2015/09/09 by Fumitaka Nakamura, Hideo Ogawa, Yoshinori Yonekura +21
Physics and Astronomy · #Amplifier #Astronomy #Astrophysics and Star Formation Studies #High-electron-mobility transistor #Intermediate frequency #Linear polarization #Magnetic field #Optics #Optoelectronics #Physics #Polarization (electrochemistry) #Radio frequency #Radio spectrum #Scientific Research and Discoveries #Spectrometer #Superconducting and THz Device Technology #Telecommunications #Telescope #Transistor #Zeeman effect #astro-ph.GA #astro-ph.IM #astro-ph.SR
paper · pdf · doi:10.1093/pasj/psv088
32 pages, 12 figures, accepted by PASJ
arxiv created 2015/09/09 · openalex publication_date 2015/10/09 · arxiv updated 2015/10/14 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
Abstract We developed a dual-linear-polarization HEMT (High Electron Mobility Transistor) amplifier receiver system of the 45-GHz band (hereafter Z45), and installed it in the Nobeyama 45-m radio telescope. The receiver system is designed to conduct polarization observations by taking the cross-correlation of two linearly polarized components, from which we process full Stokes spectroscopy. We aim to measure the magnetic field strength through the Zeeman effect of the emission line of CCS (JN = 43–32) toward pre-protostellar cores. A linear-polarization receiver system has a smaller contribution of instrumental polarization components to the Stokes V spectra than that of the circular polarization system, so that it is easier to obtain the Stokes V spectra. The receiver has an RF frequency of 42–46 GHz and an intermediate frequency (IF) band of 4–8 GHz. The typical noise temperature is about 50 K, and the system noise temperature ranges from 100 to 150 K over the frequency of 42–46 GHz. The receiver system is connected to two spectrometers, SAM45 and PolariS. SAM45 is a highly flexible FX-type digital spectrometer with a finest frequency resolution of 3.81 kHz. PolariS is a newly developed digital spectrometer with a finest frequency resolution of 60 Hz, and which has a capability to process the full-Stokes spectroscopy. The half-power beam width (HPBW) was measured to be 37″ at 43 GHz. The main beam efficiency of the Gaussian main beam was derived to be 0.72 at 43 GHz. The SiO maser observations show that the beam pattern is reasonably round at about 10% of the peak intensity and the side-lobe level was less than 3% of the peak intensity. Finally, we present some examples of astronomical observations using Z45.