• DOI:10.1093/pasj/psv088
• Corpus ID: 118498623

Z45: A New 45-GHz Band Dual-Polarization HEMT Receiver for the NRO 45-m Radio Telescope

@article{Nakamura2015Z45AN,
  title={Z45: A New 45-GHz Band Dual-Polarization HEMT Receiver for the NRO 45-m Radio Telescope},
  author={Fumitaka Nakamura and Hideo Ogawa and Yoshinori Yonekura and K. Kimura and Nozomi Okada and Minato Kozu and Yutaka Hasegawa and Kazuki Tokuda and T. Ochiai and Izumi Mizuno and Kazuhito Dobashi and Tomomi Shimoikura and Seiji Kameno and Kotomi Taniguchi and Hiroko Shinnaga and Shuro Takano and Ryohei Kawabe and Taku Nakajima and Daisuke Iono and Nario Kuno and Toshikazu Onishi and Munetake Momose and Satoshi Yamamoto},
  journal={arXiv: Instrumentation and Methods for Astrophysics},
  year={2015}
}

• F. Nakamura, H. Ogawa, +20 authors S. Yamamoto
• Published 9 September 2015
• Physics
• arXiv: Instrumentation and Methods for Astrophysics

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 ($J_N=4_3-3_2$) 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 K to 150K 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, having a capability to process the full-Stokes spectroscopy. The Half Power Beam Width (HPBW) of the beam 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.