145 research outputs found
Review of the ELI-NP-GBS low level rf and synchronization systems
The Gamma Beam System (GBS) of ELI-NP is a linac based gamma-source in construction at Magurele (RO) by the European consortium EuroGammaS led by INFN. Photons with tunable energy and with intensity and brilliance well beyond the state of the art will be produced by Compton back-scattering between a high quality electron beam (up to 740 MeV) and a 515 nm intense laser pulse. Production of very intense photon flux with narrow bandwidth requires multi-bunch operation at 100 Hz repetition rate. A total of 13 klystrons, 3 S-band (2856 MHz) and 10 C-band (5712 MHz) will power a total of 14 Travelling Wave accelerating sections (2 S-band and 12 C-band) plus 3 S-band Standing Wave cavities (a 1.6 cell RF gun and 2 RF deflectors). Each klystron is individually driven by a temperature stabilized LLRF module, for a maximum flexibility in terms of accelerating gradient, arbitrary pulse shaping (e.g. to compensate beam loading effects in multi-bunch regime) and compensation of long-term thermal drifts. In this paper, the whole LLRF system architecture and bench test results, the RF reference generation and distribution together with an overview of the synchronization system will be described
Coordinated TSO and DSO network development plan on the islands of Cres and LoĆĄinj
The paper presents an example of coordinated transmission and distribution network planning based on analyses conducted as part of the study on
long term distribution network development plan for islands of Cres and LoĆĄinj in Croatia. The observed area of two large and several smaller islands
is supplied with electricity by one long radial 110 kV TSO owned line and parallel radial 35 kV DSO owned line. Due to transmission capacity of 35 kV
line limited to 40% of the area peak demand, which is highly conditioned by tourism, the (N-1) criteria is not complied with in case of unavailability of
110 kV line during the two-month period in summer high season. Construction of the second 110 kV line as a common solution is extremely costly,
due to necessity of laying down several kilometres of submarine cables. The paper provides the cost benefit analyses of this basic scenario and other
possible alternative scenarios, including also investments in DSO network, to determine the most cost-effective solution. Due to the values of the
demands and networks lengths, the presented example is close to a worst case scenario concerning the reliability of supply requirement, requesting
thus some atypical distribution network analyses, elements and even conducted field tests of operation. The results clearly show that coordination of
TSO and DSO planning is beneficiary concerning efficiency of investments in the networks. However, further analyses are recommended presuming
contribution to satisfying the (N-1) criteria by use of non-traditional (ânon-networkâ or âthird partyâ) solutions
Improved modeling of in-ice particle showers for IceCube event reconstruction
The IceCube Neutrino Observatory relies on an array of photomultiplier tubes to detect Cherenkov light produced by charged particles in the South Pole ice. IceCube data analyses depend on an in-depth characterization of the glacial ice, and on novel approaches in event reconstruction that utilize fast approximations of photoelectron yields. Here, a more accurate model is derived for event reconstruction that better captures our current knowledge of ice optical properties. When evaluated on a Monte Carlo simulation set, the median angular resolution for in-ice particle showers improves by over a factor of three compared to a reconstruction based on a simplified model of the ice. The most substantial improvement is obtained when including effects of birefringence due to the polycrystalline structure of the ice. When evaluated on data classified as particle showers in the high-energy starting events sample, a significantly improved description of the events is observed
Citizen science for IceCube: Name that Neutrino
Name that Neutrino is a citizen science project where volunteers aid in classification of events for the IceCube Neutrino Observatory, an immense particle detector at the geographic South Pole. From March 2023 to September 2023, volunteers did classifications of videos produced from simulated data of both neutrino signal and background interactions. Name that Neutrino obtained more than 128,000 classifications by over 1800 registered volunteers that were compared to results obtained by a deep neural network machine-learning algorithm. Possible improvements for both Name that Neutrino and the deep neural network are discussed
A Search for Coincident Neutrino Emission from Fast Radio Bursts with Seven Years of IceCube Cascade Events
This paper presents the results of a search for neutrinos that are spatially and temporally coincident with 22 unique, nonrepeating fast radio bursts (FRBs) and one repeating FRB (FRB 121102). FRBs are a rapidly growing class of Galactic and extragalactic astrophysical objects that are considered a potential source of high-energy neutrinos. The IceCube Neutrino Observatory\u27s previous FRB analyses have solely used track events. This search utilizes seven years of IceCube cascade events which are statistically independent of track events. This event selection allows probing of a longer range of extended timescales due to the low background rate. No statistically significant clustering of neutrinos was observed. Upper limits are set on the time-integrated neutrino flux emitted by FRBs for a range of extended time windows
Constraining High-energy Neutrino Emission from Supernovae with IceCube
Core-collapse supernovae are a promising potential high-energy neutrino source class. We test for correlation between seven years of IceCube neutrino data and a catalog containing more than 1000 core-collapse supernovae of types IIn and IIP and a sample of stripped-envelope supernovae. We search both for neutrino emission from individual supernovae as well as for combined emission from the whole supernova sample, through a stacking analysis. No significant spatial or temporal correlation of neutrinos with the cataloged supernovae was found. All scenarios were tested against the background expectation and together yield an overall p-value of 93%; therefore, they show consistency with the background only. The derived upper limits on the total energy emitted in neutrinos are 1.7 Ă 1048 erg for stripped-envelope supernovae, 2.8 Ă 1048 erg for type IIP, and 1.3 Ă 1049 erg for type IIn SNe, the latter disfavoring models with optimistic assumptions for neutrino production in interacting supernovae. We conclude that stripped-envelope supernovae and supernovae of type IIn do not contribute more than 14.6% and 33.9%, respectively, to the diffuse neutrino flux in the energy range of about [ 103-105] GeV, assuming that the neutrino energy spectrum follows a power-law with an index of â2.5. Under the same assumption, we can only constrain the contribution of type IIP SNe to no more than 59.9%. Thus, core-collapse supernovae of types IIn and stripped-envelope supernovae can both be ruled out as the dominant source of the diffuse neutrino flux under the given assumptions
Searches for Neutrinos from Large High Altitude Air Shower Observatory Ultra-high-energy Îł-Ray Sources Using the IceCube Neutrino Observatory
Galactic PeV cosmic-ray accelerators (PeVatrons) are Galactic sources theorized to accelerate cosmic rays up to PeV in energy. The accelerated cosmic rays are expected to interact hadronically with nearby ambient gas or the interstellar medium, resulting in Îł-rays and neutrinos. Recently, the Large High Altitude Air Shower Observatory (LHAASO) identified 12 Îł-ray sources with emissions above 100 TeV, making them candidates for PeVatrons. While at these high energies the Klein-Nishina effect exponentially suppresses leptonic emission from Galactic sources, evidence for neutrino emission would unequivocally confirm hadronic acceleration. Here, we present the results of a search for neutrinos from these Îł-ray sources and stacking searches testing for excess neutrino emission from all 12 sources as well as their subcatalogs of supernova remnants and pulsar wind nebulae with 11 yr of track events from the IceCube Neutrino Observatory. No significant emissions were found. Based on the resulting limits, we place constraints on the fraction of Îł-ray flux originating from the hadronic processes in the Crab Nebula and LHAASO J2226+6057
Constraints on Populations of Neutrino Sources from Searches in the Directions of IceCube Neutrino Alerts
Beginning in 2016, the IceCube Neutrino Observatory has sent out alerts in real time containing the information of high-energy (E âł 100 TeV) neutrino candidate events with moderate to high (âł30%) probability of astrophysical origin. In this work, we use a recent catalog of such alert events, which, in addition to events announced in real time, includes events that were identified retroactively and covers the time period of 2011-2020. We also search for additional, lower-energy neutrinos from the arrival directions of these IceCube alerts. We show how performing such an analysis can constrain the contribution of rare populations of cosmic neutrino sources to the diffuse astrophysical neutrino flux. After searching for neutrino emission coincident with these alert events on various timescales, we find no significant evidence of either minute-scale or day-scale transient neutrino emission or of steady neutrino emission in the direction of these alert events. This study also shows how numerous a population of neutrino sources has to be to account for the complete astrophysical neutrino flux. Assuming that sources have the same luminosity, an E â2.5 neutrino spectrum, and number densities that follow star formation rates, the population of sources has to be more numerous than 7 Ă 10â9 Mpcâ3. This number changes to 3 Ă 10â7 Mpcâ3 if number densities instead have no cosmic evolution
Limits on Neutrino Emission from GRB 221009A from MeV to PeV Using the IceCube Neutrino Observatory
Gamma-ray bursts (GRBs) have long been considered a possible source of high-energy neutrinos. While no correlations have yet been detected between high-energy neutrinos and GRBs, the recent observation of GRB 221009Aâthe brightest GRB observed by Fermi-GBM to date and the first one to be observed above an energy of 10 TeVâprovides a unique opportunity to test for hadronic emission. In this paper, we leverage the wide energy range of the IceCube Neutrino Observatory to search for neutrinos from GRB 221009A. We find no significant deviation from background expectation across event samples ranging from MeV to PeV energies, placing stringent upper limits on the neutrino emission from this source
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