395 research outputs found
The CUORE Cryostat: A 1-Ton Scale Setup for Bolometric Detectors
The cryogenic underground observatory for rare events (CUORE) is a 1-ton
scale bolometric experiment whose detector consists of an array of 988 TeO2
crystals arranged in a cylindrical compact structure of 19 towers. This will be
the largest bolometric mass ever operated. The experiment will work at a
temperature around or below 10 mK. CUORE cryostat consists of a cryogen-free
system based on pulse tubes and a custom high power dilution refrigerator,
designed to match these specifications. The cryostat has been commissioned in
2014 at the Gran Sasso National Laboratories and reached a record temperature
of 6 mK on a cubic meter scale. In this paper, we present results of CUORE
commissioning runs. Details on the thermal characteristics and cryogenic
performances of the system will be also given.Comment: 7 pages, 2 figures, LTD16 conference proceedin
The CUORE cryostat: an infrastructure for rare event searches at millikelvin temperatures
The CUORE experiment is the world's largest bolometric experiment. The
detector consists of an array of 988 TeO2 crystals, for a total mass of 742 kg.
CUORE is presently taking data at the Laboratori Nazionali del Gran Sasso,
Italy, searching for the neutrinoless double beta decay of 130Te. A large
custom cryogen-free cryostat allows reaching and maintaining a base temperature
of about 10 mK, required for the optimal operation of the detector. This
apparatus has been designed in order to achieve a low noise environment, with
minimal contribution to the radioactive background for the experiment. In this
paper, we present an overview of the CUORE cryostat, together with a
description of all its sub-systems, focusing on the solutions identified to
satisfy the stringent requirements. We briefly illustrate the various phases of
the cryostat commissioning and highlight the relevant steps and milestones
achieved each time. Finally, we describe the successful cooldown of CUORE
Laser-controlled fluorescence in two-level systems
The ability to modify the character of fluorescent emission by a laser-controlled, optically nonlinear process has recently been shown theoretically feasible, and several possible applications have already been identified. In operation, a pulse of off-resonant probe laser beam, of sufficient intensity, is applied to a system exhibiting fluorescence, during the interval of excited- state decay following the initial excitation. The result is a rate of decay that can be controllably modified, the associated changes in fluorescence behavior affording new, chemically specific information. In this paper, a two-level emission model is employed in the further analysis of this all-optical process; the results should prove especially relevant to the analysis and imaging of physical systems employing fluorescent markers, these ranging from quantum dots to green fluorescence protein. Expressions are presented for the laser-controlled fluorescence anisotropy exhibited by samples in which the fluorophores are randomly oriented. It is also shown that, in systems with suitably configured electronic levels and symmetry properties, fluorescence emission can be produced from energy levels that would normally decay nonradiatively. © 2010 American Chemical Society
Full characterization of vibrational coherence in a porphyrin chromophore by two-dimensional electronic spectroscopy
In this work we present experimental and calculated two-dimensional electronic spectra for a 5,15-bisalkynyl porphyrin chromophore. The lowest energy electronic Qy transition couples mainly to a single 380 cm–1 vibrational mode. The two-dimensional electronic spectra reveal diagonal and cross peaks which oscillate as a function of population time. We analyze both the amplitude and phase distribution of this main vibronic transition as a function of excitation and detection frequencies. Even though Feynman diagrams provide a good indication of where the amplitude of the oscillating components are located in the excitation-detection plane, other factors also affect this distribution. Specifically, the oscillation corresponding to each Feynman diagram is expected to have a phase that is a function of excitation and detection frequencies. Therefore, the overall phase of the experimentally observed oscillation will reflect this phase dependence. Another consequence is that the overall oscillation amplitude can show interference patterns resulting from overlapping contributions from neighboring Feynman diagrams. These observations are consistently reproduced through simulations based on third order perturbation theory coupled to a spectral density described by a Brownian oscillator model
CUORE-0 results and prospects for the CUORE experiment
With 741 kg of TeO2 crystals and an excellent energy resolution of 5 keV
(0.2%) at the region of interest, the CUORE (Cryogenic Underground Observatory
for Rare Events) experiment aims at searching for neutrinoless double beta
decay of 130Te with unprecedented sensitivity. Expected to start data taking in
2015, CUORE is currently in an advanced construction phase at LNGS. CUORE
projected neutrinoless double beta decay half-life sensitivity is 1.6E26 y at 1
sigma (9.5E25 y at the 90% confidence level), in five years of live time,
corresponding to an upper limit on the effective Majorana mass in the range
40-100 meV (50-130 meV). Further background rejection with auxiliary bolometric
detectors could improve CUORE sensitivity and competitiveness of bolometric
detectors towards a full analysis of the inverted neutrino mass hierarchy.
CUORE-0 was built to test and demonstrate the performance of the upcoming CUORE
experiment. It consists of a single CUORE tower (52 TeO2 bolometers of 750 g
each, arranged in a 13 floor structure) constructed strictly following CUORE
recipes both for materials and assembly procedures. An experiment its own,
CUORE-0 is expected to reach a sensitivity to the neutrinoless double beta
decay half-life of 130Te around 3E24 y in one year of live time. We present an
update of the data, corresponding to an exposure of 18.1 kg y. An analysis of
the background indicates that the CUORE performance goal is satisfied while the
sensitivity goal is within reach.Comment: 10 pages, 3 figures, to appear in the proceedings of NEUTRINO 2014,
26th International Conference on Neutrino Physics and Astrophysics, 2-7 June
2014, held at Boston, Massachusetts, US
Status of the CUORE and results from the CUORE-0 neutrinoless double beta decay experiments
CUORE is a 741 kg array of TeO2 bolometers for the search of neutrinoless
double beta decay of 130Te. The detector is being constructed at the Laboratori
Nazionali del Gran Sasso, Italy, where it will start taking data in 2015. If
the target background of 0.01 counts/keV/kg/y will be reached, in five years of
data taking CUORE will have a 1 sigma half life sensitivity of 10E26 y. CUORE-0
is a smaller experiment constructed to test and demonstrate the performances
expected for CUORE. The detector is a single tower of 52 CUORE-like bolometers
that started taking data in spring 2013. The status and perspectives of CUORE
will be discussed, and the first CUORE-0 data will be presented.Comment: 7 pages, 4 figures, to be published in the proceedings of ICHEP 2014,
37th International Conference on High Energy Physics, Valencia (Spain) 2-9
July 201
Measurement of the Two-Neutrino Double Beta Decay Half-life of Te with the CUORE-0 Experiment
We report on the measurement of the two-neutrino double beta decay half-life
of Te with the CUORE-0 detector. From an exposure of 33.4 kgy of
TeO, the half-life is determined to be = [8.2 0.2
(stat.) 0.6 (syst.)] 10y. This result is obtained after a
detailed reconstruction of the sources responsible for the CUORE-0 counting
rate, with a specific study of those contributing to the Te
neutrinoless double beta decay region of interest.Comment: Corrected typo in section 9: 3.43E5 Bq/kg should have read 3.43E-5
Bq/k
Search for Neutrinoless Double-Beta Decay of Te with CUORE-0
We report the results of a search for neutrinoless double-beta decay in a
9.8~kgyr exposure of Te using a bolometric detector array,
CUORE-0. The characteristic detector energy resolution and background level in
the region of interest are FWHM and ~counts/(keVkgyr), respectively. The
median 90%~C.L. lower-limit sensitivity of the experiment is and surpasses the sensitivity of previous searches. We find
no evidence for neutrinoless double-beta decay of Te and place a
Bayesian lower bound on the decay half-life, ~ at 90%~C.L. Combining CUORE-0 data with the 19.75~kgyr
exposure of Te from the Cuoricino experiment we obtain at 90%~C.L.~(Bayesian), the most stringent
limit to date on this half-life. Using a range of nuclear matrix element
estimates we interpret this as a limit on the effective Majorana neutrino mass,
-- .Comment: 6 pages, 5 figures, updated version as published in PR
Analysis Techniques for the Evaluation of the Neutrinoless Double-Beta Decay Lifetime in Te with CUORE-0
We describe in detail the methods used to obtain the lower bound on the
lifetime of neutrinoless double-beta () decay in Te and
the associated limit on the effective Majorana mass of the neutrino using the
CUORE-0 detector. CUORE-0 is a bolometric detector array located at the
Laboratori Nazionali del Gran Sasso that was designed to validate the
background reduction techniques developed for CUORE, a next-generation
experiment scheduled to come online in 2016. CUORE-0 is also a competitive
decay search in its own right and functions as a platform to
further develop the analysis tools and procedures to be used in CUORE. These
include data collection, event selection and processing, as well as an
evaluation of signal efficiency. In particular, we describe the amplitude
evaluation, thermal gain stabilization, energy calibration methods, and the
analysis event selection used to create our final decay search
spectrum. We define our high level analysis procedures, with emphasis on the
new insights gained and challenges encountered. We outline in detail our
fitting methods near the hypothesized decay peak and catalog
the main sources of systematic uncertainty. Finally, we derive the
decay half-life limits previously reported for CUORE-0,
yr, and in combination with the Cuoricino
limit, yr.Comment: 18 pages, 18 figures. (Version 3 reflects only minor changes to the
text. Few additional details, no major content changes.
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Results of the MAJORANA DEMONSTRATOR's Search for Double-Beta Decay of 76Ge to Excited States of 76Se
The MAJORANA DEMONSTRATOR is searching for double-beta decay of 76Ge to excited states (E.S.) in 76Se using a modular array of high purity Germanium detectors. 76Ge can decay into three E.S.s of 76Se. The E.S. decays have a clear event signature consisting of a ββ-decay with the prompt emission of one or two γ-rays, resulting in with high probability in a multi-site event. The granularity of the DEMONSTRATOR detector array enables powerful discrimination of this event signature from backgrounds. Using 21.3 kg-y of isotopic exposure, the DEMONSTRATOR has set world leading limits for each E.S. decay, with 90% CL lower half-life limits in the range of (0.56 2.1) ⋅ 1024 y. In particular, for the 2v transition to the first 0+ E.S. of 76Se, a lower half-life limit of 0.68 ⋅ 1024 at 90% CL was achieved
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