462 research outputs found

    Isomeric states close to doubly magic 132^{132}Sn studied with JYFLTRAP

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    The double Penning trap mass spectrometer JYFLTRAP has been employed to measure masses and excitation energies for 11/2−11/2^- isomers in 121^{121}Cd, 123^{123}Cd, 125^{125}Cd and 133^{133}Te, for 1/2−1/2^- isomers in 129^{129}In and 131^{131}In, and for 7−7^- isomers in 130^{130}Sn and 134^{134}Sb. These first direct mass measurements of the Cd and In isomers reveal deviations to the excitation energies based on results from beta-decay experiments and yield new information on neutron- and proton-hole states close to 132^{132}Sn. A new excitation energy of 144(4) keV has been determined for 123^{123}Cdm^m. A good agreement with the precisely known excitation energies of 121^{121}Cdm^m, 130^{130}Snm^m, and 134^{134}Sbm^m has been found.Comment: 10 pages, 6 figures, submitted to Phys. Rev.

    Measurement of parity-nonconserving rotation of neutron spin in the 0.734-eV p-wave resonance of 139La^{139}La

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    The parity nonconserving spin rotation of neutrons in the 0.734-eV p-wave resonance of 139La^{139}La was measured with the neutron transmission method. Two optically polarized 3He^3He cells were used before and behind a a 5-cm long 139La^{139}La target as a polarizer and an analyzer of neutron spin. The rotation angle was carefully measured by flipping the direction of 3He^3He polarization in the polarizer in sequence. The peak-to-peak value of the spin rotation was found to be (7.4±1.1)×10−3 (7.4 \pm 1.1) \times 10^{-3} rad/cm which was consistent with the previous experiments. But the result was statisticallly improved. The s-p mixing model gives the weak matrix element as xW=(1.71±0.25)xW = (1.71 \pm 0.25) meV. The value agrees well with the one deduced from the parity-nonconserving longitudinal asymmetry in the same resonance

    Q_EC values of the Superallowed beta-Emitters 10-C, 34-Ar, 38-Ca and 46-V

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    The Q_EC values of the superallowed beta+ emitters 10-C, 34-Ar, 38-Ca and 46-V have been measured with a Penning-trap mass spectrometer to be 3648.12(8), 6061.83(8), 6612.12(7) and 7052.44(10) keV, respectively. All four values are substantially improved in precision over previous results.Comment: 9 pages, 7 figures, 5 table

    Electron-capture branch of 100Tc and tests of nuclear wave functions for double-beta decays

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    We present a measurement of the electron-capture branch of 100^{100}Tc. Our value, B(EC)=(2.6±0.4)×10−5B(\text{EC}) = (2.6 \pm 0.4) \times 10^{-5}, implies that the 100^{100}Mo neutrino absorption cross section to the ground state of 100^{100}Tc is roughly one third larger than previously thought. Compared to previous measurements, our value of B(EC)B(\text{EC}) prevents a smaller disagreement with QRPA calculations relevant to double-ÎČ\beta decay matrix elements

    Precision mass measurements on neutron-rich rare-earth isotopes at JYFLTRAP - reduced neutron pairing and implications for the rr-process calculations

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    The rare-earth peak in the rr-process abundance pattern depends sensitively on both the astrophysical conditions and subtle changes in nuclear structure in the region. This work takes an important step elucidating the nuclear structure and reducing the uncertainties in rr-process calculations via precise atomic mass measurements at the JYFLTRAP double Penning trap. 158^{158}Nd, 160^{160}Pm, 162^{162}Sm, and 164−166^{164-166}Gd have been measured for the first time and the precisions for 156^{156}Nd, 158^{158}Pm, 162,163^{162,163}Eu, 163^{163}Gd, and 164^{164}Tb have been improved considerably. Nuclear structure has been probed via two-neutron separation energies S2nS_{2n} and neutron pairing energy metrics DnD_n. The data do not support the existence of a subshell closure at N=100N=100. Neutron pairing has been found to be weaker than predicted by theoretical mass models. The impact on the calculated rr-process abundances has been studied. Substantial changes resulting in a smoother abundance distribution and a better agreement with the solar rr-process abundances are observed.Comment: 8 pages, 4 figures, accepted for publication in Physical Review Letter

    Parity Violation in Neutron Resonances in 107,109Ag

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    Parity nonconservation (PNC) was studied in p-wave resonances in Ag by measuring the helicity dependence of the neutron total cross section. Transmission measurements on natural Ag were performed in the energy range 32 to 422 eV with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at Los Alamos National Laboratory. A total of 15 p-wave neutron resonances were studied in 107Ag and ninep-wave resonances in 109Ag. Statistically significant asymmetries were observed for eight resonances in 107Ag and for four resonances in109Ag. An analysis treating the PNC matrix elements as random variables yields a weak spreading width of Γw=(2.67-1.21+2.65)×10-7 eV for107Ag and Γw=(1.30-0.74+2.49)×10-7 eV for 109Ag

    Parity Violation in Neutron Resonances in 115In

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    Parity nonconservation (PNC) was studied in p-wave resonances in indium by measuring the helicity dependence of the neutron total cross section in the neutron energy range 6.0–316 eV with the time-of-flight method at LANSCE. A total of 36 p-wave neutron resonances were studied in 115In, and statistically significant asymmetries were observed for nine cases. An analysis treating the PNC matrix elements as random variables yields a weak matrix element of M=(0.67-0.12+0.16) meV and a weak spreading width of Γw=(1.30-0.43+0.76)×10-7 eV

    Theory of superconductor-insulator transition in single Josephson junctions

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    A non-band theory is developed to describe the superconductor-insulator (SI) transtition in resistively shunted, single Josephson junctions. The I−VI-V characteristic is formulated by a Landauer-like formula and evaluated by the path-integral transfer-matrix method. The result is consistent with the recent experiments at around 80 mKmK. However, the insulator phase shrinks with decreasing temperature indicating that the single Josephson junction becomes all superconducting at absolute zero temperature, as long as dissipation is present.Comment: 4 pages, 3 figure

    Assessing Cut-off Points of Eosinophils, Nasal Polyp, and Lund-Mackay Scores to Predict Surgery in Nasal Polyposis : A Real-World Study

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    Background: Developing tools to identify chronic rhinosinusitis with nasal polyps (CRSwNP) patients requiring surgical treatment would help clinicians treat patients more effectively. The aim of this retrospective cross-sectional study was to identify cut-off values for eosinophil percentage, nasal polyps (NP), and Lund-Mackay (LM) scores that may predict the need for surgical treatment in Finnish CRSwNP patients. Methods: Data of CRSwNP patients (N = 378) undergoing consultation for ESS in 2001-19 were used. Data was collected from patient records and Lund-Mackay scores were determined from sinus computed tomography scans. The percentage of eosinophils was microscopically evaluated from the polyp samples available (n = 81). Associations were analyzed by Mann Whitney U test, and cut-off values by the area under the receiver operating characteristic curve (AUROC). Results: ESS was performed to 293 (77.5%) of patients. Polyp eosinophilia was associated significantly with ESS (p = 0.001), whereas peripheral blood eosinophil count, LM- score and endoscopic NP- score were not (p > 0.05). AUROC values (95% CI) for detecting those needing ESS were for polyp eosinophilia 0.71 (0.60-0.83), p = 0.001, for LM score 0.59 (0.50-0.67), p = 0.054; for NP score 0.56 (0.48-0.64), p = 0.17, and for blood eosinophil count 0.68 (0.46-0.90), p = 0.08. With the threshold value of polyp eosinophilia (>25%), the sensitivity and specificity were optimal for detecting the group needing ESS from the group not undergoing ESS. The cut-off value of blood eosinophil count (>0.26 x 10(9)/L) had relatively good, yet statistically insignificant (underpowered), predictive potential. Moderate cut-off values were found for endoscopic LM score (>= 14/24) and NP score (>= 4/8). Conclusions: Polyp eosinophilia (>25%) predicted ESS among Finnish hospital-level CRSwNP patients. A future challenge would be to find less invasive and cost-effective clinical factors predicting uncontrolled CRSwNP.Peer reviewe
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