The IceCube neutrino observatory--installed in the Antarctic ice--is the largest neutrino telescope to date. It consists of 5,160 photomultiplier-tubes spread among 86 vertical strings making a total ...detector volume of more than a cubic kilometer. IceCube detects neutrinos via Cherenkov light emitted by charged relativistic particles produced when a neutrino interacts in or near the detector. The detector is particularly sensitive to high-energy neutrinos of due to its size and photosensor spacing. In this analysis we search for dark matter that annihilates into a metastable mediator that subsequently decays into Standard Model particles. These models yield an enhanced high-energy neutrino flux from dark matter annihilation inside the Sun compared to models without a mediator. Neutrino signals that are produced directly inside the Sun are strongly attenuated at higher energies due to interactions with the solar plasma. In the models considered here, the mediator can escape the Sun before producing any neutrinos, thereby avoiding attenuation. We present the results of an analysis of six years of IceCube data looking for dark matter in the Sun. We consider mediator lifetimes between 1 ms to 10 s and dark matter masses between 200 GeV and 75 TeV.
The IceCube neutrino observatory is a 3D array of photodetectors installed in the Antarctic ice. It consists of 5,160 photomultiplier-tubes spread among 86 vertical strings making a total detector ...volume of more than a cubic kilometer. It detects neutrinos via Cherenkov light of charged relativistic particles from neutrino interactions with the detector volume. IceCube is, due to its size and photosensor spacing, particularly sensitive to high-energy neutrinos. In this analysis we search for dark matter that annihilates into a metastable mediator that subsequently decays into Standard Model particles. These models yield an enhanced high-energy neutrino flux from dark matter annihilation inside the Sun compared to models without a mediator. Neutrino signals that are produced directly inside the Sun are strongly attenuated at higher energies due to interactions with the solar plasma. In the models considered here, the mediator can escape the Sun before producing any neutrinos, thereby avoiding attenuation. IceCube is ideal to search for this enhanced high-energy neutrino signal. We present the sensitivities of an analysis of six years of IceCube data looking for dark matter in the Sun considering mediator lifetimes between 1 ms to 10 s and dark matter masses between 200 GeV and 10 TeV. We show that IceCube is sensitive to spin--dependent cross--sections of \(3.45 \times 10^{-34}~\rm cm^2\) for dark matter masses of 1 TeV.
The IceCube Upgrade consists of seven new strings to be deployed in the central region of the existing IceCube detector. The goals of the IceCube Upgrade are two-fold: to enhance sensitivity to ...neutrinos in the GeV range, and to improve the calibration of the IceCube detector as a means of reducing systematic uncertainties due to the optical properties of the ice. Among other calibration devices designed to study ice properties, a novel camera system will be deployed as part of the Upgrade. The system will include three cameras, each paired with an illumination LED, included in each of the Upgrade optical modules. In total, 2,300 cameras will be deployed. A combination of photographic images from transmitted and reflected light will measure optical properties of both the bulk ice in-between strings and the local ice refrozen in the drill hole. In this contribution, we present the operations plans for these two types of measurements and the sensitivities to the ice properties and geometry of the new modules that can be achieved with the new camera system.
Currently, an upgrade consisting of seven densely instrumented strings in the center of the volume of the IceCube detector with new digital optical modules (DOMs) is being built. On each string, DOMs ...will be regularly spaced with a vertical separation of 3 m between depths of 2160 m and 2430 m below the surface of the ice, which is a denser configuration than the existing DOMs of IceCube detector. For a precise calibration of the IceCube Upgrade it is important to understand the properties of the ice, both inside and surrounding the deployment holes. The camera system together with the LED illumination system was developed and produced at Sungkyunkwan university and are installed in almost every DOM to measure these properties. For these calibration measurements, a new simulation framework, which produces expected images from various geometric and optical variables has been developed. Images produced from the simulation will be used to develop an analysis framework for the IceCube Upgrade camera calibration system and for the design of the IceCube Gen2 camera system.
An upgrade to the IceCube Neutrino Telescope is currently under construction. For this IceCube Upgrade, seven new strings will be deployed in the central region of the 86 string IceCube detector to ...enhance the capability to detect neutrinos in the GeV range. One of the main science objectives of the IceCube Upgrade is an improved calibration of the IceCube detector to reduce systematic uncertainties related to the optical properties of the ice. We have developed a novel optical camera and illumination system that will be part of 700 newly developed optical modules to be deployed with the IceCube Upgrade. A combination of transmission and reflection photographic measurements will be used to measure the optical properties of bulk ice between strings and refrozen ice in the drill hole, to determine module positions, and to survey the local ice environments surrounding the sensor module. In this contribution we present the production design, acceptance testing, and plan for post-deployment calibration measurements with the camera system.
IceCube is a cubic-kilometer scale neutrino telescope located at the geographic South Pole. The detector utilizes the extremely transparent Antarctic ice as a medium for detecting Cherenkov radiation ...from neutrino interactions. While the optical properties of the glacial ice are generally well modeled and understood, the uncertainties which remain are still the dominant source of systematic uncertainties for many IceCube analyses. A camera and LED system is being built for the IceCube Upgrade that will enable the observation of optical properties throughout the Upgrade array. The SPICEcore hole, a 1.7 km deep ice-core hole located near the IceCube detector, has given the opportunity to test the performance of the camera system ahead of the Upgrade construction. In this contribution, we present the results of the camera and LED system deployment during the 2019/2020 austral summer season as part of a SPICEcore luminescence logger system.
The SPICEcore Hole Camera System Dujmović, Hrvoje; Jeong, Minjin; Tönnis, Christoph ...
arXiv (Cornell University),
08/2019
Paper, Journal Article
Open access
IceCube is a cubic-kilometer scale neutrino telescope located at the geographic South Pole. The detector utilizes the extremely transparent Antarctic ice as a medium for detecting Cherenkov radiation ...from neutrino interactions. As a result of extensive studies of the optical properties of ice, the light propagation in IceCube is well understood. The ice properties are, however, still dominant sources of detector systematic uncertainties in many IceCube analyses. We have designed a camera system to measure the optical properties of the Antarctic ice surrounding the SPICEcore hole that is an ice-core hole drilled down to 1.7~km near the IceCube detector. The device uses CMOS image sensors to measure the back-scattered light from bright LEDs pointing into the ice. Having a similar measurement principle, the device can also serve as a proof of concept of a camera system designed for the optical modules for IceCube Upgrade. During the 2018/2019 austral summer season, a prototype of the instrument was deployed in the ice-core hole. In this contribution, we present the hardware design of the camera system and the result of the first deployment at the South Pole.
The IceCube Neutrino Observatory is a cubic kilometer volume neutrino detector installed in the Antarctic at the geographic South Pole. Neutrinos are detected through the observation of Cherenkov ...light from charged relativistic particles generated in neutrino interactions, using an array of 86~strings of optical sensor modules. Currently an upgrade to the IceCube detector is in preparation. This IceCube Upgrade will add seven additional strings with new optical sensors and calibration devices. A new camera system is designed for this upgrade to be installed with the new optical modules. This camera system will study bulk ice properties and the refrozen ice in the drill hole. The system can also be utilized to provide information on the detector geometry including location and orientation of the optical modules and cables that can be used to calibrate IceCube Monte Carlo simulations. A better understanding of the refrozen ice in the drill hole including the complementary knowledge of the optical properties of the surrounding glacial ice will be obtained by surveying and analyzing the images from this system. The camera system consists of two types of components: an image sensor module and an illumination module. The image sensor module uses a CMOS image sensor to take pictures for the purpose of calibration studies. The illumination module emits static, monochromatic light into a given direction with a specific beam width and brightness during the image taking process. To evaluate the system design and demonstrate its functionality, a simulation study based on lab measurements is performed in parallel with the hardware development. This study allows for the development of the preliminary image analysis tool for the system. We present the prototype of the camera system and the results of the first system demonstrations.
The IceCube Neutrino Observatory instruments about 1 km3 of deep, glacial ice at the geographic South Pole. It uses 5160 photomultipliers to detect Cherenkov light emitted by charged relativistic ...particles. An unexpected light propagation effect observed by the experiment is an anisotropic attenuation, which is aligned with the local flow direction of the ice. We examine birefringent light propagation through the polycrystalline ice microstructure as a possible explanation for this effect. The predictions of a first-principles model developed for this purpose, in particular curved light trajectories resulting from asymmetric diffusion, provide a qualitatively good match to the main features of the data. This in turn allows us to deduce ice crystal properties. Since the wavelength of the detected light is short compared to the crystal size, these crystal properties include not only the crystal orientation fabric, but also the average crystal size and shape, as a function of depth. By adding small empirical corrections to this first-principles model, a quantitatively accurate description of the optical properties of the IceCube glacial ice is obtained. In this paper, we present the experimental signature of ice optical anisotropy observed in IceCube light-emitting diode (LED) calibration data, the theory and parameterization of the birefringence effect, the fitting procedures of these parameterizations to experimental data, and the inferred crystal properties.
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