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.
We present our most recent work on the use of integrated silicon pixel electronics to read out gas-filled Time Projection Chambers (TPCs). Such detectors have great promise to measure the direction ...and energy of neutral particles via nuclear recoils that ionize the gas. We report on ongoing studies and refinement of the first prototype constructed at the University of Hawaii. We present data on the detection of alpha particles and fast neutrons using Ar:CO2 (70:30) and He:CO2 (70:30) gas, respectively. We also present plans and sensitivity estimates for a future Dark Matter search based on the technology under study.
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
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.
Preliminary simulation and optimization studies of the Directional Dark Matter Detector and the Directional Neutron Observer are presented. These studies show that the neutron interaction with the ...gas-target in these detectors is treated correctly by GEANT4 and that by lowering the pressure, the sensitivity to low-mass WIMP candidates is increased. The use of negative ion drift might allow us to search the WIMP mass region suggested by the results of the non-directional experiments DAMA/LIBRA, CoGeNT and CRESST-II.
We present the results of an amplitude analysis of B¯0→J/ψK-π+ decays. A new charged charmoniumlike state Zc(4200)+ decaying to J/ψπ+ is observed with a significance of 6.2σ. The mass and width of ...the Zc(4200)+ are 4196+31-29+17-13 MeV/c2 and 370+70-70+70-132 MeV, respectively; the preferred assignment of the quantum numbers is JP=1+. In addition, we find evidence for Zc(4430)+→J/ψπ+. The analysis is based on a 711 fb-1 data sample collected by the Belle detector at the asymmetric-energy e+e- collider KEKB.
We report the first observation of the decay Λ+c→pK+π- using a 980 fb-1 data sample collected by the Belle detector at the KEKB asymmetric-energy e+e- collider. This is the first observation of a ...doubly Cabibbo-suppressed decay of a charmed baryon. We measure the branching ratio of this decay with respect to its Cabibbo-favored counterpart to be B(Λ+c→pK+π-)/B(Λ+c→pK-π+)=(2.35±0.27±0.21)×10-3, where the uncertainties are statistical and systematic, respectively.
We report a measurement of the differential cross section of π^0 pair production in single-tag two-photon collisions, y*y->π^0π^0, in e+e- scattering. The cross section is measured for Q^2up to 30 ...GeV^2 is the negative of the invariant mass squared of the tagged photon
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