共查询到20条相似文献,搜索用时 31 毫秒
1.
P. Belli R. Bernabei F. Cappella R. Cerulli F. A. Danevich A. Di Marco A. Incicchitti M. Laubenstein S. S. Nagorny S. Nisi O. G. Polischuk V. I. Tretyak 《The European Physical Journal A - Hadrons and Nuclei》2011,47(8):1-8
A search for double- $ \beta$ processes in 190Pt and 198Pt was realized with the help of ultra-low background HP Ge 468cm^3 $ \gamma$ spectrometer in the underground Gran Sasso National Laboratories of the INFN (Italy). After 1815 h of data taking with 42.5g platinum sample, T 1/2 limits on 2 $ \beta$ processes in 190Pt ( $ \varepsilon$ $ \beta^{+}_{}$ and 2 $ \varepsilon$ have been established on the level of 1014-1016y, 3 to 4 orders of magnitude higher than those known previously. In particular, a possible resonant double-electron capture in 190Pt was restricted on the level of 2.9×1016 y at 90% C.L. In addition, T 1/2 limit on 2 $ \beta^{-}_{}$ decay of 198Pt (2 $ \nu$ +0 $ \nu$ ) to the 2+ 1 excited level of 198Hg has been set at the first time: T 1/2 > 3.5×1018 y. The radiopurity level of the used platinum sample is reported. 相似文献
2.
D. Rodríguez G. Ban D. Durand F. Duval X. Fléchard E. Liénard F. Mauger A. Méry O. Naviliat-Cuncic J. -C. Thomas Ph. Velten 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):397-400
The LPCTrap setup at GANIL is fully operational since 2006. The first breakthrough was the detection of 100000 coincidences between the $ \beta$ particles and the recoil ions from the decay of 6He+ produced by the SPIRAL source. After preparation, the decaying nuclei are confined in a transparent Paul trap which is surrounded by a $ \beta$ -telescope made of a double-sided silicon strip detector followed by a scintillator, and by a micro-channel plate position-sensitive detector to record in coincidence the $ \beta$ particles and the recoil ions. Simulations of this system are needed in order to study possible systematic effects and extract with high accuracy the $ \beta$ - $ \nu$ angular-correlation coefficient. A code based on Geant4 is well suited for this purpose. In this contribution the results from the simulations compared with those from the experiment will be presented and discussed. 相似文献
3.
T. Nagatomo K. Shimada K. Asahi D. L. Balabanski J. M. Daugas M. Depuydt M. De Rydt L. Gaudefroy S. Grévy Y. Hasama Y. Ichikawa D. Kameda P. Morel L. Perrot C. St?del J. C. Thomas W. Vanderheijden N. Vermeulen P. Vingerhoets A. Yoshimi G. Neyens H. Ueno 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):383-385
The nuclear electric quadrupole moment (Q moment) of the neutron-rich nucleus 33Al (I = 5/2 , T 1/2 = 41 ms) has been measured by the $ \beta$ -ray detected nuclear quadrupole resonance ( $ \beta$ -NQR) method for the first time. The 33Al nucleus is considered to be on the border of the island of inversion within which a significant intrusion of the pf orbits occurs across the N = 20 shell gap and the intrusion causes an anomalous enhancement of the Q moment. Polarized 33Al nuclei were produced from 36S (77.5MeV/u beams through the fragmentation process and separated by LISE fragment separator at GANIL. The 33Al nuclei were implanted into a Al2O3 single-crystal plate and the $ \beta$ -NQR spectrum was successfully obtained. 相似文献
4.
W. H. Liang R. Molina E. Oset 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):479-486
We determine the radiative decay amplitudes for the decay into D* and $ \bar{{D}}$ $ \gamma$ , or D * s and $ \bar{{D}}_{s}^{}$ $ \gamma$ of some of the charmonium-like states classified as X , Y , Z resonances, plus some other hidden charm states which are dynamically generated from the interaction of vector mesons with charm. The mass distributions as a function of the $ \bar{{D}}$ $ \gamma$ or $ \bar{{D}}_{s}^{}$ $ \gamma$ invariant mass show a peculiar behavior as a consequence of the D * $ \bar{{D}}^{*}_{}$ nature of these states. The experimental search of these magnitudes can shed light on the nature of these states. 相似文献
5.
E. D. Johnson G. V. Rogachev V. Z. Goldberg S. Brown D. Robson A. M. Crisp P. D. Cottle C. Fu J. Giles B. W. Green K. W. Kemper K. Lee B. T. Roeder R. E. Tribble 《The European Physical Journal A - Hadrons and Nuclei》2009,42(2):135-139
The structure of the 18O nucleus at excitation energies above the $ \alpha$ decay threshold was studied using 14C + $ \alpha$ resonance elastic scattering. A number of states with large $ \alpha$ reduced widths have been observed, indicating that the $ \alpha$ -cluster degree of freedom plays an important role in this N $ \ne$ Z nucleus. A 0+ state with an $ \alpha$ reduced width exceeding the single-particle limit was identified at an excitation energy of 9.9±0.3 MeV. We discuss evidence that states of this kind are common in light nuclei and give possible explanations of this feature. 相似文献
6.
Charmonium rescattering effects in the M1 transition of $ \psi$ (2S) $ \rightarrow$ $ \gamma$ $ \eta_{c}^{}$ are investigated by modeling a $ \chi_{{cJ}}^{}$ or J/ $ \psi$ rescattering into a $ \eta_{c}^{}$ final state. The absorptive and dispersive part of the transition amplitudes for the rescattering loops of $ \eta$ $ \psi$ ( $ \gamma^{{\ast}}_{}$ ) and $ \gamma$ $ \chi$ ( $ \psi$ ) are separately evaluated. The numerical results show that the contribution from the $ \gamma$ $ \chi$ ( $ \psi$ ) rescattering process is negligible. Compared with the virtual D $ \bar{{D}}$ (D *) rescattering processes, the $ \eta$ $ \psi$ ( $ \gamma^{{\ast}}_{}$ ) process may be regarded as the next-leading order of the hadronic loop mechanism, which only offers the partial decay width of ~ 0.045 keV to the $ \psi$ (2S) $ \rightarrow$ $ \gamma$ $ \eta_{c}^{}$ . 相似文献
7.
M. -G. Porquet A. Astier Ts. Venkova I. Deloncle F. Azaiez A. Buta D. Curien O. Dorvaux G. Duchêne B. J. P. Gall F. Khalfallah I. Piqueras M. Rousseau M. Meyer N. Redon O. Stézowski R. Lucas A. Bogachev 《The European Physical Journal A - Hadrons and Nuclei》2009,40(2):131-141
The odd-odd 88 37Rb51 and 86 35Br51 nuclei have been produced as fission fragments in the fusion reaction 18O$ + $208Pb at 85MeV bombarding energy and studied with the Euroball IV array. Their high-spin level schemes have been built from the triple $ \gamma$ -ray coincidence data and $ \gamma$ - $ \gamma$ angular correlations have been analyzed in order to assign spin and parity values to many observed states. The proposed configurations involve proton excitations from three sub-shells located close to the Fermi levels, $ \pi$ p 3/2 , $ \pi$ f 5/2 , and $ \pi$ g 9/2 , the $ \nu$ d 5/2 neutron acting as a spectator. The residual $ \pi$ $ \nu$ interactions are extracted from the multiplets of states resulting from the $ \pi$ p 3/2 $ \nu$ d 5/2 and $ \pi$ f 5/2 $ \nu$ d 5/2 configurations. The empirical values of the latter are discussed and compared to those known in two similar configurations having j p = j n with l p = l n + 1 , where the role of the tensor force had been highlighted. 相似文献
8.
M. Abdel-Bary S. Abdel-Samad K. -Th. Brinkmann H. Clement J. Dietrich E. Doroshkevich S. Dshemuchadse K. Ehrhardt A. Erhardt W. Eyrich A. Filippi H. Freiesleben M. Fritsch W. Gast A. Gillitzer J. Gottwald H. J?ger B. Jakob R. J?kel L. Karsch K. Kilian H. Koch M. Krapp J. Kre? E. Kuhlmann A. Lehmann S. Marcello S. Mauro P. Michel K. Móller H. P. Morsch L. Naumann N. Paul C. Pizzolotto Ch. Plettner S. Reimann M. Richter J. Ritman E. Roderburg A. Schamlott P. Sch?nmeier W. Schroeder M. Schulte-Wissermann T. Sefzick M. Steinke G. Y. Sun A. Teufel W. Ullrich G. J. Wagner M. Wagner R. Wenzel A. Wilms P. Wintz P. Wüstner P. Zupranski 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):7-22
9.
In order to understand the structure of the X(3872) the effects of the ${{\rm c\overline{c}}}$ charmonium core state coupling to the ${D^0\overline{D}^{*0}}$ and D + D *? molecule states are studied. The obtained structure of the X(3872) is about 9 % of ${{\rm c}\overline{{\rm c}}}$ charmonium, 75 % of the isoscalar ${D\overline{D}}$ molecule and 16 % of the isovector ${D\overline{D}}$ molecule which explains observed properties of the X(3872) well. 相似文献
10.
Kenichi Yoshida 《The European Physical Journal A - Hadrons and Nuclei》2009,42(3):583-590
Low-frequency modes of excitation in deformed neutron-rich nuclei are studied by means of the quasiparticle random-phase approximation on the Skyrme-Hartree-Fock-Bogoliubov mean field. We investigate the microscopic structure of the soft $\ensuremath K^{\pi} = 0^{+}$ modes systematically in neutron-rich magnesium isotopes with N = 22, 24, 26 and 28 close to the drip line, and it is found that the strong collectivity in 34Mg and 40Mg is acquired due to the coherent coupling between the $ \beta$ vibration and the pairing vibration of neutrons. Microscopic structure of the $\ensuremath K^{\pi} = 2^{+}$ modes changes gradually associated with the location of the Fermi level of neutrons, and it is found that the proton particle-hole excitation generating the $ \gamma$ -vibrational mode in 24Mg continues to play a key role in the near-drip-line nucleus 40Mg . The low-frequency octupole excitations are also investigated and the microscopic mechanism for the enhancement of transition strengths is discussed. 相似文献
11.
H. Watanabe G. J. Lane G. D. Dracoulis A. P. Byrne P. Nieminen F. G. Kondev K. Ogawa M. P. Carpenter R. V. F. Janssens T. Lauritsen D. Seweryniak S. Zhu P. Chowdhury 《The European Physical Journal A - Hadrons and Nuclei》2009,42(2):163-169
The nucleus $\ensuremath {\rm ^{127}Sb}$ , which is on the neutron-rich periphery of the $\ensuremath \beta$ -stability region, has been populated in complex nuclear reactions involving deep-inelastic and fusion-fission processes with $\ensuremath {\rm {}^{136}Xe}$ beams incident on thick targets. The previously known isomer at 2325 keV in $\ensuremath {\rm {}^{127}Sb}$ has been assigned spin and parity $\ensuremath 23/2^+$ , based on the measured $\ensuremath \gamma$ - $\ensuremath \gamma$ angular correlations and total internal conversion coefficients. The half-life has been determined to be 234(12) ns, somewhat longer than the value reported previously. The 2194 keV state has been assigned $\ensuremath J^{\pi} = 19/2^+$ and identified as an isomer with $\ensuremath T_{1/2} = 14(1) {\rm ns}$ , decaying by two $\ensuremath E2$ branches. The observed level energies and transition strengths are compared with the predictions of a shell model calculation. Two $\ensuremath 15/2^+$ states have been identified close in energy, and their properties are discussed in terms of mixing between vibrational and three-quasiparticle configurations. 相似文献
12.
In the X (3872) decay, both of the ${{J/{\psi\pi\pi}}}$ and ${{J/{\psi\pi\pi\pi}}}$ branching fractions are observed experimentally, and their sizes are comparable to each other. In order to clarify the mechanism to cause such a large isospin violation, we investigate X(3872) employing a model of coupled-channel two-meson scattering with a ${{\rm c}\bar{c}}$ core. The two-meson states consist of ${{D^0\overline{D}^{*0}}}$ , D + D *?, ${{J/{\psi\rho}}}$ , and ${{J/{\psi\omega}}}$ . The effects of the ρ and ω meson width are also taken into account. We calculate the transfer strength from the ${{{\rm c}\bar{c}}}$ core to the final two-meson states. It is found that very narrow ${{J/{\psi\rho}}}$ and ${{J/{\psi\omega}}}$ peaks appear very close to the ${{D^0\overline{D}^{*0}}}$ threshold for a wide range of variation in the parameter sets. The size of the ${{J/{\psi\rho}}}$ peak is almost the same as that of ${{J/{\psi\omega}}}$ , which is consistent with the experiments. The large width of the ρ meson makes the originally small isospin violation by about five times larger. 相似文献
13.
We investigate hadronic molecule states of $K \bar K N$ and $\bar K \bar K N$ systems with I?=?1/2 and J P ?=?1/2?+?, assuming that Λ(1405) and the scalar mesons, f 0(980), a 0(980), are reproduced as quasi-bound states of $\bar KN$ and $K \bar K$ . Performing non-relativistic three-body calculations for these systems, we find weakly bound states for $K \bar K N$ and $\bar K \bar K N$ around 1900 MeV, which correspond to new baryon resonances of N * and Ξ * with J P ?=?1/2?+?. We find that these resonances have cluster structure of the two-body bound state keeping its properties as in the isolated two-particle system. 相似文献
14.
The half-life of the mirror $\beta$ decay of 31S has been measured at the IGISOL facility at the University of Jyv?skyl?. The value obtained is $T_{1/2}(^{31}S)=(2553.4\pm 1.8)$ ms, in agreement with previous measurements, but with a precision that is better by a factor of ten than the literature value previously adopted. When the new result is combined with the QEC value measured recently at JYFLTRAP, a precision of better than $10^{-3}$ is obtained for the ft value. 相似文献
15.
Zhi-Gang Wang 《The European Physical Journal A - Hadrons and Nuclei》2010,44(1):105-117
In this article, we study the vertexes $ \Xi_{Q}^{*}$ ′Q V and $ \Sigma_{Q}^{*}$ $ \Sigma_{Q}^{}$ V with the light-cone QCD sum rules, then assume the vector meson dominance of the intermediate $ \phi$ (1020) , $ \rho$ (770) and $ \omega$ (782) , and calculate the radiative decays $ \Xi_{Q}^{*}$ $ \rightarrow$ ′Q $ \gamma$ and $ \Sigma_{Q}^{*}$ $ \rightarrow$ $ \Sigma_{Q}^{}$ $ \gamma$ . 相似文献
16.
F. P. He?berger S. Antalic B. Sulignano D. Ackermann S. Heinz S. Hofmann B. Kindler J. Khuyagbaatar I. Kojouharov P. Kuusiniemi M. Leino B. Lommel R. Mann K. Nishio A. G. Popeko ?. ?áro B. Streicher J. Uusitalo M. Venhart A. V. Yeremin 《The European Physical Journal A - Hadrons and Nuclei》2010,43(1):55-66
A detailed $ \gamma$ spectroscopic decay study of two K isomers in 254No was performed. In addition to the previously reported $ \gamma$ lines two new transitions of E = 778 , 856keV could be attributed to the decay pattern of 254m1No ( T 1/2 = 275±7 ms). The population of an excited band built up on this isomer ( $\ensuremath K^{\pi} =8^{-}$ by the decay of 254m2No ( T 1/2 = 198±13 μs) could be proven by measuring delayed $ \gamma$ - $ \gamma$ coincidences between transitions stemming from the decay of both isomeric states. The energies of the band members could be established up to $\ensuremath I^{\pi} = 15^{-}$ . A spontaneous fission branch of (2.0±1.2)×10-4 was measured for 254m1No , an upper limit of $ \le$ 1.2×10-4 was estimated for 254m2No . These values demonstrate the high stability of multi-quasiparticle configurations against spontaneous fission. Evidence for an $ \alpha$ decay branch of 254m1No in the order of 1×10-4 was found. 相似文献
17.
N. N. Achasov A. A. Kozhevnikov 《The European Physical Journal A - Hadrons and Nuclei》2008,38(1):61-69
Based on the generalized hidden local symmetry as the chiral model of pseudoscalar, vector, and axial vector mesons, the excitation curve of the reaction e + e - → $ \pi^{+}_{}$ $ \pi^{-}_{}$ $ \pi^{+}_{}$ $ \pi^{-}_{}$ is calculated for energies in the interval 0.65 ? $ \sqrt{{s}}$ ? 1 GeV. The theoretical predictions are compared to available data of CMD-2 and BaBaR. It is shown that the inclusion of heavy isovector resonances ρ(1450) and ρ(1700) is necessary for reconciling calculations with the data. It is found that at $ \sqrt{{s}}$ ≈ 1 GeV the contributions of the above resonances are much larger, by a factor of 30, than the ρ(770) one, and amount to a considerable fraction ~ 0.3-0.6 of the latter at $ \sqrt{{s}}$ ~ m ρ . 相似文献
18.
G. Bendiscioli T. Bressani L. Lavezzi P. Salvini 《The European Physical Journal A - Hadrons and Nuclei》2009,40(1):11-22
The presence of a narrow peak in the $ \Lambda$ p invariant-mass distribution observed in the $ \bar{{p}}$ annihilation reaction at rest $\ensuremath \bar{p} {}^4\mathrm{He}\rightarrow p\pi^-p\pi^+\pi^-n X$ is discussed again through an analysis procedure which improves the ratio signal/background in comparison with the previous analysis. The peak is centred at 2223.2±3.2stat±1.2syst MeV and has a statistical significance of 4.7 $ \sigma$ , values compatible with those published previously. If interpreted as the result of the decay into $ \Lambda$ p of a $\ensuremath { }_{\bar{K}}{}^2\mathrm{H}$ bound system, the corresponding binding energy should be B = - 151.0±3.2stat±1.2syst MeV and the width $ \Gamma_{{FWHM}}^{}$ < 33.9±6.2 MeV. The production rate has a lower limit of 1.2 10-4. Data on the $ \bar{{p}}$ annihilation reaction at rest $ \bar{{p}}$ 4He $ \rightarrow$ p $ \pi^{-}_{}$ p $ \pi^{-}_{}$ p s X , analyzed for the first time, lead to a result in qualitative agreement with the previous one. 相似文献
19.
Zhi-Gang Wang 《The European Physical Journal C - Particles and Fields》2010,68(3-4):479-486
In this article, we study the masses and pole residues of the ${1\over2}^{\pm}$ flavor antitriplet heavy baryon states ( $\varLambda _{c}^{+}$ , $\varXi _{c}^{+},\varXi _{c}^{0})$ and ( $\varLambda _{b}^{0}$ , $\varXi _{b}^{0},\varXi _{b}^{-})$ by subtracting the contributions from the corresponding ${1\over2}^{\mp}$ heavy baryon states with the QCD sum rules, and observe that the masses are in good agreement with the experimental data and make reasonable predictions for the unobserved ${1\over2}^{-}$ bottom baryon states. Once reasonable values of the pole residues λ Λ and λ Ξ are obtained, we can take them as basic parameters to study the relevant hadronic processes with the QCD sum rules. 相似文献
20.
T. Fukuchi T. Hori T. Masue K. Tajiri A. Sato T. Furukawa A. Odahara T. Shimoda Y. Wakabayashi Y. Gono T. Suzuki M. Ukai T. Wakui A. Yamazaki Y. Miyashita N. Sato M. Tateoka M. Ohguma T. Shinozuka T. Koike K. Shirotori Y. Miura S. Kinoshita Y. Ma Y. Y. Fu H. Tamura 《The European Physical Journal A - Hadrons and Nuclei》2009,39(1):49-51
The high-spin isomer in 151Er ( E x = 10.3 MeV, T 1/2 = 420 ns) has been studied by the 116Sn ( 40Ar , 5n) 151Er reaction at 197MeV. From the $ \gamma \gamma$ coincidence relations, a new transition with an energy of 1514keV was found. This finding requires the revision of the spin-parity assignment from previous 67/2- to 61/2+ or 65/2- . The 61/2+ assignment is the one which was predicted by the deformed independent particle model as an isomer with a large oblate deformation ( $ \beta$ = - 0.17) of the $\ensuremath[\nu(f_{7/2}h_{9/2} i_{13/2}) \pi(h^4_{11/2})]_{61/2^+}$ configuration. The isomerism may be attributed to the sudden shape change of the isomer from the nearly spherical shape of the lower-spin yrast states to the oblate shape. 相似文献