Zeeshan Ahmed
A5010461468- Superconducting and THz Device Technology
- Radio Astronomy Observations and Technology
- Cosmology and Gravitation Theories
- Dark Matter and Cosmic Phenomena
- Astrophysics and Cosmic Phenomena
- Geophysics and Gravity Measurements
- Particle physics theoretical and experimental studies
- Particle Detector Development and Performance
- Galaxies: Formation, Evolution, Phenomena
- Physics of Superconductivity and Magnetism
- Astronomy and Astrophysical Research
- Photonic and Optical Devices
- Microwave Engineering and Waveguides
- Computational Physics and Python Applications
- Radiation Detection and Scintillator Technologies
- Advanced Fiber Optic Sensors
- Radio Frequency Integrated Circuit Design
- Nuclear Physics and Applications
- Superconducting Materials and Applications
- Neutrino Physics Research
- Soil Moisture and Remote Sensing
- Atomic and Subatomic Physics Research
- Satellite Communication Systems
- Advanced Thermodynamic Systems and Engines
- Adaptive optics and wavefront sensing
SLAC National Accelerator Laboratory
2016-2025
Stanford University
2015-2025
Kavli Institute for Particle Astrophysics and Cosmology
2015-2024
Menlo School
2020-2024
Karachi Medical and Dental College
2022-2023
National University of Medical Sciences
2022-2023
Iqra University
2022-2023
Toronto East General Hospital
2023
Combined Military Hospital
2023
Northwest General Hospital and Research Center
2022
The Simons Observatory (SO) is a new cosmic microwave background experiment being built on Cerro Toco in Chile, due to begin observations the early 2020s. We describe scientific goals of experiment, motivate design, and forecast its performance. SO will measure temperature polarization anisotropy six frequency bands: 27, 39, 93, 145, 225 280 GHz. initial configuration have three small-aperture 0.5-m telescopes (SATs) one large-aperture 6-m telescope (LAT), with total 60,000 cryogenic...
We report the results of a joint analysis data from BICEP2/Keck Array and Planck. BICEP2 Keck have observed same approximately 400 deg$^2$ patch sky centered on RA 0h, Dec. $-57.5\deg$. The combined maps reach depth 57 nK deg in Stokes $Q$ $U$ band at 150 GHz. Planck has full polarization seven frequencies 30 to 353 GHz, but much less deeply any given region (1.2 $\mu$K 143 GHz). detect 150$\times$353 cross-correlation $B$-modes high significance. fit single- cross-frequency power spectra...
We report results from a blind analysis of the final data taken with Cryogenic Dark Matter Search experiment (CDMS II) at Soudan Underground Laboratory, Minnesota, USA. A total raw exposure 612 kg-days was analyzed for this work. observed two events in signal region; based on our background estimate, probability observing or more is 23%. These set an upper limit Weakly Interacting Massive Particle (WIMP)-nucleon elastic-scattering spin-independent cross-section 7.0x10^{-44} cm^2 WIMP mass 70...
We present results from an analysis of all data taken by the BICEP2, Keck Array, and BICEP3 CMB polarization experiments up to including 2018 observing season. add additional Array observations at 220 GHz 95 previous 95/150/220 dataset. The Q/U maps now reach depths 2.8, 8.8 μK_{CMB} arcmin 95, 150, GHz, respectively, over effective area ≈600 square degrees ≈400 150 GHz. achieve a signal-to-noise ratio on polarized dust emission exceeding that Planck 353 take auto- cross-spectra between...
We present results from an analysis of all data taken by the BICEP2 and Keck Array cosmic microwave background (CMB) polarization experiments up to including 2014 observing season. This includes first observations at 95 GHz. The maps reach a depth 50 nK deg in Stokes Q U 150 GHz band 127 band. take auto- cross-spectra between these publicly available WMAP Planck frequencies 23 353 An excess over lensed ΛCDM is detected modest significance 95×150 BB spectrum, consistent with dust contribution...
We report results from a reanalysis of data the Cryogenic Dark Matter Search (CDMS II) experiment at Soudan Underground Laboratory. Data taken between October 2006 and September 2008 using eight germanium detectors are reanalyzed with lowered, 2 keV recoil-energy threshold, to give increased sensitivity interactions weakly interacting massive particles (WIMPs) masses below ∼10 GeV/c(2). This analysis provides stronger constraints than previous CDMS II for WIMP 9 GeV/c(2) excludes parameter...
We report results of a search for weakly interacting massive particles (WIMPS) with the silicon detectors CDMS II experiment. This blind analysis 140.2 kg day data taken between July 2007 and September 2008 revealed three WIMP-candidate events surface-event background estimate 0.41(-0.08)(+0.20)(stat)(-0.24)(+0.28)(syst). Other known backgrounds from neutrons 206Pb are limited to <0.13 <0.08 at 90% confidence level, respectively. The exposure this is equivalent 23.4 recoil energy range 7-100...
We present the science case, reference design, and project plan for Stage-4 ground-based cosmic microwave background experiment CMB-S4.
This book lays out the scientific goals to be addressed by next-generation ground-based cosmic microwave background experiment, CMB-S4, envisioned consist of dedicated telescopes at South Pole, high Chilean Atacama plateau and possibly a northern hemisphere site, all equipped with new superconducting cameras. CMB-S4 will dramatically advance cosmological studies crossing critical thresholds in search for B-mode polarization signature primordial gravitational waves, determination number...
We present results from an analysis of all data taken by the bicep2/Keck CMB polarization experiments up to and including 2015 observing season. This includes first Keck Array observations at 220 GHz additional 95 150 GHz. The Q U maps reach depths 5.2, 2.9, 26 μKCMB arcmin 95, 150, GHz, respectively, over effective area ≈400 square degrees. achieve a signal noise on polarized dust emission approximately equal that Planck 353 take auto cross spectra between these publicly available WMAP...
We describe the design of a new polarization sensitive receiver, spt-3g, for 10-meter South Pole Telescope (spt). The spt-3g receiver will deliver factor ~20 improvement in mapping speed over current spt-pol. sensitivity enable advance from statistical detection B-mode anisotropy power to high signal-to-noise measurements individual modes, i.e., maps. This lead precise (~0.06 eV) constraints on sum neutrino masses with potential directly address mass hierarchy. It allow separation lensing...
We report first results from the Cryogenic Dark Matter Search (CDMS II) experiment running with its full complement of 30 cryogenic particle detectors at Soudan Underground Laboratory. This is based on analysis data acquired between October 2006 and July 2007 15 Ge (3.75 kg), giving an effective exposure 121.3 kg-d (averaged over recoil energies 10--100 keV, weighted for a weakly interacting massive (WIMP) mass 60 \gev). A blind analysis, incorporating improved techniques event...
We present measurements of the $E$-mode ($EE$) polarization power spectrum and temperature-$E$-mode ($TE$) cross-power cosmic microwave background using data collected by SPT-3G, latest instrument installed on South Pole Telescope. This analysis uses observations a $1500\text{ }\text{ }{\mathrm{deg}}^{2}$ region at 95, 150, 220 GHz taken over four-month period in 2018. report binned values $EE$ $TE$ spectra angular multipole range $300\ensuremath{\le}\ensuremath{\ell}<3000$, multifrequency...
Abstract CMB-S4—the next-generation ground-based cosmic microwave background (CMB) experiment—is set to significantly advance the sensitivity of CMB measurements and enhance our understanding origin evolution universe. Among science cases pursued with CMB-S4, quest for detecting primordial gravitational waves is a central driver experimental design. This work details development forecasting framework that includes power-spectrum-based semianalytic projection tool, targeted explicitly toward...
The Keck Array is a system of cosmic microwave background polarimeters, each similar to the Bicep2 experiment. In this paper we report results from 2012 2013 observing seasons, during which consisted five receivers all operating in same (150 GHz) frequency band and field as Bicep2. We again find an excess B-mode power over lensed-ΛCDM expectation >5σ range 30 < ℓ 150 confirm that not due systematics using jackknife tests simulations based on detailed calibration measurements. map difference...
The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) experiment sited on Cerro Toco in the Atacama Desert Chile that promises to provide breakthrough discoveries fundamental physics, cosmology, and astrophysics. Supported by Foundation, Heising-Simons with contributions from collaborating institutions, SO will see first light 2021 start five year survey 2022. has 287 collaborators 12 countries 53 including 85 students 90 postdocs. its currently funded form...
SPT-3G is the third survey receiver operating on South Pole Telescope dedicated to high-resolution observations of cosmic microwave background (CMB). Sensitive measurements temperature and polarization anisotropies CMB provide a powerful dataset for constraining cosmology. Additionally, surveys with arcminute-scale resolution are capable detecting galaxy clusters, millimeter-wave bright galaxies, variety transient phenomena. The instrument provides significant improvement in mapping speed...
We report on the design and performance of BICEP3 instrument its first three-year data set collected from 2016 to 2018. is a 52cm aperture, refracting telescope designed observe polarization cosmic microwave background (CMB) degree angular scales at 95GHz. It started science observation South Pole in with 2400 antenna-coupled transition-edge sensor (TES) bolometers. The receiver demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, flux-activated...
We present a measurement of gravitational lensing over 1500 deg2 the Southern sky using SPT-3G temperature data at 95 GHz and 150 taken in 2018. The amplitude relative to fiducial Planck 2018 Lambda cold dark matter (ΛCDM) cosmology is found be 1.020±0.060, excluding instrumental astrophysical systematic uncertainties. conduct extensive null tests check robustness measurements, report minimum-variance combined power spectrum angular multipoles 50<L<2000, which we use constrain cosmological...
We describe the newest generation of SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector multiplexer systems, such as microwave superconducting quantum interference device multiplexers (μmux) or kinetic inductance detectors. Ultra-sensitive measurements in particle physics astronomy increasingly rely on large arrays sensors, which turn necessitate highly multiplexed accompanying room-temperature...
We report on the first axion search results from Cryogenic Dark Matter Search (CDMS) experiment at Soudan Underground Laboratory. An energy threshold of 2 keV for electron-recoil events allows a possible solar conversion into photons or local galactic electrons in germanium crystal detectors. The sets an upper limit Primakov coupling ${g}_{a\ensuremath{\gamma}\ensuremath{\gamma}}$ $2.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\text{ }\text{ }{\mathrm{GeV}}^{\ensuremath{-}1}$...
Bicep3 is a 550 mm-aperture refracting telescope for polarimetry of radiation in the cosmic microwave background at 95 GHz.It adopts methodology Bicep1, Bicep2 and Keck Array experiments -it possesses sufficient resolution to search signatures inflation-induced gravitational-wave while utilizing compact design ease construction facilitate characterization mitigation systematics.However, represents significant breakthrough per-receiver sensitivity, with focal plane area 5× larger than...
The CDMS and EDELWEISS collaborations have combined the results of their direct searches for dark matter using cryogenic germanium detectors. total data set represents 614 kg.d equivalent exposure. A straightforward method combination was chosen its simplicity before were exchanged between experiments. are interpreted in terms limits on spin-independent WIMP-nucleon cross-section. For a WIMP mass 90 GeV/c^2, where this analysis is most sensitive, cross-section 3.3 x 10^{-44} cm^2 excluded at...
Bicep Array is the newest multi-frequency instrument in Bicep/Keck program. It comprised of four 550mm aperture refractive telescopes observing polarization cosmic microwave background (CMB) at 30/40, 95, 150 and 220/270 GHz with over 30,000 detectors. We present an overview receiver, detailing optics, thermal, mechanical, magnetic shielding design. follows Bicep3's modular focal plane concept, upgrades to 6" wafer reduce fabrication higher detector count per module. The first receiver...