arXiv subjects

Huan Tran

Publications and source records attributed to Huan Tran.

22 records · Page 2Linked to original sources

arXiv2010

The EBEX Cryostat and Supporting Electronics

We describe the cryostat and supporting electronics for the EBEX experiment. EBEX is a balloon-borne polarimeter designed to measure the B-mode polarization of the cosmic microwave background radiation. The instrument includes a 1.5 meter Gregorian-type telescope and 1432 bolometric transition edge sensor detectors operating at 0.3 K. Electronics for monitoring temperatures and controlling cryostat refrigerators is read out over CANbus. A timing system ensures the data from all subsystems is accurately synchronized. EBEX completed an engineering test flight in June 2009 during which the cryogenics and supporting electronics performed according to predictions. The temperatures of the cryostat were stable, and an analysis of a subset of the data finds no scan synchronous signal in the cryostat temperatures. Preparations are underway for an Antarctic flight.

astro-ph.IM↗

arXiv2009

Study of the Experimental Probe of Inflationary Cosmology (EPIC)-Intemediate Mission for NASA's Einstein Inflation Probe

Measurements of Cosmic Microwave Background (CMB) anisotropy have served as the best experimental probe of the early universe to date. The inflationary paradigm, inspired in part by the extreme isotropy of the CMB, is now a cornerstone in modern cosmology. Inflation has passed a series of rigorous experimental tests, but we still do not understand the physical mechanism or energy scale behind inflation. A general prediction of inflation and one that can provide certain insights into inflationary physics is a background of primordial gravitational waves. These perturbations leave a distinct signature in the CMB B-modes of polarization. The EPIC (Experimental Probe of Inflationary Cosmology) study team has investigated several CMB polarization mission concepts to carry out a definitive measurement of the inflationary B-mode polarization spectrum. In this report we study a mission with an aperture intermediate between the two missions discussed in our previous report. EPIC-IM's increased aperture allows access to a broader science case than the small EPIC-Low Cost mission. In addition to the search for inflationary gravitational waves, the increase aperture allows us to mine the scale polarization and lensing shear polarization signals down to cosmological limits, so that we extract virtually all the cosmological information available from the CMB. In addition, a modest number of channels operating at higher frequencies allows for an all-sky measurement of polarized Galactic dust, which will provide a rich dataset for Galactic science related to magnetic fields. Using a combination of a large sensitivity focal plane with a new optical design, and an efficient 4K mechanical cooler, EPIC-IM realizes higher sensitivity than EPIC-Comprehensive Science mission.

astro-ph.CO↗

arXiv2008

The Experimental Probe of Inflationary Cosmology (EPIC): A Mission Concept Study for NASA's Einstein Inflation Probe

This is the Phase 1 Report on the Experimental Probe of Inflationary Cosmology (EPIC), a mission concept study for NASA's Einstein Inflation Probe. When we began our study we sought to answer five fundamental implementation questions: 1) can foregrounds be measured and subtracted to a sufficiently low level?; 2) can systematic errors be controlled?; 3) can we develop optics with sufficiently large throughput, low polarization, and frequency coverage from 30 to 300 GHz?; 4) is there a technical path to realizing the sensitivity and systematic error requirements?; and 5) what are the specific mission architecture parameters, including cost? Detailed answers to these questions are contained in this report. Currently in Phase 2, we are exploring a mission concept targeting a ~2m aperture, in between the two options described in the current report with a small (~30 cm) and large (~4m) missions.

astro-ph↗

arXiv2003

Recent Results from the MAXIMA Experiment

MAXIMA is a balloon-borne platform for measuring the anisotropy of the Cosmic Microwave Background (CMB). It has measured the CMB power spectrum with a ten-arcminute FWHM beam, corresponding to a detection of the power spectrum out to spherical harmonic multipole l~1000. The spectrum is consistent with a flat Universe with a nearly scale-invariant initial spectrum of adiabatic density fluctuations. Moreover, the MAXIMA data are free from any notable non-Gaussian contamination and from foreground dust emission. In the same region, the WMAP experiment observes the same structure as that observed by MAXIMA, as evinced by analysis of both maps and power spectra. The next step in the evolution of the MAXIMA program is MAXIPOL, which will observe the polarization of the CMB with comparable resolution and high sensitivity over a small patch of the sky.

astro-ph↗