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Half-lives and branching ratios for the two mirror $ \beta$ decays of Mg and Si have been measured at the University of Jyväskylä with the IGISOL facility. The results obtained, $ T_{1/2}=11.303(3)$ s and $ T_{1/2}= 4.112(2)$ s for the half-lives of Mg and Si , respectively, are 7 and 8 times more precise than the averages of previous measurements. The values obtained for the super-allowed branching ratios of Mg and Si are $ B.R.=92.18(8)\%$ and $ B.R.=99.74(2)\%$ , respectively. The result for Mg is three times more precise than the average of the previous measurements, while for Si the precision has not been improved, the average of the previous measurements being already very precise. Isospin-symmetry-breaking corrections have been calculated for the two nuclei to determine the corrected $ {F}t$ value. [ABSTRACT FROM AUTHOR]

Branching ratios and half-lives of $ \alpha$ -decay to the ground-state rotational bands as well as the high-lying excited states of even-even nuclei have been calculated in the framework of the generalized liquid drop model (GLDM) and Royer’s formula that we improved very recently. The calculation covers the isotopic chains from Ra to No in the mass regions 222 $ \leq$ A $ \leq$ 252 and 88 $ \leq$ Z $ \leq$ 102 . The agreement between the calculated results and the experimental data indicates the reliability of investigating the properties of the unfavored $ \alpha$ -decay with our method, especially the improved Royer’s formula, which is very valuable for the analysis of experimental data. In addition, the dependence of half-lives on excitation energies of daughter nuclei has been investigated. It is shown that the influence on half-lives becomes stronger and stronger with the increase of the excitation energies. [ABSTRACT FROM AUTHOR]

The beam asymmetry, Σ , was measured at ELSA in the reaction $ \boldsymbol\gamma$ p → η p using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range E γ = 800 to 1400MeV with the maximum polarisation of P γ = 49 % obtained at 1305MeV. Both dominant decay modes of the η into two photons and 3π0 were used to extract the beam asymmetry from the azimuthal modulation of the cross-section. The measurements cover the angular range Θcm ≃ 50 -150 degrees. Large asymmetries up to 80% are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn-Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly. [ABSTRACT FROM AUTHOR]

Low-spin states of 182Ir were populated through the β+ /EC decay of 182Pt . Two strong E2 transitions were observed for the first time: a 25.7keV transition in 182Ir and a 34.0keV transition in Re of probable mass A = 178 . Spin and parity, I π = 3+ , are firmly assigned to the 182Ir ground state (g.s.). For the excited states, the parity is established and the spin determined or restricted. These assignments support most of the interpretations of the level structure previously suggested. The systematics for the known 5+ → 3+ transitions in π h 9/2 ⊗ ν 1/2-[521] bands is presented. Using a semi-microscopic two-quasiparticle axial-rotor coupling model, particle configurations have been attributed or suggested for most of the coupled states lying at low energy in 182Ir . [ABSTRACT FROM AUTHOR]

It is reported that the width of the first excited state ( $ {\frac{{7^+}}{{2}}}$ , 37.133keV) of 121 51Sb embedded in a ZnSb alloy can be modified by reabsorption of γ -rays scattered backward on the platinum (gold) reflector. Its dependence on the reflector shape is also investigated. The decay rate is reduced about 4.5% at a temperature of 4.2K by a platinum spherical reflector of 5mm radius. [ABSTRACT FROM AUTHOR]

Photoproduction of η -mesons was studied with the Crystal-Barrel detector at ELSA for photon energies in the range from 0.75 to 3GeV. Total and differential cross-sections are presented. The η mesons are detected in two decay modes, in η → 2γ and in η → 3π0 → 6γ . The cross-sections vary slowly as functions of energy and η production angle suggesting that only few resonances make significant contributions to the cross-section. For photon energies above 1.5GeV, the differential cross-sections show a strong forward peak due to meson exchanges in the t channel. A comparison of the η -photoproduction cross-sections with SAID and MAID as well as with a partial-wave analysis performed on our data in combination with other data sets shows good agreement. The Bonn-Gatchina partial-wave analysis suggests that the largest contribution to η photoproduction for energies below 3GeV proceeds via three resonances, the well-known N(1535) S 11 , via N(1720) P 13 , and a newly suggested N(2070) D 15 . [ABSTRACT FROM AUTHOR]

We define a general procedure, based on analyticity and dispersion relations, to estimate low-energy amplitudes for processes like: φ→ e + e - M and φ→ γM, starting from cross-section data on e + e -→ φM, where M is a generic light scalar or pseudoscalar meson. In particular this procedure is constructed to obtain predictions on the radiative decay rate which are crucially linked on the assumed quark structure for the meson M under consideration. Three cases are analyzed: M = η, M = f 0( q¯) and M = f 0( qq¯). While in the η case the estimate of the branching fraction for the radiative decay φ→ ηγ is in agreement with the data, in the case of f 0, such agreement is obtained only under the hypothesis of a tetraquark scalar meson. [ABSTRACT FROM AUTHOR]

The decay of 213, 214Ra was studied by α-γ and γ-γ coincidence measurements. The nuclei were produced in the reactions 170Er(48Ca, xn)218- x Ra and 170Er(50Ti, 3n)217Th and subsequent α decay of 217Th to 213Ra. Evaporation residues recoiling out of the target were separated in-flight by the velocity filter SHIP and implanted into a position-sensitive 16-strip PIPS detector in order to study their subsequent decays. Associated γ-rays were detected by a four-fold Ge-Clover detector. In the present work we extracted new and improved data for 213, 214Ra including isomeric transitions. The results are discussed and compared with previously published data. [ABSTRACT FROM AUTHOR]

X(1835) has been treated as a baryonium with sizable gluon content, and to be almost flavor singlet. This picture allows us to rationally understand X(1835) production in J/ψ radiative decays, and its large couplings with p¯, η′ππ. The processes ϒ(1 S) → γ X(1835) and J/ψ → ω X(1835) have been examined. It has been found that Br(ϒ(1 S) → γ X(1835)) Br( X(1835) → p¯) < 6.45×10-7, which is compatible with CLEO's recent experimental result (Phys. Rev. D 73, 032001 (2006) hep-ex/0510015). The branching fractions Br( J/ψ → ω X(1835)), Br( J/ψ → ρ X(1835)) with X(1835) → p¯ and X(1835) → η′π+π- have been estimated by the quark-pair creation model. We show that they are heavily suppressed, so the signal of X(1835) is very difficult, if not impossible, to be observed in these processes. The experimental checks for these estimations are expected. The existence of the baryonium nonet is conjectured, and a model-independent derivation of their production branching fractions is presented. [ABSTRACT FROM AUTHOR]

The Viola-Seaborg formula is a well-known formula for α-decay half-lives of heavy nuclei. In this work we obtain new parameters of this formula through a least-square fit to even-even nuclei between Z = 84 and Z = 110 with N greater than 126. On average, the formula can reproduce the half-lives of heavy even-even nuclei within a factor of 1.3. The formula with new parameters works well for the superheavy region which is a hot topic of nuclear physics. The numerical results from the formula are compared with those from the cluster model. [ABSTRACT FROM AUTHOR]

The decay of 75Se to levels of 75As has been studied using an HPGe detector for gamma-ray and a mini-orange electron spectrometer for conversion electron measurements. We identify 38 transitions in this decay, including 18 gamma rays and 16 conversion electron lines reported for the first time. New results also include E2 multipolarity assignment for the 81 keV transition, M1 assignment to three newly observed transitions and M1 + E2 for the 617 keV transition. A revised 75As level scheme is constructed using the Ritz combination principle through the computer code GTOL. While confirming the existence of 10 well-established levels, two levels at 587 and 859 keV are newly placed into the decay scheme of 75Se. The interpretation of the observed levels in terms of various theoretical approaches is briefly discussed. The newly placed 586.8 keV 1/2- and 859.9 keV 1/2+ levels are studied in the light of the Interacting Boson-Fermion Model. [ABSTRACT FROM AUTHOR]

Decay properties of neutron-deficient exotic nuclei close to A=80 have been investigated at the IGISOL facility. The studied nuclei, 81Y, 81Sr, 81mKr, 85Nb, 85Zr, 86Mo and 86Nb, were produced by a 32S beam from the Jyväskylä isochronous cyclotron on 54Fe and natNi targets. The internal conversion coefficient for a 190.5 keV isomeric transition in 81mKr has been measured and the internal transition rate has been determined. The internal transition rate has been used to estimate a neutrino capture rate on 81Br, which yields a log ft of 5.13±0.09 for the reaction 81Br( ν, e-)81mKr. A new isomer with a half-life of 3.3±0.9 s has been observed in 85Nb. The existence of an earlier reported isomer with a half-life of 56 s in 86Nb has not been confirmed. [ABSTRACT FROM AUTHOR]

Recent progress in experimental decay studies in the region of the doubly magic nucleus 78Ni is discussed. In particular new data on low-energy excitations in nickel isotopes has been obtained in experiments employing fragmentation reactions. The experimental data are confronted with different shell-model calculations. The position of the 2+ energy levels and behavior of 8+ isomers in even-even 70-76Ni isotopes has been interpreted. [ABSTRACT FROM AUTHOR]

The a-decay fine structure of210-214Fr has been studied by a-?-coincidence measurements. The nuclei were produced using the12C on209Bi reaction. Evaporation residues recoiling out of the target were separated in-flight by the velocity filter SHIP and stopped in a position-sensitive 16-strip PIPS-detector in order to study their subsequent decays. In the present work new and improved results for210-214Fr, produced by a-decay of the primary reaction products214-218Ac, were extracted. The results are discussed and compared to previously published data. [ABSTRACT FROM AUTHOR]

The ß--decay of147Cs to147Ba has been studied by means of ?- and X-ray spectroscopy. A new level scheme of147Ba is significantly modified and extended in comparison to the one previously reported. The Advanced Time-Delayed ß??(t) method has been applied to measure half-lives of the 46.2 and 85.4 keV levels in147Ba yieldingT1/2 of 510(80) ps and 370(100) ps, respectively. The lifetime results combined with the deduced internal conversion coefficients allowed to assignM1 multipolarity to three ? transitions. TheB(M1) values obtained for the 39.2, 46.2 and 85.4 keV transitions range from 0.017 to 0.043 W.u. and represent typicalB(M1) strength in the Ba-Er region. Model calculations using a shell correction approach with the axially deformed Woods-Saxon potential predict for147Ba an octupole deformed ground state with ß3 = 0.11. [ABSTRACT FROM AUTHOR]

The a-decays of110Xe and106Te were studied at the GSI on-line mass separator. By using the grow-in and decay of the a activity, observed in pulsed-beam measurement, the half-life of110Xe was found to beT1/2 = 105+35-25ms. The lifetime of106Te was determined to beT1/2 = 70+20-10µs by measuring the time between two successive110Xe ?{106} Te ?{102} Sn a-decays. The newly determined half-lives were used to calculate reduced a-decay widths for106Te and110Xe. Universal systematics of reduced a widths are proposed to search for the evidence of enhancement of the a formation amplitude in the emitters above100Sn. [ABSTRACT FROM AUTHOR]

EC and a decays of235Am have been studied using a gas-jet coupled on-line isotope separator. Excited states in235Pu have been established for the first time by means of ?-ray spectroscopy following the EC decay of235Am. The deduced logftvalue suggests that the ground state of235Am should have the p5/2-[523] configuration. The a-? coincidence result has revealed that the p5/2-[523] state in231Np populated by the favored a transition of235Am is located at<15 keV, which allows us to precisely determine theQa value of235Am. [ABSTRACT FROM AUTHOR]

Heavy-ion fusion reactions48Ca +204Pb and44Ca +208Pb leading to the same compound nucleus252No* were run in attempts to produce new neutron-deficient spontaneous-fission isotopes of249,250No using the electrostatic separator VASSILISSA. Production cross-sections for the spontaneous-fission activities with the half-lives 5.6 and 54 μs observed in these reactions are compared with the measured ones for the well-known isotopes of251 - 255No formed in the heavy-ion fusion reactions48Ca +206Pb and48Ca +208Pb. The obtained excitation functions for the reaction products formed after the evaporation of 1-4 neutrons from the corresponding compound No nuclei have been compared with similar data obtained earlier and results of statistical model calculations. [ABSTRACT FROM AUTHOR]

Although assigning D s0 +(2317) to the I 3 = 0 component $ \hat{F}_{I}^{+}$ of iso-triplet four-quark mesons is favored by experiments, its neutral and doubly charged partners have not yet been observed. It is discussed why they were not observed in inclusive e + e -→ c¯ experiment and that they can be observed in B decays. [ABSTRACT FROM AUTHOR]

We formulate the microscopic theory of the two-proton radioactivity based on the real-energy continuum shell model. This microscopic approach is applied to describe the two-proton decay from the 1-2 excited state in 18Ne. [ABSTRACT FROM AUTHOR]

Gamma-rays from the odd-odd transitional proton-emitting nucleus 146Tm have been observed using the recoil-decay tagging technique. A rotational band similar to the h11/2 decoupled band in 147Tm has been observed. The particle decay of 146Tm has been measured with improved statistics. A new decay scheme for 146Tm is discussed with reference to prompt and delayed γ-rays detected in coincidence with particle decays. [ABSTRACT FROM AUTHOR]

Evidence for the proton decay of 144Tm was found in an experiment at the Recoil Mass Spectrometer at Oak Ridge National Laboratory. The 144Tm events were found in the weak p5n channel of the fusion reaction using a 58Ni beam at 340 MeV on a 92Mo target. The observed proton decay energies are 1.70 MeV and 1.43 MeV and the half-life ∼ 1.9μs. The decay properties suggest proton emission from the dominant π h11/2 part of the wave function and from the small π f7/2 admixture coupled to a quadrupole vibration. [ABSTRACT FROM AUTHOR]

New levels are reported for 124,126Cd populated in the decay of 124,126Ag isomers, respectively. In addition, new data from direct population of levels in 124Cd from alpha-induced fission of 238U are reported, along with new shell-model calculations for 126Cd. [ABSTRACT FROM AUTHOR]