A PART OF GLUCOSYLCERAMIDE FORMED FROM EXOGENOUS LACTOSYLCERAMIDE IS NOT DEGRADED TO CERAMIDE BUT RE-CYCLED AND GLYCOSYLATED IN THE GOLGI APPARATUS

Abstract The subcellular fate of glucosylceramide (GlcCer) formed from exogenous lactosylceramide (LacCer) in rat liver is investigated. LacCer radiolabeled on different positions of the molecule was intravenously administered to rats as a liposomal dispersion. A Golgi apparatus fraction 140-fold enriched in specific markers and constituted by intact cisternal stacks, as well as the lysosomal and plasma membrane fractions concurrently prepared from the same homogenate, were then studied in order to determine the time course of radioactive glycosphingolipids. LacCer quickly decreased with time in the plasma membrane, whereas in the lysosomes it increased up to 4 h and decreased thereafter. In both fractions results were regardless of the labeling position. In the Golgi apparatus, LacCer increased up to 12 h and then decreased. In this fraction, the radioactivity values of [Glc-3H]LacCer were over twice those of [Gal-3H]LacCer. GlcCer was found only after [Glc-3H]LacCer administration. In the lysosomes, its time course provided a peak similar in shape but delayed in timing with respect to that of LacCer. Conversely, in the Golgi apparatus GlcCer was earlier formed, but earlier consumed, than LacCer. Gangliosides increased in the Golgi apparatus until 4 h and then decreased after 12 h, whereas in the plasma membrane they were progressively accumulated. In both fractions the amount of [Glc-3H]gangliosides was over twice that of [Gal-3H]gangliosides was over twice that of [Gal-3H]gangliosides. Since we demonstrated that the sugars released in the course of LacCer degradation (LacCer----galactose + GlcCer----glucose + ceramide) are not incorporated into glycoconjugates, we conclude that a part of GlcCer formed during the lysosomal degradation of LacCer actually reaches the Golgi apparatus where it undergoes successive glycosylation

Double-beta decay of 130^{130}Te to the first 0+^{+} excited state of 130^{130}Xe with CUORICINO

The CUORICINO experiment was an array of 62 TeO$_{2}$ single-crystal bolometers with a total $^{130}$Te mass of $11.3\,$kg. The experiment finished in 2008 after more than 3 years of active operating time. Searches for both $0\nu$ and $2\nu$ double-beta decay to the first excited $0^{+}$ state in $^{130}$Xe were performed by studying different coincidence scenarios. The analysis was based on data representing a total exposure of N($^{130}$Te)$\cdot$t=$9.5\times10^{25}\,$y. No evidence for a signal was found. The resulting lower limits on the half lives are $T^{2\nu}_{1/2}(^{130} Te\rightarrow^{130} Xe^{*})>1.3\times10^{23}\,$y (90% C.L.), and $T^{0\nu}_{1/2}(^{130} Te\rightarrow^{130} Xe^{*})>9.4\times10^{23}\,$y (90% C.L.).Comment: 6 pages, 4 figure

Search for 14.4 keV solar axions from M1 transition of Fe-57 with CUORE crystals

We report the results of a search for axions from the 14.4 keV M1 transition from Fe-57 in the core of the sun using the axio-electric effect in TeO2 bolometers. The detectors are 5x5x5 cm3 crystals operated at about 10 mK in a facility used to test bolometers for the CUORE experiment at the Laboratori Nazionali del Gran Sasso in Italy. An analysis of 43.65 kg d of data was made using a newly developed low energy trigger which was optimized to reduce the detectors energy threshold. An upper limit of 0.63 c kg-1 d-1 was established at 95% C.L.. From this value, a lower bound at 95% C.L. was placed on the Peccei-Quinn energy scale of fa >= 0.76 10**6 GeV for a value of S=0.55 for the flavor-singlet axial vector matrix element. Bounds are given for the interval 0.15 < S < 0.55.Comment: 14 pages, 6 figures, submitted to JCA

CUORE and beyond: bolometric techniques to explore inverted neutrino mass hierarchy

The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay of $^{130}$Te. With 741 kg of TeO$_2$ crystals and an excellent energy resolution of 5 keV (0.2%) at the region of interest, CUORE will be one of the most competitive neutrinoless double beta decay experiments on the horizon. With five years of live time, CUORE projected neutrinoless double beta decay half-life sensitivity is $1.6\times 10^{26}$ y at $1\sigma$ ($9.5\times10^{25}$ y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40--100 meV (50--130 meV). Further background rejection with auxiliary light detector can significantly improve the search sensitivity and competitiveness of bolometric detectors to fully explore the inverted neutrino mass hierarchy with $^{130}$Te and possibly other double beta decay candidate nuclei.Comment: Submitted to the Proceedings of TAUP 2013 Conferenc

Validation of techniques to mitigate copper surface contamination in CUORE

In this article we describe the background challenges for the CUORE experiment posed by surface contamination of inert detector materials such as copper, and present three techniques explored to mitigate these backgrounds. Using data from a dedicated test apparatus constructed to validate and compare these techniques we demonstrate that copper surface contamination levels better than 10E-07 - 10E-08 Bq/cm2 are achieved for 238U and 232Th. If these levels are reproduced in the final CUORE apparatus the projected 90% C.L. upper limit on the number of background counts in the region of interest is 0.02-0.03 counts/keV/kg/y depending on the adopted mitigation technique.Comment: 10 pages, 6 figures, 6 table

Exploring the Neutrinoless Double Beta Decay in the Inverted Neutrino Hierarchy with Bolometric Detectors

Neutrinoless double beta decay (0nubb) is one of the most sensitive probes for physics beyond the Standard Model, providing unique information on the nature of neutrinos. In this paper we review the status and outlook for bolometric 0nubb decay searches. We summarize recent advances in background suppression demonstrated using bolometers with simultaneous readout of heat and light signals. We simulate several configurations of a future CUORE-like bolometer array which would utilize these improvements and present the sensitivity reach of a hypothetical next-generation bolometric 0nubb experiment. We demonstrate that a bolometric experiment with the isotope mass of about 1 ton is capable of reaching the sensitivity to the effective Majorana neutrino mass (|mee|) of order 10-20 meV, thus completely exploring the so-called inverted neutrino mass hierarchy region. We highlight the main challenges and identify priorities for an R&D program addressing them.Comment: 22 pages, 15 figures, submitted to EPJ

The low energy spectrum of TeO2 bolometers: results and dark matter perspectives for the CUORE-0 and CUORE experiments

We collected 19.4 days of data from four 750 g TeO2 bolometers, and in three of them we were able to set the energy threshold around 3 keV using a new analysis technique. We found a background rate ranging from 25 cpd/keV/kg at 3 keV to 2 cpd/keV/kg at 25 keV, and a peak at 4.7 keV. The origin of this peak is presently unknown, but its presence is confirmed by a reanalysis of 62.7 kg.days of data from the finished CUORICINO experiment. Finally, we report the expected sensitivities of the CUORE0 (52 bolometers) and CUORE (988 bolometers) experiments to a WIMP annual modulation signal.Comment: 9 pages, 10 figure

Search for double-β decay of 130Te to the first 0+ excited state of 130Xe with the CUORICINO experiment bolometer array

The CUORICINO experiment was an array of 62 TeO2 single-crystal bolometers with a total 130Te mass of 11.3kg. The experiment finished in 2008 after more than 3 yr of active operating time. Searches for both 0ν and 2ν double-β decay to the first excited 0+ state in 130Xe were performed by studying different coincidence scenarios. The analysis was based on data representing a total exposure of N(130Te)⋅t=9.5×1025yr. No evidence for a signal was found. The resulting lower limits on the half-lives are T2ν12(130Te→130Xe∗)\u3e1.3×1023yr (90% C.L.), and T0ν12(130Te→130Xe∗)\u3e9.4×1023yr (90% CL)

First CUORE-0 Performance Results and Status of CUORE Experiment

The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay in 130 style= position: relative; tabindex= 0 id= MathJax-Element-1-Frame \u3e130Te. Observation of the process would unambiguously establish that neutrinos are Majorana particles as well as provide information about the absolute neutrino mass scale and mass hierarchy.The CUORE setup will consist of an array of 988 tellurium dioxide crystals (containing 206 kg of 130 style= position: relative; tabindex= 0 id= MathJax-Element-2-Frame \u3e130Te in total), operated as bolometers at a temperature of ∼ style= position: relative; tabindex= 0 id= MathJax-Element-3-Frame \u3e∼10 mK. The experiment is now under construction at the Gran Sasso National Laboratory in Italy. As a first step towards CUORE, a tower (CUORE-0) has been assembled and is taking data. Here a detailed description of the CUORE-0 tower and its performance is reported. The status of the CUORE experiment and its expected sensitivity will then be discussed