An iron- plastic-scintillator shashlik calorimeter with a 4.3 X0 longitudinal segmentation was tested in November 2016 at the CERN East Area facility with charged particles up to 5 GeV . The ...performance of this detector in terms of electron energy resolution, linearity, response to muons and hadron showers are presented in this paper and compared with simulation. Such a fine-grained longitudinal segmentation is achieved using a very compact light readout system developed by the SCENTT and ENUBET Collaborations, which is based on fiber-SiPM coupling boards embedded in the bulk of the detector. We demonstrate that this system fulfills the requirements for neutrino physics applications and discuss performance and additional improvements.
Silicon Photomultipliers with cell-pitch ranging from 12 μm to 20 μm were tested against neutron irradiation at moderate fluences to study their performance for calorimetric applications. The ...photosensors were developed by FBK employing the RGB-HD technology. We performed irradiation tests up to 2×1011 n/cm2 (1 MeV eq.) at the INFN-LNL Irradiation Test facility. The SiPMs were characterized on-site (dark current and photoelectron response) during and after irradiations at different fluences. The irradiated SiPMs were installed in the ENUBET compact calorimetric modules and characterized with muons and electrons at the CERN East Area facility. The tests demonstrate that both the electromagnetic response and the sensitivity to minimum ionizing particles are retained after irradiation. Gain compensation can be achieved increasing the bias voltage well within the operation range of the SiPMs. The sensitivity to single photoelectrons is lost at ∼1010 n/cm2 due to the increase of the dark current.
We report a search for cosmic-ray boosted dark matter with protons using the 0.37 megaton×years data collected at Super-Kamiokande experiment during the 1996-2018 period (SKI-IV phase). We searched ...for an excess of proton recoils above the atmospheric neutrino background from the vicinity of the Galactic Center. No such excess is observed, and limits are calculated for two reference models of dark matter with either a constant interaction cross section or through a scalar mediator. This is the first experimental search for boosted dark matter with hadrons using directional information. The results present the most stringent limits on cosmic-ray boosted dark matter and exclude the dark matter-nucleon elastic scattering cross section between 10^{-33}cm^{2} and 10^{-27}cm^{2} for dark matter mass from 1 MeV/c^{2} to 300 MeV/c^{2}.
As a baryon number violating process with ΔB = 2, neutron-antineutron oscillation (n → n) provides a unique test of baryon number conservation. We have performed a search for n → n oscillation with ...bound neutrons in Super-Kamiokande, with the full dataset from its first four run periods, representing an exposure of 0.37 Mton − years. The search used a multivariate analysis trained on simulated n → n events and atmospheric neutrino backgrounds and resulted in 11 candidate events with an expected background of 9.3 events. In the absence of statistically significant excess, we derived a lower limit on n appearance lifetime in 16O nuclei of 3.6 × 1032 years and on the neutron-antineutron oscillation time of τn→n > 4.7 × 108 s at 90% C.L.
Abstract
In 2020, the Super-Kamiokande (SK) experiment moved to a new stage (SK-Gd) in which gadolinium (Gd) sulfate octahydrate was added to the water in the detector, enhancing the efficiency to ...detect thermal neutrons and consequently improving the sensitivity to low energy electron anti-neutrinos from inverse beta decay (IBD) interactions. SK-Gd has the potential to provide early alerts of incipient core-collapse supernovae through detection of electron anti-neutrinos from thermal and nuclear processes responsible for the cooling of massive stars before the gravitational collapse of their cores. These pre-supernova neutrinos emitted during the silicon burning phase can exceed the energy threshold for IBD reactions. We present the sensitivity of SK-Gd to pre-supernova stars and the techniques used for the development of a pre-supernova alarm based on the detection of these neutrinos in SK, as well as prospects for future SK-Gd phases with higher concentrations of Gd. For the current SK-Gd phase, high-confidence alerts for Betelgeuse could be issued up to 9 hr in advance of the core collapse itself.
We report a search for astronomical neutrinos in the energy region from several GeV to TeV in the direction of the blazar TXS 0506+056 using the Super-Kamiokande detector following the detection of a ...100 TeV neutrinos from the same location by the IceCube collaboration. Using Super-Kamiokande neutrino data across several data samples observed from 1996 April to 2018 February we have searched for both a total excess above known backgrounds across the entire period as well as localized excesses on smaller timescales in that interval. No significant excess nor significant variation in the observed event rate are found in the blazar direction. Upper limits are placed on the electron- and muon-neutrino fluxes at the 90% confidence level as 6.0 × 10−7 and 4.5 × 10−7-9.3 × 10−10 erg cm−2 s−1, respectively.
Abstract
We present the development of neutron-tagging techniques in
Super-Kamiokande IV using a neural network analysis. The detection
efficiency of neutron capture on hydrogen is estimated to be ...26%,
with a mis-tag rate of 0.016 per neutrino event. The uncertainty of
the tagging efficiency is estimated to be 9.0%. Measurement of the
tagging efficiency with data from an Americium-Beryllium calibration
agrees with this value within 10%. The tagging procedure was
performed on 3,244.4 days of SK-IV atmospheric neutrino data,
identifying 18,091 neutrons in 26,473 neutrino events. The fitted
neutron capture lifetime was measured as 218±9 μs.
We summarize in this paper the detector R&D performed in the framework of the ERC ENUBET Project. We discuss in particular the latest results on longitudinally segmented shashlik calorimeters and the ...first HEP application of polysiloxane-based scintillators.
•A compact shashlik-type calorimeter has been developed for neutrino beams.•Test beam performances at 1–5 GeV energy range validated the detector requirements.•The calorimeter was irradiated up to 1011 neutrons/cm2 and successfully operated.•We developed and tested several prototypes based on polysiloxane scintillators.
Abstract
The objective of this study was to evaluate the effect of nutritional restriction or consumption of concentrate ingredients prior to the adaptation period to high-concentrate diet on ruminal ...microorganism’s profile of cannulated Nellore cattle. The experiment was designed as a two 3 x 3 Latin squares, in which six Nellore steers (323 ± 23 kg) cannulated in the rumen were fed according to the treatments: Restriction (Tifton hay fed 1.4% BW + supplement); Control (Tifton hay fed ad libitum + supplement) and Concentrate (Tifton hay fed ad libitum + 0.5% BW of concentrate and supplement). Each period of this study lasted 33-d with two 10-d washout interval, divided as follows: 14 days of pre-adaptation (when treatments were applied), 12 days of adaptation diet (72% and 79% concentrate for 6-d each) and 7 days of finishing diet (86% concentrate). On days 17 and 29 of each period, rumen fluid was collected to evaluate populations of rumen bacteria and protozoa. Differential counting of protozoa was performed using a microscope with a reticulum and a “Sedgwick Rafter” counting chamber (x10P>0.05) was observed on populations of Fibrobacter succinogenes, Megaesphaera elsdenii, Streptococcus bovis and Entodimium on both adaptation and finishing periods. No treatment effect was observed (P=0.69) on Diplodinium population in the adaptation period, however, cattle previously restricted or receiving concentrate increased Diplodinium numbers during finishing period (Control: 13.2P<0.01). Cattle receiving concentrate prior to adaptation period had decreased numbers of Dasytricha in the adaptation period (Control: 1.65P<0.01), however, those numbers increased during finishing period(Control: 0.01P<0.01) when compared to cattle on control group. Nutritional restriction or consumption of concentrate prior to adaptation period affected only rumen protozoa populations.
Key Words:
An abstract of an article by Felizari et al evaluating the effect of nutritional restriction or consumption of concentrate ingredients prior to the adaptation period to high-concentrate diet on ...ruminal microorganism's profile of cannulated Nellore cattle is presented. Cattle receiving concentrate prior to adaptation period had decreased numbers of Dasytricha in the adaptation period (Control: 1.65P<0.01), however, those numbers increased during finishing period(Control: 0.01P<0.01) when compared to cattle on control group. Nutritional restriction or consumption of concentrate prior to adaptation period affected only rumen protozoa populations.
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