arXiv subjects

K. Bailey

Publications and source records attributed to K. Bailey.

52 records · Page 3Linked to original sources

arXiv2018

The Next White (NEW) detector

Conceived to host 5 kg of xenon at a pressure of 15 bar in the fiducial volume, the NEXT- White (NEW) apparatus is currently the largest high pressure xenon gas TPC using electroluminescent amplification in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for $ββ0ν$ decays in 136Xe in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.

physics.ins-det↗

arXiv2017

Rapid processing of 85Kr/Kr ratios using Atom Trap Trace Analysis

We report a methodology for measuring 85Kr/Kr isotopic abundances using Atom Trap Trace Analysis (ATTA) that increases sample measurement throughput by over an order of magnitude to 6 samples per 24 hours. The noble gas isotope 85Kr (half-life = 10.7 yr) is a useful tracer for young groundwater in the age range of 5-50 years. ATTA, an efficient and selective laser-based atom counting method, has recently been applied to 85Kr/Kr isotopic abundance measurements, requiring 5-10 microliters of krypton gas at STP extracted from 50-100 L of water. Previously a single such measurement required 48 hours. Our new method demonstrates that we can measure 85Kr/Kr ratios with 3-5% relative uncertainty every 4 hours, on average, with the same sample requirements.

physics.ins-det↗

arXiv2017

Setting a Limit on Anthropogenic Sources of Atmospheric 81Kr through Atom Trap Trace Analysis

We place a 2.5% limit on the anthropogenic contribution to the modern abundance of 81Kr/Kr in the atmosphere at the 90% confidence level. Due to its simple production and transport in the terrestrial environment, 81Kr (halflife = 230,000 yr) is an ideal tracer for old water and ice with mean residence times in the range of 10^5-10^6 years. In recent years, 81Kr-dating has been made available to the earth science community thanks to the development of Atom Trap Trace Analysis (ATTA), a laser-based atom counting technique. Further upgrades and improvements to the ATTA technique now allow us to demonstrate 81Kr/Kr measurements with relative uncertainties of 1% and place this new limit on anthropogenic 81Kr. As a result of this limit, we have removed a potential systematic constraint for 81Kr-dating.

physics.atom-ph↗

arXiv2013

Efficient, Tightly-Confined Trapping of 226Ra

We demonstrate a technique for transferring $^{226}$Ra atoms from a 3-dimensional magneto-optical-trap (MOT) into a standing wave optical dipole trap (ODT) in an adjacent chamber. The resulting small trapping volume (120 $μ$m in diameter) allows for high control of the electric and magnetic fields applied to the atoms. The atoms are first transferred to a traveling-wave optical dipole trap, which is then translated 46 cm to a science chamber. The atoms are subsequently transferred into an orthogonal standing-wave ODT by application of a 1-dimensional MOT along the traveling-wave axis. For each stage, transfer efficiencies exceeding 60% are demonstrated.

physics.atom-ph↗

arXiv2012

Fundamental Physics at the Intensity Frontier

The Proceedings of the 2011 workshop on Fundamental Physics at the Intensity Frontier. Science opportunities at the intensity frontier are identified and described in the areas of heavy quarks, charged leptons, neutrinos, proton decay, new light weakly-coupled particles, and nucleons, nuclei, and atoms.

hep-ex↗

arXiv2011

Optical Excitation and Decay Dynamics of Ytterbium Atoms Embedded in a Solid Neon Matrix

Neutral ytterbium atoms embedded in solid neon qualitatively retain the structure of free atoms. Despite the atom-solid interaction, the 6s6p $^3$P$_0$ level is found to remain metastable with its lifetimes determined to be in the range of ten to hundreds of seconds. The atomic population can be almost completely transferred between the ground level and the metastable level via optical excitation and spontaneous decay. The dynamics of this process is examined, and is used to explicitly demonstrate that the transition broadening mechanism is homogeneous.

physics.atom-ph↗

arXiv2011

Ar-39 Detection at the 10^-16 Isotopic Abundance Level with Atom Trap Trace Analysis

Atom Trap Trace Analysis (ATTA), a laser-based atom counting method, has been applied to analyze atmospheric Ar-39 (half-life = 269 yr), a cosmogenic isotope with an isotopic abundance of 8x10^-16. In addition to the superior selectivity demonstrated in this work, counting rate and efficiency of ATTA have been improved by two orders of magnitude over prior results. Significant applications of this new analytical capability lie in radioisotope dating of ice and water samples and in the development of dark matter detectors.

physics.atom-ph↗

arXiv2008

Nuclear charge radius of $^8$He

The root-mean-square (rms) nuclear charge radius of ^8He, the most neutron-rich of all particle-stable nuclei, has been determined for the first time to be 1.93(3) fm. In addition, the rms charge radius of ^6He was measured to be 2.068(11) fm, in excellent agreement with a previous result. The significant reduction in charge radius from ^6He to ^8He is an indication of the change in the correlations of the excess neutrons and is consistent with the ^8He neutron halo structure. The experiment was based on laser spectroscopy of individual helium atoms cooled and confined in a magneto-optical trap. Charge radii were extracted from the measured isotope shifts with the help of precision atomic theory calculations.

nucl-ex↗

arXiv2007

Quasifree Lambda, Sigma^0, and Sigma^- electroproduction from 1,2H, 3,4He, and carbon

Kaon electroproduction from light nuclei and hydrogen, using 1H, 2H, 3He, 4He, and Carbon targets has been measured at Jefferson Laboratory. The quasifree angular distributions of Lambda and Sigma hyperons were determined at Q^2= 0.35(GeV/c)^2 and W= 1.91GeV. Electroproduction on hydrogen was measured at the same kinematics for reference.

nucl-ex↗

arXiv2007

Laser-trapping of Ra-225 and Ra-226 with repumping by room temperature blackbody radiation

We have demonstrated Zeeman slowing and capture of neutral Ra-225 and Ra-226 atoms in a magneto-optical trap (MOT). The intercombination transition 1S0-3P1 is the only quasi-cycling transition in radium and was used for laser-cooling and trapping. Repumping along the 3D1-1P1 transition extended the lifetime of the trap from milliseconds to seconds. Room-temperature blackbody radiation was demonstrated to provide repumping from the metastable 3P0 level. We measured the isotope shift and hyperfine splittings on the 3D1-1P1 transition with the laser-cooled atoms, and set a limit on the lifetime of the 3D1 level based on the measured blackbody repumping rate. Laser-cooled and trapped radium is an attractive system for studying fundamental symmetries.

physics.atom-ph↗

arXiv2006

A Thermal Beam of Metastable Krypton Atoms Produced by Optical Excitation

A room-temperature beam of krypton atoms in the metastable 5s[3/2]2 level is demonstrated via an optical excitation method. A Kr-discharge lamp is used to produce VUV photons at 124 nm for the first-step excitation from the ground-level 4p6 1S0 to the 5s[3/2]1 level. An 819 nm Ti:Sapphire laser is used for the second-step excitation from 5s[3/2]1 to 5p[3/2]1, followed by a spontaneous decay to the 5s[3/2]2 metastable level. A metastable atomic beam with an angular flux density of 3 x 10^14 /s/sr is achieved at the total gas flow rate of 0.01 cm^3 STP/s (or 3 x 10^17 atoms/s). The dependences of the flux on the gas flow rate, laser power, and lamp parameters are investigated.

physics.atom-ph↗

arXiv2004

Laser Spectroscopic Determination of the 6He Nuclear Charge Radius

We have performed precision laser spectroscopy on individual 6He (t1/2 = 0.8 s) atoms confined and cooled in a magneto-optical trap, and measured the isotope shift between 6He and 4He to be 43,194.772 +/- 0.056 MHz for the 2 3S1 - 3 3P2 transition. Based on this measurement and atomic theory, the nuclear charge radius of 6He is determined, for the first time in a method independent of nuclear models, to be 2.054 +/- 0.014 fm. The result is compared with the values predicted by a number of nuclear structure calculations, and tests their ability to characterize this loosely bound, halo nucleus.

nucl-ex↗

arXiv2004

Fine Structure of the 1s3p ^3P_J Level in Atomic ^4He: Theory and Experiment

We report on a theoretical calculation and a new experimental determination of the 1s3p ^3P_J fine structure intervals in atomic ^4He. The values from the theoretical calculation of 8113.730(6) MHz and 658.801(6) MHz for the nu_{01} and nu_{12} intervals, respectively, disagree significantly with previous experimental results. However, the new laser spectroscopic measurement reported here yields values of 8113.714(28) MHz and 658.810(18) MHz for these intervals. These results show an excellent agreement with the theoretical values and resolve the apparent discrepancy between theory and experiment.

physics.atom-ph↗

arXiv2004

One million year old groundwater in the Sahara revealed by krypton-81 and chlorine-36

Measurements of 81Kr/Kr in deep groundwater from the Nubian Aquifer (Egypt) were performed by a new laser-based atom-counting method. 81Kr ages range from \~2x10^5 to ~1x10^6 yr, correlate with 36Cl/Cl ratios, and are consistent with lateral flow of groundwater from a recharge area near the Uweinat Uplift in SW Egypt. Low delta-2H values of the 81Kr-dated groundwater reveal a recurrent Atlantic moisture source during Pleistocene pluvial periods. These results indicate that the 81Kr method for dating old groundwater is robust and such measurements can now be applied to a wide range of hydrologic problems.

physics.geo-ph↗

arXiv2003

A New Method of Measuring 81Kr and 85Kr Abundances in Environmental Samples

We demonstrate a new method for determining the 81Kr/Kr ratio in environmental samples based upon two measurements: the 85Kr/81Kr ratio measured by Atom Trap Trace Analysis (ATTA) and the 85Kr/Kr ratio measured by Low-Level Counting (LLC). This method can be used to determine the mean residence time of groundwater in the range of 10^5 - 10^6 a. It requires a sample of 100 micro-l STP of Kr extracted from approximately two tons of water. With modern atmospheric Kr samples, we demonstrate that the ratios measured by ATTA and LLC are directly proportional to each other within the measurement error of +/- 10%; we calibrate the 81Kr/Kr ratio of modern air measured using this method; and we show that the 81Kr/Kr ratios of samples extracted from air before and after the development of the nuclear industry are identical within the measurement error.

physics.atom-ph↗

arXiv2003

Counting individual 41Ca atoms with a magneto-optical trap

Atom Trap Trace Analysis (ATTA), a novel method based upon laser trapping and cooling, is used to count individual atoms of 41Ca present in biomedical samples with isotopic abundance levels between 10^-8 and 10^-10. ATTA is calibrated against Resonance Ionization Mass Spectrometry, demonstrating a good agreement between the two methods. The present ATTA system has a counting efficiency of 2x10^-7. Within one hour of observation time, its 3-sigma detection limit on the isotopic abundance of 41Ca reaches 4.5x10^-10.

physics.atom-ph↗