The IceCube neutrino telescope monitors one cubic kilometer of deep Antarctic ice by detecting Cherenkov photons emitted from charged secondaries produced when neutrinos interact in the ice. The ...geometry of the detector, which comprises a lattice of 5160 photomultipliers, is optimized for the detection of neutrinos above 100 GeV. However, at subfreezing ice temperatures, dark noise rates are low enough that a high flux of MeV neutrinos streaming through the detector may be recognized by a collective rate enhancement in all photomultipliers. This method can be used to search for the signal of core collapse supernovae, providing sensitivity competitive to Mton neutrino detectors to a supernova in our Galaxy. An online data acquisition system dedicated to supernova detection has been running for several years, but its shortcomings include limited sampling frequency and the fact that the burst energy and direction cannot be reconstructed. A recently developed offline data acquisition system allows IceCube to buffer all registered photons in the detector in case of an alert with low probability to be erroneous. By analyzing such data offline, a precision determination of the burst onset time and the characteristics of rapidly varying fluxes, as well as estimates of the average neutrino energies may be obtained. For supernovae ending in a black hole, the IceCube data can also be used to determine the direction of the burst.
The Wavelength-Shifting Optical Module Bastian-Querner, Benjamin; Binn, Lucas S; Böser, Sebastian ...
Sensors (Basel, Switzerland),
02/2022, Volume:
22, Issue:
4
Journal Article
Peer reviewed
Open access
The Wavelength-shifting Optical Module (WOM) is a novel photosensor concept for the instrumentation of large detector volumes with single-photon sensitivity. The key objective is to improve the ...signal-to-noise ratio, which is achieved by decoupling the photosensitive area of a sensor from the cathode area of its photomultiplier tube (PMT). The WOM consists of a transparent tube with two PMTs attached to its ends. The tube is coated with wavelength-shifting paint that absorbs ultraviolet photons with nearly 100% efficiency. Depending on the environment, e.g., air (ice), up to 73% (41%) of the subsequently emitted optical photons can be captured by total internal reflection and propagate towards the PMTs, where they are recorded. The optical properties of the paint, the geometry of the tube, and the coupling of the tube to the PMTs have been optimized for maximal sensitivity based on theoretical derivations and experimental evaluations. Prototypes were built to demonstrate the technique and to develop a reproducible construction process. Important measurable characteristics of the WOM are the wavelength-dependent effective area, the transit time spread of detected photons, and the signal-to-noise ratio. The WOM outperforms bare PMTs, especially with respect to the low signal-to-noise ratio with an increase of a factor up to 8.9 in air (5.2 in ice). Since the gain in sensitivity is mostly in the UV regime, the WOM is an ideal sensor for Cherenkov and scintillation detectors.
IceCube was completed in December 2010. It forms a lattice of 5160 photomultiplier tubes that monitor a volume of ∼ 1 km3 in the deep Antarctic ice for particle induced photons. The telescope was ...designed to detect neutrinos with energies greater than 100 GeV. Owing to subfreezing ice temperatures, the photomultiplier dark noise rates are particularly low. Hence IceCube can also detect large numbers of MeV neutrinos by observing a collective rise in all photomultiplier rates on top of the dark noise. With 2 ms timing resolution, IceCube can track subtle features in the temporal development of the supernova neutrino burst. For a supernova at the galactic center, its sensitivity matches that of a background-free megaton-scale supernova search experiment. The sensitivity decreases to 20 standard deviations at the galactic edge (30 kpc) and 6 standard deviations at the Large Magellanic Cloud (50 kpc). IceCube is sending triggers from potential supernovae to the Supernova Early Warning System. The sensitivity to neutrino properties such as the neutrino hierarchy is discussed and simulations of tantalizing signatures, such as the formation of a quark star or a black hole as well as the characteristics of shock waves are presented. All results are preliminary.
We report on the development status of a single-photon sensor that employs wavelength-shifting and light-guiding techniques to maximize the collection area while minimizing the dark noise rate. The ...sensor is tailored towards application in ice-Cherenkov neutrino detectors embedded in inert and cold, low-radioactivity and UV transparent ice as a detection medium, such as IceCube-Gen2 or MICA. The goal is to decrease the energy threshold as well as to increase the energy resolution and the vetoing capability of the neutrino telescope, when compared to a setup with optical sensors similar to those used in IceCube. The proposed sensor captures photons with wavelengths between 250 nm and 400 nm. These photons are re-emitted with wavelengths above 400 nm by a wavelength shifting coating applied to a 90 mm diameter polymer tube. The tube guides the light towards a small-diameter PMT via total internal reflection. By scaling the results from smaller laboratory prototypes, the total efficiency of the proposed detector for a Cherenkov spectrum is estimated to exceed that of a standard IceCube optical module. The status of the prototype development and the performance of its main components will be discussed.
The field of high-energy neutrino astronomy is rapidly developing. A number of new experiments are currently being deployed and developed. Additionally, the recent successes of TeV gamma-ray ...astronomy have exciting implications for future neutrino telescopes. Here we will summarize these and other issues as they were discussed in the TeV II workshop's neutrino astronomy working group.
Patients with new-onset malignant spinal lesions often have an urgent need for local spine intervention and systemic therapy. For optimal management, it is crucial to diagnose the underlying disease ...as quickly and reliably as possible. The aim of our current study was to determine the feasibility, sensitivity, specificity, and diagnostic certainty of complementary cytological evaluation of spinal lesions suspected of malignancy. In 44 patients, we performed histopathological biopsies and in parallel cytologic preparations from the malignant site. Cytological smears were prepared and stained for May-Grunwald and Giemsa. Bone biopsies were histopathologically analyzed according to the existing standard-of-care practices. In 42 of 44 cases (95%), a cytological sample was successfully obtained. In 40 cases (95.2%, Cohen's kappa: 0.77), the cytological diagnosis agreed with the histological diagnosis regarding the identification of a malignant lesion. This resulted in a sensitivity of 97% and a specificity of 80% as well as a diagnostic safety of 95%. Cytological analysis in the context of spinal surgery proved sufficient to establish a diagnosis of malignancy or its exclusion, expanding the existing diagnostic spectrum. Furthermore, implementation of this process as a routine clinical diagnostic might shorten the time to diagnosis and improve the treatment of this vulnerable patient group.
OBJECTIVE
To describe the localization and to assess the clinical implications of areas of undetected prostate cancer in radical prostatectomy (RP) specimens, focusing on patients with unilaterally ...negative preoperative biopsy cores.
PATIENTS AND METHODS
The study included 149 of 559 consecutive patients (26.7%) who had RP for prostate cancer. Unilateral prostate cancer was diagnosed from prostate biopsies, taken by several physicians, but ≥ pT2c disease was present in the RP specimen. The prostate was dissected by standardized transversal cuts and tumour areas were mapped by one genitourinary pathologist. To estimate the tumour size and location, areas of prostate cancer were transferred to a digital grid database representing the prostate by 794 units.
RESULTS
The most frequent location of undetected prostate cancer was in the dorsalateral region and in the apex of the prostate. The mean tumour volume of the false‐negative lobe was significantly lower than contralaterally (18.9 vs 47.5 units, P < 0.001). In 36 of 149 patients (24.2%), the tumour volume on the negative biopsy side was equal or higher than on the positive biopsy side; in the final RP specimen, 60 patients (40.3%) had capsular involvement on the negative biopsy side.
CONCLUSION
Significantly many patients with newly diagnosed prostate cancer remain clinically understaged. The apical and dorsolateral region of the prostate are not adequately represented in current biopsy strategies. Undetected tumour areas are often clinically significant by size and capsular involvement, indicating a direct clinical implication when planning nerve‐sparing RP or focal therapy. Our results show a continuing need for optimized and standardized biopsy protocols.
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