C. M . B . Monteiro - Profile on Academia.edu (original) (raw)

Papers by C. M . B . Monteiro

Journal of High Energy Physics

The NEXT experiment aims at the sensitive search of the neutrinoless double beta decay in 136Xe, ... more The NEXT experiment aims at the sensitive search of the neutrinoless double beta decay in 136Xe, using high-pressure gas electroluminescent time projection chambers. The NEXT-White detector is the first radiopure demonstrator of this technology, operated in the Laboratorio Subterráneo de Canfranc. Achieving an energy resolution of 1% FWHM at 2.6 MeV and further background rejection by means of the topology of the reconstructed tracks, NEXT-White has been exploited beyond its original goals in order to perform a neu- trinoless double beta decay search. The analysis considers the combination of 271.6 days of 136Xe-enriched data and 208.9 days of 136Xe-depleted data. A detailed background modeling and measurement has been developed, ensuring the time stability of the radiogenic and cosmogenic contributions across both data samples. Limits to the neutrinoless mode are obtained in two alternative analyses: a background-model-dependent approach and a novel direct background-subtraction te...

arXiv (Cornell University), Apr 12, 2023

The search for neutrinoless double beta decay (0) remains one of the most compelling experimental... more The search for neutrinoless double beta decay (0) remains one of the most compelling experimental avenues for the discovery in the neutrino sector. Electroluminescent gas-phase time projection chambers are well suited to 0 searches due to their intrinsically precise energy resolution and topological event identification capabilities. Scalability to ton-and multi-ton masses requires readout of large-area electroluminescent regions with fine spatial resolution, low radiogenic backgrounds, and a scalable data acquisition system. This paper presents a detector prototype that records event topology in an electroluminescent xenon gas TPC via VUV image-intensified cameras. This enables an extendable readout of large tracking planes with commercial devices that reside almost entirely outside of the active medium. Following further development in intermediate scale demonstrators, this technique may represent a novel and enlargeable method for topological event imaging in 0 .

Nature Communications

If neutrinos are their own antiparticles the otherwise-forbidden nuclear reaction known as neutri... more If neutrinos are their own antiparticles the otherwise-forbidden nuclear reaction known as neutrinoless double beta decay can occur. The very long lifetime expected for these exceptional events makes its detection a daunting task. In order to conduct an almost background-free experiment, the NEXT collaboration is investigating novel synthetic molecular sensors that may capture the Ba dication produced in the decay of certain Xe isotopes in a high-pressure gas experiment. The use of such molecular detectors immobilized on surfaces must be explored in the ultra-dry environment of a xenon gas chamber. Here, using a combination of highly sensitive surface science techniques in ultra-high vacuum, we demonstrate the possibility of employing the so-called Fluorescent Bicolor Indicator as the molecular component of the sensor. We unravel the ion capture process for these molecular indicators immobilized on a surface and explain the origin of the emission fluorescence shift associated to the...

First proof of topological signature in the NEXT high pressure xenon gas TPC with electroluminescence amplification

arXiv (Cornell University), Nov 9, 2022

A : Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collect... more A : Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. In noble element systems, it is often coated with tetraphenyl butadiene (TPB) to allow detection of vacuum ultraviolet scintillation light. In this work this dependence is investigated for PTFE coated with TPB in air for light of wavelengths of 200 nm, 260 nm, and 450 nm. The results show that TPB-coated PTFE has a reflectance of approximately 92% for thicknesses ranging from 5 mm to 10 mm at 450 nm, with negligible variation as a function of thickness within this range. A cross-check of these results using an argon chamber supports the conclusion that the change in thickness from 5 mm to 10 mm does not affect significantly the light response at 128 nm. Our results indicate that pieces of TPB-coated PTFE thinner than the typical 10 mm can be used in particle physics detectors without compromising the light signal.

Journal of Instrumentation, 2016

Recent citations Gaseous and dual-phase time projection chambers for imaging rare processes Diego... more Recent citations Gaseous and dual-phase time projection chambers for imaging rare processes Diego González-Díaz et al-Background rejection in NEXT using deep neural networks J. Renner et al

Journal of Physics G: Nuclear and Particle Physics

The nature of dark matter and properties of neutrinos are among the most pressing issues in conte... more The nature of dark matter and properties of neutrinos are among the most pressing issues in contemporary particle physics. The dual-phase xenon time-projection chamber is the leading technology to cover the available parameter space for weakly interacting massive particles, while featuring extensive sensitivity to many alternative dark matter candidates. These detectors can also study neutrinos through neutrinoless double-beta decay and through a variety of astrophysical sources. A next-generation xenon-based detector will therefore be a true multi-purpose observatory to significantly advance particle physics, nuclear physics, astrophysics, solar physics, and cosmology. This review article presents the science cases for such a detector.

Recoil imaging entails the detection of spatially resolved ionization tracks generated by particl... more Recoil imaging entails the detection of spatially resolved ionization tracks generated by particle interactions. This is a highly sought-after capability in many classes of detector, with broad applications across particle and astroparticle physics. However, at low energies, where ionization signatures are small in size, recoil imaging only seems to be a practical goal for micro-pattern gas detectors. This white paper outlines the physics case for recoil imaging, and puts forward a decadal plan to advance towards the directional detection of low-energy recoils with sensitivity and resolution close to fundamental performance limits. The science case covered includes: the discovery of dark matter into the neutrino fog, directional detection of sub-MeV solar neutrinos, the precision study of coherent-elastic neutrino-nucleus scattering, the detection of solar axions, the measurement of the Migdal effect, X-ray polarimetry, and several other applied physics goals. We also outline the R&D programs necessary to test concepts that are crucial to advance detector performance towards their fundamental limit: single primary electron sensitivity with full 3D spatial resolution at the ∼100 micronscale. These advancements include: the use of negative ion drift, electron counting with high-definition electronic readout, time projection chambers with optical readout, and the possibility for nuclear recoil tracking in high-density gases such as argon. We also discuss the readout and electronics systems needed to scale-up detectors to the ton-scale and beyond.

Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, 2002

The characterisation of photodiodes used as photosensors requires a determination of the number o... more The characterisation of photodiodes used as photosensors requires a determination of the number of electron-hole pairs produced by scintillation light. One method involves comparing signals produced by X-ray absorptions occurring directly in the avalanche photodiode with the light signals. When the light is derived from light-emitting diodes in the 400-600 nm range, significant non-linear behaviour is reported. In the present work, we extend the study of the linear behaviour to large-area avalanche photodiodes, of Advanced Photonix, used as photosensors of the vacuum ultraviolet (VUV) scintillation light produced by argon (128 nm) and xenon (173 nm). We observed greater non-linearities in the avalanche photodiodes for the VUV scintillation light than reported previously for visible light, but considerably less than the non-linearities observed in other commercially available avalanche photodiodes.

SciPost Physics

The CREMA collaboration is pursuing a measurement of the ground-state hyperfine splitting (HFS) i... more The CREMA collaboration is pursuing a measurement of the ground-state hyperfine splitting (HFS) in muonic hydrogen (\muμp) with 1 ppm accuracy by means of pulsed laser spectroscopy to determine the two-photon-exchange contribution with 2\times10^{-4}2×10−4 relative accuracy. In the proposed experiment, the \muμp atom undergoes a laser excitation from the singlet hyperfine state to the triplet hyperfine state, {then} is quenched back to the singlet state by an inelastic collision with a H_22 molecule. The resulting increase of kinetic energy after the collisional deexcitation is used as a signature of a successful laser transition between hyperfine states. In this paper, we calculate the combined probability that a \muμp atom initially in the singlet hyperfine state undergoes a laser excitation to the triplet state followed by a collisional-induced deexcitation back to the singlet state. This combined probability has been computed using the optical Bloch equations including the inela...

$Research paper thumbnail of Ba$^{2+}$ ion trapping by organic submonolayer: towards an ultra-low background neutrinoless double beta decay detector$

If neutrinos are their own antiparticles [1], the otherwise-forbidden nuclear reaction known as n... more If neutrinos are their own antiparticles [1], the otherwise-forbidden nuclear reaction known as neutrinoless double beta decay (ββ0ν) can occur, with a characteristic lifetime which is expected to be very long, making the suppression of backgrounds a daunting task. It has been shown that

In the present work, relative measurements have been performed for the EL yields of xenon and xen... more In the present work, relative measurements have been performed for the EL yields of xenon and xenon-mixtures in a uniform electric field driftless GPSC. The operational parameters of the detector, including amplitude and energy resolution, were measured as a function of the reduced electric field in the scintillation region. For instance, for an E/p value of 1.5 V cm torr, the energy resolution has values about 8.5%, 9.6% and 18% for pure xenon, Xe+0.5%CH4, and Xe+1%CH4, respectively. Xe-CO2 mixtures achieve energy resolutions of about 8.6% and 9.0% for CO2 concentration of 0.11%, and 0.33%, respectively, at an E/p value of 1.5 V cm torr. For E/p values above 1.8 V cm torr, energy resolutions of around 8.4%, 8.4% and 8.7% can be obtained in Xe-0.5%CH4, Xe-0.11%CO2 and Xe-0.33%CO2 mixtures, respectively. For Xe+1%CH4 much higher electric field values would be needed in order to achieve such energy resolutions, while with Xe+2%CH4 it is impossible to achieve good energy resolutions. C...

Journal of High Energy Physics, 2020

Contents 1 Introduction 1 2 Experimental setup 4 3 Method 5 4 Experimental results and discussion... more Contents 1 Introduction 1 2 Experimental setup 4 3 Method 5 4 Experimental results and discussion 6 5 Conclusions 12

arXiv: Instrumentation and Detectors, 2020

Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection ... more Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. However, the reflectance of PTFE is a function of its thickness. In this work, we investigate this dependence in air for light of wavelengths 260 nm and 450 nm using two complementary methods. We find that PTFE reflectance for thicknesses from 5 mm to 10 mm ranges from 92.5% to 94.5% at 450 nm, and from 90.0% to 92.0% at 260 nm. We also see that the reflectance of PTFE of a given thickness can vary by as much as 2.7% within the same piece of material. Finally, we show that placing a specular reflector behind the PTFE can recover the loss of reflectance in the visible without introducing a specular component in the reflectance.

EPJ Web of Conferences, 2016

We review the status of the proton charge radius puzzle. Emphasis is given to the various experim... more We review the status of the proton charge radius puzzle. Emphasis is given to the various experiments initiated to resolve the conflict between the muonic hydrogen results and the results from scattering and regular hydrogen spectroscopy.

Journal of High Energy Physics, 2016

NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will searc... more NEXT-100 is an electroluminescent high-pressure xenon gas time projection chamber that will search for the neutrinoless double beta (0νββ) decay of 136 Xe. The detector possesses two features of great value for 0νββ searches: energy resolution better than 1% FWHM at the Q value of 136 Xe and track reconstruction for the discrimination of signal and background events. This combination results in excellent sensitivity, as discussed in this paper. Material-screening measurements and a detailed Monte Carlo detector simulation predict a background rate for NEXT-100 of at most 4 × 10 −4 counts keV −1 kg −1 yr −1. Accordingly, the detector will reach a sensitivity to the 0νββ-decay half-life of 2.8 × 10 25 years (90% CL) for an exposure of 100 kg • year, or 6.0 × 10 25 years after a run of 3 effective years.

Physical Review A, 2007

Metastable 2S muonic-hydrogen atoms undergo collisional 2S-quenching, with rates which depend str... more Metastable 2S muonic-hydrogen atoms undergo collisional 2S-quenching, with rates which depend strongly on whether the µp kinetic energy is above or below the 2S → 2P energy threshold. Above threshold, collisional 2S → 2P excitation followed by fast radiative 2P → 1S deexcitation is allowed. The corresponding short-lived µp(2S) component was measured at 0.6 hPa H2 room temperature gas pressure, with lifetime τ short 2S = 165 +38 −29 ns (i.e., λ quench 2S = 7.9 +1.8 −1.6 × 10 12 s −1 at liquid-hydrogen density) and population ε short 2S = 1.70 +0.80 −0.56 % (per µp atom). In addition, a value of the µp cascade time, T µp cas = (37 ± 5) ns, was found.

Optics Communications, 2005

Laser spectroscopy of the 2S-Lamb shift in muonic hydrogen (l À p) is being performed at the Paul... more Laser spectroscopy of the 2S-Lamb shift in muonic hydrogen (l À p) is being performed at the Paul Scherrer Institute, Switzerland, to determine the root-mean-square (rms) proton charge radius with 10 À3 precision. A multistage laser system has been developed which provides 0.2 mJ pulse energy tunable at 6 lm wavelength. An excimer pumped dye laser

Journal of Physics: Conference Series, 2011

Canadian Journal of Physics, 2011

The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measu... more The long quest for a measurement of the Lamb shift in muonic hydrogen is over. Last year we measured the 2S 1/2F=1 –2P 3/2F=2 energy splitting (Pohl et al., Nature, 466, 213 (2010)) in μp with an experimental accuracy of 15 ppm, twice better than our proposed goal. Using current QED calculations of the fine, hyperfine, QED, and finite size contributions, we obtain a root-mean-square proton charge radius of rp = 0.841 84 (67) fm. This value is 10 times more precise, but 5 standard deviations smaller, than the 2006 CODATA value of rp. The origin of this discrepancy is not known. Our measurement, together with precise measurements of the 1S–2S transition in regular hydrogen and deuterium, gives improved values of the Rydberg constant, R∞ = 10 973 731.568 160 (16) m–1 and the rms charge radius of the deuteron rd = 2.128 09 (31) fm.