arXiv subjects

K. Olchanski

Publications and source records attributed to K. Olchanski.

At least 19 recordsLinked to original sources

arXiv2026

The DarkLight Experiment at TRIUMF

This paper reports on the commissioning of the DarkLight experiment at the ARIEL superconducting electron linear accelerator located at TRIUMF in Vancouver, Canada. DarkLight was designed to utilize the ARIEL electron beam to search for a new boson, $A^\prime$, which preferentially couples to leptons, with a mass in the range 13-17 MeV/$c^2$. Such a boson could be produced via the $e^-~X\rightarrow e^-~X~A^\prime$ process, and the resulting $A^\prime\rightarrow e^+~e^-$ decay used to reconstruct the invariant mass of the $A^\prime$. The $e^+e^-$ pair is detected using a pair of magnetic spectrometers. Each spectrometer is instrumented with two triple GEM detectors and a scintillating strip hodoscope to trigger the event readout. Electron beam energies between 10 and 30 MeV were used to commission the experiment with a 1$~\mu$m thick carbon target. With both spectrometer polarities set to select electrons, elastic and M{\o}ller scattering were used to examine detector performance and compare with predicted distributions from Monte Carlo simulations. Planned upgrades to the e-linac will allow searches to be made with beam energies up to 50 MeV using a 1$~\mu$m thick tantalum target.

physics.ins-det↗

arXiv2022

Design and Performance of a Novel Low Energy Multi-Species Beamline for the ALPHA Antihydrogen Experiment

The ALPHA Collaboration, based at the CERN Antiproton Decelerator, has recently implemented a novel beamline for low-energy ($\lesssim$ 100 eV) positron and antiproton transport between cylindrical Penning traps that have strong axial magnetic fields. Here, we describe how a combination of semianalytical and numerical calculations were used to optimise the layout and design of this beamline. Using experimental measurements taken during the initial commissioning of the instrument, we evaluate its performance and validate the models used for its development. By combining data from a range of sources, we show that the beamline has a high transfer efficiency, and estimate that the percentage of particles captured in the experiments from each bunch is (78 $\pm$ 3)% for up to $10^{5}$ antiprotons, and (71 $\pm$ 5)% for bunches of up to $10^{7}$ positrons.

physics.acc-ph↗

arXiv2021

Limit on the Electric Charge of Antihydrogen

The ALPHA collaboration has successfully demonstrated the production and the confinement of cold antihydrogen, $\overline{\mathrm{H}}$. An analysis of trapping data allowed a stringent limit to be placed on the electric charge of the simplest antiatom. Charge neutrality of matter is known to a very high precision, hence a neutrality limit of $\overline{\mathrm{H}}$ provides a test of CPT invariance. The experimental technique is based on the measurement of the deflection of putatively charged $\overline{\mathrm{H}}$ in an electric field. The tendency for trapped $\overline{\mathrm{H}}$ atoms to be displaced by electrostatic fields is measured and compared to the results of a detailed simulation of $\overline{\mathrm{H}}$ dynamics in the trap. An extensive survey of the systematic errors is performed, with particular attention to those due to the silicon vertex detector, which is the device used to determine the $\overline{\mathrm{H}}$ annihilation position. The limit obtained on the charge of the $\overline{\mathrm{H}}$ atom is \mbox{$ Q = (-1.3\pm1.8\pm0.4)\times10^{-8}$}, representing the first precision measurement with $\overline{\mathrm{H}}$.

physics.atom-ph↗

arXiv2020

Study of muonium emission from laser-ablated silica aerogel

The emission of muonium ($\mu^+e^-$) atoms into vacuum from silica aerogel with laser ablation on its surface was studied with various ablation structures at room temperature using the subsurface muon beams at TRIUMF and Japan Proton Accelerator Research Complex (J-PARC). Laser ablation was applied to produce holes or grooves with typical dimensions of a few hundred $\mu$m to a few mm, except for some extreme conditions. The measured emission rate tends to be higher for larger fractions of ablation opening and for shallower depths. More than a few ablation structures reach the emission rates similar to the highest achieved in the past measurements. The emission rate is found to be stable at least for a couple of days. Measurements of spin precession amplitudes for the produced muonium atoms and remaining muons in a magnetic field determine a muonium formation fraction of $(65.5 \pm 1.8)$%. The precession of the polarized muonium atoms is also observed clearly in vacuum. A projection of the emission rates measured at TRIUMF to the corresponding rates at J-PARC is demonstrated taking the different beam condition into account reasonably.

physics.ins-det↗

arXiv2020

Mechanical Ventilator Milano (MVM): A Novel Mechanical Ventilator Designed for Mass Scale Production in Response to the COVID-19 Pandemic

Presented here is the design of the Mechanical Ventilator Milano (MVM), a novel mechanical ventilator designed for rapid mass production in response to the COVID-19 pandemic to address the urgent shortage of intensive therapy ventilators in many countries, and the growing difficulty in procuring these devices through normal supply chains across borders. This ventilator is an electro-mechanical equivalent of the old and reliable Manley Ventilator, and is able to operate in both pressure-controlled and pressure-supported ventilation modes. MVM is optimized for the COVID-19 emergency, thanks to the collaboration with medical doctors in the front line. MVM is designed for large-scale production in a short amount of time and at a limited cost, as it relays on off-the-shelf components, readily available worldwide. Operation of the MVM requires only a source of compressed oxygen (or compressed medical air) and electrical power. Initial tests of a prototype device with a breathing simulator are also presented. Further tests and developments are underway. At this stage the MVM is not yet a certified medical device but certification is in progress.

physics.med-ph↗

arXiv2019

In-situ characterization of the Hamamatsu R5912-HQE photomultiplier tubes used in the DEAP-3600 experiment

The Hamamatsu R5912-HQE photomultiplier-tube (PMT) is a novel high-quantum efficiency PMT. It is currently used in the DEAP-3600 dark matter detector and is of significant interest for future dark matter and neutrino experiments where high signal yields are needed. We report on the methods developed for in-situ characterization and monitoring of DEAP's 255 R5912-HQE PMTs. This includes a detailed discussion of typical measured single-photoelectron charge distributions, correlated noise (afterpulsing), dark noise, double, and late pulsing characteristics. The characterization is performed during the detector commissioning phase using laser light injected through a light diffusing sphere and during normal detector operation using LED light injected through optical fibres.

physics.ins-det↗

arXiv2018

First results from the DEAP-3600 dark matter search with argon at SNOLAB

This paper reports the first results of a direct dark matter search with the DEAP-3600 single-phase liquid argon (LAr) detector. The experiment was performed 2 km underground at SNOLAB (Sudbury, Canada) utilizing a large target mass, with the LAr target contained in a spherical acrylic vessel of 3600 kg capacity. The LAr is viewed by an array of PMTs, which would register scintillation light produced by rare nuclear recoil signals induced by dark matter particle scattering. An analysis of 4.44 live days (fiducial exposure of 9.87 tonne-days) of data taken with the nearly full detector during the initial filling phase demonstrates the detector performance and the best electronic recoil rejection using pulse-shape discrimination in argon, with leakage $<1.2\times 10^{-7}$ (90% C.L.) between 16 and 33 keV$_{ee}$. No candidate signal events are observed, which results in the leading limit on WIMP-nucleon spin-independent cross section on argon, $<1.2\times 10^{-44}$ cm$^2$ for a 100 GeV/c$^2$ WIMP mass (90% C.L.).

astro-ph.CO↗

arXiv2018

Design and Construction of the DEAP-3600 Dark Matter Detector

The Dark matter Experiment using Argon Pulse-shape discrimination (DEAP) has been designed for a direct detection search for particle dark matter using a single-phase liquid argon target. The projected cross section sensitivity for DEAP-3600 to the spin-independent scattering of Weakly Interacting Massive Particles (WIMPs) on nucleons is $10^{-46}~\rm{cm}^{2}$ for a 100 GeV/$c^2$ WIMP mass with a fiducial exposure of 3 tonne-years. This paper describes the physical properties and construction of the DEAP-3600 detector.

astro-ph.IM↗

arXiv2018

Precision measurement of the $β$-asymmetry in spin-polarized $^{37}\mathrm{K}$ decay

Using TRIUMF's neutral atom trap, TRINAT, for nuclear $β$ decay, we have measured the $β$ asymmetry with respect to the initial nuclear spin in $^{37}\mathrm{K}$ to be $A_β=-0.5707(13)_\mathrm{syst}(13)_\mathrm{stat}(5)_\mathrm{pol}$, a 0.3% measurement. This is the best relative accuracy of any $β$-asymmetry measurement in a nucleus or the neutron, and is in agreement with the standard model prediction $-0.5706(7)$. We compare constraints on physics beyond the standard model with other $β$-decay measurements, and improve the value of $V_\mathrm{ud}$ measured in this mirror nucleus by a factor of 4.

nucl-ex↗

arXiv2016

Measurement of $σ_{\mathrm{ABS}}$ and $σ_{\mathrm{CX}}$ of $π^+$ on carbon by DUET

The DUET Collaboration reports on the measurements of the absorption ($σ_{\mathrm{ABS}}$) and charge exchange ($σ_{\mathrm{CX}}$) cross sections of positively charged pions on carbon nuclei for the momentum range 201.6 MeV$/c$ to 295.1 MeV$/c$. The uncertainties on the absorption and charge exchange cross sections are $\sim$9.5\% and $\sim$18\%, respectively. The results are in good agreement with previous experiments. A covariance matrix correlating the 5 $σ_{\mathrm{ABS}}$ and 5 $σ_{\mathrm{CX}}$ measured data points is also reported

hep-ex↗

arXiv2015

Measurement of absorption and charge exchange of $π^+$ on carbon

The combined cross section for absorption and charge exchange interactions of positively charged pions with carbon nuclei for the momentum range 200 MeV/c to 300 MeV/c have been measured with the DUET experiment at TRIUMF. The uncertainty is reduced by nearly half compared to previous experiments. This result will be a valuable input to existing models to constrain pion interactions with nuclei.

hep-ex↗

arXiv2015

A search for two body muon decay signals

Lepton family number violation is tested by searching for $μ^+\to e^+X^0$ decays among the 5.8$\times 10^8$ positive muon decay events analyzed by the TWIST collaboration. Limits are set on the production of both massless and massive $X^0$ bosons. The large angular acceptance of this experiment allows limits to be placed on anisotropic $μ^+\to e^+X^0$ decays, which can arise from interactions violating both lepton flavor and parity conservation. Branching ratio limits of order $10^{-5}$ are obtained for bosons with masses of 13 - 80 MeV/c$^2$ and with different decay asymmetries. For bosons with masses less than 13 MeV/c$^{2}$ the asymmetry dependence is much stronger and the 90% limit on the branching ratio varies up to $5.8 \times 10^{-5}$. This is the first study that explicitly evaluates the limits for anisotropic two body muon decays.

hep-ex↗

arXiv2014

Enhancement of muonium emission rate from silica aerogel with a laser ablated surface

Emission of muonium ($μ^+e^-$) atoms from a laser-processed aerogel surface into vacuum was studied for the first time. Laser ablation was used to create hole-like regions with diameter of about 270$~μ$m in a triangular pattern with hole separation in the range of 300--500$~μ$m. The emission probability for the laser-processed aerogel sample is at least eight times higher than for a uniform one.

physics.ins-det↗

arXiv2014

In situ electromagnetic field diagnostics with an electron plasma in a Penning-Malmberg trap

We demonstrate a novel detection method for the cyclotron resonance frequency of an electron plasma in a Penning-Malmberg trap. With this technique, the electron plasma is used as an in situ diagnostic tool for measurement of the static magnetic field and the microwave electric field in the trap. The cyclotron motion of the electron plasma is excited by microwave radiation and the temperature change of the plasma is measured non-destructively by monitoring the plasma's quadrupole mode frequency. The spatially-resolved microwave electric field strength can be inferred from the plasma temperature change and the magnetic field is found through the cyclotron resonance frequency. These measurements were used extensively in the recently reported demonstration of resonant quantum interactions with antihydrogen.

physics.plasm-ph↗

arXiv2014

Design and commissioning of a timestamp-based data acquisition system for the DRAGON recoil mass separator

The DRAGON recoil mass separator at TRIUMF exists to study radiative proton and alpha capture reactions, which are important in a variety of astrophysical scenarios. DRAGON experiments require a data acquisition system that can be triggered on either reaction product ($γ$ ray or heavy ion), with the additional requirement of being able to promptly recognize coincidence events in an online environment. To this end, we have designed and implemented a new data acquisition system for DRAGON which consists of two independently triggered readouts. Events from both systems are recorded with timestamps from a $20$ MHz clock that are used to tag coincidences in the earliest possible stage of the data analysis. Here we report on the design, implementation, and commissioning of the new DRAGON data acquisition system, including the hardware, trigger logic, coincidence reconstruction algorithm, and live time considerations. We also discuss the results of an experiment commissioning the new system, which measured the strength of the $E_{\text{c}.\text{m}.} = 1113$ keV resonance in the $^{20}$Ne$\left(p, γ\right)^{21}$Na radiative proton capture reaction.

physics.ins-det↗

arXiv2013

Measurement of muonium emission from silica aerogel

Emission of muonium ($μ^{+}e^{-}$) atoms from silica aerogel into vacuum was observed. Characteristics of muonium emission were established from silica aerogel samples with densities in the range from 29 mg cm$^{-3}$ to 178 mg cm$^{-3}$. Spectra of muonium decay times correlated with distances from the aerogel surfaces, which are sensitive to the speed distributions, follow general features expected from a diffusion process, while small deviations from a simple room-temperature thermal diffusion model are identified. The parameters of the diffusion process are deduced from the observed yields.

physics.atom-ph↗

arXiv2012

Precision muon decay measurements and improved constraints on the weak interaction

The TWIST Collaboration has completed its measurement of the three muon decay parameters ρ, δ, and P_μξ. This paper describes our determination of ρ, which governs the shape of the overall momentum spectrum, and δ, which controls the momentum dependence of the parity-violating decay asymmetry. The results are ρ=0.74977\pm 0.00012(stat.)\pm 0.00023(syst.) and δ= 0.75049\pm 0.00021(stat.)\pm 0.00027(syst.). These are consistent with the value of 3/4 given for both parameters in the standard model, and each is over a factor of 10 more precise than the measurements published prior to TWIST. Our final results on ρ, δ, and P_μξhave been incorporated into a new global analysis of all available muon decay data, resulting in improved model-independent constraints on the possible weak interactions of right-handed particles.

hep-ex↗

arXiv2012

Antihydrogen and mirror-trapped antiproton discrimination: Discriminating between antihydrogen and mirror-trapped antiprotons in a minimum-B trap

Recently, antihydrogen atoms were trapped at CERN in a magnetic minimum (minimum-B) trap formed by superconducting octupole and mirror magnet coils. The trapped antiatoms were detected by rapidly turning off these magnets, thereby eliminating the magnetic minimum and releasing any antiatoms contained in the trap. Once released, these antiatoms quickly hit the trap wall, whereupon the positrons and antiprotons in the antiatoms annihilated. The antiproton annihilations produce easily detected signals; we used these signals to prove that we trapped antihydrogen. However, our technique could be confounded by mirror-trapped antiprotons, which would produce seemingly-identical annihilation signals upon hitting the trap wall. In this paper, we discuss possible sources of mirror-trapped antiprotons and show that antihydrogen and antiprotons can be readily distinguished, often with the aid of applied electric fields, by analyzing the annihilation locations and times. We further discuss the general properties of antiproton and antihydrogen trajectories in this magnetic geometry, and reconstruct the antihydrogen energy distribution from the measured annihilation time history.

physics.atom-ph↗