Tests of gases in a mini-TPC with pixel chip readout Vahsen, S.; Oliver-Mallory, K.; Lopez-Thibodeaux, M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
02/2014, Volume:
738
Journal Article
Peer reviewed
Gases for potential use as targets for directional dark matter detection were tested in a prototype detector using two sequential Gas Electron Multipliers, or GEMs. The sensitive volume consists of a ...mini-TPC of 12cm length and 7.5cm diameter. An FEI3 pixel chip, developed for the ATLAS experiment, was used to produce spatial measurements with high resolution. An Fe55 source produced photoelectrons by X-ray conversions in the sensitive volume, and images of these were recorded by the chip. Spatial resolution plots are shown for the gases, which include the practical electron range of the photoelectrons and the effects of diffusion in the mini-TPC. Avalanche gain and gain resolution measurements were made for the four gases tested, at atmospheric and sub-atmospheric pressures: Ar(70)/CO2(30), CF4, He(80)/CF4(20) and He(80)/isobutane(20).
The Directional Dark Matter Detector (D3) Vahsen, S.E.; Feng, H.; Garcia-Sciveres, M. ...
EAS publications series,
2012, 2012-00-00, 20120101, Volume:
53
Journal Article
Open access
Gas-filled Time Projection Chambers (TPCs) with Gas Electron Multipliers (GEMs) and pixels appear suitable for direction-sensitive WIMP dark matter searches. We present the background and motivation ...for our work on this technology, past and ongoing prototype work, and a development path towards an affordable, 1-m3-scale directional dark matter detector, D3. Such a detector may be particularly suitable for low-mass WIMP searches, and perhaps sufficiently sensitive to clearly determine whether the signals seen by DAMA, CoGeNT, and CRESST-II are due to low-mass WIMPs or background.
Determination of Z coordinate from track width in MiniTPC Feng, D.C.; Garcia-Sciveres, M.; Kadyk, J.A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2017, Volume:
851
Journal Article
Peer reviewed
A gas-filled Time Projection Chamber and a radioactive neutron source were used to study recoil tracks produced by scattering of the multi-MeV neutrons on gas nuclei. Since the event readout is ...triggered by the first electron arrival, the initial time and position in the electron drift direction are unknown, leading to a translational uncertainty in this direction. By using the track width due to electron diffusion, the coordinate along the drift direction was determined. With a suitable width calibration at a known drift distance, it is found that width measurements of the track can provide useful information for establishing a well-defined gas fiducial volume for the interactions. The coordinate determination is also sufficiently precise that it can be used as a third parameter in kinematic reconstruction of the neutron collision, providing improved knowledge of the neutron collision process. Despite a wide range of track ionization levels resulting from the broad spectrum of neutron energies and varying angles of scatter, the coordinate determination is not sensitive to the track ionization.
The measurement of the direction of WIMP-induced nuclear recoils is a compelling but technologically challenging strategy to provide an unambiguous signature of the detection of Galactic dark matter. ...Most directional detectors aim to reconstruct the dark-matter-induced nuclear recoil tracks, either in gas or solid targets. The main challenge with directional detection is the need for high spatial resolution over large volumes, which puts strong requirements on the readout technologies. In this paper we review the various detector readout technologies used by directional detectors. In particular, we summarize the challenges, advantages and drawbacks of each approach, and discuss future prospects for these technologies.
3-D tracking in a miniature time projection chamber Vahsen, S.E.; Hedges, M.T.; Jaegle, I. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2015, Volume:
788, Issue:
C
Journal Article
Peer reviewed
Open access
The three-dimensional (3-D) detection of millimeter-scale ionization trails is of interest for detecting nuclear recoils in directional fast neutron detectors and in direction-sensitive searches for ...weakly interacting massive particles (WIMPs), which may constitute the Dark Matter of the universe. We report on performance characterization of a miniature gas target Time Projection Chamber (TPC) where the drift charge is avalanche-multiplied with Gas Electron Multipliers (GEMs) and detected with the ATLAS FE-I3 Pixel Application Specific Integrated Circuit (ASIC). We report on measurements of gain, gain resolution, point resolution, diffusion, angular resolution, and energy resolution with low-energy X-rays, cosmic rays, and alpha particles, using the gases Ar:CO2 (70:30) and He:CO2 (70:30) at atmospheric pressure. We discuss the implications for future, larger directional neutron and Dark Matter detectors. With an eye to designing and selecting components for these, we generalize our results into analytical expressions for detector performance whenever possible. We conclude by demonstrating the 3-D directional detection of a fast neutron source.
The DIRC is a new type of Cherenkov ring imaging detector, to be used for particle identification in the BaBar detector. The basic concept of DIRC is explained and the design for its use in BaBar is ...described here. Beam tests have been performed using a prototype DIRC detector and the results are consistent with earlier cosmic ray tests and with Monte Carlo simulations, showing that the DIRC as designed is quite adequate for the particle identification demands of the BaBar experiment. The photon yield parameter, NO, was measured to be (143±8) /cm, neglecting attenuation in the DIRC bar, which was measured to be (4.1 ±0.7)%/meter.
Electron avalanches in liquid argon mixtures Kim, J.G.; Dardin, S.M.; Kadel, R.W. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2004, Volume:
534, Issue:
3
Journal Article
Peer reviewed
Open access
We have observed stable avalanche gain in liquid argon when mixed with small amounts of xenon (xe) in the high electric field (
>
7
MV/cm) near the point of a chemically etched needle in a ...point–plane geometry. We identify two gain mechanisms, one pressure dependent, and the other independent of the applied pressure. We conclude that the pressure-dependent signals are from avalanche gain in gas bubbles at the tip of the needle, while the pressure-independent pulses are from avalanche gain in liquid. We measure the decay time spectra of photons from both types of avalanches. The decay times from the pressure-dependent pulses decrease (increase) with the applied pressure (high voltage), while the decay times from the pressure-independent pulses are approximately independent of pressure or high voltage. For our operating conditions, the collected charge distribution from avalanches is similar for 60 or 122
keV photon sources. With krypton additives, instead of Xe, we measure behavior consistent with only the pressure-dependent pulses. Neon and TMS were also investigated as additives, and designs for practical detectors were tested.
In a study of B+ --> J/psi gamma K+ decays, we find evidence for the radiative decay X(3872) --> J/psi gamma with a statistical significance of 3.4 sigma. We measure the product of branching ...fractions BF(B+ --> X(3872) K+).BF(X(3872) --> J/psi gamma) = (3.3 +/- 1.0 +/- 0.3) x 10^-6, where the uncertainties are statistical and systematic, respectively. We also measure the branching fraction BF(B+ --> chi_c1 K+) = (4.9 +/- 0.2 +/- 0.4) x 10^-4. These results are obtained from (287+/-3) million BBar decays collected at the Y(4S) resonance with the BaBar detector at the PEP-II B Factory at SLAC.
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