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Search Results: 1 - 10 of 216281 matches for " W. H. Lippincott "
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Trace Detection of Metastable Helium Molecules in Superfluid Helium by Laser-Induced Fluorescence
D. N. McKinsey,W. H. Lippincott,J. Nikkel,W. Rellergert
Physics , 2005, DOI: 10.1103/PhysRevLett.95.111101
Abstract: We describe an approach to detecting ionizing radiation that combines the special properties of superfluid helium with the sensitivity of quantum optics techniques. Ionization in liquid helium results in the copious production of metastable helium molecules, which can be detected by laser-induced fluorescence. Each molecule can be probed many times using a cycling transition, resulting in the detection of individual molecules with high signal to noise. This technique could be used to detect neutrinos, weakly interacting massive particles, and ultracold neutrons, and to image superfluid flow in liquid He-4.
Comments on "First Results of the Phase II SIMPLE Dark Matter Search"
C. E. Dahl,J. Hall,W. H. Lippincott
Physics , 2011, DOI: 10.1103/PhysRevLett.108.259001
Abstract: The SIMPLE Collaboration has reported results from their superheated C2ClF5 droplet detectors, including a description of acoustic discrimination between \alpha decays and nuclear recoils. Our concern is that the events in the neutron calibration data and the events identified as neutrons in the physics data are not drawn from the same parent distribution. This fact calls into question the identification of the background events as neutrons, the use of the calibration data to define the acceptance of WIMP-induced nuclear recoils, and the observation of discrimination against \alpha's.
Scintillation yield and time dependence from electronic and nuclear recoils in liquid neon
W. H. Lippincott,K. J. Coakley,D. Gastler,E. Kearns,D. N. McKinsey,J. A. Nikkel
Physics , 2011, DOI: 10.1103/PhysRevC.86.015807
Abstract: We have performed measurements of scintillation light in liquid neon, observing a signal yield in our detector as high as (3.5 $\pm$ 0.4) photoelectrons/keV. We measure pulse shape discrimination efficiency between electronic and nuclear recoils in liquid neon from 50 and 300 keV nuclear recoil energy. We also measure the \leff\, parameter in liquid neon between 30 and 370 keV nuclear recoil energy, observing an average \leff$=0.24$ above 50 keV. We observe a dependence of the scintillation time distribution and signal yield on the pressure and temperature of the liquid neon.
Calibration of liquid argon and neon detectors with $^{83}Kr^m$
W. H. Lippincott,S. B. Cahn,D. Gastler,L. W. Kastens,E. Kearns,D. N. McKinsey,J. A. Nikkel
Physics , 2009, DOI: 10.1103/PhysRevC.81.045803
Abstract: We report results from tests of $^{83}$Kr$^{\mathrm{m}}$, as a calibration source in liquid argon and liquid neon. $^{83}$Kr$^{\mathrm{m}}$ atoms are produced in the decay of $^{83}$Rb, and a clear $^{83}$Kr$^{\mathrm{m}}$ scintillation peak at 41.5 keV appears in both liquids when filling our detector through a piece of zeolite coated with $^{83}$Rb. Based on this scintillation peak, we observe 6.0 photoelectrons/keV in liquid argon with a resolution of 6% ($\sigma$/E) and 3.0 photoelectrons/keV in liquid neon with a resolution of 19% ($\sigma$/E). The observed peak intensity subsequently decays with the $^{83}$Kr$^{\mathrm{m}}$ half-life after stopping the fill, and we find evidence that the spatial location of $^{83}$Kr$^{\mathrm{m}}$ atoms in the chamber can be resolved. $^{83}$Kr$^{\mathrm{m}}$ will be a useful calibration source for liquid argon and neon dark matter and solar neutrino detectors.
Detection and Imaging of He_2 Molecules in Superfluid Helium
W. G. Rellergert,S. B. Cahn,A. Garvan,J. C. Hanson,W. H. Lippincott,J. A. Nikkel,D. N. McKinsey
Physics , 2007, DOI: 10.1103/PhysRevLett.100.025301
Abstract: We present data that show a cycling transition can be used to detect and image metastable He$_2$ triplet molecules in superfluid helium. We demonstrate that limitations on the cycling efficiency due to the vibrational structure of the molecule can be mitigated by the use of repumping lasers. Images of the molecules obtained using the method are also shown. This technique gives rise to a new kind of ionizing radiation detector. The use of He$_2$ triplet molecules as tracer particles in the superfluid promises to be a powerful tool for visualization of both quantum and classical turbulence in liquid helium.
Measurement of scintillation efficiency for nuclear recoils in liquid argon
D. Gastler,E. Kearns,A. Hime,L. C. Stonehill,S. Seibert,J. Klein,W. H. Lippincott,D. N. McKinsey,J. A. Nikkel
Physics , 2010, DOI: 10.1103/PhysRevC.85.065811
Abstract: The scintillation light yield of liquid argon from nuclear recoils relative to electronic recoils has been measured as a function of recoil energy from 10 keVr up to 250 keVr. The scintillation efficiency, defined as the ratio of the nuclear recoil scintillation response to the electronic recoil response, is 0.25 \pm 0.01 + 0.01(correlated) above 20 keVr.
Scintillation time dependence and pulse shape discrimination in liquid argon
W. H. Lippincott,K. J. Coakley,D. Gastler,A. Hime,E. Kearns,D. N. McKinsey,J. A. Nikkel,L. C. Stonehill
Physics , 2008, DOI: 10.1103/PhysRevC.81.039901
Abstract: Using a single-phase liquid argon detector with a signal yield of 4.85 photoelectrons per keV of electronic-equivalent recoil energy (keVee), we measure the scintillation time dependence of both electronic and nuclear recoils in liquid argon down to 5 keVee. We develop two methods of pulse shape discrimination to distinguish between electronic and nuclear recoils. Using one of these methods, we measure a background and statistics-limited level of electronic recoil contamination to be $7.6\times10^{-7}$ between 60 and 128 keV of nuclear recoil energy (keVr) for a nuclear recoil acceptance of 50% with no nuclear recoil-like events above 72 keVr. Finally, we develop a maximum likelihood method of pulse shape discrimination using the measured scintillation time dependence and predict the sensitivity to WIMP-nucleon scattering in three configurations of a liquid argon dark matter detector.
A Spin-Dependent Interpretation for Possible Signals of Light Dark Matter
Matthew R. Buckley,W. Hugh Lippincott
Physics , 2013, DOI: 10.1103/PhysRevD.88.056003
Abstract: Signals broadly compatible with light (7-10 GeV) dark matter have been reported in three direct detection experiments: CoGeNT, DAMA/LIBRA, and CDMS-II silicon. These possible signals have been interpreted in the context of spin-independent interactions between the target nuclei and dark matter, although there is tension with null results, particularly from xenon-based experiments. In this paper, we demonstrate that the CoGeNT and CDMS-II silicon results are also compatible assuming a spin-dependent neutron interaction, though this is in tension with xenon-based experiments and PICASSO. The tension with the null results from XENON100 and XENON10 is approximately the same as for the spin-independent coupling. All three experimental signals can be made compatible through a combination of spin-dependent interactions with both the proton and neutron, although such a scenario increases the conflict with the null results of other experiments.
Observation of the Dependence of Scintillation from Nuclear Recoils in Liquid Argon on Drift Field
T. Alexander,H. O. Back,H. Cao,A. G. Cocco,F. DeJongh,G. Fiorillo,C. Galbiati,C. Ghag,L. Grandi,C. Kendziora,W. H. Lippincott,B. Loer,C. Love,L. Manenti,C. J. Martoff,Y. Meng,D. Montanari,P. Mosteiro,D. Olvitt,S. Pordes,H. Qian,B. Rossi,R. Saldanha,W. Tan,J. Tatarowicz,S. Walker,H. Wang,A. W. Watson,S. Westerdale,J. Yoo
Physics , 2013, DOI: 10.1103/PhysRevD.88.092006
Abstract: We have exposed a dual-phase Liquid Argon Time Projection Chamber (LAr-TPC) to a low energy pulsed narrowband neutron beam, produced at the Notre Dame Institute for Structure and Nuclear Astrophysics to study the scintillation light yield of recoiling nuclei in a LAr-TPC. A liquid scintillation counter was arranged to detect and identify neutrons scattered in the LAr-TPC target and to select the energy of the recoiling nuclei. We report the observation of a significant dependence on drift field of liquid argon scintillation from nuclear recoils of 11 keV. This observation is important because, to date, estimates of the sensitivity of noble liquid TPC dark matter searches are based on the assumption that electric field has only a small effect on the light yield from nuclear recoils.
Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon
H. Cao,T. Alexander,A. Aprahamian,R. Avetisyan,H. O. Back,A. G. Cocco,F. DeJongh,G. Fiorillo,C. Galbiati,L. Grandi,Y. Guardincerri,C. Kendziora,W. H. Lippincott,C. Love,S. Lyons,L. Manenti,C. J. Martoff,Y. Meng,D. Montanari,P. Mosteiro,D. Olvitt,S. Pordes,H. Qian,B. Rossi,R. Saldanha,S. Sangiorgio,K. Siegl,S. Y. Strauss,W. Tan,J. Tatarowicz,S. Walker,H. Wang,A. W. Watson,S. Westerdale,J. Yoo
Physics , 2014, DOI: 10.1103/PhysRevD.91.092007
Abstract: We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. We also report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from $^{83m}$Kr internal conversion electrons is comparable to that from $^{207}$Bi conversion electrons, we obtained the numbers of excitons ($N_{ex}$) and ion pairs ($N_i$) and their ratio ($N_{ex}/N_i$) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.
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