47 research outputs found
Cryogenic Characterization of 180 nm CMOS Technology at 100 mK
Conventional CMOS technology operated at cryogenic conditions has recently
attracted interest for its uses in low-noise electronics. We present one of the
first characterizations of 180 nm CMOS technology at a temperature of 100 mK,
extracting I/V characteristics, threshold voltages, and transconductance
values, as well as observing their temperature dependence. We find that CMOS
devices remain fully operational down to these temperatures, although we
observe hysteresis effects in some devices. The measurements described in this
paper can be used to inform the future design of CMOS devices intended to be
operated in this deep cryogenic regime
Quadratic electroweak corrections for polarized Moller scattering
The paper discusses the two-loop (NNLO) electroweak radiative corrections to
the parity violating electron-electron scattering asymmetry induced by squaring
one-loop diagrams. The calculations are relevant for the ultra-precise 11 GeV
MOLLER experiment planned at Jefferson Laboratory and experiments at
high-energy future electron colliders. The imaginary parts of the amplitudes
are taken into consideration consistently in both the infrared-finite and
divergent terms. The size of the obtained partial correction is significant,
which indicates a need for a complete study of the two-loop electroweak
radiative corrections in order to meet the precision goals of future
experiments
Improving the Performance of Cryogenic Calorimeters with Nonlinear Multivariate Noise Cancellation Algorithms
State-of-the-art physics experiments require high-resolution, low-noise, and
low-threshold detectors to achieve competitive scientific results. However,
experimental environments invariably introduce sources of noise, such as
electrical interference or microphonics. The sources of this environmental
noise can often be monitored by adding specially designed "auxiliary devices"
(e.g. microphones, accelerometers, seismometers, magnetometers, and antennae).
A model can then be constructed to predict the detector noise based on the
auxiliary device information, which can then be subtracted from the true
detector signal. Here, we present a multivariate noise cancellation algorithm
which can be used in a variety of settings to improve the performance of
detectors using multiple auxiliary devices. To validate this approach, we apply
it to simulated data to remove noise due to electromagnetic interference and
microphonic vibrations. We then employ the algorithm to a cryogenic light
detector in the laboratory and show an improvement in the detector performance.
Finally, we motivate the use of nonlinear terms to better model vibrational
contributions to the noise in thermal detectors. We show a further improvement
in the performance of a particular channel of the CUORE detector when using the
nonlinear algorithm in combination with optimal filtering techniques.Comment: 21 pages, 15 figures, 7 table
Search for rare or forbidden decays of the D0 meson
We present a search for nine lepton-number-violating and three lepton-flavor-violating neutral charm decays of the type D0→h'−h−ℓ'+ℓ+ and D0→h'−h+ℓ'±ℓ∓, where h and h′ represent a K or π meson and ℓ and ℓ′ an electron or muon. The analysis is based on 468 fb−1 of e+e− annihilation data collected at or close to the Υ(4S) resonance with the BABAR detector at the SLAC National Accelerator Laboratory. No significant signal is observed for any of the twelve modes, and we establish 90% confidence level upper limits on the branching fractions in the range (1.0–30.6)×10−7. The limits are between 1 and 3 orders of magnitude more stringent than previous measurements.publishedVersio
Light meson spectroscopy from Dalitz plot analyses of ηc decays to η0 K+K− , η0 π + π − , and ηπ + π − produced in two-photon interactions
We study the processes γγ→ηc→η′K+K−, η′π+π−, and ηπ+π− using a data sample of 519  fb−1 recorded with the BABAR detector operating at the SLAC PEP-II asymmetric-energy e+e− collider at center-of-mass energies at and near the Υ(nS) (n=2, 3, 4) resonances. This is the first observation of the decay ηc→η′K+K− and we measure the branching fraction Γ(ηc→η′K+K−)/(Γ(ηc→η′π+π−)=0.644±0.039stat±0.032sys. Significant interference is observed between γγ→ηc→ηπ+π− and the nonresonant two-photon process γγ→ηπ+π−. A Dalitz plot analysis is performed of ηc decays to η′K+K−, η′π+π−, and ηπ+π−. Combined with our previous analysis of ηc→K¯Kπ, we measure the K∗0(1430) parameters and the ratio between its η′K and πK couplings. The decay ηc→η′π+π− is dominated by the f0(2100) resonance, also observed in J/ψ radiative decays. A new a0(1700)→ηπ resonance is observed in the ηc→ηπ+π− channel. We also compare ηc decays to η and η′ final states in association with scalar mesons as they relate to the identification of the scalar glueball.publishedVersio
Measurements of the absolute branching fractions of B± →k±Xc c
A study of the two-body decays B±→Xc¯cK±, where Xc¯c refers to one charmonium state, is reported by the BABAR Collaboration using a data sample of 424 fb−1. The absolute determination of branching fractions for these decays are significantly improved compared to previous BABAR measurements. Evidence is found for the decay B+→X(3872)K+ at the 3σ level. The absolute branching fraction B[B+→X(3872)K+]=[2.1±0.6(stat)±0.3(syst)]×10−4 is measured for the first time. It follows that B[X(3872)→J/ψπ+π−]=(4.1±1.3)%, supporting the hypothesis of a molecular component for this resonance.publishedVersio
The commissioning of the CUORE experiment: the mini-tower run
CUORE is a ton-scale experiment approaching the data taking phase in Gran Sasso National Laboratory. Its primary goal is to search for the neutrinoless double-beta decay in 130Te using 988 crystals of tellurim dioxide. The crystals are operated as bolometers at about 10 mK taking advantage of one of the largest dilution cryostat ever built. Concluded in March 2016, the cryostat commissioning consisted in a sequence of cool down runs each one integrating new parts of the apparatus. The last run was performed with the fully configured cryostat and the thermal load at 4 K reached the impressive mass of about 14 tons. During that run the base temperature of 6.3 mK was reached and maintained for more than 70 days. An array of 8 crystals, called mini-tower, was used to check bolometers operation, readout electronics and DAQ. Results will be presented in terms of cooling power, electronic noise, energy resolution and preliminary background measurements
Results from the Cuore Experiment
The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO2 crystals arranged in a cylindrical compact structure of 19 towers, each of them made of 52 crystals. The construction of the experiment was completed in August 2016 and the data taking started in spring 2017 after a period of commissioning and tests. In this work we present the neutrinoless double beta decay results of CUORE from examining a total TeO2 exposure of 86.3kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/ (keV kg yr). In this physics run, CUORE placed a lower limit on the decay half- life of neutrinoless double beta decay of 130Te > 1.3.1025 yr (90% C. L.). Moreover, an analysis of the background of the experiment is presented as well as the measurement of the 130Te 2vo3p decay with a resulting half- life of T2 2. [7.9 :- 0.1 (stat.) :- 0.2 (syst.)] x 10(20) yr which is the most precise measurement of the half- life and compatible with previous results