35 research outputs found
Measurement of the Positive Muon Anomalous Magnetic Moment to 0.46 ppm
We present the first results of the Fermilab Muon g-2 Experiment for the
positive muon magnetic anomaly . The anomaly is
determined from the precision measurements of two angular frequencies.
Intensity variation of high-energy positrons from muon decays directly encodes
the difference frequency between the spin-precession and cyclotron
frequencies for polarized muons in a magnetic storage ring. The storage ring
magnetic field is measured using nuclear magnetic resonance probes calibrated
in terms of the equivalent proton spin precession frequency
in a spherical water sample at 34.7C. The
ratio , together with known fundamental
constants, determines
(0.46\,ppm). The result is 3.3 standard deviations greater than the standard
model prediction and is in excellent agreement with the previous Brookhaven
National Laboratory (BNL) E821 measurement. After combination with previous
measurements of both and , the new experimental average of
(0.35\,ppm) increases the
tension between experiment and theory to 4.2 standard deviationsComment: 10 pages; 4 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
A concept of a spacecraft with small initial mass placed in the near-earth orbit by a laser rocket engine
On the possibility for laboratory simulation of generation of Alfvén disturbances in magnetic tubes in the solar atmosphere
The paper deals with generation of AlfvĂ©n plasma disturbances in magnetic flux tubes through exploding laser plasma in magnetized background plasma. Processes with similar effect of excitation of torsion-type waves seem to provide energy transfer from the solar photosphere to the corona. The studies were carried out at experimental stand KI-1 representing a high-vacuum chamber 1.2 m in diameter, 5 m in length, external magnetic field up to 500 G along the chamber axis, and up to 2·10â6 Torr pressure in operating mode. Laser plasma was produced when focusing the CO2 laser pulse on a flat polyethylene target, and then the laser plasma propagated in Ξ-pinch background hydrogen (or helium) plasma. As a result, the magnetic flux tube 15â20 cm in radius was experimentally simulated along the chamber axis and the external magnetic field direction. Also, the plasma density distribution in the tube was measured. AlfvĂ©n wave propagation along the magnetic field was registered from disturbance of the magnetic field transverse component BÏ and field-aligned current Jz. The disturbances propagate at a near-AlfvĂ©n velocity 70â90 km/s and they are of left-hand circular polarization of the transverse component of magnetic field. Presumably, the AlfvĂ©n wave is generated by the magnetic laminar mechanism of collisionless interaction between laser plasma cloud and background. A right-hand polarized high-frequency whistler predictor was registered which propagated before the AlfvĂ©n wave at a velocity of 300 km/s. The polarization direction changed with the AlfvĂ©n wave coming. Features of a slow magnetosonic wave as a sudden change in background plasma concentration along with simultaneous displacement of the external magnetic field were found. The disturbance propagates at ~20â30 km/s velocity, which is close to that of ion sound at low plasma beta value. From preliminary estimates, the disturbance transfers about 10 % of the original energy of laser plasma
Reserves for raising labour productivity in blast-furnace practice
Translated from Stal' (1980) (pt.4) p. 338-340LD:5828.4F(M--26188) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Effect of a combination of arterial hypertension and insulin resistance on hemostasis activity
Lasting existence of arterial hypertension in combination with insulin-resistance inevitably disturbs functioning of all the hemostasis elements. Weakening of vascular control over platelets' aggregation, hemocoagulation and fibrinolysis is noted in these conditions. Production lowering of substances with thrombo-resistant properties in vessels, increase of endothelium permeability for macromolecules, accumulation of lipoproteins in vascular wall, adhesion of platelets and leucocytes to it lie in the basis of it. Patients with arterial hypertension and insulin-resistance are characterized by platelets' activation leading to the increase of circulating platelets with changed surface structure in blood and their aggregates. In the given category of patients it is caused by the increased content of biologically active substances in platelets and number increase of different receptors on their surface, including fibrinogen. Combination of arterial hypertension with insulin-resistance inevitably disturbs functioning of coagulative component of hemostasis system - the content of fibrinogen, VII, VIII, IX factors of coagulation, von Willebrand's Factor increases in blood at activity lowering of antithrombin III, protein C and protein S. The complexity of hemostasiopathy in arterial hypertension and insulin resistance dictate the need to continue the search for therapeutic approaches which can balance thrombophilia and simultaneously affect all the components of the hemostatic system