Walid A. Majid
A5033056860- Pulsars and Gravitational Waves Research
- Radio Astronomy Observations and Technology
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Particle physics theoretical and experimental studies
- Astronomy and Astrophysical Research
- Quantum Chromodynamics and Particle Interactions
- Astronomical Observations and Instrumentation
- GNSS positioning and interference
- Planetary Science and Exploration
- High-Energy Particle Collisions Research
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- Advanced Frequency and Time Standards
- Inertial Sensor and Navigation
- Superconducting Materials and Applications
- Geophysics and Sensor Technology
- Superconducting and THz Device Technology
- High-pressure geophysics and materials
- Astro and Planetary Science
- Space Science and Extraterrestrial Life
- Particle Detector Development and Performance
- Earthquake Detection and Analysis
Jet Propulsion Laboratory
2015-2024
California Institute of Technology
2011-2023
Institute of Navigation
2019
United States Naval Research Laboratory
2011
University of Tasmania
2011
Yale University
1999-2010
Leibniz University Hannover
2005
University of Illinois Urbana-Champaign
1993-2004
We report on NICER observations of the Magnetar SGR~1935+2154, covering its 2020 burst storm and long-term persistent emission evolution up to $\sim90$ days post outburst. During first 1120~seconds taken April 28 00:40:58 UTC we detect over 217 bursts, corresponding a rate $>0.2$ bursts s$^{-1}$. Three hours later is at 0.008 s$^{-1}$, remaining comparatively low level thereafter. The $T_{90}$ duration distribution peaks 840~ms; waiting times next fit with log-normal an average 2.1 s. 1-10...
We present the detection of a bright radio burst at frequencies between 2.2--2.3 GHz with NASA Deep Space Network (DSN) 70 m dish (DSS-63) in Madrid, Spain from FRB~20200120E. This repeating fast (FRB) was recently discovered by Canadian Hydrogen Intensity Mapping Experiment Fast Radio Burst (CHIME/FRB) instrument and reported to be associated M81 spiral galaxy distance 3.6 Mpc. The high time resolution capabilities recording system used this observation, together small amount scattering...
Abstract We are developing a purely commensal survey experiment for fast (<5 s) transient radio sources. Short-timescale transients associated with the most energetic and brightest single events in Universe. Our objective is to cover enormous volume of parameter space made available by ASKAP, an unprecedented combination sensitivity field view. Fast timescale open new vistas on physics high brightness temperature emission, extreme states matter strong gravitational fields. In addition,...
We report experimental details and results of a new measurement the decay K+→π+π−e+νe(Ke4). A sample more than 400,000Ke4 events with low background has been collected by Experiment 865 at Brookhaven Alternate Gradient Synchrotron. From these data, branching ratio (4.11±0.01±0.11)×10−5 ππ invariant mass dependence form factors F,G, H weak hadronic current as well phase shift difference δ00−δ11 for scattering were extracted. Using constraints based on analyticity chiral symmetry, value...
A search for lepton flavor violating decays, K+ --> mu+ pi-, e+ pi+ mu-, and pi0 was performed using the data collected in Experiment E865 at Brookhaven Alternating Gradient Synchrotron. No signal found any of decay modes. At 90% confidence level, branching ratios are less than 3.0x10(-9), 6.4x10(-10), 5. 2x10(-10), 5.0x10(-10), 3.4x10(-9), respectively.
ABSTRACT We present the discovery of FRB 20210410D with MeerKAT radio interferometer in South Africa, as part MeerTRAP commensal project. has a dispersion measure DM = 578.78 ± 2 ${\rm pc \, cm^{-3}}$ and was localized to subarcsec precision s images made from correlation data products. The localization enabled association an optical galaxy at z 0.1415, which when combined places it above 3σ scatter Macquart relation. attribute excess host after accounting for contributions Milky Way’s...
E865 at the Brookhaven National Laboratory AGS collected about 70 000 K(+)(e3) events to measure branching ratio relative observed K+-->pi(+)pi(0), K+-->pi(0)micro(+)nu, and K+-->pi(+)pi(0)pi(0) decays. The pi(0) in all decays was detected using e(+)e(-) pair from pi(0)-->e(+)e(-)gamma decay no photons were required. Using 2002 Particle Data Group ratios for normalization decays, we obtain BR(K(+)(e3(gamma)))=(5.13+/-0.02(stat)+/-0.09(syst)+/-0.04(norm))%, where K(+)(e3(gamma)) includes...
Recent discoveries of dispersed, non-periodic impulsive radio signals with single-dish telescopes have sparked significant interest in exploring the relatively uncharted space fast transient signals. Here we describe V-FASTR, an experiment to perform a blind search for using Very Long Baseline Array (VLBA). The runs entirely commensal mode, alongside normal VLBA observations and operations. It is made possible by features flexibility DiFX software correlator that used process data. Using...
We present the Spectroscopic Time-Resolving Observatory for Broadband Energy X-rays (STROBE-X), a probe-class mission concept selected study by NASA. It combines huge collecting area, high throughput, broad energy coverage, and excellent spectral temporal resolution in single facility. STROBE-X offers an enormous increase sensitivity X-ray timing, extending these techniques to extragalactic targets first time. is also agile capable of rapid response transient events, making it essential...
A low-background sample of 10 300 events has been collected for the decay mode ${K}^{+}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}{e}^{+}{e}^{\ensuremath{-}}$ by experiment E865 at Brookhaven Alternating Gradient Synchrotron. The branching ratio is measured to be $[2.94\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.13(\mathrm{syst})\ifmmode\pm\else\textpm\fi{}0.05(\mathrm{model})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}7}$, vector nature this...
We have carried out high frequency radio observations of the magnetic field pulsar PSR J1119-6127 following its recent X-ray outburst. While initial showed no evidence significant emission, subsequent detected pulsed emission across a large band. In this letter, we report on disappearance and prompt reactivation dramatic evolution over several months observation. The periodic pulse profile at S-band (2.3 GHz) after exhibits multi-component structure, while simultaneous X-band (8.4 shows...
We report on simultaneous radio and X-ray observations of the repeating fast burst source FRB 180916.J0158+65 using Canadian Hydrogen Intensity Mapping Experiment (CHIME), Effelsberg, Deep Space Network (DSS-14 DSS-63) telescopes Chandra Observatory. During 33 ks observations, we detect no bursts in overlapping Effelsberg or a single during CHIME/FRB transits. events excess background observations. These non-detections imply 5-$\sigma$ limit $<5\times10^{-10}$ erg cm$^{-2}$ for 0.5--10 keV...
Abstract We present results from observations of the Galactic Center magnetar, PSR J1745–2900, at 2.3 and 8.4 GHz with NASA Deep Space Network 70 m antenna, DSS-43. study magnetar’s radio profile shape, flux density, spectrum, single pulse behavior over a ∼1 year period between MJDs 57233 57621. In particular, magnetar exhibits significantly negative average spectral index <?CDATA $\langle \alpha \rangle =-1.86\pm 0.02$?> when is single-peaked, which flattens considerably double-peaked. have...
Based on results of a search for the lepton-family-number-violating decay K+→π+μ+e− with data collected by experiment E865 at Alternating Gradient Synchrotron Brookhaven National Laboratory, we place an upper limit branching ratio 2.1×10−11 (90% C.L.). Combining earlier and those previous experiment, E777, 1.3×10−11 C.L.) is obtained.3 MoreReceived 28 January 2005DOI:https://doi.org/10.1103/PhysRevD.72.012005©2005 American Physical Society
Experiment 865 at the Brookhaven Alternating Gradient Synchrotron obtained 410 K+→e+νe+e− and 2679 K+→μ+νe+e− events including 10% 19% background. The branching ratios were measured to be [2.48±0.14(stat)±0.14(syst)]×10−8 (mee>150 MeV) (7.06±0.16±0.26)×10−8 (mee>145 MeV), respectively. Results for decay form factors are presented.Received 5 April 2002DOI:https://doi.org/10.1103/PhysRevLett.89.061803©2002 American Physical Society
ABSTRACT The V-FASTR experiment on the Very Long Baseline Array was designed to detect dispersed pulses of milliseconds in duration, such as fast radio bursts (FRBs). We use all data through 2015 February report V-FASTR’s upper limits rates FRBs, and compare these with rederived from Parkes FRB detection experiments. operation at <?CDATA $\lambda =20\,{\rm{cm}}$?> allows direct comparison 20 cm rate, we derive a power-law limit $\gamma \lt -0.4$?> (95% confidence limit) index source counts,...
More than 400 K+-->pi(+)&mgr;(+)&mgr;(-) events were observed in a rare K+ decay experiment at the Brookhaven Alternating Gradient Synchrotron. Normalized to K+-->pi(+)pi(+)pi(-) decay, branching ratio is determined be [9.22+/-0.60(stat)+/-0. 49(syst)]x10(-8). This and &mgr;&mgr; mass spectrum very good agreement with measurement of K+-->pi(+)e(+)e(-) but deviates significantly from previous measurement.
XMM-Newton archival data for the Small Magellanic Cloud have been examined presence of previously undetected X-ray pulsars. One such pulsar, with a period 202 s, is detected. Its position consistent an early B star in SMC and we identify it as high mass binary (HMXB). In course this study determined pulse possible AXP CXOU J010043.1-721134 to be 8.0 correcting earlier report (Lamb et al 2002b) 5.4 s object. Pulse profiles spectra each these objects are presented well recently discovered...
Recent investigations reveal an important new class of transient radio phenomena that occur on submillisecond timescales. Often, surveys' data volumes are too large to archive exhaustively. Instead, online automatic system must excise impulsive interference and detect candidate events in real time. This work presents a case study using from multiple geographically distributed stations perform simultaneous excision detection. We present several algorithms incorporate dedispersed sites, report...
In this paper, autonomous pulsar-based spacecraft navigation is formulated in terms of a single nonlinear filter. The observability and the positioning accuracy traveling at known constant velocity are analyzed to build insights into general problem. A variation extended Kalman filter developed implemented track Poisson pulsar measurements collected by an orbiting spacecraft. This leverages multirate structure more efficiently process measurements. An alternative formulation using quadrature...
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We present the first results from V-FASTR experiment, a commensal search for fast transient radio bursts using Very Long Baseline Array (VLBA). is unique in that widely spaced VLBA antennas provide discriminant against non-astronomical signals and mechanism localization identification of events not possible with single dishes or short baseline interferometers. Thus far has accumulated over 1300 hours observation time VLBA, between 90 cm 3 mm wavelength (327 MHz - 86 GHz), providing limits on...