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Papers by C. M . B . Monteiro

Research paper thumbnail of NEXT-CRAB-0: A High Pressure Gaseous Xenon Time Projection Chamber with a Direct VUV Camera Based Readout

arXiv (Cornell University), Apr 12, 2023

Research paper thumbnail of Ba+2 ion trapping using organic submonolayer for ultra-low background neutrinoless double beta detector

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...

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

Research paper thumbnail of Reflectance and fluorescence characteristics of PTFE coated with TPB at visible, UV, and VUV as a function of thickness

arXiv (Cornell University), Nov 9, 2022

Research paper thumbnail of An homeopathic cure to pure Xenon large diffusion

Journal of Instrumentation, 2016

Research paper thumbnail of A next-generation liquid xenon observatory for dark matter and neutrino physics

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.

Research paper thumbnail of Recoil imaging for dark matter, neutrinos, and physics beyond the Standard Model

Research paper thumbnail of Non-linear behaviour of large-area avalanche photodiodes

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

Research paper thumbnail of Laser excitation of the 1s-hyperfine transition in muonic hydrogen

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

Research paper thumbnail of Electroluminescence studies on the influence of percentage quantities of CO 2 added to pure xenon

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...

Research paper thumbnail of Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

Journal of High Energy Physics, 2020

Research paper thumbnail of Dependence of polytetrafluoroethylene reflectance on thickness at visible and ultraviolet wavelengths in air

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.

Research paper thumbnail of Experiments towards resolving the proton charge radius puzzle

EPJ Web of Conferences, 2016

Research paper thumbnail of Sensitivity of NEXT-100 to neutrinoless double beta decay

Journal of High Energy Physics, 2016

Research paper thumbnail of Muonic hydrogen cascade time and lifetime of the short-lived 2S state

Research paper thumbnail of Powerful fast triggerable 6 μm laser for the muonic hydrogen 2S-Lamb shift experiment

Optics Communications, 2005

Research paper thumbnail of The proton radius puzzle

Journal of Physics: Conference Series, 2011

Research paper thumbnail of The Lamb shift in muonic hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010

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.

Research paper thumbnail of Laser spectroscopy of muonic deuterium

Science (New York, N.Y.), Jan 12, 2016

The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron p... more The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius rd and the polarizability serve as important benchmarks for understanding the nuclear forces and structure. Muonic deuterium μd is the exotic atom formed by a deuteron and a negative muon μ(-). We measured three 2S-2P transitions in μd and obtain r(d) = 2.12562(78) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value r(d) = 2.1424(21) fm. The μd value is also 3.5σ smaller than the r(d) value from electronic deuterium spectroscopy. The smaller r(d), when combined with the electronic isotope shift, yields a "small" proton radius r(p), similar to the one from muonic hydrogen, amplifying the proton radius puzzle.

Research paper thumbnail of NEXT-CRAB-0: A High Pressure Gaseous Xenon Time Projection Chamber with a Direct VUV Camera Based Readout

arXiv (Cornell University), Apr 12, 2023

Research paper thumbnail of Ba+2 ion trapping using organic submonolayer for ultra-low background neutrinoless double beta detector

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...

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

Research paper thumbnail of Reflectance and fluorescence characteristics of PTFE coated with TPB at visible, UV, and VUV as a function of thickness

arXiv (Cornell University), Nov 9, 2022

Research paper thumbnail of An homeopathic cure to pure Xenon large diffusion

Journal of Instrumentation, 2016

Research paper thumbnail of A next-generation liquid xenon observatory for dark matter and neutrino physics

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.

Research paper thumbnail of Recoil imaging for dark matter, neutrinos, and physics beyond the Standard Model

Research paper thumbnail of Non-linear behaviour of large-area avalanche photodiodes

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

Research paper thumbnail of Laser excitation of the 1s-hyperfine transition in muonic hydrogen

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

Research paper thumbnail of Electroluminescence studies on the influence of percentage quantities of CO 2 added to pure xenon

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...

Research paper thumbnail of Low-diffusion Xe-He gas mixtures for rare-event detection: electroluminescence yield

Journal of High Energy Physics, 2020

Research paper thumbnail of Dependence of polytetrafluoroethylene reflectance on thickness at visible and ultraviolet wavelengths in air

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.

Research paper thumbnail of Experiments towards resolving the proton charge radius puzzle

EPJ Web of Conferences, 2016

Research paper thumbnail of Sensitivity of NEXT-100 to neutrinoless double beta decay

Journal of High Energy Physics, 2016

Research paper thumbnail of Muonic hydrogen cascade time and lifetime of the short-lived 2S state

Research paper thumbnail of Powerful fast triggerable 6 μm laser for the muonic hydrogen 2S-Lamb shift experiment

Optics Communications, 2005

Research paper thumbnail of The proton radius puzzle

Journal of Physics: Conference Series, 2011

Research paper thumbnail of The Lamb shift in muonic hydrogenThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010

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.

Research paper thumbnail of Laser spectroscopy of muonic deuterium

Science (New York, N.Y.), Jan 12, 2016

The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron p... more The deuteron is the simplest compound nucleus, composed of one proton and one neutron. Deuteron properties such as the root-mean-square charge radius rd and the polarizability serve as important benchmarks for understanding the nuclear forces and structure. Muonic deuterium μd is the exotic atom formed by a deuteron and a negative muon μ(-). We measured three 2S-2P transitions in μd and obtain r(d) = 2.12562(78) fm, which is 2.7 times more accurate but 7.5σ smaller than the CODATA-2010 value r(d) = 2.1424(21) fm. The μd value is also 3.5σ smaller than the r(d) value from electronic deuterium spectroscopy. The smaller r(d), when combined with the electronic isotope shift, yields a "small" proton radius r(p), similar to the one from muonic hydrogen, amplifying the proton radius puzzle.