71 research outputs found
Measurement of Cosmic-ray Muon-induced Spallation Neutrons in the Aberdeen Tunnel Underground Laboratory
AbstractMuon-induced neutrons are one of the major backgrounds to various underground experiments, such as dark matter searches, low-energy neutrino oscillation experiments and neutrino-less double beta-decay experiments. Previous experiments on the underground production rate of muon-induced neutrons were mostly carried out either at shallow sites or at very deep sites. The Aberdeen Tunnel experiment aims to measure the neutron production rate at a moderate depth of 611 meters water equivalent. Our apparatus comprises of six layers of plastic-scintillator hodoscopes for tracking the incident cosmic-ray muons, and 760 L of gadolinium-doped liquid-scintillator for both neutron production and detection targets. In this paper, we describe the design and the performance of the apparatus. The preliminary result on the measurement of neutron production rate is also presented
CP Violation in Hyperon Nonleptonic Decays within the Standard Model
We calculate the CP-violating asymmetries A(Lambda_-^0) and A(Xi_-^-) in
nonleptonic hyperon decay within the Standard Model using the framework of
heavy-baryon chiral perturbation theory (chiPT). We identify those terms that
correspond to previous calculations and discover several errors in the existing
literature. We present a new result for the lowest-order (in chiPT)
contribution of the penguin operator to these asymmetries, as well as an
estimate for the uncertainty of our result that is based on the calculation of
the leading nonanalytic corrections.Comment: 21 pages, 2 figures; discussion clarified, results & conclusions
unchanged, to appear in Phys. Rev.
New Physics and CP Violation in Hyperon Nonleptonic Decays
The sum of the CP-violating asymmetries A(Lambda_-^0) and A(Xi_-^-) in
hyperon nonleptonic decays is presently being measured by the E871 experiment.
We evaluate contributions to the asymmetries induced by chromomagnetic-penguin
operators, whose coefficients can be enhanced in certain models of new physics.
Incorporating recent information on the strong phases in Xi->Lambda pi decay,
we show that new-physics contributions to the two asymmetries can be
comparable. We explore how the upcoming results of E871 may constrain the
coefficients of the operators. We find that its preliminary measurement is
already better than the epsilon parameter of K-Kbar mixing in bounding the
parity-conserving contributions.Comment: 12 pages, 2 figure
Highly-parallelized simulation of a pixelated LArTPC on a GPU
The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype
The DUNE far detector vertical drift technology. Technical design report
DUNE is an international experiment dedicated to addressing some of the questions at the forefront of particle physics and astrophysics, including the mystifying preponderance of matter over antimatter in the early universe. The dual-site experiment will employ an intense neutrino beam focused on a near and a far detector as it aims to determine the neutrino mass hierarchy and to make high-precision measurements of the PMNS matrix parameters, including the CP-violating phase. It will also stand ready to observe supernova neutrino bursts, and seeks to observe nucleon decay as a signature of a grand unified theory underlying the standard model. The DUNE far detector implements liquid argon time-projection chamber (LArTPC) technology, and combines the many tens-of-kiloton fiducial mass necessary for rare event searches with the sub-centimeter spatial resolution required to image those events with high precision. The addition of a photon detection system enhances physics capabilities for all DUNE physics drivers and opens prospects for further physics explorations. Given its size, the far detector will be implemented as a set of modules, with LArTPC designs that differ from one another as newer technologies arise. In the vertical drift LArTPC design, a horizontal cathode bisects the detector, creating two stacked drift volumes in which ionization charges drift towards anodes at either the top or bottom. The anodes are composed of perforated PCB layers with conductive strips, enabling reconstruction in 3D. Light-trap-style photon detection modules are placed both on the cryostat's side walls and on the central cathode where they are optically powered. This Technical Design Report describes in detail the technical implementations of each subsystem of this LArTPC that, together with the other far detector modules and the near detector, will enable DUNE to achieve its physics goals
Recommended from our members
An experimental review of hyperon magnetic moments
Hyperon magnetic moments are important probes for studying the structure of baryons. In this talk, I shall briefly describe how the measurements are made and discuss the current status of the determinations
Recommended from our members
Polarization of {Omega}{sup -} Hyperons Produced in 800 GeV Proton-Beryllium Collisions
- âŠ