3 research outputs found
First observations with a GNSS antenna to radio telescope interferometer
We describe the design of a radio interferometer composed of a Global
Navigation Satellite Systems (GNSS) antenna and a Very Long Baseline
Interferometry (VLBI) radio telescope. Our eventual goal is to use this
interferometer for geodetic applications including local tie measurements. The
GNSS element of the interferometer uses a unique software-defined receiving
system and modified commercial geodetic-quality GNSS antenna. We ran three
observing sessions in 2022 between a 25 m radio telescope in Fort Davis, Texas
(FD-VLBA), a transportable GNSS antenna placed within 100 meters, and a GNSS
antenna placed at a distance of about 9 km. We have detected a strong
interferometric response with a Signal-to-Noise Ratio (SNR) of over 1000 from
Global Positioning System (GPS) and Galileo satellites. We also observed
natural radio sources including Galactic supernova remnants and Active Galactic
Nuclei (AGN) located as far as one gigaparsec, thus extending the range of
sources that can be referenced to a GNSS antenna by 18 orders of magnitude.
These detections represent the first observations made with a GNSS antenna to
radio telescope interferometer. We have developed a novel technique based on a
Precise Point Positioning (PPP) solution of the recorded GNSS signal that
allows us to extend integration time at 1.5 GHz to at least 20 minutes without
any noticeable SNR degradation when a rubidium frequency standard is used.Comment: 33 pages, 19 figure
Charge division in a cylindrical drift chamber for E1097
A review of the key concepts in the operation of a drift chamber are given. The equations governing charge division are developed. In order to optimize the chamber geometry, calculations were performed so that a suitable geometry for the chamber could be chosen. Electronics to determine position information along the wire (charge division) from the pulses at the two ends of the wire were designed and constructed. A test chamber was constructed and used to demonstrate the validity of the calculations as well as the ability of the electronics to make the position measurement. Results from tests using cosmic rays demonstrate position resolution to have a of less than 4 mm
Measurement of the polarization of the muon beam for the SMC experiment
A high energy muon beam polarimeter for the SMC experiment at CERN is described, as is the analysis of the beam polarization. The polarization is determined using the shape of the energy spectrum of the positrons from the decay \mu\sp{+}\rightarrow e\sp{+}\nu\sb{e}\bar\nu\sb\mu which is described by the Michel spectrum. The parent muon is tagged upstream of a field-free decay region and its momentum is measured. A 30 m long muon decay path is defined between a shower veto hodoscope which identifies the \mu\sp{+} and a dipole analyzing magnet. The spectrometer includes the dipole magnet and several multi-wire proportional chambers which measure the momentum of the e\sp{+}. Identification of decay positrons is based on the energy deposited in a lead glass calorimeter. Muon polarization can be determined with 60 hours of data-taking to a statistical accuracy of 0.03 and a systematic uncertainty of the same order. Hence the muon beam polarization of is measured to 5% relative accuracy