the cells pre-irradiated or non-irradiated were infected with 20, 40 MOl of AdCMV-p53. Survival fraction and the relative biology effect (RBE) were determined by clonogenic assay. The results showed that the proportions of p53 positive cells in 12C6 beam induced AdCMV-p53 infected cells were more than 90%, which were significantly more than those in γ-ray induced AdCMV-p53 infected cells. The pre-exposure to low-dose 12C6 beam significantly prevented the G0/G1 arrest and activated G2/M checkpoints. The pre-exposure to 12C6 beam significantly improved cell to apoptosis. RBEs for the 12C6 AdCMV-p53 infection groups were 30%-60%, 20% -130% and 30%-70% more than those for the 12C6 -irradiated only, AdCMV-p53 infected only, and γ-irradiation induced AdCMVp53 infected groups, respectively. The data suggested that the pre-exposure to low-dose 12C6 beam significantly promotes exogenous p53 expression in NSLC, and the suppression of AdCMV-p53 gene therapy on NSLC.     

Phase analysis of <Superscript>4</Superscript>He-<Superscript>4</Superscript>He scattering at energies of 40–50 MeV

A phase analysis of ⁴He-⁴He elastic scattering is performed for energies of 40–50 MeV. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 6, pp. 74–79, June, 2007.     

Search for superheavy hydrogen isotopes <Superscript>6</Superscript>H and <Superscript>7</Superscript>H in stopped π-absorption reactions

Experimental search for superheavy hydrogen isotopes ⁶H and ⁷H was performed in the stopped pion absorption on ⁹Be and ¹¹B nuclei. The structures in the missing-mass spectra were observed in the reaction channels ⁹Be(π^-, pd )X and ¹¹B(π^-, p⁴He)X . Four states of ⁶H were proposed. Evidences for ⁷H formation were obtained in the reaction channels ⁹Be(π^-, pp)X and ¹¹B(π^-, p³He)X .     

Luminescence and thermally stimulated recombination processes in Li<Subscript>6</Subscript>Gd(BO<Subscript>3</Subscript>)<Subscript>3</Subscript>:Ce<Superscript>3+</Superscript> crystals

The luminescence and thermally stimulated recombination processes in lithium borate crystals Li₆Gd(BO₃)₃ and Li₆Gd(BO₃)₃:Ce have been studied. The steady-state luminescence spectra under X-ray excitation (X-ray luminescence), temperature dependences of the intensity of steady-state X-ray luminescence (XL), and thermally stimulated luminescence (TSL) spectra of these compounds have been investigated in the temperature range of 90–500 K. The intrinsic-luminescence 312-nm band, which is due to the ⁶ P _J → ⁸ S _7/2 transitions in Gd³⁺ matrix ions, dominates in the X-ray luminescence spectra of these crystals; in addition, there is a wide complex band at 400–420 nm, which is due to the d → f transitions in Ce³⁺ impurity ions. It is found that the steady-state XL intensity in these bands increases several times upon heating from 100 to 400 K. The possible mechanisms of the observed temperature dependence of the steady-state XL intensity and their correlation with the features of electronic-excitation energy transfer in these crystals are discussed. The main complex TSL peak at 110–160 K and a number of minor peaks, whose composition and structure depend on the crystal type, have been found in all crystals studied. The nature of the shallow traps that are responsible for TSL at temperatures below room temperature and their relation with defects in the lithium cation sublattice are discussed.     

The effect of temperature and pressure on the heat conductivity of TlSbC<Stack><Subscript>2</Subscript><Superscript>VI</Superscript></Stack> (<Emphasis Type="Italic">C</Emphasis><Superscript>VI</Superscript> → S,Se, Te)

The effect of temperature and pressure on heat conductivity of ternary compounds TiSbC ₂^VI (C ^VI → S, Se, Te) in the solid and liquid states in a temperature range of 300–800 K, as well as under the pressure up to 0.35 GPa in a temperature range of 275–450 K, is studied. The dependence of heat conductivity on average atomic weight under the S → Se → Te transition is found. Analysis of the experimental data makes it possible to attribute TlSbS₂ to the class of substances exhibiting semiconductor-semiconductor melting behavior.     

Structure and total strength of the magnetic dipole resonance in <Superscript>35</Superscript>Cl nuclei

The γ-decay of the resonance-like structure observed in the ³⁴S(pγ)³⁵Cl reaction in the energy range E _p = 1.0–3.0 MeV of accelerated protons was investigated. The M1 resonance on the ground and excited states of ³⁵Cl with E* = 1219 and 1763 keV was identified. The position of the center of gravity and total strength of the M1 resonance on ground state ³⁵Cl nucleus are determined. The position and total strength of the M1 resonance on the ground state in ³⁵Cl are explained taking into account pairing forces.     

Nuclear deformation and the two-neutrino double- β decay in <Superscript>124, 126</Superscript>Xe , <Superscript>128, 130</Superscript>Te , <Superscript>130, 132</Superscript>Ba and <Superscript>150</Superscript>Nd isotopes

The two-neutrino double-beta decay of ^{124, 126}Xe , ^{128, 130}Te , ^{130, 132}Ba and ¹⁵⁰Nd isotopes is studied in the Projected Hartree-Fock-Bogoliubov (PHFB) model. Theoretical 2ν β^-β^- half-lives of ^{128, 130}Te , and ¹⁵⁰Nd isotopes, and 2ν β⁺β⁺ , 2ν β⁺ EC and 2ν ECEC for ^{124, 126}Xe and ^{130, 132}Ba nuclei are presented. Calculated quadrupolar transition probabilities B(E2 : 0⁺ → 2⁺) , static quadrupole moments and g -factors in the parent and daughter nuclei reproduce the experimental information, validating the reliability of the model wave functions. The anticorrelation between nuclear deformation and the nuclear transition matrix element M _2ν is confirmed.