For the first time an extensive search for various double beta decay modes of 124Sn and 112Sn has been performed. A total exposure of 43.29 kg.days has been accumulated. New half-life limits of 124Sn into excited states of 124Te have been obtained; the lower half-life limit for the first excited 2+ state at 602.7keV is T_1/2 > 3.1 *10^{18}yrs (90 % CL) and for the first excited 0+ state T_1/2 > 7.7 *10^{18}yrs (90 % CL). For the very first time, ground state and excited state transitions of 112Sn have been experimentally explored. The obtained half-life limits for ECEC and beta+/EC into the first excited 2+ state of 112Cd are both T_1/2 >1.4 *10^{18}yrs (90 % CL). A resonance enhancement in the decay rate for 0nuECEC might be expected for the 0+-state at 1870.9keV due to degeneracy with the 112Sn ground state. No signal was found resulting in a lower half-life limit of T_1/2 > 1.6 *10^{18} yrs (90 % CL) for this decay. As all the excited state searches are based on gamma-lines, all half-life limits apply for both neutrino and neutrino-less modes. Neutrinoless ground state transitions were searched for in the ECEC and beta+/EC mode and a limit of T_1/2 > 1.5 *10^{18} yrs (90 % CL) was obtained for ECEC decays of 112Sn, whilst the beta+/EC mode results are inconclusive.
Thirty-eight tin isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
Currently, twenty-four calcium, thirty-eight indium, thirty-eight tin and thirty-nine platinum isotopes have been observed and the discovery of these isotopes is discussed here. For each isotope a brief synopsis of the first refereed publication, including the production and identification method, is presented.
In the given paper the total inelastic cross-sections of the reactions of protons and deuterons on nuclear targets of enriched tin isotopes were compared. The factorization of cross-sections of reactions was discussed. Furthermore, the comparison of theoretical estimations on total inelastic cross-sections with corresponding experimental ones was made.
The coefficients of symmetry energy term for fragments with Z=4,11,12 measured in multifragmentation reactions initiated by proton and deuteron with energy of 3.65A GeV on enriched tin isotopes 112,118,120,124Sn are determined. The dependence of isoscaling parameter on the excitation energy, the temperature of fragmenting systems and the density ratio for heavy mass products are analised.
Cross sections and analyzing powers for proton elastic scattering from $^{116,118,120,122,124}$Sn at 295 MeV have been measured for a momentum transfer of up to about 3.5 fm$^{-1}$ to deduce systematic changes of the neutron density distribution. We tuned the relativistic Love-Franey interaction to explain the proton elastic scattering of a nucleus whose density distribution is well known. Then, we applied this interaction to deduce the neutron density distributions of tin isotopes. The result of our analysis shows the clear systematic behavior of a gradual increase in the neutron skin thickne…
The $^{112,120}$Sn$(γ,γ')$ reactions have been studied at the S-DALINAC. Electric dipole (E1) strength distributions have been determined including contributions from unresolved strength extracted by a fluctuation analysis. Together with available data on $^{116,124}$Sn, an experimental systematics of the pygmy dipole resonance (PDR) in stable even-mass tin isotopes is established. The PDR centroid excitation energies and summed strengths are in reasonable agreement with quasiparticle-phonon model calculations based on a nonrelativistic description of the mean field but disagree with relativis…
Isospin effects in 12C ion induced reactions on enriched tin isotopes are investigated. The isoscaling parameter B is determined for different mass regions of product nuclei. It is shown that the isoscaling parameter is sensitive to the formation mechanism of products, and increases as the difference in the asymmetry is increasing. Using the exitatation energy obtained with the catcher technique temperatures, density ratio ro/ro0 for product nuclei in different mass regions and the values of symmetry energy coefficient for light mass regions of product nuclei for proton and deuteron induced re…
The isoscalar giant monopole resonance (GMR) has been investigated in a series of Sn isotopes (A=112--124) using inelstic scattering of 400-MeV alpha particles at extremely forward angles (including 0deg). The primary aim of the investigation has been to explore the role of the "symmetry-energy" term in the expression for nuclear incompressibility. It is found that the energies of the GMR in the Sn isotopes are significantly lower than those expected from the nuclear incompressibility previously extracted from the available data on the compressional-mode giant resonances.
The x-ray cascade from antiprotonic atoms was studied for 106Cd, 116Cd, 112Sn, 116Sn, 120Sn, and 124Sn. Widths and shifts of the levels due to strong interaction were deduced. Isotopic effects in the Cd and Sn isotopes are clearly seen. The results are used to investigate the nucleon density in the nuclear periphery. The deduced neutron distributions are compared with the results of the previously introduced radiochemical method and with HFB calculations.
The double beta decay study of 160-Gd has been performed in the Solotvina Underground Laboratory with the help of Gd_2SiO_5(Ce) crystal scintillator (volume 95 cc). The background of the detector in the vicinity of the 2 beta energy of 160-Gd was reduced to 1.0 cpd/keV kg. The new improved half-life limits have been established for neutrinoless 2 beta decay of 160-Gd to the ground and first excited levels of 160-Dy: T1/2 > 2.3(1.3)E21 yr at 68%(90%) C.L. The T1/2 bounds have been also set for two neutrino mode as well as for 2 beta decay with Majorons emission. Also the limits were established…
A search for alpha and double beta decays of ytterbium isotopes was performed with an ultra-low background high purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 194.7 g Yb$_2$(C$_2$O$_4$)$_3$ powder sample was measured for 11.3~d with a total Yb exposure of 1.25 kg$\times$d. Half-life limits for $α$-decay modes of $^{168}$Yb, $^{170}$Yb, $^{171}$Yb, $^{172}$Yb, $^{173}$Yb, $^{174}$Yb and $^{176}$Yb into the first excited states have been obtained between $6\times10^{14}$ yr and $2\times10^{16}$ yr. These are the first experimental constraints of these decay modes. Doub…
The current situation in double beta decay experiments , the characteristics of modern detectors and the possibility of increasing the sensitivity to neutrino mass in future experiments are discussed. The issue of the production and use of enriched isotopes in double beta decay experiments is discussed in addition.
The Q-value of the double-electron capture in Cd-108 has been determined to be (272.04 +/- 0.55) keV in a direct measurement with the double-Penning trap mass spectrometer TRIGA-TRAP. Based on this result a resonant enhancement of the decay rate of Cd-108 is excluded. We have confirmed the double-beta transition Q-values of Cd-106 and Pd-110 recently measured with the Penning-trap mass spectrometers SHIPTRAP and ISOLTRAP, respectively. Furthermore, the atomic masses of the involved nuclides Cd-106, Cd-108, Cd-110, Pd-106, Pd-108 and Pd-110 have been directly linked to the atomic mass standard.
We present a systematic configuration-interaction shell model calculation on the structure of light tin isotopes with a new global optimized effective interaction. The starting point of the calculation is the realistic CD-Bonn nucleon-nucleon potential. The unknown single-particle energies of the $1d_{3/2}$, $2s_{1/2}$ and $0h_{11/2}$ orbitals and the T=1 monopole interactions are determined by fitting to the binding energies of 157 low-lying yrast states in $^{102-132}$Sn. We apply the Hamiltonian to analyze the origin of the spin inversion between $^{101}$Sn and $^{103}$Sn that was observed …
A search for the various double beta decay modes of 124Sn and 112Sn has been performed on 75 kg.days of data. New half-life limits for excited states in 124Sn have been obtained including a lower limit for the decay into the first excited 2+ state of 124Te of T_half > 0.87e20 yrs (90% CL) and into the first excited 0+ state of T_half > 1.08e20 yrs (90% CL). Ground state and excited state transitions of 112Sn have also been experimentally explored. A limit for the 2 neutrino double electron capture of T_half > 1.8e19 yrs (90% CL) is obtained. The non-observation of de-excitation gammas from the…
SuperNEMO is a next-generation double beta decay experiment based on the successful tracking plus calorimetry design approach of the recently stopped NEMO3 experiment. SuperNEMO can study a range of isotopes, but the baseline isotope is $^{82}$Se. The total isotope mass will be 100--200 kg. A sensitivity to a $0νββ$ half-life greater than $10^{26}$ years can be reached which gives access to Majorana neutrino masses of 50--100 meV. Having successfully completed R&D stage the SuperNEMO Collaboration has commenced the construction of the first module, the Demonstrator. The present status of Super…
We measure cross sections for residual nuclide formation in the mass range 6 < A < 97 caused by bombardment with protons and deuterons of 3.65 GeV/nucleon energy of enriched tin isotopes (112-Sn, 118-Sn, 120-Sn, 124-Sn). The experimental data are compared with calculations by the codes FLUKA, LAHET, CEM03, and LAQGSM03. Scaling behavior is observed for the whole mass region of residual nuclei, showing a possible multifragmentation mechanism for the formation of light products (6 < A < 31). Our analysis of the isoscaling dependence also shows a possible contribution of multifragmentation to the…
By studying the 109Xe-->105Te-->101Sn superallowed alpha-decay chain, we observe low-lying states in 101Sn, the one-neutron system outside doubly magic 100Sn. We find that the spins of the ground state (J = 7=2) and first excited state (J = 5=2) in 101Sn are reversed with respect to the traditional level ordering postulated for 103Sn and the heavier tin isotopes. Through simple arguments and state-of-the-art shell model calculations we explain this unexpected switch in terms of a transition from the single-particle regime to the collective mode in which orbital-dependent pairing correlations, …
The dipole polarizability of stable even-mass tin isotopes 112,114,116,118,120,124 was extracted from inelastic proton scattering experiments at 295 MeV under very forward angles performed at RCNP. Predictions from energy density functionals cannot account for the present data and the polarizability of 208Pb simultaneously. The evolution of the polarizabilities in neighboring isotopes indicates a kink at 120Sn while all model results show a nearly linear increase with mass number after inclusion of pairing corrections.
Neutrinoless double beta decay is a lepton-number violating process predicted by many extensions of the standard model. It is actively searched for in several candidate isotopes within many experimental projects. The status of the experimental initiatives which are looking for the neutrinoless double beta decay in isotopes other than Xe-136 is reviewed, with special emphasis given to the projects that passed the R&D phase. The results recently released by the experiment GERDA are also summarized and discussed. The GERDA data give no positive indication of neutrinoless double beta decay of Ge-7…
It is important to identify and reduce the gamma radiation which can be a significant source of background for any double beta decay experiment. The TIN.TIN detector array, which is under development for the search of Neutrinoless Double Beta Decay in $^{124}$Sn, has the potential to utilize the hit multiplicity information to discriminate the gamma background from the events of interest. Monte Carlo simulations for optimizing the design of a Tin detector module has been performed by varying element sizes with an emphasis on the gamma background reduction capabilities of the detector array.
We link the structure of nuclei around $^{100}$Sn, the heaviest doubly magic nucleus with equal neutron and proton numbers ($N=Z=50$), to nucleon-nucleon ($NN$) and three-nucleon ($NNN$) forces constrained by data of few-nucleon systems. Our results indicate that $^{100}$Sn is doubly magic, and we predict its quadrupole collectivity. We present precise computations of $^{101}$Sn based on three-particle--two-hole excitations of $^{100}$Sn, and reproduce the small splitting between the lowest $J^π=7/2^+$ and $5/2^+$ states. Our results are consistent with the sparse available data.
High-precision ab initio calculations of nuclear binding energies: Tin isotopes from dripline to dripline
Technische Universität Darmstadt（达姆施塔特工业大学）；ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH（GSI重离子研究中心极端物质研究所EMMI）；KU Leuven, Instituut voor Kern- en Stralingsfysica（荷语鲁汶大学核与辐射物理研究所）；Institut d’Astronomie et d’Astrophysique, Université Libre de Bruxelles（布鲁塞尔自由大学天体物理学与天文学研究所）；Brussels Laboratory of the Universe – BLU-ULB（布鲁塞尔宇宙实验室）；IRFU, CEA, Université Paris-Saclay（巴黎萨克雷大学CEA IRFU）；Max-Planck-Institut für Kernphysik（马克斯·普朗克核物理研究所）
A new experiment based on tin-loaded scintillator is proposed to measure the 2nu double beta decay half-life of Sn-124 for the first time. Measurements of long term stabilitiy and optical properties of the produced scintillator are presented. In addition a sophisticated estimation of the background due to cosmic ray spallation on tin has been performed. It is shown that such a measurement is feasible and can reach half-lives of 10^22 years, thus covering all current theoretical predictions for this decay mode.
We show in the Skyrme-Hartree-Fock approach that unambiguous correlations exist between observables of finite nuclei and nuclear matter properties. Using this correlation analysis to existing data on the neutron skin thickness of Sn isotopes, we find important constraints on the value E_{sym}(rho_0) and density slope L of the nuclear symmetry energy at saturation density. Combining these constraints with those from recent analyses of isospin diffusion and double neutron/proton ratio in heavy ion collisions leads to a value of L=58\pm 18 MeV approximately independent of E_{sym}(ρ_0).
The occupancies and vacancies of the valence neutron orbitals across the stable tin isotopic chain from $112\leq A\leq 124$ have been determined. These were inferred from the cross sections of neutron-adding and -removing reactions. In each case, the reactions were chosen to have good angular-momentum matching for transfer to the low- and high-$\ell$ orbitals present in this valence space. These new data are compared to older systematic studies. The effective single-neutron energies are determined by combining information from energy centroids determined from the adding and removing reactions.…
Chemical isotope effects of calcium were studied by liquid-liquid extraction using a crown ether of dicyclohexano-18-crown-6 for the purpose of finding a cost-effective and efficient way of enrichment of Ca-48 towards the study of the neutrinoless double beta decay of Ca-48. We evaluated each contribution ratio of the field shift effect and the hyperfine splitting shift effect to the mass effect of the calcium isotopes for the first time. The present preliminary result suggests the contribution of the field shift effect is small, especially for Ca-40-Ca-48 case, compared with the case of Chrom…
We report the first energy loss spectrum obtained with a geometrically metastable type I superconducting tin strip irradiated by the beta-emission of S-35. (Nucl. Instr. Meth. A, in press)
A large experimental program is being mounted to search for neutrinoless double-beta decay over the next decade. Multiple experiments using different target isotopes are being prepared to explore the whole parameter space allowed for inverted-ordered light neutrinos, and have the potential to make discoveries in several other scenarios, including normal-ordered light neutrinos and other exotic mechanisms. We investigate to what extent long-range and exotic short-range contributions may be distinguished by combining measurements of the decay half-life across isotopes. We demonstrate how measure…
An array of sixteen 1 cm^3 CdZnTe semiconductor detectors was operated at the Gran Sasso Underground Laboratory (LNGS) to further investigate the feasibility of double-beta decay searches with such devices. As one of the double-beta decay experiments with the highest granularity the 4 x 4 array accumulated an overall exposure of 18 kg days. The setup and performance of the array is described. Half-life limits for various double-beta decay modes of Cd, Zn and Te isotopes are obtained. No signal has been found, but several limits beyond 10^20 years have been performed. They are an order of magni…
NEMO 3 is a currently running experiment to search for the neutrinoless double beta decay and to study the two-neutrino double beta decay with 10kg of enriched isotopes. On the basis of the first two years of data taking, a limit on the neutrinoless decay $T_{1/2}^{0ν} > 5.8\cdot10^{23}$ y at 90% CL was obtained with $^{100}Mo$. The two-neutrino double beta decay half-lives were measured for all seven $ββ$ isotopes located in NEMO 3. New results are obtained for two of these isotopes: $^{48}Ca T_{1/2}^{2ν}=[4.4 ^{+0.5}_{-0.4} (stat) \pm 0.4 (syst)]\cdot10^{19}$ y, $^{96}Zr T_{1/2}^{2ν}=[2.3 \p…
A search for rare decays of gadolinium isotopes was performed with an ultra-low background high-purity germanium detector at Gran Sasso Underground Laboratory (Italy). A 198 g Gd$_2$O$_3$ powder sample was measured for 63.8 d with a total Gd exposure of 12.6 kg$\times$d. $^{152}$Gd is the most promising isotope for resonant neutrinoless double electron capture which could significantly enhance the decay rate over other neutrinoless double beta decay processes. The half-life for this decay was constrained to $>4.2\times10^{12}$ yr (90\% credibility). This limit is still orders of magnitude away…
Inelastic neutron scattering and reactions on Pb isotopes can result in gamma rays near the signature endpoint energy in a number of double-beta decay isotopes. In particular, there are gamma-ray transitions in Pb-206,207,208 that might produce energy deposits at the 76-Ge Q value in Ge detectors used for double-beta decay searches. The levels that produce these gamma rays can be excited by (n,n'gamma) or (n,xngamma) reactions, but the cross sections are small and previously unmeasured. This work uses the pulsed neutron beam at the Los Alamos Neutron Science Center to directly measure reaction…
The distribution of isoscalar monopole strength in the neutron-even 112-124Sn-isotopes has been computed using a relativistic random-phase-approximation approach. The accurately-calibrated model used here (``FSUGold'') has been successful in reproducing both ground-state observables as well as collective excitations - including the giant monopole resonance (GMR) in 90Zr, 144Sm, and 208Pb. Yet this same model significantly overestimates the GMR energies in the Sn isotopes. It is argued that the question of ``Why is Tin so soft?'' becomes an important challenge to the field and one that should b…
"Why are the tin isotopes soft?" has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, $^{90}$Zr and $^{208}$Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where--and how--the softness manifests itself between $^{90}$Zr and the cadmium and tin isotopes. Th…
Beta-decay properties of neutron-rich Ca isotopes have been obtained. Half-life values were determined for the first time for 54Ca [86(7) ms], 55Ca [22(2) ms], and 56Ca [11(2) ms]. The half-life of 230(6) ms deduced for 53Ca is significantly longer than reported previously, where the decay chain 53K -> 53Ca -> 53Sc was considered. A delayed gamma ray with energy 247 keV as identified following beta decay of 54Ca, and is proposed to depopulate the first 1+ level in 54Sc. The beta-decay properties compare favorably with the results of shell model calculations completed in the full pf-space with …
Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, radioactive contamination were studied with neodymium doped yttrium-aluminum garnet (YAG:Nd). Applicability of YAG:Nd scintillators to search for double beta decay and alpha activity of natural neodymium isotopes are discussed.
Various double beta decay modes of Cd, Zn and Te isotopes are explored with the help of CdTe and CdZnTe semiconductor detectors. The data set is splitted in an energy range below 1 MeV having a statistics of 134.5 g$\cdot$d and one above 1 MeV resulting in 532 g$\cdot$d. No signals were observed in all channels under investigation. New improved limits for the neutrinoless double beta decay of Zn70 of $T_{1/2} > 1.3 \cdot 10^{16} yrs$ (90% CL), the longest standing limit of all double beta isotopes, and 0$νβ^+$EC of Te120 of $T_{1/2} > 2.2 \cdot 10^{16} yrs$ (90% CL) are given. For the first ti…
New generation experiments on search for neutrinoless double beta decay with sensitivity to effective Majorana neutrino mass on the level $\sim$ 3-5 meV is discussed. Possible restrictions at achievement of this purpose (possibility to produce big amount of enriched isotopes, possibility to reach very low background level, energy resolution and possible cost of experiments) are considered. It is shown that for realization of so ambitious project 10 tons (or more) of enriched isotope is required. Background index should be on the level $\le$ 10$^{-5}-10^{-6}$ c/kg$\cdot$ keV$\cdot$ y. Besides, …
Direct reaction techniques are powerful tools to study the single-particle nature of nuclei. Performing direct reactions on short-lived nuclei requires radioactive ion beams produced either via fragmentation or the Isotope Separation OnLine (ISOL) method. Some of the most interesting regions to study with direct reactions are close to the magic numbers where changes in shell structure can be tracked. These changes can impact the final abundances of explosive nucleosynthesis. The structure of the chain of tin isotopes is strongly influenced by the Z=50 proton shell closure, as well as the neutr…
The results of the experimental investigations of double beta processes in Zinc and Tungsten isotopes with the help of middle volume (117 g, 168 g and 699 g) low-background ZnWO_4 crystal scintillators are presented. The experiment was carried out in the low-background "DAMA/R&D" set-up at the Gran Sasso National Laboratories of the INFN (Italy) at a depth of \approx3600 m w.e. The total measurement time exceeds ten thousand hours. New improved half-life limits on double electron capture and electron capture with positron emission in ^{64}Zn have been set: T^{2ν2K}_{1/2}(^{64}Zn) \geq 6.2(6.3)…
Detector DEVIS is TPC in the magnetic field. It is dedicated to the investigation of the double-beta decay of Xe. Setup sensitivity was estimated in the series of measurements with Xe with natural isotopes composition. Detector allows measuring two-neutrino double-beta decay of $^{136}$Xe with half-life less than $3 \cdot 10^{20}$ years.
Recent network calculations suggest that a high temperature rp-process could explain the abundances of light Mo and Ru isotopes, which have long challenged models of p-process nuclide production. Important ingredients to network calculations involving unstable nuclei near and at the proton drip line are $β$-halflives and decay modes, i.e., whether or not $β$-delayed proton decay takes place. Of particular importance to these network calculation are the proton-rich isotopes $^{96}$Ag, $^{98}$Ag, $^{96}$Cd and $^{98}$Cd. We report on recent measurements of $β$-delayed proton branching ratios for…
We study for the first time the internal structure of 140Te through the beta-delayed gamma-ray spectroscopy of 140Sb. The very neutron-rich 140Sb, Z = 51 and N = 89, ions were produced by the in-flight fission of 238U beam on a 9Be target at 345 MeV per nucleon at the Radioactive Ion Beam Factory, RIKEN. The half-life and spin-parity of 140Sb are reported as 124(30) ms and (4-), respectively. In addition to the excited states of 140Te produced by the beta-decay branch, the beta-delayed one-neutron and two-neutron emission branches were also established. By identifying the first 2+ and 4+ excit…
In this paper we present the first high-resolution laser spectroscopy results obtained at the GISELE laser laboratory of the GANIL-SPIRAL2 facility, in preparation for the first experiments with the S$^3$-Low Energy Branch. Studies of neutron-deficient radioactive isotopes of erbium and tin represent the first physics cases to be studied at S$^3$. The measured isotope-shift and hyperfine structure data are presented for stable isotopes of these elements. The erbium isotopes were studied using the $4f^{12}6s^2$ $^3H_6 \rightarrow 4f^{12}(^3 H)6s6p$ $J = 5$ atomic transition (415 nm) and the tin…
Cadmium tungstate crystal scintillators enriched in 106Cd and 116Cd were developed. The produced scintillators exhibit good optical and scintillation properties, and a low level of radioactive contamination. Experiments to search for double beta decay of 106Cd and 116Cd are in progress at the Gran Sasso National Laboratories of the INFN (Italy). Prospects to further improve the radiopurity of the detectors by recrystallization are discussed.
We calculate nuclear matrix elements (NME) of neutrinoless double beta decay in four different candidate nuclei (Ge-76, Se-82, Mo-100, Te-130) within the quasiparticle random phase approximation (QRPA) and its uncertainties. We assume (up to) four coexisting mechanisms for neutrinoless double beta decay, mediated by light Majorana neutrino exchange, heavy Majorana neutrino exchange, R-parity breaking supersymmetry, and squark-neutrino, interfering either constructively or destructively with each other. We find that, unfortunately, current NME uncertainties appear to prevent a robust determinat…
We present a generator-coordinate calculation, based on a relativistic energy-density functional, of the low-lying spectra in the isotopes $^{150}$Nd and $^{150}$Sm and of the nuclear matrix element that governs the neutrinoless double-beta decay of the first isotope to the second. We carefully examine the impact of octupole correlations on both nuclear structure and the double-beta decay matrix element. Octupole correlations turn out to reduce quadrupole collectivity in both nuclei. Shape fluctuations, however, dilute the effects of octupole deformation on the double-beta decay matrix element…
Four 1cm^3 CdZnTe semiconductor detectors were operated in the Gran Sasso National Laboratory to explore the feasibility of such devices for double beta decay searches as proposed for the COBRA experiment. The research involved background studies accompanied by measurements of energy resolution performed at the surface. Energy resolutions sufficient to reduce the contribution of two-neutrino double beta decay events to a negligible level for a large scale experiment have already been achieved and further improvements are expected. Using activity measurements of contaminants in all construction…
The ``breathing mode'' of neutron-rich nuclei is our window into the incompressibility of neutron-rich matter. After much confusion on the interpretation of the experimental data, consistency was finally reached between different models that predicted both the distribution of isoscalar monopole strength in finite nuclei and the compression modulus of infinite matter. However, a very recent experiment on the Tin isotopes at the Research Center for Nuclear Physics(RCNP) in Japan has again muddled the waters. Self-consistent models that were successful in reproducing the energy of the giant monop…
We investigate the effects of newly measured beta-decay half-lives on r-process nucleosynthesis. These new rates were determined by recent experiments at the radioactive isotope beam factory facility in the RIKEN Nishina Center. We adopt an r-process nucleosynthesis environment based on a magnetohydrodynamic supernova explosion model that includes strong magnetic fields and rapid rotation of the progenitor. A number of the new beta-decay rates are for nuclei on or near the r-process path, and hence they affect the nucleosynthesis yields and time scale of the r-process. The main effect of the n…
An attempt to study the feasibility of a new experiment to search for double beta decay in $^{112}$Sn and $^{124}$Sn was carried out by using ultra-low background HPGe detector (244 cm$^{3}$) inside the Gran Sasso National Laboratory (LNGS) of the INFN (Italy). A small sample of natural Sn was examined for 2367.5 h. The radioactive contamination of the sample has been estimated. The data has also been considered to calculate the present sensitivity for the proposed search; half-life limits $\sim$ $10^{17} - 10^{18}$ years for $β^{+}$EC and EC-EC processes in $^{112}$Sn and $\sim$ $10^{18}$ yea…
A measurement of neutrinoless double beta decay in one isotope does not allow to determine the underlying physics mechanism. We discuss the discrimination of mechanisms for neutrinoless double beta decay by comparing ratios of half life measurements for different isotopes. Six prominent examples for specific new physics contributions to neutrinoless double beta decay are analyzed. We find that the change in corresponding ratios of half lives varies from 60% for supersymmetric models up to a factor of 5-20 for extra-dimensional and left-right-symmetric mechanisms.
The neutron-rich isotopes 65,67Fe and 65Co have been produced at the LISOL facility, Louvain-La-Neuve, in the proton-induced fission of 238U. Beams of these isotopes have been extracted with high selectivity by means of resonant laser ionization combined with mass separation. Yrast and near-yrast levels of 65Co have also been populated in the 64Ni+238U reaction at Argonne National Laboratory. The level structure of 65Co could be investigated by combining all the information from both the 65Fe and 65Co beta decay and the deep-inelastic reaction. The 65Fe, 65Co and 67Fe decay schemes and the 65C…
Weak decays in superheavy nuclei with proton numbers Z = 118 - 120 and neutron numbers N = 175 - 184 are studied within a microscopic formalism based on deformed self-consistent Skyrme Hartree-Fock mean-field calculations with pairing correlations. The half-lives of beta+ decay and electron capture are compared with alpha-decay half-lives obtained from phenomenological formulas. The sensitivity of the half-lives to the unknown Q-energies is studied by comparing the results obtained from different approaches for the masses. It is shown that alpha-decay is always dominant in this mass region. Th…
Energy resolution, alpha/beta ratio, and the pulse shape discrimination ability of the ZnWO_4 crystal scintillators were studied. The radioactive contamination of a ZnWO_4 crystal was investigated in the Solotvina Underground Laboratory. Possibilities to apply ZnWO_4 crystals for the dark matter and double beta decay searches are discussed. New improved half-life limits on double beta decay in zinc isotopes were established, in particular, for ECβ^+ decay of 64-Zn as: T_1/2^2nu > 8.9 10^18 yr and T_1/2^0nu > 3.6 10^18 yr, both at 68% CL.
