6 research outputs found
Ultra-pure digital sideband separation at sub-millimeter wavelengths
Deep spectral-line surveys in the mm and sub-mm range can detect thousands of
lines per band uncovering the rich chemistry of molecular clouds, star forming
regions and circumstellar envelopes, among others objects. The ability to study
the faintest features of spectroscopic observation is, nevertheless, limited by
a number of factors. The most important are the source complexity (line
density), limited spectral resolution and insufficient sideband (image)
rejection (SRR). Dual Sideband (2SB) millimeter receivers separate upper and
lower sideband rejecting the unwanted image by about 15 dB, but they are
difficult to build and, until now, only feasible up to about 500 GHz
(equivalent to ALMA Band 8). For example ALMA Bands 9 (602-720 GHz) and 10
(787-950 GHz) are currently DSB receivers. Aims: This article reports the
implementation of an ALMA Band 9 2SB prototype receiver that makes use of a new
technique called calibrated digital sideband separation. The new method
promises to ease the manufacturing of 2SB receivers, dramatically increase
sideband rejection and allow 2SB instruments at the high frequencies currently
covered only by Double Sideband (DSB) or bolometric detectors. Methods: We made
use of a Field Programmable Gate Array (FPGA) and fast Analog to Digital
Converters (ADCs) to measure and calibrate the receiver's front end phase and
amplitude imbalances to achieve sideband separation beyond the possibilities of
purely analog receivers. The technique could in principle allow the operation
of 2SB receivers even when only imbalanced front ends can be built,
particularly at very high frequencies. Results: This digital 2SB receiver shows
an average sideband rejection of 45.9 dB while small portions of the band drop
below 40 dB. The performance is 27 dB (a factor of 500) better than the average
performance of the proof-of-concept Band 9 purely-analog 2SB prototype
receiver.Comment: 5 page
8: Factors Affecting 100-Day and 1-Year Mortality Following Myeloablative Single-Unit Cord Blood Transplantation in Adults and Adolescents: A Comprehensive Meta-Analysis of CIBMTR, NCBP and Eurocord
Analytical characteristics of the electron beam distribution density over the heated spot for optimizing the electron-beam welding process
The Néel IRAM KID Arrays (NIKA)
We are developing an instrument based on Kinetic Inductance Detectors (KID) known as the Néel IRAM KID Array (NIKA). Leveraging the experience gained from the first generation NIKA in 2009, an improved, dual-band (150 GHz and 240 GHz) instrument has been designed and tested at the Institut of RadioAstronomie Millimetrique (IRAM) 30-meter telescope in October 2010. The performances, in terms of sensitivity on-the-sky at 150 GHz, are already comparable to existing state-of-the-art bolometer-based instruments. NIKA represents thus the first real proof that KID are a viable technology for ground-based Astronomy. We will describe the instrument, the most recent results and the future plans for building a large resident mm-wave camera