The ARGO-YBJ Experiment Progresses and Future Extension

Gamma ray source detection above 30TeV is an encouraging approach for finding galactic cosmic ray origins. All sky survey for gamma ray sources using wide field of view detector is essential for population accumulation for various types of sources above 100GeV. To target the goals, the ARGO-YBJ experiment has been established. Significant progresses have been made in the experiment. A large air shower detector array in an area of 1km2 is proposed to boost the sensitivity. Hybrid detection with multi-techniques will allow a good discrimination between different types of primary particles, including photons and protons, thus enable an energy spectrum measurement for individual specie. Fluorescence light detector array will extend the spectrum measurement above 100PeV where the second knee is located. An energy scale determined by balloon experiments at 10TeV will be propagated to ultra high energy cosmic ray experiments

High Altitude test of RPCs for the ARGO-YBJ experiment

A 50 m**2 RPC carpet was operated at the YangBaJing Cosmic Ray Laboratory (Tibet) located 4300 m a.s.l. The performance of RPCs in detecting Extensive Air Showers was studied. Efficiency and time resolution measurements at the pressure and temperature conditions typical of high mountain laboratories, are reported.Comment: 16 pages, 10 figures, submitted to Nucl. Instr. Met

ARGO-YBJ constraints on very high energy emission from GRBs

The ARGO-YBJ (Astrophysical Radiation Ground-based Observatory at YangBaJing) experiment is designed for very high energy $\gamma$-astronomy and cosmic ray researches. Due to the full coverage of a large area ($5600 m^2$) with resistive plate chambers at a very high altitude (4300 m a.s.l.), the ARGO-YBJ detector is used to search for transient phenomena, such as Gamma-ray bursts (GRBs). Because the ARGO-YBJ detector has a large field of view ($\sim$2 sr) and is operated with a high duty cycle ($>$90%), it is well suited for GRB surveying and can be operated in searches for high energy GRBs following alarms set by satellite-borne observations at lower energies. In this paper, the sensitivity of the ARGO-YBJ detector for GRB detection is estimated. Upper limits to fluence with 99% confidence level for 26 GRBs inside the field of view from June 2006 to January 2009 are set in the two energy ranges 10$-$100 GeV and 10 GeV$-$1 TeV.Comment: accepted for publication in Astroparticle Physic

First observation of a shape isomer and a low-lying strongly-coupled prolate band in neutron-deficient semi-magic 187Pb

Prompt and delayed γ-ray spectroscopy of the neutron-deficient, semi-magic isotope 187Pb has been performed using the recoil-decay and isomer-decay tagging techniques at the Argonne Gas-Filled Analyzer. A new 5.15(15)-μs isomeric state at only 308 keV above the spherical 3/2− ground state is identified and classified as a shape isomer. A strongly-coupled band is observed on top of the isomer, which is nearly identical to the one built on the prolate 7/2−[514] Nilsson state in the isotone 185Hg. Based on this similarity and on the result of the potential-energy surface calculations, the new isomer in 187Pb is proposed to originate from the same configuration. The retarded character of the 308-keV (7/2−)→3/2gs− transition with a deduced B(E2)=5.6(2)×10−4 W.u. can be well explained by the significant difference between the prolate parent and spherical daughter configurations, leading to the shape isomerism. The excitation energy of the isomer is surprisingly low, being roughly half of the excitation energies of the known 0+ intruder bandheads in the neighboring 186,188Pb isotopes. The combined results of the present work and the previous α-decay and laser spectroscopy studies present evidence for triple shape coexistence at low energy in the negative-parity configurations of 187Pb, which is well reproduced by the potential-energy surface calculations

Preparation of Pb(Mg

Pure phase perovskite relaxor-based (1 – x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN–PT, x = 0.2–0.4) ferroelectric ceramics were prepared by the reaction-sintering method sintered at 1240–1250 °C. The synthesized ceramics exhibit rather homogeneous microstructure morphology and relatively high density. The content of PbTiO3 (PT) exerts successive influences on sintering capability, phase structure and electrical properties of the PMN-PT ceramics. With the increase of the PT content, the crystal structure of the PMN–PT ceramics changes gradually from the rhombohedral phase, across the coexistence of rhombohedral phase and tetragonal phase, and to the tetragonal phase, accompanied by the change of the dielectric response character from typical relaxor ferroelectrics to normal ferroelectrics. The morphotropic phase boundary (MPB) of the PMN–PT system is determined locating at x = 0.3–0.34 based on the structure analysis and the electrical properties measurements, in which the PMN–PT ceramics with the MPB composition exhibit enhanced microstructure and excellent electrical properties, especially superior piezoelectric properties

Responses of intestinal morphology, immunity, antioxidant status and cecal microbiota to the mixture of glycerol monolaurate and cinnamaldehyde in laying hens

ABSTRACT: This study was to determine the effects of the mixture of glycerol monolaurate and cinnamaldehyde (GCM) supplementation on the intestinal morphology, immunity, antioxidant status and cecal microbiota of laying hens. A total of 1,120 healthy laying hens (Jingfen-1 strain) at the age of 14 wk were randomly divided into 4 groups with 10 replicates of 28 layers in each and layers were fed diets containing 0 (control group), or 250, 500, and 1,000 mg/kg GCM for 12 wk. The results showed that dietary supplementation with GCM significantly increased intestinal villus height and villus height/crypt depth, duodenal villus area, total superoxide disumutase activities in the liver and jejunum, jejunal glutathione peroxidase activities while decreased duodenal and jejunal crypt depth, hydrogen peroxide content in the liver and jejunal malondialdehyde content of laying hens aging 28 wk (P < 0.05). Meanwhile, GCM addition significantly increased serum immunoglobulin A and immunoglobulin M concentration of layers at the age of 20, 24, and 28 wk (P < 0.05). Moreover, it was observed in the 16S rRNA sequencing that the addition of GCM elevated the abundance and diversity of gut microbiota in laying hens. The predominant bacteria from each group were Bacteroidota and Firmicutes at the phylum level and Bacteroides and Lactobacillus were the dominant genera. The composition and structure of cecal microflora were changed by the addition of GCM to the diet of laying hens. In conclusion, the addition of GCM (500–1,000 mg/kg diet) can improve intestinal morphology, immune function, intestinal and liver antioxidant status and intestinal flora of laying hens, thereby improving intestinal digestion and absorption capacity. These findings provide a new way to further explore the mechanism of GCM improving intestinal health