J. Haefner
A5064293959- Neutrino Physics Research
- Radiation Detection and Scintillator Technologies
- Atomic and Subatomic Physics Research
- Dark Matter and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Radiation Therapy and Dosimetry
- Particle Detector Development and Performance
- Astrophysics and Cosmic Phenomena
- Advanced Radiotherapy Techniques
- Photocathodes and Microchannel Plates
- Electron and X-Ray Spectroscopy Techniques
- Quantum, superfluid, helium dynamics
- Muon and positron interactions and applications
- Non-Destructive Testing Techniques
- Particle Accelerators and Free-Electron Lasers
- Microwave Imaging and Scattering Analysis
- Physics of Superconductivity and Magnetism
- Particle accelerators and beam dynamics
- Plasma Diagnostics and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Nuclear Physics and Applications
- Material Properties and Applications
- Solar and Space Plasma Dynamics
- Computational Physics and Python Applications
- Ionosphere and magnetosphere dynamics
Washington University in St. Louis
2023-2024
Harvard University
2019-2023
Harvard University Press
2023
University of Michigan
2015-2017
A bstract The Neutrino Experiment with a Xenon TPC (NEXT) searches for the neutrinoless double-beta (0 νββ ) decay of 136 Xe using high-pressure xenon gas TPCs electroluminescent amplification. scaled-up version this technology about 1 tonne enriched could reach in less than 5 years operation sensitivity to half-life 0 better 10 27 years, improving current limits by at least one order magnitude. This prediction is based on well-understood background model dominated radiogenic sources....
A bstract The NEXT experiment aims at the sensitive search of neutrinoless double beta decay in 136 Xe, using high-pressure gas electroluminescent time projection chambers. NEXT-White detector is first radiopure demonstrator this technology, operated Laboratorio Subterráneo de Canfranc. Achieving an energy resolution 1% FWHM 2.6 MeV and further background rejection by means topology reconstructed tracks, has been exploited beyond its original goals order to perform a neu- trinoless search....
We present evidence of non-excimer-based secondary scintillation in gaseous xenon, obtained using both the NEXT-White TPC and a dedicated setup. Detailed comparison with first-principle calculations allows us to assign this mechanism neutral bremsstrahlung (NBrS), process that has been postulated exist xenon largely overlooked. For photon emission below 1000 nm, NBrS yield increases from about 10$^{-2}$ photon/e$^{-}$ cm$^{-1}$ bar$^{-1}$ at pressure-reduced electric field values 50 V above...
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, NEXT collaboration is investigating novel synthetic molecular sensors that may capture Ba dication produced in of certain Xe isotopes high-pressure gas experiment. use such detectors immobilized on surfaces...
Abstract Objective . In current clinical practice for quality assurance (QA), intensity modulated proton therapy (IMPT) fields are verified by measuring planar dose distributions at one or a few selected depths in phantom. A QA device that measures full 3D high spatiotemporal resolution would be highly beneficial existing as well emerging techniques such FLASH radiotherapy. Our objective is to demonstrate feasibility of measurement IMPT using dedicated multi-layer strip ionization chamber...
A bstract Natural radioactivity represents one of the main backgrounds in search for neutrinoless double beta decay. Within NEXT physics program, radioactivity- induced are measured with NEXT-White detector. Data from 37.9 days low-background operations at Laboratorio Subterráneo de Canfranc xenon depleted 136 Xe analyzed to derive a total background rate (0.84 ± 0.02) mHz above 1000 keV. The comparison data samples and without use radon abatement system demonstrates that contribution...
We report new measurements of the drift velocity and longitudinal diffusion coefficients electrons in pure xenon gas xenon-helium mixtures at 1-9 bar electric field strengths 50-300 V/cm. In we find excellent agreement with world data all E/P, for both coefficients. However, a larger value coefficient than theoretical predictions is found low E/P xenon, below range reduced fields usually probed by TPC experiments. A similar effect observed somewhat E/P. Drift velocities are to be...
136 Xe is used as the target medium for many experiments searching 0νββ.Despite underground operation, cosmic muons that reach laboratory can produce spallation neutrons causing activation of detector materials.A potential background difficult to veto using muon tagging comes in form 137 created by capture on Xe.This isotope decays via beta decay with a half-life 3.8 minutes and Q β ∼4.16 MeV.This work proposes explores concept adding small percentage 3 He xenon means thermal reduce number...
A bstract Next-generation neutrinoless double beta decay experiments aim for half-life sensitivities of ∼ 10 27 yr, requiring suppressing backgrounds to < 1 count/tonne/yr. For this, any extra background rejection handle, beyond excellent energy resolution and the use extremely radiopure materials, is utmost importance. The NEXT experiment exploits differences in spatial ionization patterns single-electron events discriminate signal from background. While former display two Bragg peak...
The Neutrino Experiment with a Xenon TPC (NEXT) searches for the neutrinoless double-beta decay of Xe-136 using high-pressure xenon gas TPCs electroluminescent amplification. A scaled-up version this technology about 1 tonne enriched could reach in less than 5 years operation sensitivity to half-life better 1E27 years, improving current limits by at least one order magnitude. This prediction is based on well-understood background model dominated radiogenic sources. detector concept presented...
Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. However, the reflectance of PTFE a function its thickness. In this work, we investigate dependence air wavelengths 260 nm and 450 using two complementary methods. We find that thicknesses from 5 mm to 10 ranges 92.5% 94.5% at nm, 90.0% 92.0% nm. also see given thickness can vary by as much 2.7% within same piece material. Finally, show placing specular...
The need for precise characterization of dual-phase xenon detectors has grown as the technology matured into a state high efficacy rare event searches. Michigan Xenon detector was constructed to study microphysics particle interactions in liquid across large energy range an effort probe aspects radiation detection xenon. We report design and performance small 3D position sensitive time projection chamber with light yield (Ly122=15.2 pe/keV at zero field), long electron lifetime (τ > 200 μs),...
Convolutional neural networks (CNNs) are widely used state-of-the-art computer vision tools that becoming increasingly popular in high energy physics. In this paper, we attempt to understand the potential of CNNs for event classification NEXT experiment, which will search neutrinoless double-beta decay $^{136}$Xe. To do so, demonstrate usage identification electron-positron pair production events, exhibit a topology similar event. These events were produced NEXT-White high-pressure xenon TPC...
High pressure xenon Time Projection Chambers (TPC) based on secondary scintillation (electroluminescence) signal amplification are being proposed for rare event detection such as directional dark matter, double electron capture and beta decay detection. The discrimination of the through topological signature primary ionisation trails is a major asset this type TPC when compared to single liquid or double-phase TPCs, limited mainly by high diffusion in pure xenon. Helium admixtures with can...
A bstract Double electron capture by proton-rich nuclei is a second-order nuclear process analogous to double beta decay. Despite their similarities, the decay signature quite different, potentially providing new channel measure hypothesized neutrinoless mode of these decays. The Standard-Model-allowed two-neutrino (2 νEC EC ) has been predicted for number isotopes, but only observed in 78 Kr, 130 Ba and, recently, 124 Xe. sensitivity this establishes benchmark ultimate experimental goal,...
Abstract Background Position verification and motion monitoring are critical for safe precise radiotherapy (RT). Existing approaches to these tasks based on visible light or x‐ray suboptimal either because they cannot penetrate obstructions the patient's skin introduce additional radiation exposure. The low‐cost mmWave radar is an ideal solution as it can monitor patient position continuously throughout treatment delivery. Purpose To develop validate frequency‐modulated continuous wave...
Motivated by the possibility of guiding daughter ions from double beta decay events to single-ion sensors for barium tagging, NEXT collaboration is developing a program R&D test radio frequency (RF) carpets ion transport in high pressure xenon gas. This would require carpet functionality regimes at higher pressures than have been previously reported, implying correspondingly larger electrode voltages existing systems. mode operation appears plausible contemporary RF-carpet geometries due...
Polytetrafluoroethylene (PTFE) is an excellent diffuse reflector widely used in light collection systems for particle physics experiments. In noble element systems, it often coated with tetraphenyl butadiene (TPB) to allow detection of vacuum ultraviolet scintillation light. this work dependence investigated PTFE TPB air wavelengths 200~nm, 260~nm, and 450~nm. The results show that TPB-coated has a reflectance approximately 92\% thicknesses ranging from 5~mm 10~mm at 450~nm, negligible...
Abstract Ultra-high dose rate (UHDR) radiotherapy (RT) or FLASH-RT can potentially reduce normal tissue toxicity. A small animal irradiator that deliver treatments similar to clinical RT is needed for pre-clinical studies of FLASH-RT. We designed and simulated a novel FLASH (SAFI) based on distributed x-ray source technology. The SAFI system comprises with 51 focal spots equally 20 cm diameter ring, which are used both onboard micro-CT imaging. Monte Carlo simulation was performed estimate...
Noble element time projection chambers are a leading technology for rare event detection in physics, such as dark matter and neutrinoless double beta decay searches. Time typically assign position the drift direction using relative timing of prompt scintillation delayed charge collection signals, allowing reconstruction an absolute direction. In this paper, alternate methods assigning distance via quantification electron diffusion pure high pressure xenon gas chamber explored. Data from...