798 research outputs found
Field dependence of electronic recoil signals in a dual-phase liquid xenon time projection chamber
We present measurements of light and charge signals in a dual-phase time
projection chamber at electric fields varying from 10 V/cm up to 500 V/cm and
at zero field using 511 keV gamma rays from a Na source. We determine
the drift velocity, electron lifetime, diffusion constant, and light and charge
yields at 511 keV as a function of the electric field. In addition, we fit the
scintillation pulse shape to an effective exponential model, showing a decay
time of 43.5 ns at low field that decreases to 25 ns at high fields.Comment: 14 pages, 8 figure
Vertex reconstruction algorithms in the PHOBOS experiment at RHIC
The PHOBOS experiment at the Relativistic Heavy Ion Collider (RHIC) at
Brookhaven National Laboratory is studying interactions of heavy nuclei at the
largest energies available in the laboratory. The high multiplicity of
particles created in heavy ion collisions makes precise vertex reconstruction
possible using information from a spectrometer and a specialized vertex
detector with relatively small acceptances. For lower multiplicity events, a
large acceptance, single layer multiplicity detector is used and special
algorithms are developed to reconstruct the vertex, resulting in high
efficiency at the expense of poorer resolution. The algorithms used in the
PHOBOS experiment and their performance are presented.Comment: presented at the Workshop on Tracking In high Multiplicity
Environments, TIME0
Symmetry energy dependence of light fragment production in heavy-ion collisions
The pre-equilibrium light cluster emission in low to intermediate energy heavy ion collisions is a way to obtain information about the density and momentum dependence of the nuclear symmetry potential, i.e. about the stiffness of the symmetry energy and the neutron-proton effective mass splitting. We study the n/p and t/3He ratios as a function of the energy of the emitted particles and find that these allow to disentangle these two aspects of the symmetry energy. The t/3He ratios are found to carry similar information as the n/p ratios, making this a promising option for experimental investigations. More n-rich systems enhance the sensitivity to the symmetry energy, while double ratios between n-rich and n-poor systems tend to reduce it
Neutrino CP violating parameters from nontrivial quark-lepton correlation: a S3xGUT model
We investigate the prediction on the lepton phases in theories with a non
trivial correlation between quark (CKM) and lepton (PMNS) mixing matrices. We
show that the actual evidence, under the only assumption that the correlation
matrix product of and has a zero in the entry , gives
us a prediction for the three CP-violating invariants , , and . A
better determination of the lepton mixing angles will give a strong prediction
of the CP-violating invariants in the lepton sector. These will be tested in
the next generation experiments. To clarify how our prediction works, we show
how a model based on a Grand Unified Theory and the permutation flavor symmetry
predicts .Comment: 7 pages, 3 figures. V2: new figure adde
Monte Carlo Simulation Variance Reduction Techniques for Photon Transport in Liquid Xenon Detectors
Monte Carlo simulations are a crucial tool for the analysis and prediction of
various background components in liquid xenon (LXe) detectors. With improving
shielding in new experiments, the simulation of external backgrounds, such as
induced by gamma rays from detector materials, gets more computationally
expensive. We introduce and validate an accelerated Monte Carlo simulation
technique for photon transport in liquid xenon detectors. The method simulates
photon-induced interactions within a defined geometry and energy range with
high statistics while interactions outside of the region of interest are not
simulated directly but are taken into account by means of probability weights.
For a simulation of gamma induced backgrounds in an exemplary detector geometry
we achieve a three orders of magnitude acceleration compared to a standard
simulation of a current ton-scale LXe dark matter experiment
Complementarity of direct detection experiments in search of light Dark Matter
Dark Matter experiments searching for Weakly interacting massive particles
(WIMPs) primarily use nuclear recoils (NRs) in their attempt to detect WIMPs.
Migdal-induced electronic recoils (ERs) provide additional sensitivity to light
Dark Matter with masses. In this work, we use
Bayesian inference to find the parameter space where future detectors like
XENONnT and SuperCDMS SNOLAB will be able to detect WIMP Dark Matter through
NRs, Migdal-induced ERs or a combination thereof. We identify regions where
each detector is best at constraining the Dark Matter mass and spin independent
cross-section and infer where two or more detection configurations are
complementary to constraining these Dark Matter parameters through a combined
analysis.Comment: 19 pages, 7 figure
Precision measurements of the scintillation pulse shape for low-energy recoils in liquid xenon
We present measurements of the scintillation pulse shape in liquid xenon for
nuclear recoils (NR) and electronic recoils (ER) at electric fields of 0 to 0.5
kV/cm for energies 15 keV and 70 keV electron-equivalent, respectively.
The average pulse shapes are well-described by an effective model with two
exponential decay components, where both decay times are fit parameters. We
find significant broadening of the pulse for ER due to delayed luminescence
from the recombination process. In addition to the effective model, we fit a
model describing the recombination luminescence for ER at zero field and obtain
good agreement. We estimate the best performance of a combined S2/S1 and pulse
shape ER/NR discrimination and show that even with 2 ns time resolution, the
improvement over S2/S1 discrimination alone is marginal, so that pulse shape
discrimination will likely not be useful for future dual-phase liquid xenon
experiments looking for elastic dark matter recoil interactions
Flux profile scanners for scattered high-energy electrons
The paper describes the design and performance of flux integrating Cherenkov
scanners with air-core reflecting light guides used in a high-energy, high-flux
electron scattering experiment at the Stanford Linear Accelerator Center. The
scanners were highly radiation resistant and provided a good signal to
background ratio leading to very good spatial resolution of the scattered
electron flux profile scans.Comment: 22 pages, 17 figure
GridPix application to dual phase TPC
GridPix is a gas-filled detector with an aluminium mesh stretched 50 ÎĽm above the Timepix CMOS pixel chip. This defines a high electric field where gas amplification occurs. A feasibility study is ongoing at Nikhef for the application of the GridPix technology as a charge sensitive device in a dual phase noble gas Time Projection Chamber (TPC), within the framework of the DARWIN design study for next generation dark matter experiments. The smallness of the device and well defined materials allow for high radio-purity and low outgassing. The high granularity of a pixel readout and the high detection efficiency of single electrons of GridPix bring benefits especially in terms of energy resolution for small energy deposits. This feature is interesting also for the measurement of the scintillation yield and the ionisation yield of noble liquids. The accurate measurements of such quantities have a direct impact on the data interpretation of dark matter experiments. The application in dual phase argon or xenon TPCs implies several technological challenges, such as the survival of the device at cryogenic temperature as well as the operation in a pure noble gas atmosphere without discharges. We describe here the recent developments of the project
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