A neutron lifetime measurement conducted at the Japan Proton Accelerator Research Complex (J-PARC) is counting the number of electrons from neutron decays with a time projection chamber (TPC). The ...\(\gamma\) rays produced in the TPC cause irreducible background events. To achieve the precise measurement, the inner walls of the TPC consist of \(^6\)Li-enriched lithium-fluoride (\(^6\)LiF) tiles to suppress the amount of \(\gamma\) rays. In order to estimate the amount of \(\gamma\) rays from the \(^{6}{\rm LiF}\) tile, prompt gamma ray analysis (PGA) measurements were performed using germanium detectors. We reconstructed the measured \(\gamma\)-ray energy spectrum using a Monte Carlo simulation with the stripping method. Comparing the measured spectrum with a simulated one, the number of \(\gamma\) rays emitted from the\(^{6}{\rm LiF}\) tile was \((2.3^{+0.7}_{-0.3}) \times 10^{-4}\) per incident neutron. This is \(1.4^{+0.5}_{-0.2}\) times the value assumed for a mole fraction of the \(^{6}{\rm LiF}\) tile. We concluded that the amount of \(\gamma\) rays produced from the \(^{6}{\rm LiF}\) tile is not more twice the originally assumed value.
In special tests, the active layers of the CALICE Digital Hadron Calorimeter prototype, the DHCAL, were exposed to low energy particle beams, without being interleaved by absorber plates. The ...thickness of each layer corresponded approximately to 0.29 radiation lengths or 0.034 nuclear interaction lengths, defined mostly by the copper and steel skins of the detector cassettes. This paper reports on measurements performed with this device in the Fermilab test beam with positrons in the energy range of 1 to 10 GeV. The measurements are compared to simulations based on GEANT4 and a standalone program to emulate the detailed response of the active elements.
Abstract
Neutrino is a major candidate of Majorana particle and the neutrinoless double beta (0
v
2
β
) decay is the key physics to prove it. In 2019, KamLAND-Zen experiment have started data taking ...to search for 0
v
2
β
decay with 745 kg of
136
Xe as the source. The sensitivity is restricted by the statistics of backgrounds and the most critical ones are induced by spallation reactions of cosmic-ray muons. Physics process and statistics are studied with FLUKA which is widely used simulation tool. The most critical background is the decay of
10
C, while FLUKA predicts that heavy isotopes such as
137
Xe can be a potential background. We apply delayed coincidence method to quantify those backgrounds and also have been developing new tools focused on space and charge features, pulse shape discrimination and particle identification.
The MEG experiment searches for the muon lepton flavor violating decay, μ+→e+γ. An upgrade of the experiment is ongoing, aiming at reaching a sensitivity of Br(μ+→e+γ)=4×10−14, an order of magnitude ...better than the sensitivity of the current MEG. To achieve this goal, all of the detectors are being upgraded. In MEG, the energy, position and timing of the gamma ray were measured by a liquid Xe calorimeter, which consists of 900l of liquid Xe and 846 2-in. round-shaped photo-multiplier tubes (PMTs). In the upgrade, the granularity at the gamma ray incident face will be improved by replacing 216 PMTs with 4092 SiPMs (MPPCs) with an active area of 12×12mm2 each. The energy resolution for the gamma ray is expected to improve by a factor of 2, because the efficiency to collect scintillation light will become more uniform. The position resolution is also expected to improve by a factor of 2. In collaboration with Hamamatsu Photonics K.K., we have successfully developed a high performance MPPC for our detector. It has excellent photon detection efficiency for the liquid xenon scintillation light in VUV range. The size of the chips is large so that it can cover large area with a manageable number of readout channels. The characteristics of the MPPCs are being tested in liquid Xe, and also at the room temperature. The results of the tests will be presented, together with the expected performance of the upgraded detector.
Odor signals are conveyed from the olfactory bulb to the olfactory cortex (OC) by mitral cells (MCs) and tufted cells (TCs). However, whether and how the two types of projection neuron differ in ...function and axonal connectivity is still poorly understood. Odor responses and axonal projection patterns were compared between MCs and TCs in mice by visualizing axons of electrophysiologically identified single neurons. TCs demonstrated shorter onset latency for reliable responses than MCs. The shorter latency response of TCs was maintained in a wide range of odor concentrations, whereas MCs responded only to strong signals. Furthermore, individual TCs projected densely to focal targets only in anterior areas of the OC, whereas individual MCs dispersedly projected to all OC areas. Surprisingly, in anterior OC areas, the two cell types projected to segregated subareas. These results suggest that MCs and TCs transmit temporally distinct odor information to different OC targets.
An odor induces food-seeking behaviors when humans and animals learned to associate the odor with food, whereas the same odor elicits aversive behaviors following odor-danger association learning. It ...is poorly understood how central olfactory circuits transform the learned odor cue information into appropriate motivated behaviors. The olfactory tubercle (OT) is an intriguing area of the olfactory cortex in that it contains medium spiny neurons as principal neurons and constitutes a part of the ventral striatum. The OT is therefore a candidate area for participation in odor-induced motivated behaviors. Here we mapped c-Fos activation of medium spiny neurons in different domains of the mouse OT following exposure to learned odor cues. Mice were trained to associate odor cues to a sugar reward or foot shock punishment to induce odor-guided approach behaviors or aversive behaviors. Regardless of odorant types, the anteromedial domain of the OT was activated by learned odor cues that induced approach behaviors, whereas the lateral domain was activated by learned odor cues that induced aversive behaviors. In each domain, a larger number of dopamine receptor D1 type neurons were activated than D2 type neurons. These results indicate that specific domains of the OT represent odor-induced distinct motivated behaviors rather than odor stimuli, and raise the possibility that neuronal type-specific activation in individual domains of the OT plays crucial roles in mediating the appropriate learned odor-induced motivated behaviors. Significance statement: Although animals learn to associate odor cues with various motivated behaviors, the underlying circuit mechanisms are poorly understood. The olfactory tubercle (OT), a subarea of the olfactory cortex, also constitutes the ventral striatum. Here, we trained mice to associate odors with either reward or punishment and mapped odor-induced c-Fos activation in the OT. Regardless of odorant types, the anteromedial domain was activated by approach behavior-inducing odors, whereas the lateral domain was activated by aversive behavior-inducing odors. In each domain, dopamine receptor D1 neurons were preferentially activated over D2 neurons. The results indicate that specific OT domains represent odor-induced distinct motivated behaviors rather than odor types, and suggest the importance of neuronal type-specific activation in individual domains in mediating appropriate behaviors.
Background:Because the early diagnosis of subclinical cardiac sarcoidosis (CS) remains difficult, we developed a deep learning algorithm to distinguish CS patients from healthy subjects using ...echocardiographic movies.Methods and Results:Among the patients who underwent echocardiography from January 2015 to December 2019, we chose 151 echocardiographic movies from 50 CS patients and 151 from 149 healthy subjects. We trained two 3D convolutional neural networks (3D-CNN) to identify CS patients using a dataset of 212 echocardiographic movies with and without a transfer learning method (Pretrained algorithm and Non-pretrained algorithm). On an independent set of 41 echocardiographic movies, the area under the receiver-operating characteristic curve (AUC) of the Pretrained algorithm was greater than that of Non-pretrained algorithm (0.842, 95% confidence interval (CI): 0.722–0.962 vs. 0.724, 95% CI: 0.566–0.882, P=0.253). The AUC from the interpretation of the same set of 41 echocardiographic movies by 5 cardiologists was not significantly different from that of the Pretrained algorithm (0.855, 95% CI: 0.735–0.975 vs. 0.842, 95% CI: 0.722–0.962, P=0.885). A sensitivity map demonstrated that the Pretrained algorithm focused on the area of the mitral valve.Conclusions:A 3D-CNN with a transfer learning method may be a promising tool for detecting CS using an echocardiographic movie.
The core losses of an interior permanent-magnet synchronous motor (PMSM) have been reduced by about 50% using an amorphous magnetic material (AMM) stator core instead of a nonoriented (NO) steel ...stator core. Numerical calculation and experimental tests data have been compared to evaluate the reliability of the results. The AMM stator core has been realized using the latest improvements in manufacturing technologies.
Humans use a family of more than 400 olfactory receptors (ORs) to detect odorants. However, deorphanization of ORs is a critical issue because the functional properties of more than 80% of ORs remain ...unknown, thus, hampering our understanding of the relationship between receptor function and perception. HEK293 cells are the most commonly used heterologous expression system to determine the function of a given OR; however, they cannot functionally express a majority of ORs probably due to a lack of factor(s) required in cells in which ORs function endogenously. Interestingly, ORs have been known to be expressed in a variety of cells outside the nose and play critical physiological roles. These findings prompted us to test the capacity of cells to functionally express a specific repertoire of ORs. In this study, we selected three cell lines that endogenously express functional ORs. We demonstrated that human prostate carcinoma (LNCaP) cell lines successfully identified novel ligands for ORs that were not recognized when expressed in HEK293 cells. Further experiments suggested that the LNCaP cell line was effective for functional expression of ORs, especially with a high basal activity, which impeded the sensitive detection of ligand-mediated activity of ORs. This report provides an efficient functional assay system for a specific repertoire of ORs that cannot be characterized in current cell systems.
PDF
