Mass measurements near the rr-process path using the Canadian Penning Trap mass spectrometer

The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.Comment: 15 pages, 16 figures. v2 updated, published in Physical Review

Double-beta decay Q values of 130Te, 128Te, and 120Te

The double-beta decay Q values of 130Te, 128Te, and 120Te have been determined from parent-daughter mass differences measured with the Canadian Penning Trap mass spectrometer. The 132Xe-129Xe mass difference, which is precisely known, was also determined to confirm the accuracy of these results. The 130Te Q value was found to be 2527.01(32) keV which is 3.3 keV lower than the 2003 Atomic Mass Evaluation recommended value, but in agreement with the most precise previous measurement. The uncertainty has been reduced by a factor of 6 and is now significantly smaller than the resolution achieved or foreseen in experimental searches for neutrinoless double-beta decay. The 128Te and 120Te Q values were found to be 865.87(131) keV and 1714.81(125) keV, respectively. For 120Te, this reduction in uncertainty of nearly a factor of 8 opens up the possibility of using this isotope for sensitive searches for neutrinoless double-electron capture and electron capture with positron emission.Comment: 5 pages, 2 figures, submitted to Physical Review Letter

Studies of neutron-rich nuclei using the CPT mass spectrometer at CARIBU

The nucleosynthetic path of the astrophysical r-process and the resulting elemental abundances depend on neutron-separation energies which can be determined from the masses of the nuclei along the r-process reaction path. Due to the current lack of experimental data, mass models are often used. The mass values provided by the mass models are often too imprecise or disagree with each other. Therefore, direct high-precision mass measurements of neutron-rich nuclei are necessary to provide input parameters to the calculations and help refine the mass models. The Californium Rare Isotope Breeder Upgrade (CARIBU) facility of Argonne National Laboratory will provide experiments with beams of short-lived neutron-rich nuclei. The Canadian Penning Trap (CPT) mass spectrometer has been relocated to the CARIBU low-energy beam line to extend measurements of the neutron-rich nuclei into the mostly unexplored region along the r-process path. This will allow precise mass measurements (∼ 10 keV/c2) of more than a hundred very neutron-rich isotopes that have not previously been measured

β-delayed neutron spectroscopy using trapped radioactive ions

A novel technique for β-delayed neutron spectroscopy has been demonstrated using trapped ions. The neutron-energy spectrum is reconstructed by measuring the time of flight of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection, such as backgrounds from scattered neutrons and γ rays and complicated detector-response functions. I+137 ions delivered from a Cf252 source were confined in a linear Paul trap surrounded by radiation detectors, and the β-delayed neutron-energy spectrum and branching ratio were determined by detecting the β- and recoil ions in coincidence. Systematic effects were explored by determining the branching ratio three ways. Improvements to achieve higher detection efficiency, better energy resolution, and a lower neutron-energy threshold are proposed. © 2013 American Physical Society

Tensor interaction limit derived from the α-β-ν̄ correlation in trapped Li8 ions

A measurement of the α-β-ν̄ angular correlation in the Gamow-Teller decay Li8→Be*8+ν̄+β, Be*8→ α+α has been performed using ions confined in a linear Paul trap surrounded by silicon detectors. The energy difference spectrum of the α particles emitted along and opposite the direction of the β particle is consistent with the standard model prediction and places a limit of 3.1% (95.5% confidence level) on any tensor contribution to the decay. From this result, the amplitude of any tensor component CT relative to that of the dominant axial-vector component CA of the electroweak interaction is limited to |CT/CA|\u3c0.18 (95.5% confidence level). This experimental approach is facilitated by several favorable features of the Li8 β decay and has different systematic effects than the previous β-ν̄ correlation results for a pure Gamow-Teller transition obtained from studying He6 β decay. © 2013 American Physical Society

Limit on Tensor Currents from Li 8 β Decay

In the standard model, the weak interaction is formulated with a purely vector-axial-vector (V-A) structure. Without restriction on the chirality of the neutrino, the most general limits on tensor currents from nuclear β decay are dominated by a single measurement of the β-ν¯ correlation in He6 β decay dating back over a half century. In the present work, the β-ν¯-α correlation in the β decay of Li8 and subsequent α-particle breakup of the Be8∗ daughter was measured. The results are consistent with a purely V-A interaction and in the case of couplings to right-handed neutrinos (CT=-CT′) limits the tensor fraction to |CT/CA|2\u3c0.011 (95.5% C.L.). The measurement confirms the He6 result using a different nuclear system and employing modern ion-trapping techniques subject to different systematic uncertainties

Carbonic anhydrase activation is associated with worsened pathological remodeling in human ischemic diabetic cardiomyopathy.

BACKGROUND: Diabetes mellitus (DM) has multifactorial detrimental effects on myocardial tissue. Recently, carbonic anhydrases (CAs) have been shown to play a major role in diabetic microangiopathy but their role in the diabetic cardiomyopathy is still unknown. METHODS AND RESULTS: We obtained left ventricular samples from patients with DM type 2 (DM-T2) and nondiabetic (NDM) patients with postinfarct heart failure who were undergoing surgical coronary revascularization. Myocardial levels of CA-I and CA-II were 6- and 11-fold higher, respectively, in DM-T2 versus NDM patients. Elevated CA-I expression was mainly localized in the cardiac interstitium and endothelial cells. CA-I induced by high glucose levels hampers endothelial cell permeability and determines endothelial cell apoptosis in vitro. Accordingly, capillary density was significantly lower in the DM-T2 myocardial samples (mean±SE=2152±146 versus 4545±211/mm(2)). On the other hand, CA-II was mainly upregulated in cardiomyocytes. The latter was associated with sodium-hydrogen exchanger-1 hyperphosphorylation, exaggerated myocyte hypertrophy (cross-sectional area 565±34 versus 412±27 μm(2)), and apoptotic death (830±54 versus 470±34 per 10(6) myocytes) in DM-T2 versus NDM patients. CA-II is activated by high glucose levels and directly induces cardiomyocyte hypertrophy and death in vitro, which are prevented by sodium-hydrogen exchanger-1 inhibition. CA-II was shown to be a direct target for repression by microRNA-23b, which was downregulated in myocardial samples from DM-T2 patients. MicroRNA-23b is regulated by p38 mitogen-activated protein kinase, and it modulates high-glucose CA-II-dependent effects on cardiomyocyte survival in vitro. CONCLUSIONS: Myocardial CA activation is significantly elevated in human diabetic ischemic cardiomyopathy. These data may open new avenues for targeted treatment of diabetic heart failure