262 research outputs found
Free electron lasers driven by linear induction accelerators: High power radiation sources
The technology of Free Electron Lasers (FELs) and linear induction accelerators (LIAs) is addressed by outlining the following topics: fundamentals of FELs; basic concepts of linear induction accelerators; the Electron Laser Facility (a microwave FEL); PALADIN (an infrared FEL); magnetic switching; IMP; and future directions (relativistic klystrons). This presentation is represented by viewgraphs only
DM-like anomalies in neutron multiplicity spectra
Publisher Copyright: © 2022 Institute of Physics Publishing. All rights reserved.A new experiment collects data, since November 2019, at a depth of 210 m.w.e. in the Callio Lab in the Pyhasalmi mine in Finland. The setup, called NEMESIS (New Emma MEasurementS Including neutronS), incorporates infrastructure from the EMMA experiment with neutron and large-area plastic scintillator detectors. The experiment's primary aim is to combine muon tracking with position-sensitive neutron detection to measure precision yields, multiplicities, and lateral distributions of high-multiplicity neutron events induced by cosmic muons in various materials. The data are relevant for background evaluation of the deep-underground searches for Dark Matter (DM), neutrino-less double beta decay, etc. Preliminary analysis revealed anomalies in muon-suppressed neutron multiplicity spectra collected during a 344-day run (live time) with a 565 kg Pb target. The spectra, otherwise well described by an exponential fit, show three peaks at high multiplicities. Although still at a low statistical significance, these small excesses match the outcome of an earlier measurement. The nature of the anomalies remains unclear, but, in principle, they may be a signature of self-annihilation of a WIMP with a mass close to 13 GeV/c2. With that assumption, the expected cross-section would be around 10-42 cm2 for Spin-Dependent or 10-46 cm2 for Spin Independent interactions. We propose verifying this hypothesis with an upgraded NEMESIS experiment, able to collect an order of magnitude more data than this measurement. Based on the statistical uncertainty, analysis of the event rate indicates that cross-section limits for DM mass range of approximately 3-40 GeV/c2 can be investigated with such a setup.Peer reviewe
New NEMESIS Results
Funding Information: This work has been supported in part by the EU INTERREG for the Baltic Sea programme within the BSUIN project, and by the Polish Ministry of Science and Higher Education (Grant no. Funding Information: This work has been supported in part by the EU INTERREG for the Baltic Sea programme within the BSUIN project, and by the Polish Ministry of Science and Higher Education (Grant no. 3988/INTERREG BSR/2018/2). Publisher Copyright: © Copyright owned by the author(s) under the terms of the Creative Commons.Preliminary results from a 349-day run (live time) with a 565 kg Pb target and a 166-day background measurement are presented. Three minor anomalies were detected in muon-suppressed neutron multiplicity spectra. The multiplicities of these small excesses match the outcome of an earlier, similar but independent measurement. The nature of the anomalies remains unclear, but, in principle, they may be a signature of self-annihilation of a Weakly Interacting Massive Particle (WIMP) with a mass around 10 GeV/c2. If our interpretation is correct, the expected cross section would be of the order of 10-42 cm2 for Spin Dependent and 10-46 cm2 for Spin Independent interactions. Analysis of the event rate, based on the statistical uncertainty, indicates that cross-section limits for Dark Matter (DM) mass range of approximately 3-40 GeV/c2 can be investigated with an upgraded NEMESIS setup.Peer reviewe
NEMESIS setup for Indirect Detection of WIMPs
We summarize the evidence for DM-like anomalies in neutron multiplicity spectra collected underground with Pb targets by three independent experiments: NEMESIS (at 210 m.w.e.) NMDS (at 583 m.w.e.), and ZEPLIN-II (at 2850 m.w.e.). A new analysis shows small but persistent anomalies at high neutron multiplicities. Adjusted for differences in detection efficiencies, the positions of the anomalies are consistent between the three systems. Also, the intensities match when corrected for the acquisition time and estimated detection efficiency. While the three measurements are inconclusive when analyzed separately, together, they exclude a statistical fluke to better than one in a million. To prove the existence of the anomalies above the 5-sigma discovery threshold, we propose to upgrade the current NEMESIS setup. The upgrade concept and the critical components of the new experiment are described. The upgraded setup would already acquire the needed data sample during the first year of operation. Additional information, vital for the physics interpretation of the analysis, will be obtained with a Cu target.Peer reviewe
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Explosively driven facture and fragmentation of metal cylinders and rings
Cylinders and rings fabricated from AerMet{reg_sign} 100 alloy and AISI 1018 steel have been explosively driven to fragmentation in order to determine the fracture strains for these materials under plane strain and uniaxial stress conditions. The phenomena associated with the dynamic expansion and subsequent break up of the cylinders are monitored with high-speed diagnostics. In addition, complementary experiments are performed in which fragments from the explosively driven cylinder are recovered and analyzed to determine the statistical distribution associated with the fragmentation process as well as to determine failure mechanisms. The data are used to determine relevant coefficients for the Johnson-Cook (Hancock-McKenzie) fracture model. Metallurgical analysis of the fragments provides information on damage and failure mechanisms
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Adiabatic shear band formation in explosively driven AerMet-100 alloy cylinders
Two differently heat-treated AerMet-100 alloy cylinders were explosively driven to fragmentation. Soft-captured fragments were studied to characterize the deformation and damage induced by high explosive loading. The characterization of the fragments reveals that the dominant failure mechanism appears to be dynamic fracture along adiabatic shear bands. These shear bands differ in size and morphology depending on the heat-treated conditions. Nanoindentation measurements of the adiabatic shear bands in either material condition indicate higher hardness in the bands compared to the matrix regions of the fragments
Phase separation transition in liquids and polymers induced by electric field gradients
Spatially uniform electric fields have been used to induce instabilities in
liquids and polymers, and to orient and deform ordered phases of
block-copolymers. Here we discuss the demixing phase transition occurring in
liquid mixtures when they are subject to spatially nonuniform fields. Above the
critical value of potential, a phase-separation transition occurs, and two
coexisting phases appear separated by a sharp interface. Analytical and
numerical composition profiles are given, and the interface location as a
function of charge or voltage is found. The possible influence of demixing on
the stability of suspensions and on inter-colloid interaction is discussed.Comment: 7 pages, 3 figures. Special issue of the J. Phys. Soc. Ja
The BSUIN project
Baltic Sea Underground Innovation Network (BSUIN) is an European Union funded project that
extends capabilities of underground laboratories. The aim of the project is to join efforts in making
the underground laboratories in the Baltic Sea Region’s more accessible for innovation, business
development and science by improving the availability of information about the underground
facilities, service offerings, user experience, safety and marketing.The development of standards
for the characterization of underground laboratories will allow to compared them with each other.
This will help you choose the best places for physical measurements such as neutrino physics or
searching for dark matter. The project concerns laboratories where so far no measurements have
been made, and even undergrounds where there are no organized laboratories yet.The description
of the BSUIN project and the first results of characterization of natural radioactive background in
underground laboratories will be presented Ë™ The BSUIN Project is funded by Interreg Baltic Sea
funding cooperation [2]
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Strongly-driven laser plasma coupling
An improved understanding of strongly-driven laser plasma coupling is important for optimal use of the National Ignition Facility (NIF) for both inertial fusion and for a variety of advanced applications. Such applications range from high energy x- ray sources and high temperature hohlraums to fast ignition and laser radiography. We discuss a novel model for the scaling of strongly-driven stimulated Brillouin and Raman scattering. This model postulates an intensity dependent correlation length associated with spatial incoherence due to filamentation and stimulated forward scattering. We first motivate the model and then relate it to a variety of experiments. Particular attention is paid to high temperature hohlraum experiments, which exhibited low to modest stimulated Brillouin scattering even though this instability was strongly driven. We also briefly discuss the strongly nonlinear interaction physics for efficient generation of high energy electrons either _ by irradiating a large plasma with near quarter-critical density or by irradiating overdense targets with ultra intense lase
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Characterization of X-ray streak cameras for use on Nova
There are many different types of measurements that require a continuous time history of x-ray emission that can be provided with an x-ray streak camera. In order to properly analyze the images that are recorded with the x-ray streak cameras operated on Nova, it is important to account for the streak characterization of each camera. We have performed a number of calibrations of the streak cameras both on the bench as well as with Nova disk target shots where we use a time modulated laser intensity profile (self-beating of the laser) an the target to generate an x-ray comb. We have measured the streak camera sweep direction and spatial offset, curvature of the electron optics, sweep rate, and magnification and resolution of the electron optics
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