The IceCube Upgrade -- Design and Science Goals (1908.09441v1)

Abstract: The IceCube Neutrino Observatory at the geographic South Pole has reached a number of milestones in the field of neutrino astrophysics. The achievements of IceCube include the discovery of a high-energy astrophysical neutrino flux, and the temporal and directional correlation of neutrinos with a flaring blazar. The IceCube Upgrade, which will be constructed in the 2022/23 Antarctic Summer season, is the next stage of the IceCube project. The IceCube Upgrade consists of seven new columns of photosensors, densely embedded near the bottom center of the existing cubic-kilometer-scale IceCube Neutrino Observatory. An improved atmospheric neutrino event selection efficiency and reconstruction at a few GeV can be achieved with the dense infill of the Upgrade's photosensor array. The Upgrade will provide world-leading sensitivity to neutrino oscillations and will enable IceCube to take unique measurements of tau neutrino appearance with a high precision. Furthermore, the new array will also improve the existing IceCube detector. The Upgrade strings will include new calibration devices designed to deepen the knowledge of the optical properties of glacial ice and the detector response. The improved calibration resulting from the Upgrade will be applied to the entire archive of IceCube data collected over the last 10 years, improving the angular and spatial resolution of the detected astrophysical neutrino events. Finally, the Upgrade represents the first stage in the development of IceCube-Gen2, the next-generation neutrino telescope at the South Pole.

• The paper outlines the upgrade design for IceCube, emphasizing enhanced calibration and improved neutrino event reconstruction at energies around a few GeV.
• It details the deployment of 700 new optical sensors and innovative calibration tools, promising refined measurements of glacial ice properties and astrophysical neutrino events.
• The paper discusses how these improvements support neutrino oscillation studies, potential new physics discoveries, and pave the way for the future IceCube-Gen2 project.

Overview of the IceCube Upgrade: Design and Science Goals

The IceCube Neutrino Observatory, situated at the geographic South Pole, has been instrumental in progressing the understanding of neutrino astrophysics through fundamental observations, including the discovery of a high-energy astrophysical neutrino flux and the identification of coincidences between neutrinos and a flaring blazar. The envisaged IceCube Upgrade seeks to extend these achievements by augmenting the existing infrastructure with seven additional columns of photosensors deployed near the bottom center of the cubic-kilometer-scale detector. Scheduled for the 2022/2023 Antarctic Summer season, this Upgrade aims to enhance the atmospheric neutrino event selection efficiency and reconstruction accuracy at energies around a few GeV, thereby significantly improving sensitivity to phenomena such as neutrino oscillations.

Design and Infrastructure Enhancements

The deployment will consist of approximately 700 optical sensors installed in the clearest regions of glacial ice at depths between 2150 m and 2425 m. These additions include advanced optical modules: the Multi-PMT Digital Optical Module (mDOM) and the Dual optical sensors in an Ellipsoid Glass for Gen2 (D-Egg). These are engineered to optimize photon detection efficiencies and bolster the calibration capabilities, allowing for robust statistical analyses that are crucial for oscillation studies and new physics discovery.

Notably, the Upgrade strings will feature new calibration devices—such as fast LEDs, CCD cameras, and other sensor technologies—that are expected to significantly refine the understanding of the ice's optical properties and the detector's response. This recalibration effort will be retrospectively applied to the entire dataset collected by IceCube over the past decade, thus improving the resolution of previously recorded astrophysical neutrino events.

Scientific Capabilities and Implications

Enhancing photon detection sensitivity and refining reconstruction processes holds promise for advancing studies in neutrino oscillations and tau neutrino appearance, fortifying predictions made on the PMNS matrix's unitarity, potentially uncovering new physics beyond the Standard Model through observations at cosmological distances.

Moreover, the augmented calibration accuracy from the Upgrade is poised to improve sensitivity to high-energy cosmic neutrino fluxes, while markedly elevating precision in cascade directional reconstructions. Such improvements will expand opportunities for neutrino point-source searches using historical IceCube data, potentially contributing to multi-messenger astronomy.

The Upgrade will further serve as a developmental platform for IceCube-Gen2, an ambitious next-generation 8 km$^3$ scale neutrino detector, and provide valuable insights and testing ground for prototype instruments and narrow-hole sensor designs to optimize large-scale deployment and reduce construction costs.

Future Prospects in Neutrino Astronomy

The IceCube Upgrade represents a critical step towards expanding observational capabilities and enhancing scientific rigor in neutrino astrophysics. By integrating next-generation technology and calibration techniques into current research practices, the IceCube Collaboration is positioned to exploit these advancements fully, contributing significantly to the quest for understanding fundamental particle interactions and the high-energy universe through neutrino detection, setting the stage for future exploration with IceCube-Gen2.