460 research outputs found
Background suppression in massive TeO bolometers with Neganov-Luke amplified light detectors
Bolometric detectors are excellent devices for the investigation of
neutrinoless double-beta decay (0). The observation of such
decay would demonstrate the violation of lepton number, and at the same time it
would necessarily imply that neutrinos have a Majorana character. The
sensitivity of cryogenic detectors based on TeO is strongly limited by the
alpha background in the region of interest for the 0 of
Te. It has been demonstrated that particle discrimination in TeO
bolometers is possible measuring the Cherenkov light produced by particle
interactions. However an event-by-event discrimination with NTD-based light
detectors has to be demonstrated. We will discuss the performance of a
highly-sensitive light detector exploiting the Neganov-Luke effect for signal
amplification. The detector, being operated with NTD-thermistor and coupled to
a 750 g TeO crystal, shows the ability for an event-by-event identification
of electron/gamma and alpha particles. The extremely low detector baseline
noise, RMS 19 eV, demonstrates the possibility to enhance the sensitivity of
TeO-based 0 experiment to an unprecedented level
ZnO-based scintillating bolometers: New prospects to study double beta decay of Zn
The first detailed study on the performance of a ZnO-based cryogenic
scintillating bolometer as a detector to search for rare processes in zinc
isotopes was performed. A 7.2 g ZnO low-temperature detector, containing more
than 80\% of zinc in its mass, exhibits good energy resolution of baseline
noise 1.0--2.7 keV FWHM at various working temperatures resulting in a
low-energy threshold for the experiment, 2.0--6.0 keV. The light yield for
/ events was measured as 1.5(3) keV/MeV, while it varies for
particles in the range of 0.2--3.0 keV/MeV. The detector demonstrate
an effective identification of the / events from events
using time-properties of only heat signals. %(namely, Rise time parameter). The
radiopurity of the ZnO crystal was evaluated using the Inductively Coupled
Plasma Mass Spectrometry, an ultra-low-background High Purity Ge
-spectrometer, and bolometric measurements. Only limits were set at the
level of (1--100) mBq/kg on activities of \Nuc{K}{40},
\Nuc{Cs}{137} and daughter nuclides from the U/Th natural decay chains. The
total internal -activity was calculated to be 22(2) mBq/kg, with a
major contribution caused by 6(1) mBq/kg of \Nuc{Th}{232} and 12(2) mBq/kg of
\Nuc{U}{234}. Limits on double beta decay (DBD) processes in \Nuc{Zn}{64} and
\Nuc{Zn}{70} isotopes were set on the level of
-- yr for various decay modes profiting from 271
h of acquired background data in the above-ground lab. This study shows a good
potential for ZnO-based scintillating bolometers to search for DBD processes of
Zn isotopes, especially in \Nuc{Zn}{64}, with the most prominent spectral
features at 10--20 keV, like the two neutrino double electron capture. A
10 kg-scale experiment can reach the experimental sensitivity at the level of
yr.Comment: Prepared for submission to JINST; 27 pages, 9 figures, and 7 table
A New Limit on the Neutrinoless DBD of 130Te
We report the present results of CUORICINO a cryogenic experiment on
neutrinoless double beta decay (DBD) of 130Te consisting of an array of 62
crystals of TeO2 with a total active mass of 40.7 kg. The array is framed
inside of a dilution refrigerator, heavily shielded against environmental
radioactivity and high-energy neutrons, and operated at a temperature of ~8 mK
in the Gran Sasso Underground Laboratory. Temperature pulses induced by
particle interacting in the crystals are recorded and measured by means of
Neutron Transmutation Doped thermistors. The gain of each bolometer is
stabilized with voltage pulses developed by a high stability pulse generator
across heater resistors put in thermal contact with the absorber.
The calibration is performed by means of two thoriated wires routinely
inserted in the set-up. No evidence for a peak indicating neutrinoless DBD of
130Te is detected and a 90% C.L. lower limit of 1.8E24 years is set for the
lifetime of this process. Taking largely into account the uncertainties in the
theoretical values of nuclear matrix elements, this implies an upper boud on
the effective mass of the electron neutrino ranging from 0.2 to 1.1 eV. This
sensitivity is similar to those of the 76Ge experiments.Comment: 4 pages, 2 figure
Maraviroc Intensification Modulates Atherosclerotic Progression in HIV-Suppressed Patients at High Cardiovascular Risk. A Randomized, Crossover Pilot Study
Background
Experimental CCR5 antagonism with maraviroc in atherosclerosis-prone mice and preliminary data in humans suggest an anti-atherosclerotic effect of the drug. We assessed the impact of maraviroc treatment in persons living with HIV on subclinical indicators of atherosclerosis.
Methods
Persons living with HIV on effective antiretroviral therapy (ART) including only protease inhibitors were recruited if they had a Framingham risk score >20% and brachial flow-mediated dilation (bFMD) <4%, as indices of high cardiovascular risk. Maraviroc (300 mg per os for 24 weeks) was administered, in addition to ongoing ART, to all patients using a crossover design. Brachial FMD, carotid-femoral pulse wave velocity (cfPWV), and carotid intima-media thickness (cIMT) were measured as markers of atherosclerosis. Vascular competence—as expressed by the ratio of circulating endothelial microparticles (EMPs) to endothelial progenitor cells (EPCs)—and markers of systemic inflammation and monocyte and platelet activation were assessed.
Results
Maraviroc treatment significantly improved bFMD, cfPWV, and cIMT by 66%, 11%, and 13%, respectively (P = .002, P = .022, P = .038, respectively). We also found a beneficial effect of maraviroc on the EMP/EPC ratio (P < .001) and platelet/leucocyte aggregates (P = .013). No significant changes in markers of systemic inflammation, monocyte activation, and microbial translocation were observed.
Conclusions
Maraviroc led to significant improvements in several markers for cardiovascular risk, endothelial dysfunction, arterial stiffness, and early carotid atherosclerosis, which was accompanied by an increase of vascular competence, without seeming to affect systemic inflammation. Our data support the need for larger studies to test for any effects of maraviroc on preventing atherosclerosis-driven pathologies
The PopuList: A Database of Populist, Far-Left, and Far-Right Parties Using Expert-Informed Qualitative Comparative Classification (EiQCC)
Abstract With a proliferation of scholarly work focusing on populist, far-left, and far-right parties, questions have arisen about the correct ways to ideologically classify such parties. To ensure transparency and uniformity in research, the discipline could benefit from a systematic procedure. In this letter, we discuss how we have employed the method of ‘Expert-informed Qualitative Comparative Classification’ (EiQCC) to construct the newest version of The PopuList (3.0) – a database of populist, far-left, and far-right parties in Europe since 1989. This method takes into account the in-depth knowledge of national party experts while allowing for systematic comparative analysis across cases and over time. We also examine how scholars have made use of the previous versions of the dataset, explain how the new version of The PopuList differs from previous ones, and compare it to other data. We conclude with a discussion of the strengths and limitations of The PopuList dataset.</jats:p
In Quest of Neutrino Masses at (eV) Scale
Neutrino oscillation and tritium beta decay experiments taken simultaneously
into account are able to access the so far imperceptible absolute neutrino
masses at the electronvolt level. The neutrino mass spectrum derived in this
way is independent of the nature of neutrinos (Dirac or Majorana). Furthermore,
the lack of neutrinoless double beta decay gives additional constraints on the
Majorana neutrino mass spectrum. A case of three neutrinos is examined.
Influence of different solutions to the solar neutrino deficit problem on the
results is discussed. Apart from the present situation, four qualitatively
distinct experimental situations which are possible in the future are
investigated: when the two decay experiments give only upper bounds on
effective neutrino masses, when either one of them gives a positive result, and
when both give positive results. The discussion is carried out by taking into
account the present experimental errors of relevant neutrino parameters as well
as their much more precise expected estimations (e.g. by factories). It
is shown in which cases the upgraded decay experiments simultaneously with
neutrino oscillation data may be able to fix the absolute scale of the neutrino
mass spectrum, answer the question of the neutrino nature and put some light on
CP phases in the lepton sector.Comment: 30 pages, 6 figs, to appear in PR
Proposal for taking data with the KLOE-2 detector at the DANE collider upgraded in energy
This document reviews the physics program of the KLOE-2 detector at
DANE upgraded in energy and provides a simple solution to run the
collider above the -peak (up to 2, possibly 2.5 GeV). It is shown how a
precise measurement of the multihadronic cross section in the energy region up
to 2 (possibly 2.5) GeV would have a major impact on the tests of the Standard
Model through a precise determination of the anomalous magnetic moment of the
muon and the effective fine-structure constant at the scale. With a
luminosity of about cms, DANE upgraded in energy
can perform a scan in the region from 1 to 2.5 GeV in one year by collecting an
integrated luminosity of 20 pb (corresponding to a few days of data
taking) for single point, assuming an energy step of 25 MeV. A few years of
data taking in this region would provide important tests of QCD and effective
theories by physics with open thresholds for pseudo-scalar (like
the ), scalar (, etc...) and axial-vector (, etc...)
mesons; vector-mesons spectroscopy and baryon form factors; tests of CVC and
searches for exotics. In the final part of the document a technical solution
for the energy upgrade of DANE is proposed.Comment: 19 pages, 8 figure
A Cryogenic Underground Observatory for Rare Events: Cuore, an Update
CUORE is a proposed tightly packed array of 1000 TeO_{2} bolometers, each
being a cube 5 cm on a side with a mass of 750 gms. The array consists of 25
vertical towers, arranged in a square, of 5 towers by 5 towers, each containing
10 layers of 4 crystals. The design of the detector is optimized for ultralow-
background searches for neutrinoless double beta decay of ^{130}Te (33.8%
abundance), cold dark matter, solar axions, and rare nuclear decays. A
preliminary experiment involving 20 crystals of various sizes (MIBETA) has been
completed, and a single CUORE tower is being constructed as a smaller scale
experiment called CUORICINO. The expected performance and sensitivity, based on
Monte Carlo simulations and extrapolations of present results, are reported.Comment: in press: Nucl. Phys. of Russian Academy of Sc
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