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Aguilar, J. A.; Allison, P.; Beatty, J. J.; Besson, D.; Bishop, A.; Botner, O.; Bouma, S.; Buitink, S.; Cataldo, M.; Clark, B. A.; et al(
, Journal of Glaciology)
Abstract Over the last 25 years, radiowave detection of neutrino-generated signals, using cold polar ice as the neutrino target, has emerged as perhaps the most promising technique for detection of extragalactic ultra-high energy neutrinos (corresponding to neutrino energies in excess of 0.01 Joules, or 10 17 electron volts). During the summer of 2021 and in tandem with the initial deployment of the Radio Neutrino Observatory in Greenland (RNO-G), we conducted radioglaciological measurements at Summit Station, Greenland to refine our understanding of the ice target. We report the result of one such measurement, the radio-frequency electric field attenuation length $L_\alpha$ .more »We find an approximately linear dependence of $L_\alpha$ on frequency with the best fit of the average field attenuation for the upper 1500 m of ice: $\langle L_\alpha \rangle = ( ( 1154 \pm 121) - ( 0.81 \pm 0.14) \, ( \nu /{\rm MHz}) ) \,{\rm m}$ for frequencies ν ∈ [145 − 350] MHz.« less
Free, publicly-accessible full text available May 30, 2023
Aguilar, J. A.; Allison, P.; Beatty, J. J.; Bernhoff, H.; Besson, D.; Bingefors, N.; Botner, O.; Bouma, S.; Buitink, S.; Carter, K.; et al(
, The European Physical Journal C)
Abstract Since summer 2021, the Radio Neutrino Observatory in Greenland (RNO-G) is searching for astrophysical neutrinos at energies $${>10}$$ > 10 PeV by detecting the radio emission from particle showers in the ice around Summit Station, Greenland. We present an extensive simulation study that shows how RNO-G will be able to measure the energy of such particle cascades, which will in turn be used to estimate the energy of the incoming neutrino that caused them. The location of the neutrino interaction is determined using the differences in arrival times between channels and the electric field of the radio signal ismore »reconstructed using a novel approach based on Information Field Theory. Based on these properties, the shower energy can be estimated. We show that this method can achieve an uncertainty of 13% on the logarithm of the shower energy after modest quality cuts and estimate how this can constrain the energy of the neutrino. The method presented in this paper is applicable to all similar radio neutrino detectors, such as the proposed radio array of IceCube-Gen2.« less
Free, publicly-accessible full text available February 1, 2023
Ade, P. A.; Ahmed, Z.; Amiri, M.; Barkats, D.; Thakur, R. Basu; Bischoff, C. A.; Beck, D.; Bock, J. J.; Boenish, H.; Bullock, E.; et al(
, The Astrophysical Journal)
Abstract We report on the design and performance of the B icep3 instrument and its first three-year data set collected from 2016 to 2018. B icep3 is a 52 cm aperture refracting telescope designed to observe the polarization of the cosmic microwave background (CMB) on degree angular scales at 95 GHz. It started science observation at the South Pole in 2016 with 2400 antenna-coupled transition-edge sensor bolometers. The receiver first demonstrated new technologies such as large-diameter alumina optics, Zotefoam infrared filters, and flux-activated SQUIDs, allowing ∼10× higher optical throughput compared to the Keck design. B icep3 achieved instrument noise equivalentmore »temperatures of 9.2, 6.8, and 7.1 μ K CMB s and reached Stokes Q and U map depths of 5.9, 4.4, and 4.4 μ K arcmin in 2016, 2017, and 2018, respectively. The combined three-year data set achieved a polarization map depth of 2.8 μ K arcmin over an effective area of 585 square degrees, which is the deepest CMB polarization map made to date at 95 GHz.« less
Free, publicly-accessible full text available March 1, 2023
Ade, P. A.; Ahmed, Z.; Amiri, M.; Barkats, D.; Basu Thakur, R.; Beck, D.; Bischoff, C.; Bock, J. J.; Boenish, H.; Bullock, E.; et al(
, 2022 Cosmology session of the 56th Rencontres de Moriond)
For the past decade, the BICEP/Keck collaboration has been operating a series of telescopes at the Amundsen-Scott South Pole Station measuring degree-scale B-mode polarization imprinted in the Cosmic Microwave Background (CMB) by primordial gravitational waves (PGWs). These telescopes are compact refracting polarimeters mapping about 2% of the sky, observing at a broad range of frequencies to account for the polarized foreground from Galactic synchrotron and thermal dust emission. Our latest publication "BK18" utilizes the data collected up to the 2018 observing season, in conjunction with the publicly available WMAP and Planck data, to constrain the tensor-to-scalar ratio r. It particularlymore »includes (1) the 3-year BICEP3 data which is the current deepest CMB polarization map at the foreground-minimum 95 GHz; and (2) the Keck 220 GHz map with a higher signal-to-noise ratio on the dust foreground than the Planck 353 GHz map. We fit the auto- and cross-spectra of these maps to a multicomponent likelihood model (ΛCDM+dust+synchrotron+noise+r) and find it to be an adequate description of the data at the current noise level. The likelihood analysis yields σ(r)=0.009. The inference of r from our baseline model is tightened to r0.05=0.014+0.010−0.011 and r0.05<0.036 at 95% confidence, meaning that the BICEP/Keck B-mode data is the most powerful existing dataset for the constraint of PGWs. The up-coming BICEP Array telescope is projected to reach σ(r)≲0.003 using data up to 2027.« less
Free, publicly-accessible full text available March 1, 2023
Schillaci, A.; Ade, P. A.; Ahmed, Z.; Amiri, M.; Barkats, D.; Basu Thakur, R.; Bischoff, C. A.; Beck, D.; Bock, J. J.; Buza, V.; et al(
, Journal of low temperature physics)
The BICEP/Keck Collaboration is currently leading the quest to the highest sensitivity measurements of the polarized CMB anisotropies on degree scale with a series of cryogenic telescopes, of which BICEP Array is the latest Stage-3 upgrade with a total of ∼32,000 detectors. The instrument comprises 4 receivers spanning 30 to 270 GHz, with the low-frequency 30/40 GHz deployed to the South Pole Station in late 2019. The full complement of receivers is forecast to set the most stringent constraints on the tensor to scalar ratio r. Building on these advances, the overarching small-aperture telescope concept is already being used asmore »the reference for further Stage-4 experiment design. In this paper I will present the development of the BICEP Array 150 GHz detector module and its fabrication requirements, with highlights on the high-density time division multiplexing (TDM) design of the cryogenic circuit boards. The low-impedance wiring required between the detectors and the first-stage SQUID amplifiers is crucial to maintain a stiff voltage bias on the detectors. A novel multi-layer FR4 Printed Circuit Board (PCB) with superconducting traces, capable of reading out up to 648 detectors, is presented along with its validation tests. I will also describe an ultra-high density TDM detector module we developed for a CMB-S4-like experiment that allows up to 1,920 detectors to be read out. TDM has been chosen as the detector readout technology for the Cosmic Microwave Background Stage-4 (CMB-S4) experiment based on its proven low-noise performance, predictable costs and overall maturity of the architecture. The heritage for TDM is rooted in mm- and submm-wave experiments dating back 20 years and has since evolved to support a multiplexing factor of 64x in Stage-3 experiments.« less
Free, publicly-accessible full text available November 29, 2022
Ade, P. A. R.; Ahmed, Z.; Amiri, M.; Barkats, D.; Thakur, R. Basu; Bischoff, C. A.; Beck, D.; Bock, J. J.; Boenish, H.; Bullock, E.; et al(
, Physical Review Letters)
Free, publicly-accessible full text available October 1, 2022
Allison, P.; Archambault, S.; Beatty, J. J.; Chen, C. C.; Chen, C. H.; Chen, P.; Clark, B. A.; Connolly, A.; Cremonesi, L.; Davies, J.; et al(
, Physical review)
The Askaryan Radio Array (ARA) is an ultrahigh energy (UHE, >10^17 eV) neutrino detector designed to observe neutrinos by searching for the radio waves emitted by the relativistic products of neutrino-nucleon interactions in Antarctic ice. In this paper, we present constraints on the diffuse flux of ultrahigh energy neutrinos between 1016 and 1021 eV resulting from a search for neutrinos in two complementary analyses, both analyzing four years of data (2013–2016) from the two deep stations (A2, A3) operating at that time. We place a 90% CL upper limit on the diffuse all flavor neutrino flux at 1018 eV of EF(E)=5.6×10^−16 cm^−2 s^−1 sr^−1. This analysismore »includes four times the exposure of the previous ARA result and represents approximately 1/5^th the exposure expected from operating ARA until the end of 2022.« less
