arXiv subjects

T. O'Donnell

Publications and source records attributed to T. O'Donnell.

65 records · Page 4Linked to original sources

arXiv2014

Initial performance of the CUORE-0 experiment

CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of ^{130}Te. We present the first data analysis with 7.1 kg y of total TeO_2 exposure focusing on background measurements and energy resolution. The background rates in the neutrinoless double-beta decay region of interest (2.47 to 2.57 MeV) and in the α background-dominated region (2.70 to 3.90 MeV) have been measured to be 0.071 \pm 0.011 and 0.019 \pm 0.002 counts/keV/kg/y, respectively. The latter result represents a factor of 6 improvement from a predecessor experiment, Cuoricino. The results verify our understanding of the background sources in CUORE-0, which is the basis of extrapolations to the full CUORE detector. The obtained energy resolution (full width at half maximum) in the region of interest is 5.7 keV. Based on the measured background rate and energy resolution in the region of interest, CUORE-0 half-life sensitivity is expected to surpass the observed lower bound of Cuoricino with one year of live time.

physics.ins-det↗

arXiv2014

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 $1σ$ ($9.5\times10^{25}$ 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.

physics.ins-det↗

arXiv2014

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.

nucl-ex↗

arXiv2014

CeLAND: search for a 4th light neutrino state with a 3 PBq 144Ce-144Pr electron antineutrino generator in KamLAND

The reactor neutrino and gallium anomalies can be tested with a 3-4 PBq (75-100 kCi scale) 144Ce-144Pr antineutrino beta-source deployed at the center or next to a large low-background liquid scintillator detector. The antineutrino generator will be produced by the Russian reprocessing plant PA Mayak as early as 2014, transported to Japan, and deployed in the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND) as early as 2015. KamLAND's 13 m diameter target volume provides a suitable environment to measure the energy and position dependence of the detected neutrino flux. A characteristic oscillation pattern would be visible for a baseline of about 10 m or less, providing a very clean signal of neutrino disappearance into a yet-unknown, sterile neutrino state. This will provide a comprehensive test of the electron dissaperance neutrino anomalies and could lead to the discovery of a 4th neutrino state for Delta_m^2 > 0.1 eV^2 and sin^2(2theta) > 0.05.

physics.ins-det↗

arXiv2013

Laboratory Studies on the Removal of Radon-Born Lead from KamLAND's Organic Liquid Scintillator

The removal of radioactivity from liquid scintillator has been studied in preparation of a low background phase of KamLAND. This paper describes the methods and techniques developed to measure and efficiently extract radon decay products from liquid scintillator. We report the radio-isotope reduction factors obtained when applying various extraction methods. During this study, distillation was identified as the most efficient method for removing radon daughters from liquid scintillator.

physics.ins-det↗

arXiv2013

Sensitivity and Discovery Potential of CUORE to Neutrinoless Double-Beta Decay

We present a study of the sensitivity and discovery potential of CUORE, a bolometric double-beta decay experiment under construction at the Laboratori Nazionali del Gran Sasso in Italy. Two approaches to the computation of experimental sensitivity for various background scenarios are presented, and an extension of the sensitivity formulation to the discovery potential case is also discussed. Assuming a background rate of 10^-2 cts/(keV kg y), we find that, after 5 years of live time, CUORE has a 1 sigma sensitivity to the neutrinoless double-beta decay half-life of T_1/2(1 sigma) = 1.6 \times 10^26 y and thus a potential to probe the effective Majorana neutrino mass down to 40-100 meV; the sensitivity at 1.64 sigma, which corresponds to 90% C.L., will be T_1/2(1.64 sigma) = 9.5 \times 10^25 y. This range is compared with the claim of observation of neutrinoless double-beta decay in 76Ge and the preferred range of the neutrino mass parameter space from oscillation results.

nucl-ex↗

arXiv2012

Limits on Majoron-emitting double-beta decays of Xe-136 in the KamLAND-Zen experiment

We present limits on Majoron-emitting neutrinoless double-beta decay modes based on an exposure of 112.3 days with 125 kg of Xe-136. In particular, a lower limit on the ordinary (spectral index n = 1) Majoron-emitting decay half-life of Xe-136 is obtained as T_{1/2}^{0νχ^{0}} > 2.6 x 10^{24} yr at 90% C.L., a factor of five more stringent than previous limits. The corresponding upper limit on the effective Majoron-neutrino coupling, using a range of available nuclear matrix calculations, is < (0.8 - 1.6) x 10^{-5}. This excludes a previously unconstrained region of parameter space and strongly limits the possible contribution of ordinary Majoron emission modes to 0νββdecay for neutrino masses in the inverted hierarchy scheme.

hep-ex↗

arXiv2011

Measurement of the 8B Solar Neutrino Flux with the KamLAND Liquid Scintillator Detector

We report a measurement of the neutrino-electron elastic scattering rate from 8B solar neutrinos based on a 123 kton-day exposure of KamLAND. The background-subtracted electron recoil rate, above a 5.5 MeV analysis threshold is 1.49+/-0.14(stat)+/-0.17(syst) events per kton-day. Interpreted as due to a pure electron flavor flux with a 8B neutrino spectrum, this corresponds to a spectrum integrated flux of 2.77+/-0.26(stat)+/-0.32(syst) x 10^6 cm^-2s^-1. The analysis threshold is driven by 208Tl present in the liquid scintillator, and the main source of systematic uncertainty is due to background from cosmogenic 11Be. The measured rate is consistent with existing measurements and with Standard Solar Model predictions which include matter enhanced neutrino oscillation.

hep-ex↗

arXiv2008

Step-up converter for electromagnetic vibrational energy scavenger

This paper introduces a voltage multiplier (VM) circuit which can step up a minimum voltage of 150 mV (peak). The operation and characteristics of this converter circuit are described. The voltage multiplier circuit is also tested with micro and macro scale electromagnetic vibrational generators and the effect of the VM on the optimum load conditions of the electromagnetic generator is presented. The measured results show that 85% efficiency can be achieved from this VM circuit at a power level of 18 ?W.

cs.OH↗

arXiv2007

Macro and Micro Scale Electromagnetic Kinetic Energy Harvesting Generators

This paper is concerned with generators that harvest electrical energy from the kinetic energy present in the sensor nodes environment. These generators have the potential to replace or augment battery power which has a limited lifetime and requires periodic replacement which limits the placement and application of the sensor node.

cs.OH↗

arXiv2007

Scaling Effects for Electromagnetic Vibrational Power Generators

This paper investigates how the power generated by electromagnetic based vibrational power generators scales with the dimension of the generator. The effects of scaling on the magnetic fields, the coil parameters and the electromagnetic damping are presented. An analysis is presented for both wire-wound coil technology and micro-fabricated coils.

cs.OH↗